Today will be a transitional day with low clouds slowly burning off and few residual showers (see satellite pic at 10:15 AM). Want sunny skies for sure? Head just east of the Cascade crest and down into eastern Washington. The air is still cold aloft so we could get some instability and cumulus development, but that will be increasingly suppressed by high pressure building aloft.
Here is the 2 PM Satellite picture.... you see the mottled effect over land...but not clouds over water? A beautiful exam of surface heating causing lots of cumulus!
Here is the upper level (500 mb for tomorrow)--strong ridging over us and ridges are associated with sinking motion, which works against cloud formation.
With strong sun (the intensity today is like mid-August!) and warming temperatures aloft as the winds in the lower atmosphere turn southerly, temperatures will jump on Sunday into the 60s and even some lower 70s west of the Washington and Oregon Cascades. (see forecast for tomorrow afternoon from probcast). Summer will hit the Willamette Valley!
But another trough and an accompanying Pacific front will arrive on Monday...so this warmth won't last.
It is now certain that we will have the coldest April (maximum temperature) on record for Sea Tac (since 1948). And their are a whole collection of other regional cold records that will be broken as well. This month will be Portland's coldest April in 36 years as well as third wettest in history (1940-2011) at the Portland Airport. Astoria, Oregon has still not reached 60 degrees this calendar year, smashing the old record of April 19th 1945. I could go on and on, but I suspect you don't need much convincing.
Many of you have asked what this all portends for this summer's weather. To be honest, I can't tell you--there is simply no relationship that I know of that can provide a useful answer. One thing for sure...there will be plenty of water supply this summer for irrigation and power generation. And this says NOTHING about global warming.
This blog discusses current weather, weather prediction, climate issues, and current events
April 30, 2011
April 28, 2011
Are the Eastern U.S. tornadoes and our cold weather connected?
We are about to finish the coldest April in at least 60 years. And it appears that April will bring the all-time record number of tornadoes to the U.S., including yesterday's catastrophic event with over 250 deaths.
Are they connected? I think one can make a very plausible case that they are.
But before I discuss this connection, let me note that around 6 PM tonight a funnel cloud was observed near Mt. Vernon. You can tell how unstable the air is around here with all the towering cumulus and cumulonimbus. Here is a video of the Mt. Vernon funnel and a good still picture, courtesy of KOMO TV:
Returning to the April records. It is now clear that we will break the all-time-record for the coldest average maximum April temperature at Sea-Tac airport---and plenty of other local observing locations will report similar records.
There is a particular and highly persistent flow pattern that has been associated with our cold and I have illustrated that below. This figure shows the flow at 500 mb last night--actually it gives the height of the 500 mb pressure surface above sea level. Winds are nearly parallel to those lines. Yellows indicate low heights in troughs. You will notice one trough just east of us that has brought cold, unstable air into the Northwest. The places where the lines are close together are associated with strong winds--which we call the jet stream when it is strong and extensive enough.
Anyway, with a trough over us the jet stream heads farther south than normal--directed towards the southeast U.S. The upper flow is wave-like so that a trough over us generally means a ridge over the Rockies and a trough somewhere over the eastern U.S. This trough...which is clearly evident in this image...is ideally situated to provide all the ingredients for severe convection over the SE--moist air from the south, strong uplift, large wind shear in the vertical. This flow pattern has developed repeatedly this month.
When I saw this configuration setting up, it provoked me to suggest in my previous blog that severe weather was a possibility over the eastern U.S., and I was not the only one to see this. But no one knew it would be this bad .
Thus, I believe that there was a direct and compelling connection between our historic spring cold wave and an historic tornado month over the eastern U.S.
An interesting note is that the largest tornado event in U.S. history, the super tornado outbreak of April 3 - 4, 1974, occurred in a La Nina year, as we are this year.
Finally, let me note that the National Weather Service did a very good job in forecasting and nowcasting (providing constant updates) on these severe storms. The fact that so many people have died shows the unique severity of this outbreak and how much effort is still required in spreading warnings and insuring that people take shelter. Another issue is the vulnerability of mobile homes to strong winds.
Are they connected? I think one can make a very plausible case that they are.
But before I discuss this connection, let me note that around 6 PM tonight a funnel cloud was observed near Mt. Vernon. You can tell how unstable the air is around here with all the towering cumulus and cumulonimbus. Here is a video of the Mt. Vernon funnel and a good still picture, courtesy of KOMO TV:
Returning to the April records. It is now clear that we will break the all-time-record for the coldest average maximum April temperature at Sea-Tac airport---and plenty of other local observing locations will report similar records.
There is a particular and highly persistent flow pattern that has been associated with our cold and I have illustrated that below. This figure shows the flow at 500 mb last night--actually it gives the height of the 500 mb pressure surface above sea level. Winds are nearly parallel to those lines. Yellows indicate low heights in troughs. You will notice one trough just east of us that has brought cold, unstable air into the Northwest. The places where the lines are close together are associated with strong winds--which we call the jet stream when it is strong and extensive enough.
Anyway, with a trough over us the jet stream heads farther south than normal--directed towards the southeast U.S. The upper flow is wave-like so that a trough over us generally means a ridge over the Rockies and a trough somewhere over the eastern U.S. This trough...which is clearly evident in this image...is ideally situated to provide all the ingredients for severe convection over the SE--moist air from the south, strong uplift, large wind shear in the vertical. This flow pattern has developed repeatedly this month.
When I saw this configuration setting up, it provoked me to suggest in my previous blog that severe weather was a possibility over the eastern U.S., and I was not the only one to see this. But no one knew it would be this bad .
Thus, I believe that there was a direct and compelling connection between our historic spring cold wave and an historic tornado month over the eastern U.S.
An interesting note is that the largest tornado event in U.S. history, the super tornado outbreak of April 3 - 4, 1974, occurred in a La Nina year, as we are this year.
Finally, let me note that the National Weather Service did a very good job in forecasting and nowcasting (providing constant updates) on these severe storms. The fact that so many people have died shows the unique severity of this outbreak and how much effort is still required in spreading warnings and insuring that people take shelter. Another issue is the vulnerability of mobile homes to strong winds.
April 26, 2011
Making Fun of Weathermen Reaches New Depths
Weatherfolk are often the butt of jokes and I have experienced that many times myself. How many times have I heard snide remarks about weather forecasters predicting with dice, that "meteorologists can be wrong 50% of the time and still get paid" and similar comments. You get a thick skin eventually or leave the field.
But I have to admit that many of us in the weather community are not a little upset with the latest Subaru ad campaign: "The weather doesn't matter if you have a Subaru" .
The main character of this campaign is "the world's worst weatherman." Want to see him in action? Take a look at one of their clips:
INSULTING! And worst of all, especially for me, he says he is not good with numbers and that is why he became a weatherman. You know how I feel about that! Math is critical to being a good weatherman.
But it gets worse. Here is the Subaru weatherman's take on being a storm chaser (click on image for video)
Did you notice the guy looks quite a bit like the Verizon's "do you hear me?" spokesman? As if all weathermen look like geeks with greased-back hair!
