Friday, September 4, 2015

The Eastern Washington Radar Gap: An Acute Need for Fireweather, Flood Forecasting, and Agriculture

In a previous blog, I discussed the large weather radar gap over the eastern slopes of the Cascades and nearby eastern Washington.  The map below shows the coverage at various elevations from the existing National Weather Service radars.  The eastern slopes of the Cascades and the adjacent portions of the Okanogan have no coverage below 10,000 ft.   Vast areas of eastern Oregon have no coverage, but few folks live there.  Coastal Oregon is also bad news.  The problem, of course, is the blocking effects of our mountains, coupled with radar beams that slope upwards away from the ground.


So why should you care?     First, did you know that weather radars are wonderful tools for seeing wildfires?   That weather radars can spot exploding wildfires at an early stage, helping to provide warnings to firefighters so they can get out of the way?  That the smoke plumes are prominent on National Weather Service radars?

Let me show you some examples.    Here is a view from the Spokane radar of some fires over the Okanogan at 7:02 PM on August 28th.


or how about the impressive plume from the Canyon Creek fire near Mt. Adams?  You see the colored area stretching towards the NE?  That is a smoke plume from the fire.

The closer the fire, the better it shows on radars, and my experience is that it doesn't take a big fire to be seen if the radar is close.  Weather radars scan frequently, roughly once every 5 minutes, so a rapid update is possible.

Imagine how helpful it would be if there were a few additional radars near the eastern slopes of the Cascades that would paint out fire positions and evolution in real time.   A potential life saver.

Wildfires show up well in weather radar

The eastern slopes of the Cascades may be a generally dry area, but they DO get very heavy thunderstorms, with torrential rains, mudslides, debris flows, and flooding.   Right now such events are hard to see on current radars because the beam is so high over the region (10,000 ft and more).


There are many cases of flash floods in Yakima, Kittitas, Chelan, and Okanogan Counties, some with substantial loss of life and property.




And then there is agriculture...the massive agriculture of the eastern slopes of the Cascades, with apples, grapes, hops, and many other crops worth billions of dollars per year.   Local weather radars would help provide accurate distributions of precipitation, warn of impending heavy rain, guide planting and spraying.

And then there is value of having the weather radar to guide folks in Yakima, Ellensburg, Wenatchee, and Omak in their daily lives.  To know when showers are approaching so they can get that visit to the park in, that bike ride, or whatever.  Folks on the western side have good coverage, why shouldn't those to the east of the Cascade crest enjoy the same benefits?

So how can the radar gap be fixed?  We need more radars!  The radars acquired for the eastern slopes do not have to be as expensive as those on the West, since heavy precipitation is not as extensive (bigger radars can handle attenuation of the radar beam better).   So more modest "C Band" radars would be appropriate.  I suspect two would do the job for the eastern slopes of the Cascades.    TV stations buy these radars all the time (including KING-5 and KCPQ in Seattle a few decades ago), so they are not that expensive.   Last time I priced them the cost was about a million a piece.

An eastern Washington group is starting to work on this project, including meteorologists at the Spokane National Weather Service office , representativesof Chelan County Public Works and Kittitas County, and local agricultural interests.


In the end it will take the intervention of Senators Maria Cantwell and Patty Murray, local congressional folks, the Governor, or others with access to resources to make this happen.  Perhaps the Secretary of the Interior, Sally Jewel, a long-time Northwestener who surely knows the issue, could help.

Enhanced weather radar coverage over the eastern slopes will rapidly pay back the modest cost of its acquisition and maintenance, and I believe save lives of wildland firefighers and others.  Hopefully, we can make this happen.

Wednesday, September 2, 2015

Godzilla El Nino Versus The BLOB: Who Will Win?

Environmental monster match-ups are familiar to many of you.

For example, who could forget Godzilla versus Hedorah, The Smog Monster?


And then there was the remarkable battle between Godzilla and the storm-producing Mothra

But many are enthralled with the outcome of the latest super-monster battle, this time a real one:

Godzilla El Nino versus The  Pacific Blob


The media is covering this battle with substantial attention, with headlines bannering the conflict in many outlets:




OK, let's deal with the big question.  Will Godzilla El Nino and the BLOB battle each other?   Or will they combine forces to produce the warmest period in NW history?  Or the stormiest?

Much is riding on this conflict and this blog will consider the potential outcome.

The Match-Up

On one hand, one of the strongest El Ninos in decades is developing, the Godzilla El Nino.    NOAA is so sure about its effects this winter that it is going for a 90% chance of a strong El Nino, which would make the Northwest warmer than normal, slightly drier than normal, with roughly 20-30% less snowpack than normal in the mountains.

