Tuesday, March 31, 2009

Endless cold and strong winds at Camp Muir

The extraordinary cool March continues.... the climatology (red-average max, blue-average min) at Seattle versus observed temperatures shows the sad situation (image). During the last month only 3 days have reached or exceeded the normal maximum temperature, while over half the days have had minima below the normal lows. We should have highs in the mid-50s now.An underlying cause of the cold air has been the persistence of a certain atmospheric configuration, with a ridge over the eastern Pacific and a trough somewhere over our region--and this pattern is not going away soon (see example for later this week). This very persistent pattern results in a cold northerly flow and embedded troughs aloft (weather disturbances) that move in this northerly flow giving us intermittent cold precipitation. Last spring was also very cool...and I had some fun with the "barbeque index" last year to quantify the cold (the barbeque index is the number of days in spring reaching at least 60F, last year had the least number of such days from mid-March to mid-June since 1918!). Another major anomaly this year is Spokane's snow...with added snow this week, this is that city's snowiest winter on record. There was a strong pressure gradient at the surface at this time.

The next question you have is why is this happening? La Nina years have a higher frequency of such configurations...and this has been a La Nina year...so perhaps some of the blame can rest with the colder than normal sea surface temps over the tropical Pacific that are associated with La Nina. But even with that said, the cold pattern this year has been unusually persistent.

One of you (Mbeebe) noted the strong winds at Camp Muir...at 10,000 ft on Mt. Rainier.. this morning with winds gusting to 140 mph. Check the following link to see the winds at this site (
http://www.nwac.us/products/OSOMUR). Now it was windy in the lower mountain stations....but nothing like this. The strong winds accompanied a strong frontal passage this morning (see surface pressure, wind and near surface temp plot attached for 10 AM), in which the winds switched to northwesterly as a trough pushed through (image). The computer wind prediction (sustained not gusts) for 10 AM shows strong NW winds..but far less than occurred. Clearly, the observed trough aloft was strong than predicted---assuming the Camp Muir obsevations are reliable.

Saturday, March 28, 2009

Storms of the Pacific Museum

What does the Washington coast have in spades? ... great storms. And people are very interested in severe weather. How can we provide a wonderful education resource on this topic, give a major boost to the economy of the Washington coast, and offer a wonderful recreational experience?

Imagine a "Pacific Storms Museum" in Westport (or some other coastal town). A facility with exhibits on past great storms (like the Columbus Day Storm), explanations of the structure and nature of major Pacific storms, pictures and videos of strong events--perhaps even a surround-type experience for a strong event. An exhibit describing the effects of strong storms on the forests. A weather station with the latest readings. A room describing local shipwrecks. And, of course, a gift shop. This facility could also include an exhibit on tsunamis.

This museum could be a major educational and tourist attraction that would bring
tens of thousands --even hundreds of thousands--of visitors a year to Westport or some other lucky town...and could have a nationwide draw. And it could be an economic boom for the region.

But the fun doesn't stop there. People spend thousands of dollars to
go storm chasing in the midwest (I have a friend who is in the business...and it is booming even in bad times). Imagine storm weekends or longer in Westport. They could experience the weather themselves during the November-February season, enjoy lectures from weather experts and locals, enjoy special "storm meals" at local restaurants (perhaps even illuminated by storm lanterns), and stay in local B&Bs and hotels. Perhaps even field trips to see blowdowns or shipwrecks. I tell you..this could be a very large attraction, at least as big as Lewis and Clarke museum near North Head and the marine museum in Astoria....and probably much bigger. What do you think? How could this idea be improved? How could we get started on this?

The Washington coast have a tremendous resource--the storms--and my
intuition is that there is a very viable business model for a "storm industry" . Then as long as you have this free-spending crowd, there are lots of other things local shops can sell them..like coastal art, watercolor paintings, and yes...teeshirts. It has always bothered me that people drive all the way to Cannon Beach for a quality beach experience. Why not much closer and something much more authentic?