And there are other videos, including one in which the Subaru weatherman locks his keys in a running vehicle.
But there is more, much more.
They have a calculator function on the Subaru website on HOW MUCH TIME YOU HAVE WASTED THINKING ABOUT THE WEATHER. Can you imagine that? Thinking about the weather is NEVER a waste.
Lets say you are 40 years old and spend 3 hours a day thinking about the weather. That is not much. Hell, I spend at least 10 hrs a day thinking about weather, sometimes more. OK, assuming 3 hrs a day and forty years old, their calculator tells you that you have WASTED over three years. Outrageous.
I was so incensed that I called University Subaru to complain. The sales manager listened to me patiently and told me I was completely wrong. " Subaru actually loves weathermen" he said and particularly the ones that exaggerated snowstorms and bad weather. He explained that since most Subarus had all-wheel drive, sales surged as conditions got bad. I asked him who his favorite weather person was and he immediately answered Jim Forman of King TV. I had to stop myself from saying anything more.
I am in the market for a new car, looking to replace my trusty 19 year old Ford Taurus, and I was going to consider Subaru products. No way now. I am going to boycott them until they become more weatherman friendly. And so should you.
April 25, 2011
Thanks, Budget Cuts, and an Inside Look
I would like to begin this blog with a heartfelt thanks to all of you that have contributed to the UW weather prediction research fund noted in the upper right of this blog and here. Over one-hundred of you have contributed both small and larger amounts and these funds (several thousand dollars so far) will help maintain our regional weather research and our real-time local weather prediction models running. Others contributed to the student scholarship fund, which is extraordinarily important as tuition zooms and financial pressure on our students increase.
It is really impressive that there is a community of Northwest residents who are so committed to keeping the collection of regional weather data, state-of-the-art weather models, and local forecasting research going in this period of cutbacks and retrenchment.
And the support is truly needed. This month for example, I learned that the funding I had gotten from the NWS for over a decade is ending due to their cutting of university funding in half. This was the money I was going to use to assimilate the new coastal radar into our local weather prediction efforts! Anyway, with your support I will work to keep our efforts going.
But since you are investors in our regional modeling, let me give you a little glimpse "behind the curtain" to see what you are supporting.
The local weather prediction computing facility is in the atmospheric sciences building on the UW campus. I have about two-hundred processors, most of them on dual quad-core servers (8 processors per board or node) and over 300 terabytes (trillion bytes) of disk storage. And to keep the thing running when lights flicker, there are uninterruptable power supplies (UPSs). Some of these processors can communicate through high-speed (40 gigabit per second) interconnects. All this stuff is packed into several clusters in very special racks (more on this later). Here is an example of one of the clusters:
This computer facility is one of the greenest around! The UW didn't have enough funds to give us a decent air conditioning system, so we came up with our own approach...we blow all the hot air outside and bring in cool air from the outside to make it up! To make this work we got fancy enclosures with BIG fans inside them. It pulls air across the processors and then out big ducts to the exterior of the building. Here are two pictures of our Rube Goldberg set up:
Ok, it is not pretty. And the UW AC guys didn't like the looks of it, but it really works! It is like all the heat from the computers doesn't exist. We have a big intake in one of the computer rooms that brings in the cool outside air. Only when the outside air is hot (a VERY, VERY short period here in Seattle!) do we need AC and the weak units the university gave us, plus an auxiliary unit we bought, does the trick. Why use energy to cool hot air when you can get rid of it! If we were really clever we would redirect the computer air to the heat ducts of the building and no external heat would be needed. Is anyone designing buildings to do this? They should.
You know the WRF model I am always showing on this blog? Generally we run this 0n 64 processors simultaneously, in other words the code is parallelized so that the problem can be split efficiently on many processors. And fast communication between the processors speeds this up immensely.
This computers not only run the forecast models, but they include web servers and other needs. This is not an inexpensive enterprise, and that is why your help is so valuable. Disks continuously fail, UPS batteries die, backup tapes are continuously needed, and we find that we have to replace the processors roughly every five years. Our system programmers, Dave Warren and Harry Edmon, are marvelous in keeping the system going and it rarely fails (at least 99% availability). And the department charges us per processor for support.
The amount of data moving through the system is amazing. Every day we bring in hundreds of gigabytes of weather data (NWS models, satellite and radar data, surface obs) and we acquire the data from over 70 local weather networks...all in real time. The models we run produce hundreds of gigabytes more a day. And the graphics you see on the web....we produce over 50,000 images a day! A tape and removal disk back system allows us to save key observations and data --again more expense.
And then there are the people... right now I have 3 staff members who spend much of their time developing improved weather prediction systems and maintaining this enterprise. And of course the students who are doing their theses on understanding weather systems and developing future technologies--like figuring how to get the maximum benefit from the new coastal radar.
This all started in 1995 with a single processor computer.
Again, thanks for all your help...cliff
April 24, 2011
PDO and Long-Term Trends
After Saturday's spectacular sun and warmth, we have returned to normal again. Saturday was warmest day for the region so far this year, with temperatures climbing into the mid to upper 60s for most western WA locations away from the water. As expected some of the warmest temperatures were east of the Cascade foothills, where compressional heating from descending easterly flow and distance from the cold water allowed a boost into the lower 70s. North Bend, WA got to 71F for example.
Looking at the latest forecast model output, I am afraid that we have showers and cooler weather ahead of us this week.
Through April 20th, April temperatures for many observing sites (e.g., Sea-Tac) have been on the coldest on record--since roughly 1950. This is also true looking at the air temperatures approaching our region aloft in the lower atmosphere (850 mb--roughly 5000 ft--at Forks on the NW WA coast). Thus, by any measure this has been an unusually cold spring.
What does this all mean? What are the trends? Will moss take over our lawns forever? Several of you have complained that springs are getting worse lately--La Nina or not. So in this blog, lets look at some facts.
Here is a two-plot panel showing the trend in April temperatures in the lower atmosphere (mainly Forks, 5000 ft) and at Sea-Tac for the surface since 1948 (click to enlarge). The dots are the annual values and the other lines are curves fit to these variations with various degrees of smoothing. One is struck by the similarity of the long-term temperature changes in these two plots-- temperatures seemed to peak around 1990 and have cooled since. Temperatures were cooler in the early 70s back into the 60s.
Some researchers have suggested there is a multi-decadal variation in the atmospheric circulation over the eastern Pacific (period roughly 30 years) and have termed it the Pacific Decadal Oscillation (PDO for short). This oscillation influences temperature and snowpack over the NW. UW scientists (like Nate Mantua) have led the study of this feature and have even plotted values of a PDO index, shown in the figure below. Blue (negative values) indicate cold PDO (and generally colder and snowier over the NW), and red is warmer. According to this index, the PDO was associated with colder temperatures into the 50s into the mid-70s, and then began a warm-up phase. More recently, it looks like we may have headed back into a cold-phase PDO.
The trouble with this is that data before 1900 is really not good enough to tell whether this oscillation is robust over a long period and we really don't understand why it exists--just that there appears to be a natural mode of variation that predates any possible global warming forcing. As I have noted before, because of our position downstream of the Pacific, global warming will be weaker and start slower around here compared to most of the globe.