El Ninos are associated with warmer than normal water in the central/eastern tropical Pacific and along our immediate coast.

Then there is the BLOB, the name affectionately given to an area of warm warm over the northeast Pacific.  There is strong evidence that the BLOB has warmed surface temperatures over the Northwest by 2-4C over the past year, contributing to our record high temperatures and lack of snow.

Together, will they destroy Northwest snow and normal weather?  Bring another torrid winter in our region?   Terminate our ski industry?

I suspect I know what will happen.

They will NOT combine forces.  They will fight,  and one will win.



Godzilla  

Just like in the movies,  Godzilla will become our ally.  And it makes sense that the mighty Godzilla will prevail.

Let me tell you why.


The BLOB, as documented in a nice paper by State Climatologist Nick Bond and colleagues was the stepchild of a huge area of high pressure along and east of the West Coast of the U.S.  High pressure resulted in less wind and mixing of the upper ocean layers, leading to reducing mixing of cooler sub-surface water to the surface.  Thus, the ocean surface was warmer than normal.  

The anomalous high pressure also resulted in less movement of cooler Pacific waters from the north.  Weaker cold advection in technical terms.

Here is an example of the sea surface temperature (actually the difference from normal, or the anomaly) associated with the BLOB.  BLOB is warm.

But now El Nino is forming...and not just any El Nino...a SUPER GODZILLA El Nino.    The warm waters over the central and eastern tropical Pacific associated with El Nino have a big impact on the global atmosphere, alternating the global circulation.  Let me show you.

Here is the typical sea level pressure anomaly associated with El Nino (the difference of pressure from normal).   Pressures are LOWER THAN NORMAL over the eastern Pacific (purple colors).  A BLOB KILLER.  Why?  Because it is exactly opposite of the pattern that produced the BLOB--- high pressure in the same area.
What do our latest seasonal forecast models predict?  Let me show you.

Here is the predicted sea surface temperatures for this winter.  A narrow zone of warm water immediately off our coast (which is typical of El Ninos), but no BLOB.  In fact, cooler than normal waters offshore.  You can see the very warm water over the central and eastern tropical Pacific...a sign of a powerful El Nino.
We are already seeing evidence of these changes.  The water in the central Pacific is cooling.  The ridge of high pressure over us has weakened and high pressure has established itself over the central Pacific.  Precipitation is increasing over our area.

And there are other signs in the sky that suggest my hypothesis is correct....



The BLOB is vulnerable.  And I believe that Godzilla El Nino will destroy it.  Nature is cruel.

What does that mean for our weather?  A strong  El Nino bring modestly warmer than normal temperatures, with a snowpack about 20% below normal.  Much better than last winter.  The correlation with Northwest precipitation is weak.  Less lowland snow and fewer major storms.  Enhanced precipitation over southern/central California.

In short, far more normal conditions than the weird weather we have experienced during the last year.  Our region should rejoice in Godzilla El Nino's strength.  But deep down we will be sad for the vanquished BLOB.






Monday, August 31, 2015

The Strongest Summer Storm In Northwest History

Saturday was a historic day during a historic summer.

On that day western Oregon and Washington was lashed by the strongest summer windstorm in its historic record.

A "perfect storm" that would bring respect during November ravaged the region, producing 40-50 mph gusts over Puget Sound, 60-70 mph gusts over NW Washington, and winds reaching 90 mph on the coast.   As the center of the low passed over Tatoosh Island, on the NW tip of the Olympic Peninsula, the pressure dropped to 986 hPa....extraordinarily low for August (see graphic)


This is the lowest pressure ever observed at this location in the historical record during summer, at least for the period (1984-2008) shown below.


Nearly a half million people lost power and even today tens of thousands are without electricity in the region (see map of Seattle outages at 9 PM Sunday).  Two people were killed by falling branches and several were injured.   Major roads were closed due to fallen trees. Damage is certainly in the tens of millions of dollars.

Power outages over a day later in Seattle

But the most amazing thing about this storm was when it took place:   the end of August.  

As far as my research has shown, there has never been a summer storm even close to this one for western Washington.   The most powerful summer storm EVER to hit our region.  A cause for wonder and amazement.  We are talking about a major midlatitude cyclone, whose winds and damage were spread over a large areas.

What is my basis for this claim?

I began by searching the most comprehensive site for major windstorm information, one created by Dr. Wolf Read.  My findings:  no comparable storm from May through September, in any year.

Then I went through all the coastal and buoy sites on the official NOAA site.


Nothing like it in the historical record at any of the WA coastal or NW Washington sites.

Consider Destruction Island on the WA coast.  The historic maximum gust  between May and September was 58 knots.  Yesterday, it rose to 78 knots.

