January 30, 2020

Heavy Mountain Rain, River Flooding, and Then a Major Cool-down

There will be plenty of action during the next week---more than I can possibly describe in this blog.

We start with a modest atmospheric river--a plume of enhanced low-level moisture--aimed at our area on Friday and early Saturday (see below), bringing substantial rain to the Olympics and north Cascades.

Atmospheric moisture early Friday evening, reds and white indicate high values--the 
atmospheric river

This atmospheric river will result in substantial rain over the next 48h, as shown by the figure below (accumulated precipitation through 4 PM Saturday).  Over 5 inches over the upper windward slopes of the Olympics and north Cascades.   Much less rain in the lowlands, with a dramatic rainshadow centered south of Port Townsend.  This is not a record-breaking rain event, but typical of the stronger ones we have several times a winter.

This rain is falling on saturated ground and flowing into rivers that are already high.  The past 72 hr have been quite wet over the southwest Olympics, mountains of Vancouver Island, and the north Cascades (see below), with many of these regions receiving 3-5 inches.

With wet ground, high river levels, and substantial rain, some flooding is inevitable, particularly since warm air and strong winds will accompany the heavy rain.  Such warmth will melt some of the lower-elevation snow, contributing to rising rivers.

 The latest forecasts of the Portland River Forecast Center predictions project major flooding (purple diamonds) on several rivers draining off the central and northern Cascades, and moderate or nominal flooding on several others (see below).

To further illustrate the flooding potential , here is the predicted river levels for the Snoqualmie River at Carnation.  A very rapid rise on Friday and Saturday to a peak level of roughly 58 ft, roughly ten feet above normal.  Followed by a rapid fall.

On late Saturday, cold air will flood into the region.  Trust me, you will notice it.  Not quite as cold as last time, but cold enough to bring large amounts of snow to the mountains, and a chance of lowland snow in some areas (particularly if a Puget Sound Convergence Zone forms on that day).

I will leave the snow and cold analysis to Saturday, when I can provide a more accurate forecast.  And that gives me enough time to pick up milk, eggs, and bread. 😊

January 28, 2020

The Western Washington Swamp

If it were only a bit warmer, we might gators around here.  After incessant rain, grass is like mush, water is ponding and accumulating everywhere, landslides have started, the rivers are flooding, and the aroma of wetness is everywhere.

A typical scene in North Seattle

Western Washington is more like a swamp than a high-tech center, and much, more precipitation is coming.   A little over a month ago, some folks were talking about a progressive drought for our region.  The drought talk has ended.

Some amazing statistics were noted by my colleagues at the National Weather Service this morning (see below)---nearly every day this month has rained and a number of observing sites will break their all-time record for number of days with rain in January.  Quillayute, Hoquiam, and Olympia will all beat the record, Seattle may tie it.

And the rain totals have been extraordinary as well.  Quillayute, on the NW coast, has received 22.63 inches so far this month, 9.31 inches above normal.  Sodden Olympia has been wetted by 13.76 inches, 6.62 inches above normal.  Some monthly records will be broken along the coast and southwest Washington.

Rivers throughout the region are either flooding or soon to flood, as shown by the following graphic from the NWS Portland river forecast center.  Moderate flooding is expected for major rivers draining westward from the central and northern Cascades.

And much more is coming.  The latest infrared satellite picture shows a huge plume of moisture and clouds extended across the Pacific....this moisture is heading our way.

During the next 90 hours (through 4 AM Saturday), the European Center model shows heavy precipitation accumulating over the western slopes of the Cascades, Olympics and coastal mountains, with some places drenched by 3-6 inches.    Flooding will be widespread.
 But what is really scary, is the European Center ten-day total (below).  Just unbelievable, with some locations in the Olympics getting 10 inches of rain.

This month essential guarantees enough water to get through the summer, both through total precipitation and the substantial snowpack.  But the flooding will be serious and everyone should be careful about driving on flooded roads.   There will be road closures from slides...you can bet on it.

And yes, I know some critters that will be very happy during the next few weeks.

