Monday, July 27, 2015

Will the Northwest Have A Water Problem This Fall?

Today, the city of Seattle announced a water advisory and asked folks to be careful with their water usage.  The reason is clear:   the city's reservoir levels are well below normal and dropping rapidly (see graphic).  

The origin of the plummeting water levels is no mystery:
  1. record-low snowpack, resulting in less streamflow during the late spring and summer
  2. dry conditions during the same period
  3. MUCH warmer than normal temperatures the last few months, resulting in enhanced evaporation from the surface and greatly increased water usage.
Fortunately, the city has some back-up sources of water, such as wells near Seattle-Tacoma Airport, and extra pumps at Chester Morse reservoir for increasing "low-water" capacity.

But the assumption is that rains will come back in the fall, preventing a serious water shortage.  But what if the fall is unusually dry? We don't have the multi-year storage like California.  Could we have a problem?

I starting thinking about such questions as I looked at the latest seasonal forecasts, particularly since the latest numerical predictions are for an extremely dry fall.  

Let's start with the latest forecast from the National Weather Service's Climate Forecast System (CFS) model. I will show you the precipitation anomalies (difference from normal) for Sept to November and December through February.

As you can see for yourself, the forecasts are for the fall to be dry and winter to be VERY dry.
 Winter temperatures? Warmer than normal (see graphic)
OK, that is just one U.S. seasonal forecast system.  How about the North American seasonal forecasting system (NMME), averaging more American and Canadian seasonal forecasts?  Here are the precipitation anomalies for November through January from this system: much drier than normal.
And there is an international seasonal prediction systems as well (IMME).  Here is the precipitation anomaly forecast for the same months.  Same story.....dry.

You will note that all of these forecasts are not only dry around here, but far wetter than normal in California.   This is a typical El Nino pattern, especially for the strong events.  And it looks like we are going to have a very strong El Nino in place this fall and winter.  So strong that we are already seeing the effects of El Nino on our weather this summer (southern CA has been unusually wet the past few months and we have been unusually dry).  This situation will save California, providing real relief for their multi-year drought.

Keep in mind that drier than normal for us does not mean no rain.  Clouds and rain will return, but conditions should be perceptibly drier and warmer than normal this fall.  Our reservoirs will get very low before the serious rains return.   And I worry about next summer.  Drier and warmer than normal conditions will result in another low snowpack year, although probably not as extreme as this year.  Why do I say this?   The warmth next year will probably not be as crazy hot as last year.


Seattle water managers are watching the situation carefully and I suspect they will soon ratchet things down another notch, restricting the amount of water used for irrigating lawns. Time to let our grass go brown.  Next winter, regional water agencies, like Seattle's SPU will have to be very careful to save as much water as possible for use next summer.

One final thing.   Forty years ago, our ability to make seasonal forecasts was basically non-existent and we didn't understand the implications of El Nino.  Today, we have useful guidance.   We have come a long way.

Sunday, July 26, 2015

Seattle School Board Races

An important election is coming up for Seattle School Board members, one that will decide whether there will be a functioning majority that will be able to keep the district moving forward.  Three school board directors will be selected and fortunately the choices are quite clear.
First, in district 2, in which no incumbent is running, there is an extraordinary candidate:  Rick Burke.  If you want our district's children to have a good math education, Rick is your clear choice.  He has lead the Seattle group of Where's the Math, co-founded the Seattle Math Coalition, and has played a leading role in the successful upgrade of Seattle's elementary school math curriculum.  He has been PTA co-president, has had three children in Seattle public schools, and is a high-tech professional.   I have known Rick for years and have been ceaselessly impressed with his leadership skills, focus, hard work, and excellent people skills.   He will become a leader on the board.

Rick Burke

In district 6  the best choice is Marty McLaren, who has served on the board since 2011.  I know Marty well, having worked with her for years to improve math education in the Seattle district.  Some of you may remember that she sued the district with her own money when it choose extremely poor math books for our children.  Then as a school board member she worked to correct the situation and today Seattle's elementary school children enjoy a decent math curriculum.   If elected, one of her priorities will be to revamp middle school math...and I bet she will succeed.