West Point in North Seattle got to 48 knots yesterday.  The previous record was 38.5 knots  This was not only the biggest storm, but it smashed previous records.

Yesterday we experienced a radically different animal than we have ever seen during the summer here in the Northwest.   

 I know some folks will say this is due to global warming, represents the "new normal", or was due to the BLOB (the warm water off our coast).   At this point, there is no reason to expect that any of these hypotheses are true.  Climate simulations do not produce stronger midlatitude cyclones like Saturday's.   Natural variability can produce extremes and this is probably a good example.  I should also note the IPCC report on extremes (IPCC is the international group evaluating the impacts of greenhouse warming), had low confidence of any connection between global warming and changes in the regional intensity of midlatitude cyclones (like the one on Saturday).  A direct quote from their report Managing the Risks of Extreme Events and Disaster to Advance Climate Change Adaptation:

In summary it is likely that there has been a poleward shift in the main Northern and Southern Hemisphere extratropical storm tracks during the last 50 years. There is medium confidence in an anthropogenic influence on this observed poleward shift. It has not formally been attributed. There is low confidence in past changes in regional intensity. There is medium confidence that an increased anthropogenic forcing will lead to a reduction in the number of mid-latitude cyclones averaged over each hemisphere, and there is also medium confidence in a poleward shift of the tropospheric storm tracks due to future anthropogenic forcings. Regional changes may be substantial and CMIP3 simulations show some regions with medium agreement. However, there are still uncertainties related to how the poorly resolved stratosphere in many CMIP3 models may influence the regional results. In addition, studies using different analysis techniques, different physical quantities, different thresholds, and different atmospheric vertical levels to represent cyclone activity and storm tracks result in different projections of regional changes. This leads to low confidence in region-specific projections

But in the end it was perhaps fitting and expected that we had this storm.   The warmest and most unusual summer in Northwest history is capped by the most severe summer windstorm in recent record.  Large amounts of precipitation have quenched a dry landscape.   Air quality has been restored.  Many fires have been damped down.  A great anomaly requires a great correction. 

Yin and yang. 

Something to ponder.


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Saturday, August 29, 2015

Extraordinary August Storm

This is perhaps the strongest August storm on record---certainly the most impressive in my memory.

  Here are the maximum winds during the 24h ending 9 PM Saturday. 87 mph at Destruction Island on the central WA coast.  Lots of 60-70 mph gusts from Everett northward, with 40-50 mph being common over the rest of the region.


And here is a close-up view of the Puget Sound area.  Note...the zero winds should be ignored.


Nearly a half million folks lost power...perhaps the biggest wind-related August blackout in regional history. Why so many without power?  Strong winds, first storm of the season, and dry conditions (which appear to make trees more susceptible to limb loss).

Want to see something really amazing?  Here is the maximum hourly gust at Destruction Island.

It peaked at 78 knots. That is NINETY MILES PER HOUR.

And what about precipitation?   Here is the 24h amounts for the same period. OVER 4 inches over the SE side of the Olympics, with1-3 elsewhere over that range.  This will have a huge impact on the drought conditions there.  1-3 inches over the north Cascades,which will help knock back of the fires in that area.  Heavy amounts over SW Washington.


But it is NOT over yet. A large band of very heavy precipitation is now over western Washington (see radar).


And the forecast precipitation for the next 48h is considerable (several inches) over the Olympics and North Cascades (see map).


And plenty more rainfall after this period.

The Coastal Radar Sees the Storm Center

There is some amazing imagery this morning.    First, the infrared satellite imagery around 5 AM.  You can see the swirl of clouds around the low center.  Just a beautiful, classic storm.  A very deep low center (around 990 hPa) for this time of the year.


But now the real treat....here is a recent (8 AM) image from the Langley Hill radar near Hoquiam. You can clearly see the swirl of precipitation around the low center.   We get these images roughly every 6 minutes and they tels us exactly where this storm (and others) are located.  An extraordinary tools for local meteorologists.  I should show this to Senator Cantwell, who played a major role in getting the radar.


The latest NWS HRRR (High Resolution Rapid Refresh) forecast has the low deepening as it approaches us (to around 988 hPa) and passing over the NW tip of the Olympic Peninsula (see forecast for 11 AM)

Seattle WindWatch is always a good place to check out high wind situations in our area and its display of the UW wind forecast shows strong gusts (greater than 50 mph) over Puget Sound, the coast, and over NW Washington.  Over 40 mph possible over Seattle.

Some of you will lose power....sorry.  Charge your phones and devices NOW!

Friday, August 28, 2015

Major Autumn Storm Approaching--In Summer!