January 26, 2020

The Future of U.S. Weather Prediction Will Be Decided During the Next Month

During the next few weeks, leadership in NOAA (the National Oceanic and Atmospheric Administration (NOAA) and the National Weather Service (NWS) will make a key decision regarding the future organization of U.S. numerical weather prediction.  A decision that will determine whether U.S.  weather forecasting will remain third rate or advance to world leadership.   It is that important.

Specifically, they will define the nature of new center for the development of U.S. numerical weather prediction systems in a formal solicitation of proposals  (using something called a RFP--Request for Proposals).

This blog will describe what I believe to be the essential flaws in the way NOAA has developed its weather prediction models.  How the U.S. came to be third-rate in this area, why this is a particularly critical time with unique opportunities, and how the wrong approach will lead to continued mediocrity.

 I will explain that only profound reorganization of how NOAA develops, tests, and shares its models will be effective.  It will be a relatively long blog and, at times, somewhat technical, but there is no way around that considering the topic.  I should note that this is a topic I have written on extensively over the past several decades (including many blogs and an article in the peer-reviewed literature), given dozens of presentations at professional meeting, testified about  in Congress, and served on a number of NOAA/NWS advisory committees and National Academy panels dealing with these issues.

The Obvious Problems

As described in several of my previous blogs, U.S. numerical weather prediction, the cornerstone of all U.S. weather prediction, is behind other nations and far behind the state-of-the-art.   Our global model, the GFS, is usually third or fourth ranked; behind the European Center and the UK Met Office, and often tied with the Canadians.

We know the main reason for this inferiority:  the U.S. global data assimilation system is not as good as those of leading centers.  (data assimilation is the step of using all available observations to produce a comprehensive, physically consistent, description of the atmosphere).

The U.S. seasonal model, the CFSv2, is less skillful than the European Model and is aging, while the U.S. is running a number of poorly performing legacy modeling systems (e.g., the NAM and Short-Range Ensemble System).  Furthermore,  our global ensemble system has too few members and lacks sufficient resolution.  The physics used in our modeling systems are generally not state-of-the-art, and the U.S. lacks a large, high-resolution ensemble system capable of simulating convection and other small-scale phenomena. Finally, operational statistical post-processing, the critical last step in weather prediction, is behind that of the private sector, like weather.com or accuweather.com. 

The latest global statistics for upper air forecast skill at 5 days shows the U.S. in third place.

There is one area where U.S. numerical weather prediction is doing well:  high-resolution rapid refresh weather prediction.  As we will see there is a reason for this positive outlier.

The generally inferior U.S. weather modeling is made much worse by NOAA's lack of computer resources.  NOAA probably has 1/00th of what they really need, crippling NOAA's modeling research as well as its ability to run state-of-the-science modeling systems.

Half-way Steps Are Not Enough

Although known to the professional weather community for decades, the inferiority of U.S. weather prediction become obvious to the media and the general U.S. population during Hurricane Sandy (2012), when the European Center model provided a skillful forecast days ahead of the U.S. GFS.  After a number of media stories and congressional inquiries, topped off by a segment on the NBC nightly news about abysmal state of U.S. weather prediction (see picture below), NOAA/NWS leadership began to take steps that were funded by special congressional budget supplements.

New computers were ordered (the U.S. operational weather prediction effort previously possessed only had 1/10th the computer resources of the Europeans), an improved hurricane model was developed, and NOAA/NWS began an effort to replace the aging U.S. global model, the GFS.   The latter effort, known as the Next Generation Global Prediction System --NGGPS, included funds to develop a new global model and to support applicable research in the outside community.

During the past 8 years, there has been a lot of activity in NOAA/NWS with the goal of improving U.S. weather prediction, and some of it has been beneficial:

  • NOAA management has accepted the need to have one unified modeling system for all scales, rather than the multitude of models they had been running.
  • NOAA management has accepted the idea that the U.S. operational system must be a community system, available to and used by the vast U.S. weather community.
  • NOAA management has increased funding for outside research, although they have not done this in an effective way
  • NOAA has replaced the aging GFS global modeling system with the more modern FV-3 model.
  • NOAA has made some improvements to its data assimilation systems, making better use of ensemble techniques.
  • Antagonistic relationships within NOAA, particularly between the Earth System Research Lab (ESRL) and the NWS Environmental Modeling Center (EMC) have greatly lessened.

