Wednesday, November 16, 2016

Lots of Snow Today But the Long- Term Outlook is Not Favorable

As promised, the combination of cooler temperatures aloft coupled with an unstable, showery air mass, has resulted in substantial (several inches to a foot) of snow mainly above 4000ft.  Compare the snow depth at 10 PM Sunday and Tuesday...quite an increase.


 

Cam shots Wednesday show Steven Pass and Paradise on Mt. Rainier looking quite wintery.  Stevens got 9 inches today--a good start.



For the next 72 hr, residual snow showers will bring only modest amounts to the  Cascades.

The following 72 hr brings much more substantial snow to the north Cascades and mountains in BC.


Why so little over the more southern Cascades?   The air will being getting much warmer as the persistent troughing over the northeast Pacific is reestablished.

The Climate Prediction Center's 6-10 day forecast (below) illustrates the problem--warmer than normal conditions over the Pacific Northwest and Rockies.


And the offshore troughing (low pressure) is illustrated by the upper level (500 hPa) for 7 PM on Friday evening.  With a strong low offshore, strong southerly/southwesterly flow moves northward into our region bringing warmer air.


Now I am worried about the mountain snow pack this winter.   We start with a weak La Nina that transitions into neutral conditions by early 2017.  This would typically bring near normal snowpack over the Cascades.

But there is something else going on for the past month: the persistent troughing off the west coast and inland ridging, and the latest model runs suggest it will remain in place during the next few weeks.  The higher elevation (about 4500 ft) and more northern areas (e.g., Whistler) might be salvaged, but the lower areas will have a problem developing a base.

My own rough rule of thumb is that when the temperature rises above 50F in Seattle, rain will invade the lower ski areas of our region.  Keep that in mind the next few days.
___________________________________

Announcement:  Meeting of the Puget Sound Chapter of the American Meteorological Society at 10 AM Saturday Nov 19 at  Seattle's Lake City Library.

As many of you know, a potentially historic wind storm was forecast to impact the Pacific Northwest on October 15th. Ultimately, the experienced winds were  lower than predicted.  Many wondered what went wrong--was it the forecasts, poor communication, or what? National Weather Service's Andy Haner, UW's Cliff Mass and KOMO's Scott Sistek will be presenting about the ides of October Storm windstorm.  In addition, we will have discussions about future meetings, general elections and, of course, refreshments!  Anyone interested in weather is invited.

Getting to the Library:

 http://www.spl.org/locations/lake-city-branch/lcy-getting-to-the-branch

14 comments:

Sulla said...

Predict warm winters and you're likely to be more right than wrong. There's a different culprit every time. The Blob has now been replaced by this persistent trough, but the result is the same. Warm winters. I'd be interested to hear the last time that SeaTac airport had as many Winters in a row with so little snow accumulation. Hopefully the mountains do better.

cgt said...

I always think below 47 in Bellingham equals wet snow at Mt. Baker Ski Area. If it warms during the day, which it usually does, then the lower parking experiences freezing rain or worse and the top half of mountain may have some wet snow accumulation.
Still builds a wet solid/dense base to build upon.

Terry McDonald said...

Looking at 7-14 day weather forecasts for Vancouver and other parts of BC... I'm not seeing this... yet? ; looks pretty average temp and precip for this time of year. If we have a similar jet stream set up like had throughout much of October the BC mountains should do quite well; albeit perhaps not great at lower elevations ? ... But if we continue to just get hammered by a barrage of pineapple express systems and super mild weather like the first 10 days of November, then we'd be screwed. I hope that is not what you're predicting?

Brian Blackmore said...

"Tests with the expanded 4/3-km domain have been successful. We will continue to run the new domain and closely monitor its reliability. D. Ovens 3:45 pm PST 11/16/2016."

Has it expanded an additional 12hr (to 72)?

Buddy said...

I'm staying more optimistic with the possibility of stronger cool zonal flow the Euro is suggesting towards Thanksgiving weekend. We finally hit near the freezing mark last night in eastern Washington. We average 32 on October 20 and currently the average low is 26 so this was our first freeze in that period. Remarkable.

richard583 said...

.. I'm looking at main colder air mass('s being at a cyclical recess where considering a basic more inner-seasonal cycle of expansion south and recession more back north, set to begin to move and spread south again, daily more at the point.

mig said...

We only rarely have decent skiing before Dec. 15th or so. November is often a frustrating mix of big snow and big melt. What's the best guess for the holidays?

Ansel said...

We're just too warm for decent, reliable skiing. Unlike the Rockies, we've always been on the razor's edge of being cold enough. We don't have a safety margin: If we depend on snow for water and winter recreation, and this is the "new normal" under Global Warming, we're toast. I hope "the Donald" is listening.

sunsnow12 said...

And yet, as you pointed out in May, Stevens Pass "...melt out dates are trending later (which implies cooling or greater snowpacks or both)." (Blog post 5/25/16). Snoqualmie Pass showed the same trend.

It seems a little premature to be sounding the warning bell on snowpack. One thing is for sure: our reservoirs are not lacking for water. Neither is California. Shasta at 105% of normal.

Bill Reiswig said...

It's crazy warm in the arctic as well...https://www.washingtonpost.com/news/energy-environment/wp/2016/11/17/the-north-pole-is-an-insane-36-degrees-warmer-than-normal-as-winter-descends/?hpid=hp_hp-more-top-stories-2_ee-northpole-624pm%3Ahomepage%2Fstory&utm_term=.67d5fd88b2f0

sunsnow12 said...

"If we depend on snow for water.."

Yes... but we don't. We depend on precipitation for water. This has been discussed multiple times on this blog by Cliff. The 14/15 water year was a good example of what happens under an (extremely) low snowpack - SPU finished that water year with 20 billion gallons of surplus water. Cliff posted on the bogus drought claims as well, including the infamous "wet drought" claims (12/19/15).

As was noted on this blog back in May re: Stevens Pass: “There is no evidence of a long-term trend for earlier melt-out dates. In fact, just the opposite....melt out dates are trending later (which implies cooling or greater snowpacks or both)”. (5/24/16) The same is true for Snoqualmie Pass.

In other words, the trend is up, as supported by data, for either cooling or snowpack or both, even including the snowpack shortfall of the 14/15 water year.

It seems a little early to be sounding an alarm here. One thing is for sure today: we do not have a shortage of water and it is not close. Our reservoirs are as full as they can be for this time of year (only flood control prevents them from being topped off.) California is wet as well. Shasta at 105% of normal.

Alex and Phoebe said...

Update for snow!!!

Just read the NOAA forecast discussion, which calls for 3000' snow levels next Tuesday through Thanksgiving! Read below:
http://forecast.weather.gov/product.php?site=SEW&issuedby=SEW&product=AFD&format=CI&version=1&glossary=1

I also checked the models and the extended GFS looks great! Looks like several feet of snow for the WA and OR Cascades by Friday 11/25!!! Fingers crossed!

Eric Blair said...

Well, the latest forecast for the mountains near Portland are calling for over two feet of fresh snow come Black Friday. Much colder temps and another storm coming in on Wednesday, hope it pans out.

John A said...

GFS runs for the next 2 weeks show wave after wave of storms hitting the NW coast and even down into California. Not sure what the worry is. Even if it's warmer than usual, should still get plenty of precipitation:
http://www.tropicaltidbits.com/analysis/models/