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Potential first significant snowstorm

snowdude

By snowdude,
in Central/Western States

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snowdude

snowdude

Posted
Posted

For the past few days, computer models have been showing an Alberta clipper dropping down into Montana sometime next week and bringing with it some moisture and much colder air behind it. But the timing and intensity have been fluctuating drastically.

The latest computer models are looking better and better for the possibility of the first significant winter storm for portions of central Montana, including Great Falls and Helena for next Tuesday November 16th . The GFS and ECMWF look the most bullish for snow, while the NAM is still weaker. Obviously, it's still too early to make any predictions but the possibility exists for the first winter storm of the season. Just thought I'd put it out there. Also, the first Arctic outbreak is likely sometime shortly after this storm.

Stay tuned...

GFS (78hrs-90hrs)

post-98-0-51599000-1289637567.jpg

post-98-0-49755300-1289637583.jpg

post-98-0-91759000-1289637595.jpg

ECMWF(Valid Tuesday)

post-98-0-38679400-1289637642.jpg

NAM(84hrs)

post-98-0-80195200-1289637659.jpg

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snowdude

snowdude

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Winter Storm Watches up for the Tuesday storm and Advisories for tonight. Models don't look as impressive as before, but still look good.

MTZ012-050-051-053-055-142200-/O.NEW.KTFX.WW.Y.0037.101114T1800Z-101115T1200Z//O.NEW.KTFX.WS.A.0008.101116T0000Z-101117T0000Z/CASCADE-JUDITH BASIN-FERGUS-BROADWATER-GALLATIN-INCLUDING THE FOLLOWING LOCATIONS...GREAT FALLS...KINGS HILL PASS...STANFORD...LEWISTOWN...LEWISTOWN DIVIDE...TOWNSEND...BOZEMAN...BOZEMAN PASS...WEST YELLOWSTONE...TARGHEE PASS339 AM MST SUN NOV 14 2010...

WINTER WEATHER ADVISORY IN EFFECT FROM 11 AM THIS MORNING TO5 AM MST MONDAY FOR ELEVATIONS ABOVE 4500 FEET......WINTER STORM WATCH IN EFFECT FROM MONDAY AFTERNOON THROUGH TUESDAY AFTERNOON...THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A WINTER WEATHER ADVISORY FOR ELEVATIONS ABOVE 4500 FEET FOR SNOW...WHICH IS IN EFFECT FROM 11 AM THIS MORNING TO 5 AM MST MONDAY.

A WINTER STORM WATCH HAS ALSO BEEN ISSUED. THIS WINTER STORM WATCH IS INEFFECT FROM MONDAY AFTERNOON THROUGH TUESDAY AFTERNOON.

FOR THE WINTER WEATHER ADVISORY...

* TIMING AND MAIN IMPACT: SNOW...MODERATE AT TIMES...WILL DEVELOP OVER THE HIGHER ELEVATIONS TODAY AND CONTINUE INTO TOMORROW MORNING. VISIBILITIES WILL BE REDUCED AND ROADWAYS COULD BECOME SNOW COVERED AND SLIPPERY.* SNOW ACCUMULATIONS: 2 TO 4 INCHES OF SNOW ARE EXPECTED ACROSS THE HIGHER TERRAIN.

* WINDS AND VISIBILITY: VISIBILITY COULD DROP TO LESS THAN ONE HALF MILE AT TIMES DUE TO HEAVIER SNOW SHOWERS.* ELEVATIONS: SNOWFALL SHOULD MAINLY EFFECT ELEVATIONS ABOVE 4500 FEET.

* LOCATIONS AFFECTED INCLUDE: BOZEMAN...BOZEMAN PASS...WEST YELLOWSTONE...TARGHEE PASS...STANFORD...LEWISTOWN... LEWISTOWN DIVIDE...KINGS HILL PASS.

A WINTER STORM WATCH HAS ALSO BEEN ISSUED. THIS WINTER STORM WATCH IS IN EFFECT FROM MONDAY AFTERNOON THROUGH TUESDAY AFTERNOON.

