Thursday, February 11, 2016

Wacky Icicle Does Not Seem To Know About Gravity

One of the best things about doing this blog is the interesting pictures folks send me.   This week Anne Fox sent along a startling picture of some icicles from her cabin in Winthrop (see below).   This icicle curved upward and them curled around in a circle.   If you look carefully, there are a few more that had a similar behavior.


How could this be?  Icicles should be directed towards the ground as gravity acts on the melting water.!

I had my theory about this, but asked for more pictures with additional perspectives (see below).  Before the spoiler, think about this yourself.




My hypothesis.   Snow fell on the roof and temperatures starting to warm.  The snow started to flow slowly down and off the roof, with some icicles on below the leading edge as melted water refroze below.  Yes, icicles that WERE directed downward.  Naturally, the snow layer, under the influence of gravity, started to bend downwards as it extended off the roof.  Away from the relatively warm roof or because the exposure to the sun changed, the snow layer cooled and refroze, maintaining the curve.  As more snow pushed off the roof, the snow layer in the air below naturally had an increased curvature, causing the icicles on its leading edge to slow turn upward.   Perhaps because of warming air or because the icicle got close to the warmer post (darker colors absorb solar radiation better), the tip of the icicle started to curve downward, producing the strange curved tip.

Anyway, I am open to other explanations for these amazing pictures.    Could persistent wind contribute to curving?  Even aliens, if you can make that work.

This case of highly curved icicles, although unusual, is not unique.  Here is an example from a cabin near Truckee, CA:


Northwest Weather Workshop

The big local weather workshop is less than a month away (March 4-5, Seattle).  If you are interested in attending, the agenda and registration information can be found here.

Tuesday, February 9, 2016

Super-Inversion Over Western Washington

I was going to call it Inverzilla, but perhaps that is getting old....
But the truth is that today we have one of the strongest inversions I have ever seen here in Seattle.

Take a look at the temperatures above Seattle this morning.   The inversion (temperature increasing with height) is incredible. 13C increase between the surface and 500 m (1640 ft).   That is 23F increase in 1640 ft!!

Can you imagine taking a hike up one of our foothill peaks?  It would be amazing.  Cold at the bottom and sweating at the top!

The inversion is so strong because temperatures have warmed up aloft, a very strong offshore pressure gradient developed (producing strong subsidence/compression warming on the western slopes), and cool/foggy air is trapped at low levels.  The Space Needle Cam this morning showed the shallow cold/foggy layer very well.


I love the Space Needle Cam and today there was a spectacular optical effect visible...what is known as a glory surrounding the shadow of the top of the Space Needle.  You see the rainbow-like circular ring of colors?  Sort of like a rainbow halo.  That's it.


Glory's are found opposite the sun  and result from a combination of reflection, refraction and diffraction of sunlight by a field of cloud droplets of similar size.   One sees this effect all the time from airplanes.  But not the Space Needle.

Another amazing observation....Paradise on Mt. Rainier got into the lower to mid 60s yesterday and today.  Here is the proof:


Finally, the warmth above us today is very, very unusual.  Here is the plot of this morning's temperature at 850 hPa (about 5000 ft) over Quillayute, WA.   The warmest on record for an January, February, or March day!
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Northwest Weather Workshop

The big local weather workshop is less than a month away (March 4-5, Seattle).  This is the big regional meeting to talk about Northwest weather. If you are interested in attending, the agenda and registration information can be found here.



Monday, February 8, 2016

Mid-summer Air over the Northwest

The air above us is so toasty, that it is warmer than normal even for July!  And associated with this unusual warmth is an amazingly intense inversion--which in turn created some strange optical effects.

First, the high temperatures today.  Lots of locations got to 60F, but some places  in the western foothills of the Cascades and Olympics surged to 70F and more, as warm air aloft subsided and warmed by compression.


Like 80s?  No need to go to Mexico or Hawaii...a drive to the coastal foothills near Tillamook would have done it.

We broke some all time daily records for temperatures at 850hPa (around 5000ft) today. Here is the climatology of 850 hPa temperatures at Quillayute (UIL) on the WA coast for the 0000 UTC (4 PM PST) radiosonde launch time.  The grey dot is today   The top red line is the  DAILY record--we beat it.  The black line is the average.  Today, we were well above the average temperatures for mid-summer.   If there had been summer sun, we would have been in the 80s near sea level.