So where does this all leave us?
(1) It is clear from the above information and others, that the region has cooled the past few years during the spring. You are not crazy thinking things are getting worse.
(2) Such cooling is consistent with us going into a negative (cool) phase of the PDO.
(3) Natural variability like the PDO is probably dominant around here at this point in time...far more significant than any global warming signal.
(4) Eventually the PDO will switch into the warm phase and the global warming signal here will get stronger....so don't throw out your tee shirts yet. It is going to get warmer.
And one final note...the return to last week's pattern implies not only that we will go back to cool and wet weather, but the eastern part of the U.S. may be on tap to experience more savage storms. In fact, the computer models are predicting this.
April 21, 2011
A Great Historical Dust Storm and FINALLY a Warm Day
Today is the 80th anniversary of the greatest dust storm in the history of our area. On 21 April 1931, very high pressure developed over southwest Canada and eastern Montana, while low pressure deepened over the intermountain west (see figure, with sea level pressures).
Between these two features a HUGE pressure difference developed, which led to very strong winds...we are talking about 50-60 mph on both sides of the Cascades! These strong winds combined with a previous period of warm, dry weather and recently tilled fields to result in an immense dust storm.
Dust over the Columbia Basin turned the sun into a weak, reddish orb, car lights were needed during the daytime, and dust extended to 10,000 ft. Dust pushed westward through Columbia Gorge and lower Cascade passes, extending artificial darkness over the Willamette Valley. Continuing its eastward movement, the dust pushed out into the Pacific, where the freighter Maui ran into the cloud 500 miles off the coast!
The winds during this event were so strong that thousands of trees were uprooted and power failures extended over both sides of the Cascades. Someone should make a movie about that event.
Dust storms still strike our region, particularly eastern Washington during the spring. Such storms often result in multiple car accidents due to the poor visibility and yes, some motorists follow WAY TO CLOSE. Not any of you, of course. Here is some video of such an event:
http://www.youtube.com/watch?v=ca_6cbkSR60
And sometimes tumbleweed come with the dust:
http://www.youtube.com/watch?v=VrXObmAYNcA
And now the good news. The lastest model forecasts suggest that Saturday is going to be extraordinary--sunny and the warmest yet this year. REACHING INTO THE MID-60s over western Washington. Even upper 60s on the eastern side of the Sound due to easterly flow off the Cascades. Here are the forecast temperatures Saturday afternoon from UW PROBCAST:
Unfortunately, the sun won't last...with rain coming in on Sunday. So make your plans for Saturday.
Between these two features a HUGE pressure difference developed, which led to very strong winds...we are talking about 50-60 mph on both sides of the Cascades! These strong winds combined with a previous period of warm, dry weather and recently tilled fields to result in an immense dust storm.
Dust over the Columbia Basin turned the sun into a weak, reddish orb, car lights were needed during the daytime, and dust extended to 10,000 ft. Dust pushed westward through Columbia Gorge and lower Cascade passes, extending artificial darkness over the Willamette Valley. Continuing its eastward movement, the dust pushed out into the Pacific, where the freighter Maui ran into the cloud 500 miles off the coast!
The winds during this event were so strong that thousands of trees were uprooted and power failures extended over both sides of the Cascades. Someone should make a movie about that event.
Dust storms still strike our region, particularly eastern Washington during the spring. Such storms often result in multiple car accidents due to the poor visibility and yes, some motorists follow WAY TO CLOSE. Not any of you, of course. Here is some video of such an event:
http://www.youtube.com/watch?v=ca_6cbkSR60
And sometimes tumbleweed come with the dust:
http://www.youtube.com/watch?v=VrXObmAYNcA
And now the good news. The lastest model forecasts suggest that Saturday is going to be extraordinary--sunny and the warmest yet this year. REACHING INTO THE MID-60s over western Washington. Even upper 60s on the eastern side of the Sound due to easterly flow off the Cascades. Here are the forecast temperatures Saturday afternoon from UW PROBCAST:
Unfortunately, the sun won't last...with rain coming in on Sunday. So make your plans for Saturday.
April 19, 2011
Adult Theme Blog --Mammatus Clouds
This blog contains material that may be inappropriate for preteen audiences, so if you are underage, please click here.
For the rest of you, lets continue. A number of readers of this blog have sent me emails the past few days about some strange looking clouds. Here is an example provided by Pam Keeley of Columbia City:
Scary.
And our favorite high-definition time-lapse video provider, Dale Ireland of Silverdale, sent out this video yesterday showing the rapid formation of a similar phenomenon:
If you go to the second video, you will see another example of mammatus.
Both the still pictures and videos show evidence of sack-like protuberances extending below the cloud base---generally from base of the anvils of cumulonimbus clouds. Since they appear similar to female breasts (or udders if you know your way around cows), they are known as mammatus clouds. (that is about as racy as this blog is going to get).
Mammatus clouds can really look quite extraordinary....he is a particularly dramatic example:
So what is the origin of these other-worldly clouds?
As noted earlier, mammatus clouds tend to form under the anvils of cumulonimbus clouds. Here are some schematics of cumulonimbus clouds (thunderstorms) that show the positions of the mammatus.
There is some debate about the origin of these clouds, but the most frequently quoted explanation starts with the updraft sending lots of liquid water droplets or ice crystals in the anvil. The weight of all these particles results in negatively buoyant air (air denser that air around it) and this forces descent into the drier air below. This is just the opposite of normal convection you are used to, where warmer air rises to produce the turrets of convection. In this case, denser air descends producing downward-directed turrets. There are more details, of course, but you get the idea.
Just an amusing note to end. Some of use an IPHONE App by PointAbout, Inc. to view this blog. These folks produce all kinds of great weather apps (like IRADAR) and they did mine for free. For some reason, Apple gave this blog a rating of 9+ "Infrequent/Mild Mature/Suggestive Themes." I just can't imagine why!
Perhaps my talk about math education.....
For the rest of you, lets continue. A number of readers of this blog have sent me emails the past few days about some strange looking clouds. Here is an example provided by Pam Keeley of Columbia City:
Scary.
And our favorite high-definition time-lapse video provider, Dale Ireland of Silverdale, sent out this video yesterday showing the rapid formation of a similar phenomenon:
If you go to the second video, you will see another example of mammatus.
Both the still pictures and videos show evidence of sack-like protuberances extending below the cloud base---generally from base of the anvils of cumulonimbus clouds. Since they appear similar to female breasts (or udders if you know your way around cows), they are known as mammatus clouds. (that is about as racy as this blog is going to get).
Mammatus clouds can really look quite extraordinary....he is a particularly dramatic example:
So what is the origin of these other-worldly clouds?
As noted earlier, mammatus clouds tend to form under the anvils of cumulonimbus clouds. Here are some schematics of cumulonimbus clouds (thunderstorms) that show the positions of the mammatus.