But Marty has achieved many things during her first term.  When Jose Banta, decided to leave our district for California, she was one of the majority that voted to put Larry Nyland in place to replace him. Nyland is probably the best superintendent the district has had in decades. Competent, approachable, and deeply knowledgeable about the region and district. Importantly, Marty is supported by teachers. Jonathan Knapp, president of the Seattle Education Association, said that McLaren is thr one person on the school board who “will listen to educators,” noting that she was a teacher. He said she’s the one person on the board who can help get to consensus to fix problems, instead of “grandstanding.”


Marty believe in listening,  Of showing respect for others, even when she disagrees with them.    And she now has deep experience and knowledge of the district.  It would be a mistake to replace her.  

Marty McLaren

So there is  a clear choice for Seattle voters.  Elect Rick Burke and Marty McLaren and there is a good chance that the district can maintain its impressive movement with improving academics, increased enrollment, and smoother functioning district administration.   Midde school math will get fixed.  If you live in Seattle, please vote for them.


Friday, July 24, 2015

Finally! Arid Western Washington Gets Relief

It is strange to say this, but it seems strange to see rain reaching western Washington.

Stranger yet, it will be occurring during the climatologically driest period of the year (see plot below of average daily rainfall, which shows the dip to a minimum during this time)


The last month or so has been startling dry.   Here is the plot of the observed and climatological rainfall at Seattle Tacoma Airport since June 5th.  A few hundredths of an inch in June--we are down by roughly 2 inches. A trace (less than .01 inch) in July.   Sahara in Seattle.

Fortunately, the latest radar image (below) is reason for joy for many parched Northwesteners, folks that have had moisture envy of our brethren down in southern CA, of all places.  And it will be a potent tool for those fighting local wildfires.  Associated with an approaching Pacific front, moderate rain is now falling over the NE Olympics and southern Vancouver Is.  It is raining in Vancouver (see cam below).




Today, this front will slowly move through the region, reaching Seattle this afternoon and tonight.   Here is the predicted 24h precipitation totals ending 5 AM Saturday. SW British Columbia, the Olympics and the northern Cascades get the most--roughy a half inch.  The Puget Sound area will only get some light rain later today....not that much (see more detailed map below)


But this is just the appetizer.  On Saturday, a weak upper-level disturbance will move though, bringing light showers (see 24h precip ending 5 AM Sunday).  More over the southern Cascades.



The main event will be on Sunday as a robust upper level trough pushes into us (see upper air map for Sunday AM).   Goodbye big ridge of high pressure.


And here is the 24- precipitation ending 5 AM Monday (both wide and close-in view).  Extensive light rain, with particularly heavy amounts in the north Cascades and Olympics.




For most, this will not be a big rain event...but nearly all in the mountains and west of the Cascade crest will get some light rain.. Temperatures will drop back to the mid 60s to low 70s over the weekend.

The only problem?   There could be lightning on Sunday.  And guess what...the pesky ridge comes back quickly...pushing us back into the 80s and into dry conditions.

Wednesday, July 22, 2015

Cooler, more seasonal weather for the next week

We are now entering a magical period for all Northwest residents:  the climatologically driest period of the year (last week of July and first week of August).

The time of year to schedule outdoor weddings and major outdoor receptions.

But ironically, we will cool down over the next week and showers will be felt by many.


Now, a bit of an admission...when I want to get a quick forecast without looking at any data, I often turn to weather.com.   They have a very sophisticated model post-processing system that combines a lot of model forecasts and observations using an advanced statistical system to provide a really excellent forecast for most locations.  The quality of their forecasts over the NW has been confirmed by verification at my department and by a firm that runs a web site:  weatheradvisor.com. Weather.com forecasts are generally more skillful than the National Weather Service (BUT KEEP IN MIND THEY HEAVILY USE NATIONAL WEATHER SERVICE MODELS AND DATA)

Here is their forecast for the next 10 days for Seattle.   For the next week, lots of temps in the 70s. Very typical, but the chances for showers increases late Friday and on into the weekend as an upper trough moves through.  My apologizes to all brides with outdoor weddings.