But with all of these changes and improvements in approach, U.S. operational weather prediction run by NOAA/NWS has not advanced compared to other nations or against the state-of-the science.  We are still third or fourth in global prediction, with the vaunted European Center maintaining its lead.  Large number of inferior legacy systems are still being run (e.g., NAM and SREF), computer resources are still inadequate, and the NOAA/NWS modeling system is being run by very few outside of the agency.

This is not success.  This is stagnation.

But why?  Something is very wrong.

As I will explain, the key problems holding back NOAA weather modeling can can be addressed (and quickly), but only if NOAA and Congress are willing to follow a different path.  The problem is not money, it is not the quality of NOAA's scientists and technologists (they are motivated and competent).  It is about organization.  

Let me repeat this.  It is all about ineffective organization.

With visionary leadership now at NOAA and the potential for a new center for model development, these deficiencies could be fixed.  Rapidly.

The REAL Problems Must be Addressed

So with substantial resources available, the acute need for better numerical weather prediction in the U.S., and the acknowledged necessity for improvement, why is U.S. numerical weather prediction stagnating?  There are several reasons:

1.  No one individual or entity is responsible for success

Responsibility for U.S. numerical weather prediction is divided over too many individuals or groups, so in the end no one is responsible.  To illustrate:

  • The group responsible for running the models, the NWS Environmental Model Center (EMC), does not control most of the folks that develop new models (located OUTSIDE of the NWS in NOAA ( the ESRL and NOAA labs).  
  • Financial responsibility for modeling systems is divided among several groups including OSTI (Office of Science and Technology Integration) and OWAQ (NOAA Office of Weather and Air Quality), and a whole slew of administrators at various levels (head of the National Weather Service, head of NCEP, head of EMC, NOAA Administrator, and many more).

U.S. weather prediction is not the best?  No one is responsible and fingers are pointed in all directions.

2.  The research community is mainly using other models, and thus not contributing to the national operational models.

The U.S. weather research community is the largest and best in the world, but in general they are NOT using NOAA weather models.  Thus, research innovations are not effectively transferred to the operational system.

The National Center for Atmospheric Research in Boulder, Colorado

Most American weather researchers use the weather modeling systems developed at the National Center for Atmospheric Research (NCAR), such as the WRF and MPAS systems.  They are well documented, easy to use,  supported by NCAR staff and large user community, with tutorials and annual workshops.  Time after time, NOAA has rejected using NCAR models, decided to go with in-house creations, which has led to a separation of the operational and research communities.   It was a huge and historic mistake that has left several at NCAR reticent about working with NOAA again.

There is one exception to this depressing story:  the NOAA ESRL group took on WRF as the core of its Rapid Refresh modeling systems (RAP and HRRR).  These modeling systems, not surprisingly, have been unusual examples of great success and state-of-science work in NOAA.

3.  Computer resources are totally inadequate to produce a world-leading numerical weather prediction modeling system.

NOAA currently has roughly 1/10 to 1/100th of the amount of computer resources necessary for success.  Proven technologies (like 4DVAR and high-resolution ensembles) are avoided,  ensembles (running the models many times to secure uncertainty information) are low resolution and small, and insufficient computer resources are available for research and testing.

Even worse, NOAA computer resources are very difficult for visitors to use because of security and bureaucracy issues, taking the better part of a year, if they are ever allowed on.

There is a lot of talk about using cloud computing, but there is still the issue of paying for it, and cloud computing has issues (e.g., great expense) for operational computing that requires constant, uninterruptible large resources.

With responsibility for U.S. numerical weather prediction diffused over many individuals and groups, no one has put together a coherent strategic plan for U.S. weather computing or made the case for additional resources.    Recently, I asked key NWS personnel to share a document describing the availability and use of NWS computer resources for weather prediction:  no such document appears to exist.