With warm air aloft, and residual cool air at the surface, there was a very strong inversion (temperature increasing with height) above us....here is the plot of temperature (degrees C) over NE Seattle this morning every hour from 4 AM to 10 AM.  Time are in UTC (the one ending in 18 is 10 AM).  Temperatures increased about 10C (or about 18F) between the surface and 800 m (about 2500ft).  Would have been fun to climb one of the foothills peaks this AM...the contrast would have been amazing.
Strong inversions can have optical effects, distorting visible light so that objects seem to loom in the vertical.    Richard Burte of Snoqualmie sent me this one, from a park at 600 ft there.  If you look closely,  you will see some strange distortions of the Olympics.  The work of the inversion.


Well, if you liked today, wait until tomorrow....the latest UW WRF hi-res model forecast for 2 PM suggests lots of 70s in the foothills.  Much cooler in eastern WA.

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Northwest Weather Workshop

The big local weather workshop is less than a month away (March 4-5, Seattle).  If you are interested in attending, the agenda and registration information can be found here.

Saturday, February 6, 2016

National Weather Service: Time to Fix the Stampede Pass Weather Station!

One of the most important weather stations of our area has been offline for the better part of last year, and was intermittent at best during the previous years:  the National Weather Service's  Stampede Pass weather station.  Located at 4000 ft at Stampede Pass in the central Washington Cascades, this reporting location provides key information for pilots, travelers across the mountains, and those attempting to understand how climate change is impacting the weather of our region.


To orient you, here is a map of the station's position.    Stampede Pass is a full National Weather Service/FAA ASOS station, with very high quality instrumentation.  In addition to standard observations (like temperature, pressure, and winds), it has a ceilometer (tells the altitude of the cloud base), freezing rain sensor, visibility sensor, and precipitation type sensor.  The ASOS observation system is the gold standard in the U.S., located at major and minor airports around the nation.


For civil aviation, the Stampede Pass weather station has been very important, since Stampede is one of the lowest passes across the Cascades and represents a relatively straight shot, unlike the dangerous hairpin turns of Snoqualmie.  Having ceiling and visibility information is important for flight safety.  

Stampede Pass provides a detailed view of the weather at crest level and helps characterize the meteorology of the central Cascades.   There is nothing remotely like it.  The NW Avalanche Center and WSDOT have some sensors at ski areas and on major roadways, but these have less weather parameters, often have poor exposure (e.g., the WSDOT roadway sensors), and are sometimes not available (avalanche sensors during the summer).   



In these days of concern about global warming, Stampede Pass is unique:  a high-altitude weather station in an area without development that goes back a very long time--in this case, since June 1935. Extraordinarily valuable and a terrible loss to have data collection there interrupted.

So what is the current situation?   The sensors are fine and being maintained.  The observations are being taken.  But the National Weather Service has had severe problems maintaining communication (i.e., telephone lines) to the station and the 1980s technology of ASOS observations can not store information for long.  Thus, not only is the information being lost for operational use, it is being lost for climate studies.  Very bad.

Take a look at a plot of temperatures at Stampede Pass (SMP) for the past few years.   You will see the big gaps.

Fixing the communications to Stampede Pass has been relatively low priority for the National Weather Service.   In January, there tried to set up an alternative approach using cell phone communication, but failed.  Perhaps one of the tech firms in town could help.

A major problem for Stampede Pass, and virtually all National Weather Service/FAA ASOS observations, is that the communications/data technology is from the 1980s.  I was at the Seattle NWS forecast office and they showed me how they communicate with local ASOS stations (in this case, Boeing Field).    They had to use an ancient 9600 baud telephone modem.   You remember those, with the blinking lights and strange sounds?   For younger folks probably haven't seen them, here is what one looks like.   They probably have them in Paul Allen's computer museum.


The National Weather Service and FAA need to modernize the data handling for the still important ASOS observational system, using 2016 data loggers, digital storage, and communication.  This is not rocket science and not expensive.

I think it is time for those of you who are interested in Stampede Pass to let NWS management know about your concerns.  The NWS Western Region is responsible for Stampede Pass:  so they are the ones to contact.  They have a web page to leave comments on:

http://www.nws.noaa.gov/survey/nws-survey.php?code=WRH

 The director of the NWS Western Region is Grant Cooper (grant.cooper at noaa.gov)
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Thursday, February 4, 2016

Ridgezilla

The radioactive revenger has visited the U.S. in many forms during past year,  including Godzilla El Nino and Snowzilla.   But starting on Sunday, the fearsome monster will morph into a terrifying RIDGEZILLA, a weather phenomenon of amazing strength and persistence.