PS: Arthur Grunbaum, who leaves on Gray's Harbor, suggested a version of this to me a few years ago...so he deserves the credit (or the blame).

Friday, March 27, 2009

Snow Returns

The mountains will be getting plenty of snow..but there is a chance the lowlands--particularly above 500 ft--could see some snow mixing in tomorrow AM. The latest WRF-GFS run in fact has light amounts over portions of the lowlands (see graphic for 3-h snow ending 11 AM), while the MM5-NAM keeps the lowlands snowfree. The biggest threat should be over the Kitsap and lower hood canal areas as a developing low center moves towards us from the south (see graphic). Temperature will warm during the day...so rain will dominate in any case. And it should be quie a wet day over the western portion of Washington. The below normal temps continue.

Wednesday, March 25, 2009

Snow! (In the Mountains)

One of you asked about the snow in the mountains...well, the snowpack has recovered quite nicely the last week or so...take a look at the map. Southern and central Cascades..western slopes and crest..are now above normal. The northern Cascades and Okanogan have gotten some...but still are about 25-35% below normal.
We had a cold winter and the spring is no better. Look at the temps at Sea Tac versus climo...generally below normal temps. In fact, of the last 100 days, approximately 75 have been below normal. So the complaints I have heard are well founded. I really hope we don't repeat last spring, which according to my Barbeque index, was the coldest since 1918! Two cold springs in a row will not only be bad for my vegetable garden, but would really be a downer. Good for water supply and late season skiing though.

The Storms of the Pacific Museum!

What does the Washington coast have in spades? ... great storms. And
people are very interested in severe weather. How can we provide a wonderful education resource on this topic, give a major boost to the economy of the Washington coast, and offer a wonderful recreational experience?

Imagine a "Pacific Storms Museum" in Westport (or some other coastal
town). A facility with exhibits on past great storms (like the Columbus Day Storm), explanations of the structure and nature of major Pacific storms, pictures and videos of strong
events--perhaps even a surround-type experience for a strong event. An exhibit describing the effects of strong storms on the forests A weather station with the latest readings. A room describing local shipwrecks. And, of course, a gift shop. This facility could also include an exhibit on tsunamis.

This museum could be a major educational and tourist attraction that would bring
tens of thousands --even hundreds of thousands--of visitors a year to Westport or some other lucky town...and could have a nationwide draw. And it could be an economic boom for the region.

But the fun doesn't stop there. People spend thousands of dollars to
go storm chasing in the midwest (I have a friend who is in the
business...and it is booming even in bad times). Imagine storm
weekends or longer in Westport. They could experience the weather
themselves during the November-February season, enjoy lectures from
weather experts and locals, enjoy special "storm meals" at local
restaurants (perhaps even illuminated by storm lanterns), and stay
in local B&Bs and hotels. Perhaps even field trips to see blowdowns
or shipwrecks. I tell you..this could be a very large attraction, at least as big as Lewis and Clarke museum near North Head and the marine museum in Astoria....and probably much bigger. What do you think? How could this idea be improved? How could we get started on this?

The Washington coast have a tremendous resource--the storms--and my
intuition is that there is a very viable business model for a "storm industry" . Then
as long as you have this free-spending crowd, there are lots of other
things local shops can sell them..like coastal art, watercolor paintings, and yes...teeshirts. It has always bothered me that people drive all the way to Cannon Beach for a quality beach experience. Why not much closer and something much more authentic?

PS: Arthur Grunbaum, who leaves on Gray's Harbor, suggested a version of this to me a few years ago...so he deserves the credit (or the blame).