* TIMING AND MAIN IMPACT: SNOW...HEAVY AT TIMES...WILL DEVELOP OVER THE AREA MONDAY NIGHT AND CONTINUE THROUGH THE DAY TUESDAY.

* SNOW ACCUMULATIONS: SNOW ACCUMULATIONS GREATER THAN 6 INCHES WILL WILL BE POSSIBLE OVER THE LOWER ELEVATIONS WITH LOCATIONS IN THE MOUNTAINS POSSIBLY RECEIVING OVER A FOOT OF NEW ACCUMULATION.

* WINDS AND VISIBILITY: GUSTY NORTH WINDS WILL OCCUR DURING THIS EVENT...ALONG WITH HEAVY SNOW FALL AT TIMES. THIS WILL BRING VISIBILITIES DOWN TO LESS THAN ONE QUARTER MILE AT TIMES.

* LOCATIONS AFFECTED INCLUDE: BOZEMAN...BOZEMAN PASS...WEST YELLOWSTONE...TARGHEE PASS...STANFORD...LEWISTOWN... LEWISTOWN DIVIDE...TOWNSEND...GREAT FALLS... AND KINGS HILL PASS.

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baroclinic_instability

baroclinic_instability

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Seriously, what the heck is up with Great Falls? Everything goes around it.

Great Falls will get snow. High res models almost always underestimate snowfall in valleys with powerful shortwaves and strong cold fronts. If you followed a high res model all winter, some valleys would never get precipitation.

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Mallow

Mallow

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Great Falls will get snow. High res models almost always underestimate snowfall in valleys with powerful shortwaves. If you followed a high res model all winter, some valleys would never get precipitation.

I have used the Washington WRF-extensively in Utah...and the 4 km grossly underestimates snowfall for valleys. It is so bad it was not usable in an operational sense.

See, I had never used it for that area, so I wouldn't know. I know for out here it does... well, as well as you can expect for a hi-res model based on the GFS. Which is to say, better than nothing. But it seems for you guys, it's worse than nothing! :guitar:

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baroclinic_instability

baroclinic_instability

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See, I had never used it for that area, so I wouldn't know. I know for out here it does... well, as well as you can expect for a hi-res model based on the GFS. Which is to say, better than nothing. But it seems for you guys, it's worse than nothing! :guitar:

It definitely isn't worthless. It definitely has a major dry bias for mountain valleys in UT. For east of Divide, it may do better. I have a feeling some brief but heavy snow showers will develop east of the Divide when that shortwave plows through.

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baroclinic_instability

baroclinic_instability

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FWIW, 4-km WRF shows nothing for Great Falls... Maybe a half inch Tuesday evening :(

http://www.atmos.was...m5d3_snow3+///3

A good example showing the dry bias of the high res UW WRF-GFS with strong shortwaves. http://www.wrh.noaa....sid=KGTF&num=72

It seems its bias in northern UT extends to MT east of the divide as well. I am glad though, I don't want any high res models replacing us thumbsupsmileyanim.gif

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Mallow

Mallow

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A good example showing the dry bias of the high res UW WRF-GFS with strong shortwaves. http://www.wrh.noaa....sid=KGTF&num=72

It seems its bias in northern UT extends to MT east of the divide as well. I am glad though, I don't want any high res models replacing us :thumbsup:

:thumbsup:

To be fair, the latest run did give KGTF about 3" or so:

http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?mm5d3_snow24+///3

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baroclinic_instability

baroclinic_instability

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:thumbsup:

To be fair, the latest run did give KGTF about 3" or so:

http://www.atmos.was...5d3_snow24+///3

Well that is certainly better. From my experiences, I have seen a lot of high res models overestimate downslope into valleys when either a strong and deep cold front circulation is present and/or there is a large range of mountains blocking the large scale flow. In Utah, this happens along the Salt Lake City Wasatch Front Corridor as the Wasatch Range essentially "blocks" highly stable air behind the cold front from ascending the range. The whole flow backs up into the valley and heavy snow lingers for a long time. In the case of Great Falls, the same thing happens under stable NNW flow associated with flow backing up into Great Falls as it is blocked by the Little/Big Belt mountains south if it.

http://maps.google.c....836731&t=p&z=9

I have a feeling once the 12Z GFS came out with much stronger stable flow and copiuos moisture behind the front, it was able to correct the high res UW WRF-GFS.

