Late Winter Heat Wave With a Twist

 It felt like spring today in western Oregon and Washington, with some temperatures soaring into the 60s.

The high-temperature map for today (Wednesday) reveals low 60s east of Puget Sound and along the Washington coast and UPPER 60s along the Oregon coast.   In contrast, eastern Washington and Oregon were much cooler, with temperatures stuck mainly in the low to mid-50s. Even some 30s on the eastern slopes of the Cascades.

A close-in view around Puget Sound shows the contrasts (below), with 65F in Carnation, near the western footfills of the Cascades, but ten degrees cooler over western Seattle.

For many locations, this was the warmest day so far this winter.

So why was the coast so warm? Why so warm over the eastern suburbs of Seattle?

One can get a hint by looking at the regional sea level pressure pattern this afternoon at 2 PM (see below).  Relatively high pressure inland and lower pressure along the coast.

The pressure pattern forces easterly winds (from the east), directed from high to low pressure.

Such easterly winds remove the cooling effects of the Pacific.

It also produces downslope flow on the western side of the Cascades and coastal mountains.  This downslope flow produces localized warming as the air is compressed as it moves from lower pressure aloft to higher pressure near the surface.  Warming just like in your bicycle pump.

You can see this downslope warming effect in the temperature forecasts of the UW WRF model for 10 AM this morning/ Reds areas are the warmest temperatures.

At this time, the warmest temperatures are on the western slopes of regional terrain due to the downsloping, sinking air.  You can also see cool air (blue colors) being pushed up the eastern slopes of the Cascades.

Tomorrow should remain relatively warm over Western Washington south of Everett and over all of western Oregon but somewhat cooler along the coast as the easterly winds weaken.

Similar conditions on Friday, followed by a slow cool-down over the weekend.  Dry at least through Saturday.

Time to get the garden cleaned up or to enjoy that long-neglected outdoor recreation.

Announcement

I will hold a special online Zoom session at 10 AM on Saturday for Patreon supporters. I will talk about the extended spring forecast and new AI forecasting technology.

The great disappearing low. Where will it go?

 The infrared satellite image tonight is impressive, with a beautiful convergence of clouds into the low center west of the Olympic Peninsula (see below).

But you have to feel sorry for this low:  it is collapsing as it approaches landfall.

All of the modeling systems agree on the collapse, but there are subtle differences model solutions.

And that will influence what happens to us.

 For example, the American GFS model at 4 PM today (Monday) showed a potent low center of 972 hPa central pressure:

But my 7 AM Tuesday it was a wimpy 1003 hPa.   Sad.

The NOAA HRRR model forecast for the same time (7AM) is about 1000 hPa and the low center is a bit further to the west:

While the UW WRF model has a 999 hPa low a little further to the east.

Finally, the uber-accurate European Center model drops the low to about 1000 hPa and takes it over Sequim.

You would think that such a disappearing low would not produce any winds of note over western Washington.  

But yet Seattle WindWatch, which presents a whole range of forecasts, is still going for decent winds over Seattle (see below, these are the strong winds ANYWHERE in the City, even close to the water).  Gusts to 30-40 mph are found in many models, with some going into the 40s.  

One thing that is helping maintain the winds is that there is relatively high pressure to the south so that even a poor excuse for a low can produce a large north-south pressure difference and strong winds.

But like the late-night commercial...there is more!   

As the low passes to the north, winds from the west will hit the Olympics and they descend on the NE side of the barrier.  As the air sinks, it warms by compression, which causes pressure to fall (warm air is less dense than cold air).  

As shown in the forecast map pressure map for  7 AM, the mini-low is predicted by the UW WRF model on the NE side of the Olymics, which contributes to a locally enhanced pressure gradient (change of pressure over distance) over western Seattle and the Kitsap area. 

A wind boost due to the terrain.