Tuesday, March 24, 2009

Doppler Radar


This is lots of talk about Doppler radar...but the interesting thing is that most of you NEVER see the Doppler part. That will end right now! Normally, the only radar images you see show you where it is precipitating. More technically, the normal radar images show you reflectivity...how much of the microwave radar beam is scattered back to the radar. Heavier precipitation generally has a higher reflectivity...so that is why radar is useful.
But you don't need a Doppler radar to see precipitation. A Doppler radar has an additional capability...it can measure the velocity of the precipitation particles towards or away from the radar. And since precipitation is pushed around by the winds, that give you information about the winds. TV stations tell you about their super Doppler radars, their pinpoint Dopplers, their Storm-Tracker Dopplers, and for a short time a decade ago...their Wappler Doppler radar. At one point, there was a pinpoint, severe-weather center, storm tracker Doppler radar! But they never ever show the Doppler imagery on TV. I should correct myself..when KING 5 got their own radar, Jeff Renner showed the Doppler velocities for a few days. It was taken off VERY quickly, never to return. OK, want to see what you are missing?
Tonight there is a very nice convergence zone over central Puget Sound (see image). A nice example...and most of you probably recognize the band of cloud extending across the Sound (see image). Next, take a look at the Doppler velocity image (image). Both are for the lowest radar angle (.5 degree above the horizontal). Enough to drive you to drink?
Cool colors (e.g, blue and green) show velocites towards the radar and warm colds (yellow, red) indicate velocities moving away. The radar is located in the center of image at Camano Island. So air is moving towards the radar in the Strait of Juan de Fuca (since the colors are green and blue) and away from the radar in the very north Sound (see the small area of yellow). Those are northerlies. And you see the gray area over the Sound? There is no velocity towards or away from the radar....this is the center of the convergence zone. Anyway, it is lots of fun and not a little challenging sometime to figure out the wind directions from the Doppler image...since it is only giving you one component of the wind (towards or away from the radar). I bet you now understand why this is not shown on TV...my colleagues at the TV stations would spend all their time explaining the images!

Sunday, March 22, 2009

Ferry Weather




If you ever do any boating...or just interested in weather over the water...few web sites are more educational than the Ferry Weather web site (http://i90.atmos.washington.edu/ferry/Ferryjs/mainframe1.htm). Many of the Washington State ferries have weather sensors on them and send the information back to WSDOT and the University of Washington in real-time (see screenshot). At the UW we plot the winds and temperatures on this web site...and add nearby land observations to complete the picture. As you see by the second image...one thing is clear...winds are generally stronger over the water than over the land...often by 50-200%!! Why is that? Water is much smoother aerodynamically than the land..with its trees, buildings, and hills, and this rougher surface slows the winds.

I am sure you have noticed this effect when you drive across one of the local floating bridges (which have weather instrumements as well). As you can see from the image, when land is upwind of a ferry, the winds really drop. I have seen winds blowing at 30 mph in the central Sound...and only 5-8 mph in harbor. When air goes from land to water the wind speed does eventually speed up...takes a few miles to do so, as higher momentum air from aloft is mixed down. The ferry weather web site is heavily used by recreational boaters, the WA State Ferries themselves, and commercial shipping. It is also invaluable for meteorologists to learn about the details of our local winds.
Today is a nice example...a Puget Sound convergence zone has developed (see radar image wind SW-NE band across Puget Sound). Look at the Ferry Weather...you can see it clearly..with northerly winds on the Kingston run and southerly winds on the Bainbridge run.

Friday, March 20, 2009

The "Weak" Front


OK...that turned out not to be such a weak front. There was no indication in the models we would have such a sharp transition and with no coastal radar we could not see it coming. A convective line formed on the front with very heavy precipitation...take a look at the radar..you can see the reddish color of very intense precipitation. The observations at the top of the UW Atmos. Sci building shows the dramatic nature of the transition...substantial wind shift, sharp pressure trough, sudden drop of temperature and increase of humidity, and increase in winds to 30 mph (see figure). Or look at the Seattle profiler (image)...a very sharp shift from southerly to SW winds and big temp decline. Finally, you can see the line in the visible satellite imagery if you look carefully (image).

Weak Front

A weak front is moving through today...with good rainshadowing over Sequim and Port Townsend right now. It will move through this evening, with cooler air in its wake. Tomorrow should be mostly dry....which is unfortunate since I will be at the NW weather workshop all day tomorrow (info on this at right). Then another weak front Saturday night/Sunday AM, with a chance of showers on Sunday. Wish we had some exciting weather coming....nothing on the horizon.