The second thing I often look at is the output from the joint U.S./Canadian ensemble (many forecast) system (NAEFS), which provides uncertainty and probabilistic information.  Here is the output for Seattle.  Cool the next week, plenty of clouds, and the chance of light rain.

Good weather to keep the fire danger down.

And then my next step is to look directly as a variety of model output, starting, of course, with the UW high-resolution WRF model.  Here is the forecasts of precipitation for the next two 72h periods.  With the east Pacific ridge replaced by upper troughs moving into BC, we see some rain extending from Seattle into British Columbia.  So you want cool and damp?-- go north. Warmer and drier, head to Portland and south.  California should dry out for a while.


So after endless heat and drought, some minor relief is in the bag.   But next week our old friend the ridge of high pressure rebuilds.  And temperatures back in to the 80s.

And what do I check after looking at more models?  That will be a future blog....



Monday, July 20, 2015

Northwest is Toast, While Southern California Floods

Southern California is usually dependably uber-dry during July, helping make it the "golden state."   But not this year.    While the Pacific Northwest has been very dry this summer, southern California is enjoying lots of rain, leading to localized flooding and even the destruction of part of Interstate-10.  The Los Angeles Angels' had their first rainout in 20 year, the San Diego Padres' had the first rainout since 2006, and Los Angeles enjoyed the wettest July day (.36 inches) in 130 years.  July rainfall records are falling all over CA.


Let's explore what has happened and why.   First, take a look at the percentage of normal rainfall during the last month.  Some places in southern CA had over 800% of normal (which is admittedly a small amount).   And Washington and western Oregon have been MUCH drier than normal (but admittedly we generally don't get much this time of the year).  Our long range models very skillfully predicted this pattern months ago.   Very impressive.

To get a different perspective, here is the precipitation over  the past seven days over southern CA--very wet for this time of the year, with several locations securing daily or monthly 24-h records.   Some locations in the mountains got hit by roughly 3 inches.

The last 24-h....more rain!  Here are the 24-totals ending 11 PM Monday over southern CA.  A number of mountain locations enjoyed more than an inch.  All this rain is very welcome and helps lessen the fire danger, as well as reducing water needs for irrigation.

So what is going on?  Why is southern California hugely wetter than the Pacific Northwest?   During the last few days, the precipitation has been the result of the weakening Hurricane Dolores.  Two days ago, the moisture advancing ahead of the storm brought thunderstorms and rain to Monterrey and the central coast (see below)


And today, as the weakened low center of Dolores was just offshore of Southern CA, moisture streamed over the southern CA coastal zone.    Why was Dolores able to come so far north?   One reason is the unusually warm water over the eastern Pacific this year.

There is substantial evidence that the most important cause of the southern CA precipitation is the surging El Nino, which tends to bring stronger upper level flow into the region.   Here are the upper air (200 hPa) wind anomalies (differences from normal) for the past two weeks.   Stronger than normal westerly and southwesterly flow into the upper Baja and the  SW U.S.  A split flow west of the Northwest.  Classic El Nino signal.

The El Nino is rapidly strengthening....this may well be an historically strong event.   California needs to prepare for a wet winter and we need to be ready for a boring one.


Saturday, July 18, 2015

Reorganizing National Weather Service Forecast Offices

Last month, U.S. Senator John Thune submitted legislation to centralize National Weather Service forecasting operations from roughly 120 field offices to only 6.
This legislation ignited a firestorm of criticism by both the NWS unions and users (an example here), and subsequently it was tabled.  Quite frankly, the legislation had a lot of problems and was probably written by someone without a deep knowledge of the strengths and weaknesses of the NWS office system.

But Thune's bill leaves an interesting question: Does the current NWS field office structure make sense today?   Could it be reorganized in a way that could better serve the country?