4.  There is a lack of careful, organized strategic planning.

NOAA/NWS lacks a detailed, actionable strategic plan on how it will advance U.S.  numerical weather prediction. How will modeling systems advance over the next decade, including detailed plans for coordinated research and computer acquisition.  Major groups, such as the European Center and UKMET office, have such plans.  We don't.   Such plans are hard to make when no one is really responsible for success.

NOAA has tried to deal with the lack of planning by asking  U.S. researchers to join committees pulling together a Strategic Implementation Plan (SIP), but these groups have been of uneven quality, have tended to produce long laundry lists, and their recommendations do not have a clear road to implementation.

5.  The most innovative U.S. model development talent is avoiding NOAA/NWS and going to the private sector and other opportunities.

U.S. operational weather prediction cannot be the best, when the best talent coming out of our universities doesn't want to be employed there.  Unfortunately, that is the case now.  Many of the best U.S. graduate students do not want to work for NOAA/NWS--they want to do cutting edge work in a location that is intellectually exciting.

EPIC:  The Environmental Prediction Innovation Center

Congress and others have slowly but surely realized that U.S. numerical weather prediction is still in trouble want to deal with this problem.  To address the issue, Congress passed recent legislation (The National Integrated Drought Information System Reauthorization Act of 2018 ), which instructs NOAA to establish the Earth Prediction Innovation Center (EPIC) to accelerate community-developed scientific and technological enhancements into operational applications for numerical weather prediction (NWP).  Later appropriation legislation provided funding.

Last summer, NOAA held a community workshop regarding EPIC and asked for input on the new center.  There was strong support, most participants supporting a new center outside of NOAA.  The general consensus:  it will take real change in approach to result in real change in outcome.  They are right.
Two Visions for EPIC

There are two visions of EPIC and the essential question is which NOAA will propose in its request for proposals to be released during the next month.

A Center Outside of NOAA with Substantial Autonomy and Independence

In this vision, EPIC will be an independent center outside of NOAA.  It will be responsible for producing the best unified modeling system in the world, supplying the one point of responsibility that has been missing for decades.

This EPIC  center would maintain advisory committees that would directly couple to model developers, and should have sufficient computer resources for development and testing.   It would build and support a community modeling system, including comprehensive documentation, online support, tutorials, and workshops.

 Such a center should be in a location attractive to visitors and should entrain groups at NCAR and UCAR (like the Developmental Testbed Center).  It will maintain a vibrant lecture series and employ some of the leading model and physics scientists in the nation.

EPIC should be led by a scientific leader of the field, with a strong core staff in data assimilation and physics.  This EPIC center will be able to secure resources from entities outside of NOAA (although NOAA funding will provide the core support).

Such an EPIC center might well end up in Boulder, Colorado, the intellectual center of U.S. weather research (with NCAR, NOAA ESRL lab, University of Colorado, Joint Center for Satellite Data Assimilation, and more), and there is hope that UCAR (the University Corporation for Atmospheric Research) might bid on the new center.  If it did so and won the contract, substantial progress could be made in reducing the yawning divide between the U.S research and operational numerical weather prediction communities.

The Alternative: A Virtual Center Without Independence Or Responsibility

There are some in NOAA that would prefer that the EPIC center would simply be a contractor to NOAA that supplies certain services.  It would not have responsibility for providing the best modeling systems in the world, but would accomplish NOAA-specified tasks like external support for the unified modeling system and fostering the use of cloud computing.   It is doubtful that UCAR would bid on such a center, but might be attractive to some "beltway bandit" entity.   This would be a status-quo solution.

The Bottom Line

From all my experience in dealing with this issue, I am convinced that an independent EPIC, responsible for producing the best weather prediction system in the world, might well succeed. It is the breakthrough that we have been waiting for.

Why?  Because it can simultaneously solve the key issues that have been crippling U.S. operational numerical weather prediction centered in NOAA:  a lack of single point responsibility, that complex array of too many players and decision makers,  and the separation of the research and operational communities, to name only a few.