It is enough to put shivers down the spines of true Northwesteners.   Finally, some real weather.   Heavy rain, wind, and, yes, I suspect some power outages.

For the fires in the Olympics and the Cascades it should be the turning point.

The satellite imagery Friday evening was impressive (see below).  Lots of clouds, and a potent low center is developing in the swirl of clouds west of the northern CA.


Today was just a very slight taste of tomorrow.  Here is the total rain as of 8 PM Friday.  3/4 inch in the Olympics and North Cascades. Only light rain over the Sound...that will change.


The models are forecasting a deep low pressure center (for this time of the year, for sure) to be poised to approach our coast a 5 AM tomorrow morning (see plot).  This map shows the pressure and temperature pattern...with a very large pressure gradient south of the low.


One of the best ways to forecast is to use ensembles---using many forecasts, each a bit different.  Here is the ensemble "plume" diagram for sustained surface winds at Seattle.  Each color is a different model wind forecast and the black line is the average...the ensemble average.   Wow.  The sustained winds get to around 25 knots, which means gusts will get between 30 and 40 knots.


The time shown is in UTC (GMT), so the peak winds will be between 11 AM and 2 PM.  I was going to go fishing tomorrow with Greg Johnson of Skunk Bay fame, but put it off based on this forecast.  The latest UW WRF model gust forecast for 11 AM Saturday is very windy, with crazy strong gusts along the coast and over northern Puget Sound.  If you were thinking of going out there in a boat, think again.

 With lots of growth over the summer and some branches weakened by drought, I suspect there will some power outages tomorrow.  My friends at Seattle City Light are prepared...they will even have some extra crews ready to go!

Precipitation?   Here is a plot of cumulative precipitation this weekend  at Seattle for the various ensemble members.  1-1.5 inches at Seattle over the weekend is a good bet.


The 24h precipitation ending 5 PM is shown below:  1-2 inches in the Olympics and north Cascades....and this is not the end of it.


To be amazed, examine the 72hr rainfall totals starting 5 PM Friday--some locations in the N. Cascades and Olympics are predicted to get over 5 inches of rain!  2-5 over a lot territory.  The Paradise fire is a goner...as are the fires around Nehalem.



Enjoy the weather...I certainly will.

Thursday, August 27, 2015

Major Weather Shift Will Bring Substantial Rain And Help Bring Cascade Wildfires Under Control

The end of August often brings the entrance of a major weather system and a touch of fall, and this year will follow this pattern.

The atmosphere has been shifting into a different configuration the past week, and during the next few days a major transition will occur, with persistent strong troughing (low pressure) over the Northwest.  It will bring large amounts of rain to our mountains, knock back and end some of the fires, and allow firefighters to gain control of the situation for Cascade Mountain fires.   It will bring substantial water to reservoirs that have dropped to extremely low levels.

Want to be impressed?  Here is the forecast precipitation over the next 72h,  1-2 inches over that period for much of western Washington and the north Cascades.



 The next 72h?  As much or more over Washington's mountains.  The BC Cascades get hammered with 2-5 inches.


 Want to see a close-in view of WA precipitation for the 72h ending 5 AM Sunday?  The north Cascades and western slopes of the Cascades get hit very hard. This will have a HUGE impact on the fires along the eastern slopes of the Cascades.  Much of the Okanogan region will enjoy several tenths of an inch.


These storms should have a profoundly positive impact for the Cascade fires. There will be less rain over the Okanogan area and winds will pick up there (which is not good).  On the other hand, temperature will fall and humidity will rise over NE Washington.

So what is going on?  The persistent ridge that has given us warm temperatures and little precipitation has been shifting far out into the Pacific, leaving a series of troughs over the Pacific Northwest.  To illustrate, let me show you the upper level (500-hPa)  maps for several times for this weekend and next week.

Saturday morning:  trough over the eastern Pacific and big ridge to the west.


 Monday at 5 PM:  same general pattern.


 Wednesday afternoon, the trough has strengthened.


This change is not a one-day affair.  That is why it is so important.  It will end a chapter in this summer's fire season.  The latest NWS Climate Prediction Center's 6-10 day forecasts?   Much cooler than normal over the western U.S., with above-normal precipitation over the Northwest.



Fall is not here and eventually warmer conditions will return, but this will be the big break that many were waiting for--and expecting.   The strengthening El Nino is disturbing the atmospheric circulation in a way that is weakening the crazy-persistent West Coast ridge.  As I will explain in a future blog:  Godzilla El Nino will kill the BLOB.

Finally, I should note that the requests for water conservation have had a big impact here in Seattle, as shown by the accompanying graphs, folks are using less water and the reservoir levels have stabilized.  There will be some refilling during the next week.