Sunday morning at 8 AM?  Huge ridge of high pressure over the U.S. (this upper level map is for 500hPa)

8 AM Monday?   Still here and even stronger.
 Tuesday at 8 AM?  You guessed it.

A view on Monday at 1 PM shows that there are troughs on both sides of the ridge.  The result is ann an omega block, since it looks like the greek letter omega, and is very stable and hard to change.

This is a very dry pattern for the West Coast, so that once a front moves through on Saturday morning, we will rapidly dry out and stay dry.  But the eastern U.S. will become very cold as strong northerly flow moves arctic air southward.  

If we get some offshore flow on Monday and Tuesday and don't fog out, temperatures could climb to 60F and above, particularly over the southern portion of WA.  With the strengthening sun, it will feel like spring.

To illustrate, here are the temperatures at 1 PM Monday.  70s in California and southwest Oregon.  Sixties getting into southwest WA.

Clearly, Ridgezilla  has a hot breath!



Tuesday, February 2, 2016

California Reservoirs Filling Rapidly After Heavy Precipitation

If you enjoy vegetables, fruit, and wine from California at a reasonable price, this has been a good week for you.  Heavy rain has been hitting the mountains of northern CA and the Sierra, with many reservoirs filling rapidly.    Let me show you.

Here is the  precipitation over the past 7 days over the southwest U.S.  Some locations in the northern Sierra range have gotten over 6 inches of liquid water, as have the coastal mountains over the northwest corner of the state.  Not too much to cause flooding, but enough to provide large volumes of water.

California has a LOT of reservoirs with a huge, multi-year, storage capacity.   A nice summary of some of the major reservoirs are shown below.


The three biggest reservoirs are Lake Shasta, Lake Oroville, and Millerton Lake;  Folsom Lake is near the precipitation maximum.   Looking at the big Kahuna first, Lake Shasta, one sees a precipitous and huge increase in water storage (the blue color shows average levels for various times of the year).   Impressive.


The second largest reservoir shows a similar, but more modest, large increase.
But if you really want to be impressed, take a look at Folsom Lake--now above normal!

And even with the substantial atmospheric river activity, the California snowpack has been maintained at above-average levels.


California is going to have be content with their watery bounty for a while, since the circulation is shifting with more ridging along the West Coast and rainfall moving back towards the Northwest.   To illustrate, here is the 10-day total precipitation from the NWS GFS model. Plenty in our mountains and enough to keep northern CA moist, but nothing over the southern half of the state.


It will be cold enough for lots of snow in our mountains.  The Northwest drought is over and I suspect the same will be said for California in a few months.

Sunday, January 31, 2016

Stop the El Nino Forecast Complaints!

I have been bombarded by complains from folks regarding the El Nino forecasts.

Wasn't El Nino going to bring dry weather?   Less snow in the mountains?

Complain after complaint.

But the truth is that the forecasts have actually been really quite good, with a lot of the misunderstanding coming from media folks that have not gotten the story quite right.

As they say in sports....let's go to the video tape.


Last summer, meteorologists were sure that a strong El Nino was going to occur this winter.  And we knew what this typically for NW weather:

Before January first there is no real correlation with precipitation or temperature.
After January 1, the Northwest tends to be warmer than normal, with precipitation SLIGHTLY below normal, little snowfall near sea level, and modestly below normal snow in the mountains, resulting in the snowpack on April 1 ending up around 80% of normal.  There is also a tendency after January 1 to have a trough over the northeast Pacific, with California ending up wetter than normal.  We also forecast that El Nino would kill the BLOB.

Don't believe me?  Check my blogs on
Sept 2Dec. 28...and many others.  Nick Bond, WA State Climatologist, was saying the same thing, as were many other local meteorologists.

Believe it or not....reality has followed these predictions quite closely.

The BLOB is dead, as shown by the latest sea surface temperature analysis, with modestly warm water immediately off the coast (typical of El Nino) and cooler than normal water offshore (blue colors).  Good forecast.