A NOAA-dependent virtual center, which does not address the key issues of responsibility and organization, will almost surely fail.

And let me stress.  The problems noted above are  the result of poor organization and management.  NOAA and NWS employees are not the problem.  If anything, they have been the victims of a deficient organization, working hard to keep a sinking ship afloat.

The Stars are Aligned

This is the best opportunity to fix U.S. NWP I have seen in decades.  We have an extraordinary NOAA administrator (Neil Jacobs) for whom fixing this problem is his top priority (and he is an expert in numerical weather prediction as well).  The nation (including Congress) knows about the problem and wants it fixed.  The President's Science Advisory (Kelvin Drogemaier) is also a weather modeler and wants to help.  There is bipartisan support in Congress.

During the next month, the RFP (request for proposals) for EPIC will be released by NOAA.  We will then know NOAA's vision for EPIC, and thus we will know whether this country will reorganize its approach and potentially achieve a breakthrough success, or fall back upon the structure that failed us in the past.

January 24, 2020

Super RainShadow

Sometimes the precipitation contrasts in our area can be mind blowing, and today was such a day.

During the past 24-48 h, we have observed extremely heavy rain on the southwest side of the Olympics, with a super-rain shadow to the northeast.

Below is total precipitation over the past 48 hours (ending 7 PM Thursday).

Remarkable. On the southwest side of the Olympics, totals are as high as 9.45 inches, while just downstream of the barrier on the lee side (the Port Townsend area) one site only received .01 inch.

Let me put it another way.  There was nearly one thousand times more precipitation on one side of the Olympics than over the other.   With huge differences in rain over very small differences.

You will notice that precipitation was relatively low from Seattle northward to the San Juans and then picks up substantially on the western side of the Cascades.

This pattern was evident in regional weather radar imagery, with the view at 7 PM Wednesday night providing a good illustration.

A high-resolution visible satellite image earlier today strongly suggests a lessening of the clouds northwest of the Olympics....in fact, some luck folks undoubtedly caught a glimpse of the sun, while the rest of us were immersed in the darkness, gloom, and rain.  You can see why retirees like Sequim, Port Townsend and northern Whidbey Island.

The explanation for this contrast?  That's easy.  Strong, moist southwesterly flow was approaching the Olympics and was forced to rise by the barrier.  Such lift causes the air to cool and release the bountiful water vapor of the approaching flow.   In contrast, on the northeast side of the barrier air descends and warms by compression.   This causes the relative humidity to drop and precipitation to evaporate.

Finally, I should note that our computer models nailed this pattern, as illustrated by the forecast for the three-hour precipitation ending 7 PM tonight.    Very nice rain shadow, with lots of rain on the upstream side of the Olympics.

January 22, 2020

Tornado Warning on the Washington Coast, Tornado on the Oregon Coast

One coast has a weather radar, which facilitated warning of a potential tornado.

The other coast had no radar coverage, allowing a tornado to strike without warning.

Yesterday (Tuesday), very unstable air mass with strong convection (thunderstorms) made landfall on the Northwest coastline. 

The visible satellite image from the NASA MODIS satellite around noon showed lines of strong convection approaching the Oregon/Washington coast (see below)

Why so active?  Cold air was moving over water water, which created a large temperature change with height that in turn produces substantial instability--the tendency of the atmosphere to convect.

Roughly an hour before this satellite image, a funnel cloud was observed off of Manzanita, Oregon (on the northern coast) and around 11:15 AM it made landfall as a tornado, causing minor damage.   No tornado warning was provided.  This was a weak tornado:  an EF-0 with winds gusting to 65-75 mph.

One reason there was little warning, is that there is very limited no low-level radar coverage over the Oregon coast, something made obvious by the weather radar map at around 11:15 AM Tuesday.

The Washington State coastal zone is well covered by the Langley Hill radar near Hoquiam, but there is no National Weather Service radar on the Oregon coast.

In contrast, around 5 PM yesterday, the National Weather Service in Seattle provided a tornado warning for the area around Hoquiam and Aberdeen, based on the the Langley Hill radar.