Thursday, March 19, 2009

Snow expose and other items

The Seattle Times has a nice story on the poor snow removal of the December 2008 snows. Check out:

http://seattletimes.nwsource.com/html/politics/2008885019_sdot19m.html

and KIRO TV is doing their storm special again at 10 PM.



Nice example of rainshadowing today NE of the Olympics (both in the radar AND the visible satellite picture). Those retirees in Sequim may be golfing in the sun right now, while I had to bike in in the rain! The models handle this kind of situation well...take a look at the 3-h precipitation ending 10 AM....

Tuesday, March 17, 2009

Cold Wave



Over the weekend and Monday I was busy giving public talks...but I am back again. Nice to meet several of you.

Many have complained about the cold temps...and in general we have seen substantially below normal temps during the past two weeks in western Washington. Above you see the temps for Seattle, Yakima, and Spokane...with the normal highs and lows shown. Except for one day, the Seattle max temps have all been below normal--most well below normal. Eastern Washington was cold early in the period, but the last few days have been near normal. On the 12th Spokane's temp fell to near zero, and Yakima had several days in the teens. It does look that a moderating period is ahead though.

On the road, several people asked me about the interpretation of the weather radar images...so let me try that a bit (see image). What is shown is reflectivity...a measure of how much the target (precipitation) scatters the radar signal (which is in the microwave part of the spectrum). Grey is drizzle (5-10), reds are light rain (15-25), green is moderate rain (30-35), and above that is either absolutely pouring...or wet hail. The concentric range circles are 100 and 200 km from the radar. If you look at the upper left corner you see some additional information. This radar picture is for an elevation angle of .5 degrees, which means the radar is canted slightly up from the horizontal. Thus, the beam is sweeping out a conical surface as it rotates...or in other words...the beam gets higher and higher the farther out it gets from the radar. How how? The second row of numbers tell you. The radar is at 196 meters, and the beam gets to 1068 and 1941 meters by the first and second range circles. That beam is way overhead by the time it gets to the south Sound for example. So shallow drizzle can be missed for such locations.
Now why don't we see the mountains on the radar? Special software remembers where the mountains out and removes that part. In the right corner you see max=44 ..that means the maximum reflectivity anywhere in the domain was 44.

Rain shows up better than snow on weather radar. And big raindrops show up better than small ones. Anyway, enough radar 101.

On Thursday night at 10 PM KIRO TV is repeating their hour-long special on the Dec 3-4, 2007 windstorm/rainstorm, if you are interested.

Sunday, March 15, 2009

Snow


Snow piling up at Silverdale this morning (thanks to Dale Ireland cam)

Huge flakes are falling around the area right now. In the central Sound it is really not accumulating at the surface because the temps are too warm...but cams in the south sound show perhaps a 1/2 inch. It is much worst on the Kitsap and near Hood Canal...take a look at Dale Ireland's cam in Silverdale(attached). This is what the models were indicating last night. The precipitation is front a a warm frontal band associated with the incoming system and temperatures are just cold enough for very wet snow (see radar).The snow is full of large aggregates (many crystals stuck together)...that is why they are so large (the surfaces of the snowflakes are melitng and wet...and this acts as a sort of glue to allow them to stick to each other). This happens in marginal temp situations, like we have now.

The Seattle profiler temp soundings show how temps are just at freezing above us (subtract 1C from the values shown--this is actually something called virtual temp which includes moisture effects). Evaporation and melting of snow from aloft helped to push us over. Anyway, enjoy it...it won't last. The warm front will move warmer temperatures into us in a few hours and end the snow for everywhere except near the Olympics...and even there during the afternoon.Want to see where the warm front is at the surface..check out the surface obs and look towards the Astoria area....southerly flow in the upper forties on the N. Oregon Coast and easterly flow in the 30s along the central WA coast. The warm southerlies will move northward this morning.And later it will get breezy later today...although the latest model runs indicate the low will be crossing Vancouver island sufficiently north that Puget Sound will be spared the strong stuff.