I believe the answer is yes....and I will propose some major changes that could greatly improve the NWS's ability to deliver timely and skillful forecasts, as well as providing better service to users.   As I shall describe, the current office structure maintains ineffective legacy structures and is not consistent with an age of high-capacity internet communications.

The Spokane National Weather Service Office.  The Doppler radar dome is right behind it.

But first some history.

Prior to roughly 1990, before the NWS went through its "modernization",  there was roughly one Weather Service Forecast Office (WSFO) per state (actually 53), all with professional meteorologists, and 204 Weather Service Offices (WSO), with observers and meteorological technicians. Modernization brought the installation of 122 Doppler radars (WSR-88Ds) and an expansion of the Weather Service Forecasts Offices to 122--one for each radar.   This was not an accident---in those days the Internet was a shadow of what we have today and real-time transmission of all the high-volume radar data was difficult.  Thus, most forecast offices were at or near the radar (there are exceptions to this--such as our Langley Hill radar installed 3 years ago).   Part of the modernization deal was the elimination of the 204 WSOs, so that the "modern" NWS only had 122 offices.  A map of the current office locations are shown below.


You will note that the office distribution is very uneven.  For example, there is a large number of offices from northern Georgia/Alabama to Detroit.  Out West the offices are more sparse.  You notice the colors?  Those are the NWS regions (e.g., western region, southern region, eastern region, central region, Alaska region, Pacific region).    Each region has a director, staff, a substantial bureaucracy, and support staff for the offices.  More on this later!

It is important to note that many of the individual offices have marginal internet capacity and do not get the full range of products from National Weather Service weather modeling centers.   For example, the offices do NOT get the full resolution output of the NWS global model or all of the ensemble (multiple forecasts) available to some of the national centers.

And there is an additional bureaucratic structure in the National Weather Service:  the River Forecast Centers (RFCs).  Tasked with flood and water resources forecasting and warning, river modeling, and hydrological modeling, the 13 regional river forecast centers each have substantial staffs (see the map of RFC centers) and ca be co-located with only one of the  NWS forecasting offices providing them with precipitation information (a RFC area encompasses the domains of many offices).


So we have 122 forecast offices, 5 regions, and 13 river forecast centers--each part of the NWS forecasting enterprise.    But it doesn't end there.  The National Weather Service has its National Centers for Environmental Prediction (NCEP)--another 9 centers, several with operational forecasting responsibilities, including:
  • The Storm Prediction Center
  • The Weather Prediction Center
  • The Aviation Weather Center
  • The Environmental Modeling Center
  • The Hurricane Prediction Center
  • The Ocean Prediction Center
  • The Space Weather Center
  • NCEP Central Operations Center
  • The Climate Prediction Center
Many of these centers do absolutely unique tasks, but an honest appraisal reveals substantial overlaps with other forecasting entities in the National Weather Service.  For example, the Weather Prediction Center (WPC) makes national forecasts of precipitation (including snowfall and heavy rain), temperature, and serious weather threats....but this overlaps with the responsibilities of local offices, and some of the forecasts of other centers (like the Storm Prediction Center).   I have asked over a dozen NWS forecasters from around the country whether they needed WPC forecasts.  Every one said not really.  Don't get me wrong...the WPC is full of very talented folks, but they spend a lot of time doing tasks that are redundant with others (and some that are not redundant, like preparation of the national manual surface analysis).


The Storm Prediction Center is undoubtedly the most talented, experienced, and technically savvy convective forecasting operation in the world.  No one is better at predicting thunderstorms, hail, tornadoes and the like.   But why are they getting involved in other areas like Fire Weather?   They have also developed wonderful forecast tools (like ensemble and HRRR viewers) that SHOULD have been developed centrally.  They did it because there was a need and no one else was doing it.

So let's imagine we had the power to rationalize the the National Weather Service office and center structure to maximize the National Weather Service's ability to deliver the best forecasts to the American people....and to do so efficiently.   This is what I suspect Senator Thune wanted to do. Based on many decades of thinking about this and working with the National Weather Service. here is how I would fix things.