This kind of situation on steroids occurred in 1979 during the Hood Canal Storm, when a mini-low formed south of Port Townsend, resulting in winds reaching 100 mph (see below).  

Washington State residents had a very expensive bridge replacement after that.

Will there be a big windstorm tomorrow night?

 Update Tonight

There is an interesting ultra-local potential twist to this event.... a Hood Canal twist.   The storm is going to rapidly weaken and staff as it makes landfall, with it exact location making a big difference on the localized winds.

________________ 

I have gotten over a dozen emails asking about a potential storm.  The amateur sites are going into overdrive talking about the birth of a "monster storm" and other over-the-top descriptions.

So let's examine what the latest model simulations are predicting.

Before I do that, let me note that it was quite windy during the last several hours as a strong trough of low pressure moved through, creating a large north-south pressure difference over western Washington (see model forecast for 7 PM).  The solid lines are isobars of constant sea-level pressure.

This large pressure change produced some serious wind gusts (see max wind today below), reaching an impressive 63 mph at Paine Field in Everett.   Several thousand customers have lost power.

This is an appetizer for the meteorological buffet tomorrow.

Let me show you a series of forecast maps of sea level pressure for tomorrow.  We are close enough in time that this forecast should be reliable.

At 1 PM, an impressive-looking low center, with a central pressure of 982 hPa, is found west of northern Oregon.  For some perspective, this is not even close to the central pressure of the "bomb" cyclone in November (which got down to around 940 hPa).

By 10 PM tomorrow (Monday) night, the low has weakened slightly (to 987 hPa) and has moved towards the central Washington coast.    Very strong pressure difference (and thus winds) along the Oregon coast.

By 4 AM Tuesday, the low has weakened to 996 hPa and is crossing the Olympic Peninsula.

By 7 AM Tuesday, the low had weakened to 1002 hPa and located near Everett.

At 1 PM Tuesday, the low had greatly weakened and was now in NE Washington.

If this forecast is correct, Puget Sound will not see a major blow.  

One thing I have learned about such events is that rapidly weakening lows are rarely big wind producers.  Also, the trajectory of the low is not optimal for strong winds over Puget Sound and NW Washington.  Too far south.

Looking at the highest winds predicted during this event (below), the northern Oregon coast looks like the place to be for a strong blow, with gusts reaching 65 kt.   It's not so exciting over the western WA interior.  Gusts to 30-40 mph perhaps.

But a good forecaster never forgets about uncertainty and the forecast of this storm has varied quite a bit over the past several days.   One way to explore this uncertainty is by looking at ensembles of many forecasts.  

For example, the ensemble of many forecasts for wind at Seattle indicates that most of the solutions are for only modest sustained winds of about 15 kt (12Z/25 is 4 AM on Tuesday, the black line is the average of many forecasts, and winds are at the surface in knots)

In any case, there will be plenty of precipitation, which our region needs.

Why do Atmospheric Rivers Occur?

A significant atmospheric river event will occur tomorrow (Sunday) and Monday, with heavy precipitation in the mountains and South Sound.

The latest UW WRF model forecast predicts up to 10 inches in the Cascades, with the southern WA Cascades being hit the hardest (see below).   In contrast, a profound rain shadow will extend from the NE Olympics to Bellingham. 

It is now clear that there will be some serious flooding in some locations. For example, the NOAA/NWS River Forecast Center is forecasting major flooding on the Snoqualmie River near Carnation.   

Want to see something spectacular?   Go to Snoqualmie Falls on Monday.  If you can get there.😁

Atmospheric rivers in our region are associated with plumes of warm, moist air from the south, southwest, and west.

NOAA weather satellites can sense the water vapor, which is very evident in the water vapor image from this morning (below).  A massive plume of water vapor is moving our way.

 

Numerical weather prediction models, like the UW WRF model, can skillfully forecast such water vapor plumes, which release massive amounts of water as the air is forced to rise by our region's substantial terrain.