9:30 Am..the air is warming rapidly aloft and it is raining...

PS: I am heading to Bainbridge today (Eagle Harbor Books) at 3 PM today to talk weather..and Olympia tomorrow (see info to the right). Will have to shovel my driveway first!

Saturday, March 14, 2009

Approach low and winds

Today was the kind of typical Seattle weather that has been nearly absent this year, wet, showery, and windy. Makes you feel normal again. A front is moving through now and the rain should back off soon. But the real fun is later tomorrow afternoon.
A developing low center will approach tomorrow afternoon and move north of us around dinner time (see attached). As a result, rain will come back in late tomorrow morning and the winds should pick up during the afternoon...peaking between 6 and 10 PM. Some locations could see gusts to 50 mph, such as over the Sound and waters of NW Washington. As the low moves past strong westerly winds could develop in the Strait (see graphic).
And did I mention the snow? Yes, the mountains will get loads of it...but tomorrow morning, a low freezing level and southeasterly winds could leave the western Kitsap in several inches of snow (graphic).

Friday, March 13, 2009

Major Weather Changes Coming

Today will be the last sunny, dry day for a long time. You can see the changes aloft as thin cirrus moves in aloft and contrails fill the sky. Contrails are a real sign of an approaching system since the air has to be close to saturation for them to form...the extra water vapor from combustion supplies the water needed to produce saturation and cloud droplets.
A weak front will approach tonight....and rain should start in the lowlands after midnight. The front should get through around breakfast time and then there will be a few hour break before the next...and stronger...frontal system moves in. Both of these fronts will bring considerable snow to the mountains. Colder air will move in behind the second front on Saturday night...and a few snow showers could reach the lowland hills on Sunday AM. But no big accumulation.
On Sunday, a low center will approach from the SW and this will bring more rain to the lowlands and snow to the mountains on Sunday afternoon. The low will bring strong winds to the northern Oregon coast and then breezy conditions over the Puget Sound lowlands on Sunday night.
The rest of the week remains cold and wet..with the mountains picking up lots of snow.

Thursday, March 12, 2009

How Snowy? How cold?

The National Weather Service released some interesting snow statistics yesterday....this winter was the snowiest since 1971-72 and the 8th snow-filled on record.

TOP TEN SNOW YEARS AT SEA-TAC (OCTOBER 15 - APRIL 15)

SNOWFALL SNOW YEAR
67.5 1968-9
63.6 1949-50
27.4 1950-1
26.9 1971-2
24.2 1955-6
23.3 1953-4
22.9 1965-6
22.8 2008-9 (35 DAYS REMAINING)
21.4 1948-9
20.3 1985-6

As of 11 March, 2008-2009 now ranks as the 4th snowiest year in
Spokane with 88.9 inches of snowfall. Only 4.6 inches more snowfall is
needed to become the snowiest year on record, but normal snowfall for
the remainder of the season appears to be about 2 inches, so we are
fast running out of time. Last year (2007-2008) was the 2nd snowiest
on record with 89.5 inches, so 2nd place is easily within reach.

and what about cold records?

Mark Albright noted to me that Meacham OR recorded unusually cold minimum temperatures of -11 F and -12 F the past two mornings (11-12 March 2009). Coop records were maintained at the Meacham airport from 1948 to 1976. During that 29 year period the latest subzero reading was -4 F on 5 March 1955.

Spokane yesterday(11 March 2009) reported a low temperature of 2 deg F! The only comparable temperatures in the historical record are the 3 deg on 13 March 1897 and 2 deg on 6 March 1891, over 118 years ago.

Deer Park (KDEW), 30 miles north of Spokane, reported a low temperature of -12 deg F yesterday, with 10 consecutive hours below zero! The Deer Park 2E coop site which ran from 1911-1977 never reported a temperature this cold so late into March. The coldest this late into March had been -8 deg F recorded in 1943 and 1950.