First, I would change the office structure.   122 weather forecast offices were established because of a need for proximity with the 122 Doppler radars.  Today, high-bandwidth internet has made such proximity unnecessary.  Ironically, many of the forecast offices have inadequate internet capacity, and can't receive some important forecast guidance (e.g., full resolution forecast model output). Another issue is that local NWS offices, with restricted staffing, can be overwhelmed when a weather disaster strikes.  Furthermore, with so many offices, there are numerous seams between their areas of responsibility, producing discontinuities in the forecasts (see sample below, of % skycover; there is a sudden change along the central WA coast, the boundary between the areas of responsibility of the Portland and Seattle offices).


So here is my first suggestion: instead of 122 forecast offices, create 10-20 large regional forecast offices, each covering a meteorologically distinct area of the country.  The map below is my five-minute attempt at dividing the lower-48 states into regional forecast areas.  Add another two for Alaska, one for Hawaii, and one for Puerto Rico and the Virgin Islands, perhaps.


Each large forecast office would be staffed a substantial contingent of forecasters (24-h a day of course), a warning coordination meteorologist, and several research meteorologists, among other staff.   All the forecasters would be intimately knowledgeable about the meteorology of their entire region. The beauty of having larger regional offices is that if something major is happening over a portion of the region, there will be sufficient staff to surge on the problem.  More forecasters will be on duty at any time, allowing interactions and consensus among forecasters, which is generally associated with superior forecasts.   Furthermore, having to deal with a larger region will help improve forecaster skills.

 Regional offices would ALL have substantial internet bandwidth and would receive full resolution model products and all ensembles.   Such regional offices would be co-located at or near major atmospheric sciences departments if possible.    Regional offices would be staffed sufficiently so that local research was possible, including providing detailed feedback to national modeling centers (i.e., EMC, the NOAA Environmental Modeling Center) regarding strengths and weaknesses of current models.  There would be less emphasis on manipulating forecast grids and more on evaluating model output and dealing with the deficiencies of model/statistical guidance.

What about the 122 current offices?  A small number would transition into one of the regional offices noted above and 50-70 would be retained as local NWS offices.    Such local offices, spaced evenly around the nation, would include meteorological technicians cable of maintaining and repairing NWS observations systems, such as the Doppler radars.  Each would also have a warning coordination meteorologist and a research/outreach meteorologist to coordinate with local industry, emergency managers, and others.  They would service as point of contacts and educational resources for the local communities. Such local offices would not be staffed at night (perhaps open 6 AM to midnight), with technicians on call during emergencies.

In my plan, the expensive regional bureaucracies  (e.g., NWS Western Region, Eastern Region, etc.) would be disbanded, with most of their functions falling to the regional centers (such as the research efforts).  Educational activities would move to the NCEP Weather Prediction Center.  Administrative demands would be centralized.  Time after time, local NWS meteorologists have told me that the regions contribute little to their work.  They represent a legacy structure that no longer serves NWS needs and waste substantial resources.

Another major improvement would be to combine/colocate the River Forecast Centers (RFCs) with the new regional forecasting centers, so that hydrological and meteorological forecasting would be integrated.   The current situation of keeping the meteorologists and hydrologists in separate centers never made sense.


NWS National Centers would also evolve.  The Weather Prediction Center (WPC) would give up its operational prediction activities to the regional forecasting centers. WPC would evolve to take on a much more important and creative role:   to serve as the national clearinghouse of new forecasting technologies and prediction techniques, while providing new tools to the regional centers.  The WPC would take on all the training functions previously covered by the present National Weather regional staff.  WPC would be a leader in the transition to probabilistic prediction.   It could also take on creation and maintenance of national forecasting tools, such as the ensemble "plume" viewers and High Resolution Rapid Refresh (HRRR) viewers created by the Storm Prediction Center.