Meteorologists favorite diagnostic for atmospheric rivers is integrated water vapor transport (IVT), which is the amount of water vapor times the wind speed, summed up in the vertical (that is where the integrated comes from).   This quantity is more closely related to the potential for regional rainfall.

The prediction of IVT for Sunday morning is shown below, with the arrows showing both the direction and magnitude of the moisture transport   Large values, but not record-breaking by any means.  

Such moisture plumes are generally warm as well.   In fact, to get large values they HAVE to be warm since the amount of moisture air can hold depends on temperature (warm air can potentially hold more water vapor than cold air).

Atmospheric rivers form in our region when strong southwesterly atmospheric wind currents occur, currents that move large values of water vapor out of the subtropics.

The atmospheric flow pattern that does this is usually characterized by a strong low-pressure area in the Gulf of Alaska and higher pressure west of southern California.

Not surprisingly, this is exactly the pattern forecast for Sunday morning at 10 AM for a level around 5000 ft  (below).  With high pressure to the south and low pressure to the northwest, a strong pressure/height change is created, which produces a strong southwesterly flow. 

The interesting thing about atmospheric rivers is that they are like regular rivers in another way...not only does water come into the river at the beginning, but there is a convergence of water vapor from the sides along the way, not unlike the small streams that drain into a river over its entire path.

 

Heavy Rain Coming This Weekend

Our dry period is about to end dramatically.

Several plumes of moisture... popularly known as atmospheric rivers--will make landfall on Saturday, Sunday, and Monday.

Reservoirs will get substantial inflow and several rivers will approach minor flood stage.

Consider the regional accumulated precipitation through Tuesday morning (below).

Wow.  Some parts of the Cascades and coastal mountains will get as much as ten inches of liquid water.

Zooming into Washington State, one can view the profound rain shadows downstream of the terrain.  One is located northwest of the Olympic Mountains and the other one...much larger in extent...is east of the Cascades.

Precipitation picks up again as it rises on the western slopes of the Rockies.

As noted earlier, this heavy precipitation is associated with a potent atmospheric river in which warm, moist air from the subtropics pushes northward into the region.  You can see this moisture plume on Sunday at 4 AM below, with the air coming from north of Hawaii.

Associated with this subtropical plume, the freezingly level will be as high as 9000 ft over SW Washington and 5000 ft over the north Cascades (see map below at 7AM Sunday).

With the influx of warm air, most of the precipitation below roughly 5000 ft will fall as rain and not snow during the weekend and Monday.  

The snowfall total through Tuesday morning (below) indicates that the higher elevations in the North Cascades do well with snow, but Snoqualmie Pass gets very little (mostly rain)

Finally, this pulse of precipitation, coupled with a high freezing level, will cause many regional rivers to greatly increase their flows, some to near flood level.  For example, the Snoqualmie River will rapidly surge to near flood level early next week (see below).

Anyway, this event will greatly aid in alleviating the dry conditions of the past month.

NOAA Is Critically Needed But Requires Reform

The meteorological and climatology community is going through a difficult period right now, with fears about cutbacks in NOAA (National Oceanographic and Atmospheric Administration) and related agencies.

The headlines in major and minor media are scary (see below), with much of the information without factual basis (such as the suggestion of 50% cuts in personnel).

The truth is that NOAA does critical and irreplaceable work. 

It is also true NOAA has fallen seriously behind in important areas, with an inefficient bureaucracy that has impeded progress.

NOAA needs to be retained but also requires serious reform.

NOAA's Importance to the Nation

NOAA does essential work, such as collecting important weather and climate information. 

 NOAA is responsible for many weather satellites as well as the backbone surface and upper air data upon which the entire weather forecast enterprise is based.

NOAA's National Ocean Service provides valued products from tidal and ocean level information to coastal surveys and support for marine sanctuaries.  

NOAA provides critical warnings that the private sector will not produce because of legal risks.