There is some debate about the origin of these clouds, but the most frequently quoted explanation starts with the updraft sending lots of liquid water droplets or ice crystals in the anvil. The weight of all these particles results in negatively buoyant air (air denser that air around it) and this forces descent into the drier air below. This is just the opposite of normal convection you are used to, where warmer air rises to produce the turrets of convection. In this case, denser air descends producing downward-directed turrets. There are more details, of course, but you get the idea.
Just an amusing note to end. Some of use an IPHONE App by PointAbout, Inc. to view this blog. These folks produce all kinds of great weather apps (like IRADAR) and they did mine for free. For some reason, Apple gave this blog a rating of 9+ "Infrequent/Mild Mature/Suggestive Themes." I just can't imagine why!
Perhaps my talk about math education.....
April 17, 2011
Unstable Air and the Northwest Weather Workshop
Although the cold air that has been moving in aloft these days may have its down sides for gardening and some outdoor activities, there IS a silver lining to the situation....very nice cumulus and cumulonimbus clouds for viewing (an example shown above from the Puget Sound Clean Air Agency "Visibility Cam."
Believe it or not, the sun is actually getting fairly strong (the sun's strength today was the same as late August!!!), so the surface is getting quite a bit of solar radiation when the sky opens up. And the day is quite long now (like late August!).
Now the result of cold air aloft, but warming at the surface is that a large difference in temperature develops with height. In the business, we call that a large temperature lapse rate.
So why do we care about this? Well, when the lapse rate gets large enough the atmosphere can get unstable and it starts to convect. This is exactly what happens when you make hot cereal by the way (and if you don't eat hot cereal, you should, it is good for you). You put the a saucepan on the burner and when the vertical lapse rate because large enough the cereal starts to convect....some moving up and some moving down. Add some brown sugar...
Or you can see convection take place in a Lava Lamp--which those growing up in the 60s and 70s will remember well. Heating the lower portion causes colorful blobs to rise and then fall. Here is a video of one for the younger crowd:
People frequently ingested illicit substances while watching such displays, but meteorologists have no need for such aids--the convection is more than enough.
On these cool spring days you can watch the atmosphere go unstable--either by keeping your eyes on the clouds or by viewing one of the many cam videos--
My department has a good one:
http://www.atmos.washington.edu/~ovens/loops/flash2.cgi?/images/webcam2/movies/20110417.swf
By the way, spring is typically the most unstable time of the year around here. The atmosphere takes time to warm up and spring often brings some of the coldest temperatures aloft, while the strengthening sun causes the surface to warm up more quickly.
So put on a warm sweater and enjoy the convection...it is a great show, with some of the cauliflower-shaped cumulonimbus rising several miles into the sky.
Finally, let me note that the big local meteorological gathering of the year will occur on May 13-14th...the NORTHWEST WEATHER WORKSHOP. Meteorologists from throughout the Northwest gather to talk about the latest in our regional weather and layfolk (like most of you) are very welcome. Topics will include everything from radioactivity from Japan and the latest on the new radar and local modeling, to a panel discussion of the use of social media to communicate weather information.
The web site for the meeting, which included the agenda, is found at
http://www.atmos.washington.edu/pnww/
You can register for the meeting and/or the Friday-night banquet if you are interested.
Believe it or not, the sun is actually getting fairly strong (the sun's strength today was the same as late August!!!), so the surface is getting quite a bit of solar radiation when the sky opens up. And the day is quite long now (like late August!).
Now the result of cold air aloft, but warming at the surface is that a large difference in temperature develops with height. In the business, we call that a large temperature lapse rate.
So why do we care about this? Well, when the lapse rate gets large enough the atmosphere can get unstable and it starts to convect. This is exactly what happens when you make hot cereal by the way (and if you don't eat hot cereal, you should, it is good for you). You put the a saucepan on the burner and when the vertical lapse rate because large enough the cereal starts to convect....some moving up and some moving down. Add some brown sugar...
Or you can see convection take place in a Lava Lamp--which those growing up in the 60s and 70s will remember well. Heating the lower portion causes colorful blobs to rise and then fall. Here is a video of one for the younger crowd:
People frequently ingested illicit substances while watching such displays, but meteorologists have no need for such aids--the convection is more than enough.
On these cool spring days you can watch the atmosphere go unstable--either by keeping your eyes on the clouds or by viewing one of the many cam videos--
My department has a good one:
http://www.atmos.washington.edu/~ovens/loops/flash2.cgi?/images/webcam2/movies/20110417.swf
By the way, spring is typically the most unstable time of the year around here. The atmosphere takes time to warm up and spring often brings some of the coldest temperatures aloft, while the strengthening sun causes the surface to warm up more quickly.
So put on a warm sweater and enjoy the convection...it is a great show, with some of the cauliflower-shaped cumulonimbus rising several miles into the sky.
Finally, let me note that the big local meteorological gathering of the year will occur on May 13-14th...the NORTHWEST WEATHER WORKSHOP. Meteorologists from throughout the Northwest gather to talk about the latest in our regional weather and layfolk (like most of you) are very welcome. Topics will include everything from radioactivity from Japan and the latest on the new radar and local modeling, to a panel discussion of the use of social media to communicate weather information.
The web site for the meeting, which included the agenda, is found at
http://www.atmos.washington.edu/pnww/
You can register for the meeting and/or the Friday-night banquet if you are interested.
April 15, 2011
Are Northwest Springs Getting Worse?
I have heard two questions over and over again this week:
Are springs getting worse?
Is this the worst spring on record?
Looking at the data one might argue that the answer to both of these is yes.
For me, it starts feeling spring-like when temperatures get over 55F. In the forties and lower fifties there is a chill in the air, but above 55F there is a different feel, and one doesn't need a sweater to work outdoors. Above 55F I can comfortably run in a tee shirt and shorts.
So let me propose a Spring-Fever Index that counts the numbers of days the temperature is above 55F from February 1 to April 14th. Why April 14th? Because today is April 15th! And April 15th (except this strange year) is tax day.
I think you are learning how science is done!
Now here is a plot of my spring-fever index for Seattle-Tacoma Airport from 1948 though 2011....the entire record at this site (thanks go to Neal Johnson of my department for gathering this data):
2011 is clearly the worst year on record with the fewest number of days above 55F!!!
Only two.
You would have to go back to the 1950s to find the runner up.
But it is worse than that.
The biggest decline in the number spring days between two years is between 2010 and 2011! Just like big changes in temperature can crack concrete, a big decline in spring temperatures in consecutive years can crack our spirits! And it has.
Just think of it, last year there were 26 days of over 55F during the period, this year only 2.
A casual glance at this chart suggests the 1950s were somewhat chilly (there was a cold war then of course!) and temperatures warmed up into the early to mid-90s.
In 1992 there were 43 days above 55F! Forget Hawaii that year (1992 had a very strong El Nino)
The last decade has been generally cool except for a few isolated years, like 2010. And these cool years have been reflected in the Cascade snowpack, which has actually been increasing recently.
So it is not your imagination that this was an absolutely abysmal spring...one of the worst ever. Now part of the blame can probably be pinned on the strong La Nina of this winter, but not all, since this year is so extreme.
So the answer to our questions? Yes on both looks pretty good to me.