Why did they distribute this warning?  Because the Langley Hill radar picked a collection of intense thunderstorm cells (see below) and some of the some of the cells possessed some rotation--something known as a mesocyclone.

At this point, there are no reports of a tornado--but the potential was there.

Interestingly, Manzanita, on the northern Oregon coast, seems to be a tornado hotbed, with another funnel hitting the town in 2016.  Sounds like my kind of place for a beach vacation!

More seriously, it is outrageous that the Oregon coast has virtually no radar coverage.  Such coverage would not only help protect coastal residents, but would give a heads up for approaching storms for the densely populated Willamette Valley and Puget Sound regions.

January 20, 2020

Crazy Temperature Spikes in Bellingham

Folks around Bellingham have been noting some wild temperature swings, with temperatures warming by 15-25F over an hour or two, before dropping back to the previous level. These features, known as "temperature spikes" in the weather business, are frequently noted in certain areas of the  Northwest.

Let me illustrate what happened by showing you the temperatures at Bellingham during the past few days (see below).   On 14th and 15th temperatures were in the teens, as uber cold air from the interior of British Columbia, pushed through the Fraser River Valley and then over Bellingham and northwest Washington.  Temperatures slowly warmed on the 16th.  But suddenly over one hour, temperatures surged 20F to 45F.   Instant defrost.    But then temperatures dropped just as suddenly two hours later, back to the low 20s.    Startling.

On the 17th temperatures dropped back down to 15F and everything froze solid again. But that would not last long. First, temperature rose rapidly to around 30F and held around 30F for much of January 18. But later that day, temperatures surged 15F in one hour to 45F, rose to near 50F, and then dropped back to 35F over one hour.  How weird is that?

So what is going on?   How can temperature rise and fall tens of degrees in an hour?

To get a hint, let's plot the wind direction at Bellingham for the same period.

Ah ha!  For most of the period, winds at Bellingham were from the northeast, associated with cold, arctic air flowing out of the Fraser River Valley.  But look carefully.   There was a switch to southeasterly winds early on the 16th when temperatures started to warm, and a sudden spike to easterly winds later on the 16th when the temperatures surged!  And later on the 18th there was a sudden shift to southerly winds associated with the sudden warm-up on that day,

A better approach is to look at local weather maps before and after.    At 1 AM on the 16th, cool northeasterly air was over the Bellingham.

But by 3 AM, strong southeasterly flow had surged in bringing warm air (see below).  But the cool air was not far away.  A meteorological battle was going on between cold and warm airstreams!

A similar situation occurred two days later. 

So why this big change on the 16th?  As shown below (surface map at 10 PM that day), a strong low center approached on the 16th.  On one hand this low produced a large pressure difference between high pressure in British Columbia and the low center, which would tend to produce cold northeasterly flow in the Fraser Valley.  But the low center also resulted in strong southerly/southeasterly flow over the lowlands, and for a few hours that warmer, southerly flow was dominant--thus the surge in temperatures.  After the low moved through, the cold northeasterlies returned to Bellingham.

Other areas of Washington State can also get large temperature swings.   For example, shallow cold air in eastern Washington can be rapidly displaced by strong downslope flow from local mountains.  And Portland can have rapid temperature changes depending on the air flow in the Columbia River Gorge.

You can imagine the future impacts of these huge temperature swings.

January 18, 2020

Why Were the Snow Forecasts So Challenging During the Past Week?

This has been a hard week for meteorologists, with multiple threats of cold and snow.  Some aspects of the forecasts worked out, some did not.    For example, Seattle Public Schools cancelled classes, but the predicted snow did not show up.   I have gotten a number of emails asking:  why were the snow forecasts so good last February, but not so good this time around?

I will try to answer these questions in this blog.  A big message will be that my profession needs to work harder to communicate the uncertainty of our forecasts, and society needs to learn how to use it.