Note the radar and how the moisture gets blocked by the range. http://rap.ucar.edu/...e=-1&duration=4

Being from Washington, I know none of this is new to you Mallow, but it may serve a good example to others. I will admit though, the high res WRF is useful under certain circumstances. It does real well with Salt Lake effect snow, for instance.

Highly stable flow being blocked or "bunching up" behind a mountain range is a great example of the froude number in action. http://www.fsl.orst.edu/geowater/FX3/help/8_Hydraulic_Reference/Froude_Number_and_Flow_States.htm

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Mallow

Mallow

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Well that is certainly better. From my experiences, I have seen a lot of high res models overestimate downslope into valleys when either a strong and deep cold front circulation is present and/or there is a large range of mountains blocking the large scale flow. In Utah, this happens along the Salt Lake City Wasatch Front Corridor as the Wasatch Range essentially "blocks" highly stable air behind the cold front from ascending the range. The whole flow backs up into the valley and heavy snow lingers for a long time. In the case of Great Falls, the same thing happens under stable NNW flow associated with flow backing up into Great Falls as it is blocked by the Little/Big Belt mountains south if it.

http://maps.google.c....836731&t=p&z=9

I have a feeling once the 12Z GFS came out with much stronger stable flow and copiuos moisture behind the front, it was able to correct the high res UW WRF-GFS.

Note the radar and how the moisture gets blocked by the range. http://rap.ucar.edu/...e=-1&duration=4

Being from Washington, I know none of this is new to you Mallow, but it may serve a good example to others. I will admit though, the high res WRF is useful under certain circumstances. It does real well with Salt Lake effect snow, for instance.

Highly stable flow being blocked or "bunching up" behind a mountain range is a great example of the froude number in action. http://www.fsl.orst....Flow_States.htm

The Froude number! I love that thing. :thumbsup:

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baroclinic_instability

baroclinic_instability

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The Froude number! I love that thing. :thumbsup:

I wrote a brief article on it on my weather blog. It was a good case example. That cold front was impressive too. G to 61 at Great Falls and 60+ at Cutbank too. Fun storm!

http://jasonahsenmacher.wordpress.com/2010/11/16/the-froude-number-and-stable-flow-mountain-blocking/

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baroclinic_instability

baroclinic_instability

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I am. I learned about the Froude number from none other than Cliff Mass, of course. :arrowhead:

Haha, I enjoy reading Mr. Mass' blog about Pacific NW weather and hearing him talk about the sad state of Washington mathematics :) Kidding, I do like Cliff Mass a lot. The U of W modeling he is part of is quite good, and I respect the program. I have a special respect for Dr. Durran...he is a genius...and his research regarding mountain waves is awesome.

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CoastalWx

CoastalWx

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Haha, I enjoy reading Mr. Mass' blog about Pacific NW weather and hearing him talk about the sad state of Washington mathematics :) Kidding, I do like Cliff Mass a lot. The U of W modeling he is part of is quite good, and I respect the program. I have a special respect for Dr. Durran...he is a genius...and his research regarding mountain waves is awesome.

Hey, nice blog you have. I just checked out your dynamic height fall blog....nice explanation on that! :thumbsup:

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snowdude

snowdude

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I got 3 inches out of the storm yesterday...and am really waiting for the below zero temps starting this weekend!

Yeah, we got about that here too. So anyone at the office thinking good snow potential for Great Falls this weekend into next week? I think we could get some advisory snows again.

Giggity. Welcome to Montana snowdude ;)

Thanks :)

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