Eventually, global warming will change the trends upwards, but the coastal Northwest is one of last places on the planet that will experience warming because of our proximity to the slow-to-warm eastern Pacific.
The forecast for this weekend? Just showers, but considerably cooler than normal with temperatures dropping into the 30s on Sunday morning. Don't even think about putting any tomato plants out until June.
Are springs getting worse?
Is this the worst spring on record?
Looking at the data one might argue that the answer to both of these is yes.
For me, it starts feeling spring-like when temperatures get over 55F. In the forties and lower fifties there is a chill in the air, but above 55F there is a different feel, and one doesn't need a sweater to work outdoors. Above 55F I can comfortably run in a tee shirt and shorts.
So let me propose a Spring-Fever Index that counts the numbers of days the temperature is above 55F from February 1 to April 14th. Why April 14th? Because today is April 15th! And April 15th (except this strange year) is tax day.
I think you are learning how science is done!
Now here is a plot of my spring-fever index for Seattle-Tacoma Airport from 1948 though 2011....the entire record at this site (thanks go to Neal Johnson of my department for gathering this data):
SPRING FEVER INDEX at Sea-Tac (click to expand)
The results are shocking, but no surprise to the wet, chilled residents of western Washington.2011 is clearly the worst year on record with the fewest number of days above 55F!!!
Only two.
You would have to go back to the 1950s to find the runner up.
But it is worse than that.
The biggest decline in the number spring days between two years is between 2010 and 2011! Just like big changes in temperature can crack concrete, a big decline in spring temperatures in consecutive years can crack our spirits! And it has.
Just think of it, last year there were 26 days of over 55F during the period, this year only 2.
A casual glance at this chart suggests the 1950s were somewhat chilly (there was a cold war then of course!) and temperatures warmed up into the early to mid-90s.
In 1992 there were 43 days above 55F! Forget Hawaii that year (1992 had a very strong El Nino)
The last decade has been generally cool except for a few isolated years, like 2010. And these cool years have been reflected in the Cascade snowpack, which has actually been increasing recently.
So it is not your imagination that this was an absolutely abysmal spring...one of the worst ever. Now part of the blame can probably be pinned on the strong La Nina of this winter, but not all, since this year is so extreme.
So the answer to our questions? Yes on both looks pretty good to me.
Eventually, global warming will change the trends upwards, but the coastal Northwest is one of last places on the planet that will experience warming because of our proximity to the slow-to-warm eastern Pacific.
The forecast for this weekend? Just showers, but considerably cooler than normal with temperatures dropping into the 30s on Sunday morning. Don't even think about putting any tomato plants out until June.
April 12, 2011
Revenge of a Dying La Nina
Its days are numbered. There is no doubt about it anymore. The handwriting is on the wall. All the expert pundits are in agreement. But it won't easily release its grip for another month or so.
The regime in Libya?
No, we are talking about this year's La Nina and the cool, wet weather it has brought.
Astronomical spring might have arrived on March 21, but the past few weeks have been cool and wet, and nearly every day has been below normal. Here is the temperature difference from climatology (average conditions) for the past month: lots of below normal conditions (blue) in our part of the woods. In fact, this has been one of the worst early springs on record.
A month and a half ago the snowpack was well below normal. Now the tide has reversed with above-normal snowpack over virtually the entire region (see graphic).
Here is an amazing plot from the Seattle Public Utilities web site showing the extraordinary jump in snow pack over the past month. You will be able to water your lawn this summer!
Over Texas and the southeast, La Nina has brought warm and dry condition--the result has been a series of destructive wildfires over Texas: here is some dramatic video footage:
But La Nina is dying. Look at the temperatures in the tropical Pacific:
The colder than normal anomaly is weakening. And if you look below the surface, colder than normal water has been replace by warmer water...ready to push the surface! (see graphic)
And the latest computer simulations indicate a transition to a neutral state (neither la nina nor el nino)....but keep in mind there is plenty of uncertainty (see graph)
But none of this will do us any good this spring and the National Weather Service is forecasting colder than normal temperatures over the next month:
Don't blame me....
The regime in Libya?
No, we are talking about this year's La Nina and the cool, wet weather it has brought.
Astronomical spring might have arrived on March 21, but the past few weeks have been cool and wet, and nearly every day has been below normal. Here is the temperature difference from climatology (average conditions) for the past month: lots of below normal conditions (blue) in our part of the woods. In fact, this has been one of the worst early springs on record.
A month and a half ago the snowpack was well below normal. Now the tide has reversed with above-normal snowpack over virtually the entire region (see graphic).
Here is an amazing plot from the Seattle Public Utilities web site showing the extraordinary jump in snow pack over the past month. You will be able to water your lawn this summer!
Over Texas and the southeast, La Nina has brought warm and dry condition--the result has been a series of destructive wildfires over Texas: here is some dramatic video footage:
But La Nina is dying. Look at the temperatures in the tropical Pacific:
The colder than normal anomaly is weakening. And if you look below the surface, colder than normal water has been replace by warmer water...ready to push the surface! (see graphic)
And the latest computer simulations indicate a transition to a neutral state (neither la nina nor el nino)....but keep in mind there is plenty of uncertainty (see graph)
But none of this will do us any good this spring and the National Weather Service is forecasting colder than normal temperatures over the next month:
Don't blame me....
April 10, 2011
UW Admissions and the Budget Cuts
After the Seattle Times published a front page article: Why Straight-A Students Won't Get into the UW this Year there has been a firestorm of comments in the media and blogosphere--and I have gotten quite a few emails about it.
Let me give you my take on this article and on a variety of related topics ( budget cuts, the quality of the UW student body, and the quality of out-of-state students) from the viewpoint of someone in the system and the undergraduate adviser for my department.
First, it is a fact that the UW has been hit by large budget cuts over the past few years and that the impacts have been profound. On top of the loss of hundreds of millions of dollars of State support over the past two years, the proposed state budget cuts UW funding by roughly a third--190 million. Tuition increases (13% authorized) only make up a small proportion of this. A few more years of such State cut-backs and tuition increases and the UW will be essentially be a private school.
The impact of past cuts have been substantial and to give you a feeling for this let me tell you what has happened in my department. First, we have lost teaching assistants (TAs). I teach 101 and we used to have 3 for 240 students. Now I have only two (and there is a possibility it might be one next fall). Let me assure you that this TA reduction has a significant impact for students--less help, less interactions from the TAs. In addition,we have lost roughly half of our state-supported staff. In the "old" days there were funds for curriculum improvements and equipment for undergrad labs. No more.
To keep the doors open, we have increasingly used research funds to fill gaps when appropriate (and sometimes when it is not), but this action has taken away funds that should have been applied for long-term improvement of our research efforts. And while our competitors in other states have gotten new buildings, ours has major problems, from inferior labs to lack of power/cooling for our computers. And deductions for medical insurance, parking, and other fees are going up rapidly for all staff and faculty. Most departments are not replacing faculty that retire or are hired away by other schools--the UW teaching staff is shrinking.