Other subzero cold spots yesterday were the Freestone Inn at Mazama with -1 F , and in the next valley north, Princeton BC in the Similkameen Valley reported -13 F the day before yesterday and -9 F yesterday. The Mazama coop site, where records extend back to 1950, has never experienced subzero cold this late into March.

But please! No comments about all this disproving global warming! One year means nothing.


PS: I will be on the road this weekend giving some talks"

Sunday, 3 PM, Bainbridge Island, Eagle Harbor Books
Monday, Olympia:

noon, Olympia, General Administration Building, sponsored by Olympia State Capitol Museum, NW Weather and Climate lecture and signing
South Puget Sound Community College, Olympia, reception 5 PM, lecture 7 PM, Kenneth J. Minnaert Center Fine Arts Auditorium, small suggested contribution

Wednesday, March 11, 2009

Coastal Weather Radar Receives Partial Funding


All, this is a big day for the local meteorological community and for the citizens of the state....2 million dollars for the coastal weather radar was in the omnibus spending bill passed by the Senate yesterday--and President Obama will sign it. For years the Northwest has been the only coastal area of the continental U.S. without weather radar coverage...perhaps this day will soon be over.

Major credit for this advance should go to Senator Maria Cantwell, who has been a champion of the radar acquisition, and who worked to get this item in the appropriations bill. Senator Cantwell's staff has also been very supportive, as have been other members of our Washington delegation. The radar will cost more than this amount (roughly 4 million for the hardware, plus installation and maintenance), but this is a major down payment. Hopefully, we can get a contribution of the land needed for this facility or install it on public property, and the additional appropriations that will finish the job (or perhaps NOAA could use some of the stimulus money it was given for infrastructure improvement to make this happen this year!). Many of us hope that Gary Locke, now secretary of commerce and someone certainly well acquainted with the problem, will intervene since NOAA and the NWS are under his authority.

Anyway, in this period of uncertain news, it is nice to have something very positive occur.

In 2001 we had a radar on the coast for 2 months, attached is a teaser image, showing you what we could see. In that image you can view an offshore front approaching...a feature invisible in the current radar at Camano Island (whose beam is blocked by the Olympics).

Tuesday, March 10, 2009

The Geography of Cold

This morning it was mightly cold out there...particularly as I biked into work. But such cold varies greatly over the area, particularly on cold mornings in winter when the winds are light. This morning was a good example (see map). At 8 AM the temps varied from the upper teens in the western foothills of the Cascades to the mid-30s over Puget Sound. The range of temperatures were somewhat limited last night by the considerable cloudiness, that lessens the ability of the surface to radiate heat to space. Thus, on some nights the range of temperatures are even greater. In my NW weather book, I describe a night when five cars of UW students and staff drove around the region in instrumented cars. We found temperatures ranging from 25 near Maple Valley to 45 near the sound. Temperatures were several degrees cooler in valleys that were only 50-100 feet lower than the crests. Tomorrow morning should be just as cold, with temps certainly getting into the mid and lower 20s. My rhodies are not doing well.
The models are in agreement that conditions should stay dry until this weekend, when some frontal systems will approach, bring rain and warming conditions. But the real excitement may be early next week, when some models are suggesting a potential pineapple express period..with heavy rain in the mountains.
F

Monday, March 9, 2009

A New Weather Survey

A month ago, we had a weather survey designed to help us understand how people deal with weather forecast uncertainty. This was valuable information, but now we have a follow up. Only take this survey if YOU did NOT respond to the survey in January! We will post results in the next couple of months from both surveys.

Here is the link, but don't try it if you did the last survey...it will mess up the statistics!

We have all the responses we need right now...thanks for all your help...

PS: Several people have asked me whether Costco still has copies of my book. The answer is yes. Unfortunately (for me), they highly discount the book....about the same as Amazon.

PS: Weather is over until this weekend...