NOAA is filled with very competent and highly educated scientists and technologists.  I have and still work with many of them.

NOAA Needs Reform

But with all its strengths, NOAA is profoundly in need of serious reform and improvement.

Few NOAA products are as important as numerical weather prediction, but unfortunately, NOAA global prediction now greatly lags behind others in forecast skill and reliability (NOAA is now in fourth place).

National Weather Service forecasts (produced by local offices) are generally less skillful than the WeatherChannel, Apple, and leading private sector firms.

NOAA is well behind the European Center and private firms in using cutting-edge machine-learning approaches.

NOAA computer resources for weather and climate prediction are inadequate at best, limiting progress in improving forecast skill.

National Weather Service offices have been underfunded and understaffed for decades.  NOAA management has prioritized climate efforts over weather prediction for a long time.

And NOAA is an inefficient bureaucratic nightmare, with responsibilities divided among too many offices and individuals, with a lack of responsibility within one individual or group.  Too many folks in middle management.    The buck stops nowhere.

I could write volumes about NOAA deficiencies...and in fact, I have written two papers on the topic, testified in Congress on this issue, and served on several advisory committees.  

The dominant attention given to climate change work should give way to a more balanced research portfolio including ocean pollution, extreme weather, weather and ocean prediction, wildfire meteorology, and other important areas.

Finally,  NOAA is spending a lot of money on ineffective and divisive DEI and Social Justice activities that have little to do with its mission.

What The New Administration Needs to Do

Before starting any surgery, the new administration needs to understand the problems and strengths of the organization.  

NOAA needs to appraise what NOAA is doing well and where it lags.  Where reorganization is required and where its mission needs clarification.

There is no doubt that major change is required.

There are many in the weather, climate, and ocean community that are ready to advise, including the American Meteorological Society and those in the general community.  

We know what is wrong.  We know which NOAA closets have skeletons.   We know the steps needed to catch up in weather prediction.   DOGE needs to talk to us.

With strong leadership, a reorganized NOAA would provide the nation with the best environmental guidance in the world.

The Spring Transition Comes Early in the Northwest

Ask someone when spring starts and you expect to hear around March 20-22, during the time of the Spring Equinox.

But here in western Washington, the biggest transition generally occurs weeks earlier, generally during the past week in February or the first week of March.

Let me demonstrate this to you.

Consider lowland snow.    The figure below shows the daily average (green) and daily extreme (blue) snowfall in Seattle.  The red line indicates March 15.   

The big stuff is all in January.   We have enjoyed as much as 5 inches into early March, but only light snow after the first week of the month.

No snow days after March 7.  Sorry kids.

An early March end of snow  is also observed in the Tri-Cities (Richland shown below)

What about temperature?

Let's start with the daily averages for mean (brown), lows (blue), and highs (red) at Seattle. 

 Low temperatures stagnate until about February 20th, after which they steadily rise.  The average temperature is similar.    The highs start to rise earlier.

Very similar situation at Pasco (below), except the highs really start to rev up in February.

Why?  I suspect the substantial decline in low clouds and the increasing solar radiation in February are the explanations.

What about temperature EXTREMES?    I have an interesting story for you there.

In the figure below, the red color indicates the daily record highs, and blues the daily record lows.

For Seattle, early February represents the end of really cold temps (15F or less) and after early March, the low 20s are unattainable.   In January, highs have never reached the mid-60s but 80F has happened after the Ides of March.

For Passo, there is a near-step function in temperature in early March, when record highs consistently rising into the upper 70s while lows below 15F just don't happen anymore.

This year the atmosphere seems antsy to go through the spring transition.  In Seattle, temperatures will jump into the low to mid-50s by the end of the week.

And in Pasco, temperatures will surge to near 60F by next Monday.

The icing on the "spring transition" cake will be the beginning of Daily Savings Time on March 9th!   

The unbeatable combination of warmth and more evening sun.