The state budget cuts are so large that the UW administration has turned to a desperation measure: increasing the number of out-of-state students. This is clearly a hot-button topic--one inflamed by the irresponsible article in the Seattle TImes headlining the rejection of "straight-A" students...more on this later. Out-of-state students pay three-times more tuition than in-state undergrads--and supply net financial surpluses. Importantly, by accepting more out-of-staters the UW can secure enough funds to SUSTAIN THE NUMBER OF IN-STATE STUDENTS. This is such an important point that it bears repeating. The State is cutting funding so substantially that economizing (getting rid of TA, bigger classes, less profs) is not enough to maintain the current in-state student body. So by increasing the number of out-of-state students in-state student support can be partially stabilized.
At first, the UW was simply going to increase the number of out-of-state students, with the same number of in-staters, but things got so bad they were forced to a small (150 slots) drop of in-state students (replaced by out of state) to make things balance. Now lets us take up some major myths.
Myth 1: Out-of-state-students generally have inferior grades/SATs than in-state students.
Not true. In general out-of-staters have superior records--this is based on my direct experience and from UW statistics. Consider the students accepted this fall that indicated an interested in atmospheric sciences. The GPAs for in and out of staters were essentially identical (3.80), but the out-of-state students had math SAT scores that were 76 points higher. This is a huge increment.
Myth 2: The UW is rejecting straight-A students with excellent qualifications in lieu of weaker out-of-state students.
The Seattle Times made a big deal about this. The truth is that UW admission is based on more than just grades...and it has to be so. There has been huge grade inflation, particularly in our state. An "A" grade does not mean what an "A" signified 20-30 years ago. Many students have 3.8 GPAs and beyond. That is why the UW has wisely turned to a more holistic evaluation. Are the courses taken challenging? ("A"s in less challenging courses don't mean so much). Does the student has strong SATs? What about extracurricular activities than demonstration interest and motivation? So it is theoretically quite possible for an A student not to get in if other factors are not strong. And top schools like Stanford follow the same approach. Even with all that said I suspect the very few 4.0 GPA students with reasonable course loads and board scores are rejected by the UW.
My next point will probably get me into huge trouble. So be it--it needs to be said.
Not all UW students belong in the UW.
Ok, I got it out. My feeling (one shared by many UW faculty that I have talked to) is that the UW student body can be divided into roughly three parts:
The Golden Quarter: About 1/4 of our students are simply stellar--bright, motivated, prepared...as good as you get in ANY school. They do well in college and generally go on to highly successful careers. They take advantage of the huge opportunities of the UW (e.g,. participation in research). Just a pleasure to teach and interact with.
The Middle 50%: These are students with the ability to do well, but their motivation and interest varies. They are happy with B grades and even the occasional C. Some of these students can really be turned around, while others are happy to float through.
The Bottom 25%: These students basically aren't interested in learning. For them, the idea is simply to pass with minimal grades. The UW is high-school continued and they are here because they didn't know what else to do or were pressured by family and friends. Most of the them came to the UW with very weak backgrounds (far weaker than any serious freshman should have). For example, many of these folks are not comfortable with basic high school math--like fractions and solving simple algebraic equations. They shouldn't be wasting the classroom space.
Now some of the problems above are due to our state's poor K-12 educational system and you know I have discussed the math part many times. A large percentage of our high school students are coming to college unprepared: they can't do basic math, they can't write well (or spell well), or work creatively. And the problem is just not their skills but their attitudes towards learning.
When I teach 101 I am really shocked by these attitudes--many expect that the exams will just be the homework with different numbers and that they can do a make-up if their grade is poor (you should see the look when I disabuse them of this notion!) Many have the attitude that their poor grades are the INSTRUCTOR's problem. Each class I am stunned by how many students are playing with their cell phones and smartphones during class--or spending most of the class on their laptops. And I don't think this is an issue of class quality...my ratings are uniformly high.
So lets get back to the UW admitting more out-of-state students. From my perspective, this is a good thing. Yes, it helps partially make up for the legislature's draconian cuts. But more importantly, the UW is a nationally, if not internationally, leading university and we SHOULD be drawing students from far afield, with the assurance that a large proportion of the students (say at least 50%) come from our state. The UW is more than just about educating students...it is a vital research enterprise that provides intellectual vitality to the state. We supply individuals that will help ensure the economic future of Washington..and quite frankly the origin of the the students doesn't matter as much as where they end up (here). To put it another way, the UW is an effective tool to effect a brain drain of the nation's best into Washington State--something necessary by our poor attempts to educate our own students.
By drawing more nationally, the UW student body will progressively get stronger and as these students graduate the reputation of the University will strengthen (as has happened for Michigan). And replacing the bottom 25% with highly motivated, successful students is really a good thing for everyone...including the students that don't really belong here. Many of them never graduate anyway.
Let me give you my take on this article and on a variety of related topics ( budget cuts, the quality of the UW student body, and the quality of out-of-state students) from the viewpoint of someone in the system and the undergraduate adviser for my department.
First, it is a fact that the UW has been hit by large budget cuts over the past few years and that the impacts have been profound. On top of the loss of hundreds of millions of dollars of State support over the past two years, the proposed state budget cuts UW funding by roughly a third--190 million. Tuition increases (13% authorized) only make up a small proportion of this. A few more years of such State cut-backs and tuition increases and the UW will be essentially be a private school.
The impact of past cuts have been substantial and to give you a feeling for this let me tell you what has happened in my department. First, we have lost teaching assistants (TAs). I teach 101 and we used to have 3 for 240 students. Now I have only two (and there is a possibility it might be one next fall). Let me assure you that this TA reduction has a significant impact for students--less help, less interactions from the TAs. In addition,we have lost roughly half of our state-supported staff. In the "old" days there were funds for curriculum improvements and equipment for undergrad labs. No more.
To keep the doors open, we have increasingly used research funds to fill gaps when appropriate (and sometimes when it is not), but this action has taken away funds that should have been applied for long-term improvement of our research efforts. And while our competitors in other states have gotten new buildings, ours has major problems, from inferior labs to lack of power/cooling for our computers. And deductions for medical insurance, parking, and other fees are going up rapidly for all staff and faculty. Most departments are not replacing faculty that retire or are hired away by other schools--the UW teaching staff is shrinking.
The state budget cuts are so large that the UW administration has turned to a desperation measure: increasing the number of out-of-state students. This is clearly a hot-button topic--one inflamed by the irresponsible article in the Seattle TImes headlining the rejection of "straight-A" students...more on this later. Out-of-state students pay three-times more tuition than in-state undergrads--and supply net financial surpluses. Importantly, by accepting more out-of-staters the UW can secure enough funds to SUSTAIN THE NUMBER OF IN-STATE STUDENTS. This is such an important point that it bears repeating. The State is cutting funding so substantially that economizing (getting rid of TA, bigger classes, less profs) is not enough to maintain the current in-state student body. So by increasing the number of out-of-state students in-state student support can be partially stabilized.
At first, the UW was simply going to increase the number of out-of-state students, with the same number of in-staters, but things got so bad they were forced to a small (150 slots) drop of in-state students (replaced by out of state) to make things balance. Now lets us take up some major myths.
Myth 1: Out-of-state-students generally have inferior grades/SATs than in-state students.