An important note:   my suggestions do NOT necessarily mean a reduction in the NWS workforce, but rather the use of that workforce in a far more effective and creative way.  There are a lot of legacy structures in the NWS system--structures that may have made sense decades ago, but which are no longer really functional

I am sure that many in the community could greatly improve upon my above suggestions.   But two things I think are clear:   the current structure is hardly optimal and a careful evaluation of the way the NWS makes operational forecasts is both appropriate and necessary.


Thursday, July 16, 2015

Why won't a tropical storm EVER hit the Pacific Northwest?

The visible satellite image Thursday afternoon (see below) has a lot of interesting features, but none struck the eye like Hurricane Dolores moving up the Mexican coast (A).  There is also low clouds (stratocumulus/stratus) moving up the coast (B), clear skies where continental air is pushing offshore (D), and ship tracks, where particles from ship exhausts are producing lines of enhanced cloudiness (C).


Hurricane Dolores is prediction to move up Baja California  and reach the offshore waters west of San Diego by Tuesday AM (see graphic), but it will never reach us.


No tropical storm will ever reach our shores (as a tropical system that is).  The reason?  Because the eastern Pacific off our coast is too cold.

Hurricanes, Typhoons, and tropical storms in general require warm sea surface temperatures, specifically, above roughly 80F or 27 C.

Here is a recent sea surface temperature analysis over the eastern Pacific.   The 27C contour is the at the boundary between yellow and yellow/green.  The hurricane will soon enter a region that is too cold for development....and the system should progressively weaken.    No tropical storm can even get close to us.

If you look carefully, you will see cold water off of New England as well.   Rarely, a tropical storm has reached them (e.g., the great 1938 storm) but only because the very warm Gulf Stream gets close, so tropical storms can maintain their strength until the end, after which they start to weaken rapidly.

Will things change under global warming?  No chance.   Remember this year has much warmer than normal water offshore and we are not even in the neighborhood.  Even more important is that our average sea surface temperature (around 50F) is roughly 30F colder than the minimum.  So it won't even be close- sea surface temperatures might become 5-10F warmer in a century---not anywhere close to 80F.

But the water temperatures around Hawaii are on the margin, so they will have to be watchful.





Tuesday, July 14, 2015

The Warm Pacific Helps Keep the Northwest Toasty

If one looks at the recent temperatures at Northwest stations for the past month,  one is struck by the fact the minimum temperatures have persistently shifted towards warmer temperatures.  Let's look at  the proof:

 Here are the observed temperature at Quillayute, Olympia, and Sea-Tac Airport for the past 12 weeks.   The average daily highs and lows for the dates are shown by the red and blue lines, respectively.  Note how the low temperatures are consistently 5-8F above normal.
Why is this the case?   One reason is that we have had very warm water off our coast; the air reaching us has to transverse this warm H2O.   Here is the  sea surface temperature anomaly for the past 3 months. A lot of water around 3C (5.5F) about normal.
For the last week the water has been even warmer! (see below)
Our low level air passes over this warm water for thousands of kilometers and warms up;  thus, the low temperatures at night are very sensitive to the offshore water temperature.   During the day when the surface is heated and air is mixed in the lower atmosphere, the upper air temperatures are much more important.

To prove this to myself, I decided to have some modeling fun....to play god with the atmosphere! Dave Ovens, who runs the WRF modeling at the UW,  took one of our real-time forecasts and replaced the warm sea surface temperatures over the Pacific with the lower climatological sea surface temperatures.  Here is the difference in the sea surface temperatures between the two runs we tried, one with the actual warm warm and the other with the normal cooler water (see below)  The time for the start of the simulations is 4 PM April 24, 2015.


All we changed was the surface surface temperatures.    Here is the difference in surface air temperature for the 168h (7 day) forecast.  The temperatures over our region warmed up by 2-3C.

We did a few other runs, with similar results.

Another contributor to the warmth has been the ridge of high pressure over the West Coast and eastern Pacific--a ridge that has been crazy persistent.  And to complete the circle, most of the warm sea surfaces over the eastern Pacific resulted from the high pressure over the West Coast.