The successes

Well before the snow and cold hit, Northwest folks were warned.   Days ahead of time, meteorologists warned you that the weather pattern would shift, that cold and potentially snow would hit the lowlands, and that the mountains would get hit hard by huge amounts of snow.  Check my blogs of January 6 and January 7 if you need proof. The mountains did get massive snow, it did get colder, and the lowlands would get some snow.

The problems

But there were the problems.   Although we correctly forecast cooling, our models went too far, predicting temperatures 3-8F too cold.  The convergence zone snow on Sunday night was stronger and farther north than expected. And the snow band on Tuesday night was shifted 50-75 miles farther north than predicted, leaving Seattle pretty much snow free, while NW Washington had a major event.

Why did we seem to do so much better last year?

Last February represented a tour de force of snow prediction for our region.  But many of the events were relatively easy, since cold air was in place and the precipitation was associated with relatively large scale systems approaching the region (e.g., fronts, large low-pressure centers).   The large systems are easier to forecast and the precipitation areas were large (see satellite image from last February).

But that was not true of last week.   We had far more difficult to predict, smaller-scale features to contend with.  Last Sunday, a Puget Sound convergence zone was the key feature, in which small errors regarding the winds on the coast could greatly alter the position and intensity of the low-level convergence (between air coming in the Strait of Juan de Fuca and flow passing around the south side of the Olympics).   Not surprisingly, the excellent European Center model got the position/intensity better than the American models.

Then there was the unusual, small precipitation band that moved off the Pacific on Tuesday (see picture)

This small feature came barreling in, but the forecasts were off by 50-75 miles.  The Olympics (and Port Angeles) got hit hard--which was forecast--but the southern edge shifted north, leaving Seattle high and dry.  The more northern shift became evident during the early evening, but Seattle decided to cancel schools based on the earlier forecast.   

A communications failure mode we need to work on

Consider the Tuesday situation.   The models WERE showing lots of uncertainty--something I noted on my blog discussing the situation.    To illustrate, here is the ensemble of many model snow forecasts for that period for a location in Seattle (North Seattle near Magnusson Park).  HUGE variation in forecasts from very little to six inches.  Uncertainty was large.  We need to communicate this better.

And the fact that the high-resolution  models started backing off for Seattle snow after 6 PM was another sign of non-event over the city.  What Seattle Schools and others should have done was to hold on their decision to close the schools (or other events) until later in the evening, perhaps starting with a few hour delay.    The University of Washington waited to decide and keep the university going the next day.    Dealing with such uncertainty and securing the latest forecasts is one reason we created SnowWatch for city of Seattle.  I hope others will use it.

Lowland snow forecasting is always challenging in our region, since it involves the unusual occurrence of cold and precipitation at the same time.  But improving forecast models, coupled with the communication of uncertainty, should help society make better decisions.

January 16, 2020

Huge Increase in Northwest Snowpack and Water Resources

A month ago, there were considerable concerns about the Northwest snowpack.  True, mid-December is too early to get worried, since there is a long history of poor December snowpack leading to bountiful snowpack by April 1.  But snowpack was sparse in December and folks were nervous.

 Below is the snowpack summary from the SNOTEL network on December 14, 2010.

Not good.  The Olympics and western slopes of the Cascades were at roughly 33% of normal, as was the eastern slopes of the central WA Cascades.  Only a small portion of the region (mainly SE Oregon) was at normal or above (green and blue colors).

Fast forward to this morning (January 16th).  Wow.  No more red colors (less than 50% of normal) and most of the region is green.  Huge improvement.

The meteorological bounty extended beyond snow.  There has been lots of rain that has helped to fill local reservoirs.   For example, consider Seattle's reservoir system (see below).  Its reservoirs have surged--not only WAY above normal (blue line), but as high as typical as the normal high in June.  Seattle will have plenty of water in the future.

 That confidence is supported by Seattle's watershed snowpack (below), which only a few days ago was almost exactly at normal.

Much more water is coming!  Here is the predicted precipitation through Tuesday at 4 PM, which shows wet conditions from California to British Columbia.

 And much of that will go into snowpack (note substantial amounts in the Cascades and Sierra Nevada.

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