Not true. In general out-of-staters have superior records--this is based on my direct experience and from UW statistics. Consider the students accepted this fall that indicated an interested in atmospheric sciences. The GPAs for in and out of staters were essentially identical (3.80), but the out-of-state students had math SAT scores that were 76 points higher. This is a huge increment.
Myth 2: The UW is rejecting straight-A students with excellent qualifications in lieu of weaker out-of-state students.
The Seattle Times made a big deal about this. The truth is that UW admission is based on more than just grades...and it has to be so. There has been huge grade inflation, particularly in our state. An "A" grade does not mean what an "A" signified 20-30 years ago. Many students have 3.8 GPAs and beyond. That is why the UW has wisely turned to a more holistic evaluation. Are the courses taken challenging? ("A"s in less challenging courses don't mean so much). Does the student has strong SATs? What about extracurricular activities than demonstration interest and motivation? So it is theoretically quite possible for an A student not to get in if other factors are not strong. And top schools like Stanford follow the same approach. Even with all that said I suspect the very few 4.0 GPA students with reasonable course loads and board scores are rejected by the UW.
My next point will probably get me into huge trouble. So be it--it needs to be said.
Not all UW students belong in the UW.
Ok, I got it out. My feeling (one shared by many UW faculty that I have talked to) is that the UW student body can be divided into roughly three parts:
The Golden Quarter: About 1/4 of our students are simply stellar--bright, motivated, prepared...as good as you get in ANY school. They do well in college and generally go on to highly successful careers. They take advantage of the huge opportunities of the UW (e.g,. participation in research). Just a pleasure to teach and interact with.
The Middle 50%: These are students with the ability to do well, but their motivation and interest varies. They are happy with B grades and even the occasional C. Some of these students can really be turned around, while others are happy to float through.
The Bottom 25%: These students basically aren't interested in learning. For them, the idea is simply to pass with minimal grades. The UW is high-school continued and they are here because they didn't know what else to do or were pressured by family and friends. Most of the them came to the UW with very weak backgrounds (far weaker than any serious freshman should have). For example, many of these folks are not comfortable with basic high school math--like fractions and solving simple algebraic equations. They shouldn't be wasting the classroom space.
Now some of the problems above are due to our state's poor K-12 educational system and you know I have discussed the math part many times. A large percentage of our high school students are coming to college unprepared: they can't do basic math, they can't write well (or spell well), or work creatively. And the problem is just not their skills but their attitudes towards learning.
When I teach 101 I am really shocked by these attitudes--many expect that the exams will just be the homework with different numbers and that they can do a make-up if their grade is poor (you should see the look when I disabuse them of this notion!) Many have the attitude that their poor grades are the INSTRUCTOR's problem. Each class I am stunned by how many students are playing with their cell phones and smartphones during class--or spending most of the class on their laptops. And I don't think this is an issue of class quality...my ratings are uniformly high.
So lets get back to the UW admitting more out-of-state students. From my perspective, this is a good thing. Yes, it helps partially make up for the legislature's draconian cuts. But more importantly, the UW is a nationally, if not internationally, leading university and we SHOULD be drawing students from far afield, with the assurance that a large proportion of the students (say at least 50%) come from our state. The UW is more than just about educating students...it is a vital research enterprise that provides intellectual vitality to the state. We supply individuals that will help ensure the economic future of Washington..and quite frankly the origin of the the students doesn't matter as much as where they end up (here). To put it another way, the UW is an effective tool to effect a brain drain of the nation's best into Washington State--something necessary by our poor attempts to educate our own students.
By drawing more nationally, the UW student body will progressively get stronger and as these students graduate the reputation of the University will strengthen (as has happened for Michigan). And replacing the bottom 25% with highly motivated, successful students is really a good thing for everyone...including the students that don't really belong here. Many of them never graduate anyway.
I think the above direction is inevitable, since the State Legislature looks at the colleges and universities as a big piggy bank to be raided....and we are all to blame for this situation...at least everyone who has voted for the Eyman initiatives or supported candidates who don't understand the importance of investing in our schools and our future. And for those--including many in our education schools---who have allowed the quality of state instruction to decline to such a low level.
Perhaps strangely, I am very optimistic about UW's future. We will go through some wrenching years as we transition to being essentially an essentially private school--and the UW administration will have to be careful to maintain the core strengths of the institution as we adapt (they are doing a good job at this so far). But after roughly five years we will be on our own...no longer dependent on the vagaries of the State legislature and state coffers..and no longer worried about the next ill-advised initiative. Tuition will rise to perhaps 12,000-15,000 a year...a bargain for such a excellent education (thankfully we starting with very low tuition compared to comparable schools). And some of the tuition increase will go into scholarship aid, insuring that those of lesser means are not prevented from getting a UW education. The UW funding will be stable again and the student body will be stronger. A better time.
Perhaps strangely, I am very optimistic about UW's future. We will go through some wrenching years as we transition to being essentially an essentially private school--and the UW administration will have to be careful to maintain the core strengths of the institution as we adapt (they are doing a good job at this so far). But after roughly five years we will be on our own...no longer dependent on the vagaries of the State legislature and state coffers..and no longer worried about the next ill-advised initiative. Tuition will rise to perhaps 12,000-15,000 a year...a bargain for such a excellent education (thankfully we starting with very low tuition compared to comparable schools). And some of the tuition increase will go into scholarship aid, insuring that those of lesser means are not prevented from getting a UW education. The UW funding will be stable again and the student body will be stronger. A better time.
April 08, 2011
Upside Down Rainbow
Several people sent me pictures of what they described as an upside down rainbow high in the sky around 5 PM today. Here are some examples:
The colors in these "smiley faced" rainbows were very vivid.
What was causing this unusual occurrence? It is what is called a circumzenithal arc.
This arc are caused by the same general phenomenon that creates halos: the refraction of light in ice crystals. Circumzenithal arcs occur when the sun is relatively low in the sky (below 32 degrees above the horizon) in the presence of ice crystals with generally horizontal orientation.
Ice crystal have a hexagonal (six sided) structure and often are in the form of hexagonal plates (see figure). As they fall, they tend to have relatively horizontal orientation (not unlike leaves falling out of trees). Light passing through the top plate and then out the sides is bent (refracted) by roughly 46 degrees. The light (which initially has all colors is divided into the whole visible spectrum by this refraction--just like a prism--in a process known as dispersion)
The light of the C- arc is found about 46 degrees ABOVE the sun--with the arc (generally no more than 1/4 of circle) appearing to circle around the zenith of the sky.
Current research has not found any evidence for a pot of gold at the end of this rainbow. Apparently, it is too high for leprechauns to deal with.
The colors in these "smiley faced" rainbows were very vivid.
What was causing this unusual occurrence? It is what is called a circumzenithal arc.
This arc are caused by the same general phenomenon that creates halos: the refraction of light in ice crystals. Circumzenithal arcs occur when the sun is relatively low in the sky (below 32 degrees above the horizon) in the presence of ice crystals with generally horizontal orientation.