3 PM Snow Story


The northerly arctic air is now pushing south past Seattle, with clear skies behind. At its leading edge there is a wintry mix...particularly over the eastern suburbs (see radar and satellite). Sunny, dry conditions are found behind. So if you are north of Seattle..the game is over. Protect your plants.

snow update

If it is going to snow signficantly in Seattle and the adjacent lowlands--it will be later this afternoon as the low rotates southeastward. This morning Seattle was rainshadowed by the westerly winds....and the eastern suburbs and foothills areas got a few inches. But as the low moves over (or even better south) of us the rainshadowing will weaken and the northerly winds will strengthen...that is when we will get it. You can see the enhanced cloud over the NW Olympic Peninsula...associated with the low..moving this way. The game is not over yet...although there are no guarantees here...

Snow showers


Some snow showers are moving through the area...except for the northern Sound area, which is in the rainshadow (now snowshadow) of the Olympics. The rainshadow is there because the wind are from the southwest aloft. Northerly winds will push southward today and showers will be enhanced at and north of that interface, aided by a weak upper level shortwave disturbance. Don't expect a major snowstorm, but an inch or two is possible.

Sunday, March 8, 2009

More snow


This is really quite extraordinary. We could actually get more snow tomorrow. Continental air is now moving through the Fraser (see map)...the sign is the low dewpoint...very dry air. But the big push comes tomorrow morning. The computer models show a great strengthening of the cold flow through the Fraser and lower terrain tomorrow morning between 7 and 10 AM, and that this air will push southward into Puget Sound. This push of cold is being initiated by a disturbance aloft...warmer, moister air will rise over the cold air producing light snow over the Puget Sound lowlands that could add up to a few inches (see map). I hate to say this...the TV types will go crazy. This is not certain, but now looks more likely than not.

Arctic air in March

Yesterday was a fairly successful day for the forecasting community, and the NWS forecasts of light snow amounts with the CZ were on target. The predicted heavy snow fell in the mountains...and the radar really helped us follow the action over the lowlands. Do you see how valuable having the radar is? Isn't it clear why the coastal zone, with its extraordinary active weather needs it? Isn't it outrageous that they don't? Well, you know how I feel about it. My other pet peeve...the failure of Metro's bus tracker software during snow periods when the hit rate climbed...appears to be on the way to being fixed, according to Metro management who emailed yesterday with their assurances that this problem will be addressed before next winter.
A look at the latest satellite pictures shows that shower activity is greatly reduced particularly over the northern portion of western Washington. Mountain snow showers have also declined. The radar shows the weak remnant of the convergence zone across Whidhey and northern Snohomish counties, and some showers basing eastward south of the Olympics. All snow showers.
The next stage in this event will be the movement of much colder air into the region...first evident as gap flow starts to push through the Fraser gap later today...so in Bellingham and NW Washington, the cool northeasterlies should come in late today and tomorrow AM..with some snow showers possible on its leading edge. I have included a prediction for sea level pressure, temp, and wind for 2 PM, you can see the cold air and higher pressure to our north. Upslope snow showers on the NE side of the Olympics should occur tomorrow..but at this point they look light due to the dryness of the air. Monday AM and particularly Tuesday AM should be very cold..perhaps record breaking, with minima in the 20s. So protect those sensitive plants. Tuesday and Wed a major ridge develops over us for sunny, cool and dry conditions.

Finally, for all of you who look at weather charts and obs, remember we are in PDT now and the difference between GMT (UTC) and PDT is 7 hours.

Saturday, March 7, 2009

Convergence Zone snow hits I90


My son is turning back from his trip to Snoqualmie Pass for his snowboard lesson. The reason....too much snow and chains are required. The convergence zone has moved south and is now aligned nearly NW-SE...with the heaviest amounts aligned on I90 at and west of the Pass. The radar shows the story...and look at the cam up there--snowy driving. Convergence zones can greatly enhanced the snow at Stevens or Snoqualmie...depending exactly on how they set up. Outside of the convergence zone, some of you getting bright sunshine (see high res sat picture).

The heavier showers are now approaching western Washington....