At the end of December WA snowpack was huge...about 150% in places.   Now, things have relaxed back to near normal in the Northwest, while California is above normal (see below).  Snowpack percentiles have dropped substantially in the Cascades.  The forecast is right on track.


Folks have been complaining about all the rain around here, lately, BUT IT ALWAYS RAINS A LOT IN JANUARY in our area.  Here is the precipitation departure from normal for the last 30 days.  Slightly drier than normal on the western slopes  the Cascades, but considerable wetter than normal over northern CA.  Good forecast.
 
Temperatures?   Warmer than normal over western WA and Oregon.  As predicted (although eastern Montana and North Dakota are cooler than normal, and usually El Nino brings warmth then).   Not perfect overall, but good over the Northwest!

Snowfall over the lowlands?  Much lower than normal...just a dusting one day here in Seattle.   Excellent forecast.  

What about the flow pattern over the eastern Pacific and western North America?  Here is the anomaly (difference from normal) at 500 hPa (upper level around 18K feet) for the past month. CLASSIC EL NINO circulation, with a negative anomaly (low heights or  pressure, purple color) over the eastern Pacific. Truly excellent prediction.

One could quibble about details, but PLEASE give meteorologists some credit...we got this one basically correct.

A hell of a lot better than political pundits and the Presidential election!

El Nino is not the end of the world in our area.    And a typical El Nino year is way better than the crazy ridge pattern of last year, a pattern that we believe is the result of natural variability.

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Please support KPLU's fund drive to allow it to survive. The link.  On Friday, they reached a major milestone:  one million dollars.  But they need to raise seven million to avoid destruction.   A good segment on the race to save KPLU was broadcast on Friday, found here.


Friday, January 29, 2016

The Finest Hours Storm of February 17, 1952




A weather-related movie opened today, one I saw earlier this week at a studio preview: the Finest Hours, the story of an extraordinary rescue of the crew of a tanker that split in two off the coast of Cape Cod on February 17-18, 1952 during a very powerful nor'easter.

In this movie, Coast Guardsman Bernard Webber and three volunteers headed offshore near Chatham, Massachusetts in a 36-foot wooden motorized lifeboat in 60-foot seas and 70-knot winds, rescuing 32 crewmen from the stricken tank vessel Pendleton.

This was a very strong storm, noted for heavy snowfall offshore and destruction of not one, but TWO, World War II era ships in the offshore waters.  As a meteorologist, I was curious about this powerful cyclone and tried to find some weather information.   Let me show you what I found.

Turning to the NOAA/NWS historical surface map website, I first found the surface chart for 7 AM Sunday, Feb. 17th (see below).    This map shows the fronts, sea level pressure, and areas of precipitation (shaded).  You will note a weak low along the Delaware coast, with a central pressure of around 1004 hPa.

One day later, the storm had exploded, deepening in to an intense midlatitude cyclone with the central pressure dropping to around 977 hPa (below is a general and close-up view).  That is 27 hPa in 24 hr, which means this storm can be classified as an explosive deepener or bomb.    Explosive deepeners are defined as storms that intense more than 24 hPa in a day.  The low at this time is just south of Cape Cod, with heavy snow and strong winds over coastal Massachusetts. 12-30 inches of snow accumulated with 43 weather-related deaths.



At the Boston Airport (some distance from the strongest winds), sustained winds hit 50 mph and the gusts would have hit 60-70 mph.   Worse over the water.  Pressure dropped to 989 hPa at Boston, with temperatures in the lower 30s,

Snow was intense NE of the low center;  as shown below, Portland Maine had it 4th worst snow event in the entire observational record:

1) 31.9" Feb. 8-9, 2013
2) 27.1" Jan. 17-18, 1979
3) 25.3" Feb. 17-18, 1952
4) 23.8" Jan 26-28, 2015

The upper level flow pattern (500 hPa, around 18,000 ft) showed a sharp trough over the eastern US on Sunday AM:
The upper trough rapidly deepened into an amazingly intense upper level low over the next 24 h.

There was no weather satellites or operational weather radars during that period....sorry.

The Feb 1952 was a powerful storm and certainly in the top 50 for nor'easter events.  But it was't in the first tier and certainly far weaker than Sandy or other mega-events.

Movie Comments:   A B picture which starts VERY slowly with a boring relationship angle.  Not much talk about meteorology.   A shame really.