Ice crystal have a hexagonal (six sided) structure and often are in the form of hexagonal plates (see figure). As they fall, they tend to have relatively horizontal orientation (not unlike leaves falling out of trees). Light passing through the top plate and then out the sides is bent (refracted) by roughly 46 degrees. The light (which initially has all colors is divided into the whole visible spectrum by this refraction--just like a prism--in a process known as dispersion)
The light of the C- arc is found about 46 degrees ABOVE the sun--with the arc (generally no more than 1/4 of circle) appearing to circle around the zenith of the sky.
Current research has not found any evidence for a pot of gold at the end of this rainbow. Apparently, it is too high for leprechauns to deal with.
April 06, 2011
Convergence Zone Snow in April!
Today we had a strong convergence zone and with cool air aloft the result was that in the heavier convergence showers the snow level was driven to the surface over some of the lowlands.
This morning dawned with a spectacular convergence zone over the north Sound.
Just beautiful. And there was also snow showers in the mountains, some quite heavy at the same time (over a foot today in the passes!)
The convergence zone moved south during the day, producing snow showers during the last afternoon in Brier and Lynnwood, and subsequently farther south on the eastside.
Here is a nice video of the snow action in Bellevue:
And with the convergence zone there was an extra bonus of lightning and thunder. My bike ride home tonight around 7 PM was enhanced by such atmospheric pyrotechnics in the vicinity.
Why does a convergence zone help produce snow?
When temperatures are close to being cold enough for snow, but not quite there, the precipitation from the convergence zone can start as rain and then turn to snow or mixed snow/rain. When precipitation starts there is first strong evaporation, that rapidly cools the air to the wet bulb temperatures. The air rapidly humidifies and after 15 minutes to a half hour the air is saturated and evaporation doesn't do much anymore. But the atmosphere has another cooling trick!---melting. The snow aloft melts as it falls into above-freezing air and it takes energy to do that...so that air cools further...sometimes enough to bring the snow level down to the surface. This happened today.
Want to see this in action? Here are the weather observations on top of the roof of my building. At roughly 5 PM (00z, time in red), you will see the precipitation started, the temperature fell, and the relative humidity rose (click to expand!). The initial evaporative cooling was very intense and short-lived. Then as the precipitation continued melting continued the cooling. Classic traces.
April 05, 2011
California Versus the Northwest
It is often true that California and the Northwest are often in contention for the wet stuff (and we usually win!). We have seen a number of periods this winter when a trough developing over the West Coast has sent the jet stream and all the moisture down into California. And it is going to happen again.
Last week I was staying in Monterey, California attending the Cyclone Workshop, a regular gathering of meteorologists interested in midlatitude and tropical cyclones. The locals were all talking about the heavy rain that had struck central California for over two weeks in March when the jet had moved south over them (see upper level map below for a sample).Monterey, CA, for example, had 4.95 inches in March, 3.29 inches above normal, and the mountains of coastal CA had much larger amounts. A major impact was a major slope failure along Route 1 between Monterey and Big Sur, closing the road. Broccoli and Cauliflower crops were damaged. And California became amazingly green.
Here is a video showing the failure.
The jet moved back up here during late March and they got warm and dry...and you know what happened here.
But those smug Californians are going to exchange places with us again in a few days! Take a look at the upper level chart for Thursday at 4 AM---a trough will drive the flow and rain into the palm-infested California climes.
Here is the 24h rain ending 4 AM on Friday. We dry out and coastal CA gets soaked. But they will probably take refuge in their hot tubs.
So enjoy our break on Friday....it won't last long. A weak system will hit Saturday and heavier rain on Sunday.
Last week I was staying in Monterey, California attending the Cyclone Workshop, a regular gathering of meteorologists interested in midlatitude and tropical cyclones. The locals were all talking about the heavy rain that had struck central California for over two weeks in March when the jet had moved south over them (see upper level map below for a sample).Monterey, CA, for example, had 4.95 inches in March, 3.29 inches above normal, and the mountains of coastal CA had much larger amounts. A major impact was a major slope failure along Route 1 between Monterey and Big Sur, closing the road. Broccoli and Cauliflower crops were damaged. And California became amazingly green.
Here is a video showing the failure.
The jet moved back up here during late March and they got warm and dry...and you know what happened here.
But those smug Californians are going to exchange places with us again in a few days! Take a look at the upper level chart for Thursday at 4 AM---a trough will drive the flow and rain into the palm-infested California climes.
Here is the 24h rain ending 4 AM on Friday. We dry out and coastal CA gets soaked. But they will probably take refuge in their hot tubs.
So enjoy our break on Friday....it won't last long. A weak system will hit Saturday and heavier rain on Sunday.
April 03, 2011
Radioactivity Measurements
During the past few days a great deal of information has come in about the amount of radiation reaching the U.S. from the Fukushima reactors in Japan. Measurable radiation has reached our shores, but thousands of times below intervention standards.
Recently, a University of Washington team presented highly sensitive results based on measuring the radioactive particles trapped by the filters for the UW Physics and Astronomy Building (their web site is http://www.npl.washington.edu/monitoring/).
Let me show you some examples of their findings and remember the tsunami occurred on March 11. Here is a plot of the amount of radiation measured on 16 March and 17 March, based on the energy levels associated with Iodine-131. The signal is very clear on 17 March.
Here is an alternative presentation for more radioactive species. A clear signal was evident around 7 days after the tsunami, peaking a few days later, and then declining.Again, these levels, although measurable are very low and not a threat.
EPA has been actively taking samples of rainwater and milk around the country. The rainwater results, released yesterday, revealed that for most of the country the radioactivity increase was unmeasurable except for Richmond, CA, Boise, Id. and St. Paul, Mn. Boise was particularly high. WHY?
But keep in mind that we generally don't drink rainwater and I131 has a half life of eight days. By the time water is used (either percolating to the water table and entering a well or reaching the intake of a reservoir--where it has hugely been diluted--little I 131 radioactivity will be left.
A number of the media is hyping the radioactivity levels by making the implicit assumption that the relatively high values will continue for an entire year...which of course is ridiculous. A few locations in the U.S. have had some one-day spikes, but the dosage would be very low...even if you drank rainwater...because radioactivity levels rapidly drop down into the noise level.
Regarding milk, screening samples taken March 25 at Spokane, WA detected 0.8 pCi/L of iodine-131, which is more than 5,000 times lower than the Intervention level set by the U.S. Food and Drug Administration.
The fact that some of the radiation has reached the NW in minute quantities should not surprise us. Several scientists (such as Dr. Dan Jaffe of the UW) regularly measure small amounts of Asian pollution over the Northwest, particularly as specially equipped labs at Cheeka Peek (NW Washington) and Oregon's Mt. Bachelor.
Subscribe to:
Posts (Atom)
Comet Viewing Tonight
Tonight may be the best night this week to view Comet Comet Tsuchinshan-ATLAS in the western sky just after sunset. The biggest issue will ...
-
Mother Nature seems to have forgotten about the current strong El Nino and the record warmth of the past month. Massive snow will fall over ...
-
Update Tonight On the Arctic Air Entering Our Region and Localized Areas of Snow __________________________ The buzz is up regarding the pot...