One last quiet day . . .

Monday, February 18, 2013 at 10:06 am

Monday PM update:

Winter Storm Watch in effect for the Wasatch south of I-80… NWS calling for 1-2 feet of snow by Thursday with 6-12″ north of I-80 in the mountains.  I feel that is a bit excessive and still think 6-14″ is more realistic with 4-8″ north of I-80.  12-18″ is possible for some of the high mountains of S. Utah.

Weak system on Thursday night into Friday will keep light snow showers going, mostly in the mountains.  Strong storm arrives Saturday.  I’m not willing to say it will be “major” just yet, but it definitely has potential. Here is an excerpt from the NWS’s discussion:

CURRENT EUROPEAN AND GFS MODELS INDICATE A VIGOROUS STORM SYSTEM
WILL AFFECT NORTHERN UTAH…PERHAPS WESTERN VALLEYS SOUTH TO CEDAR
CITY…THIS UPCOMING WEEKEND. THIS SYSTEM HAS A VERY NICE MOISTURE
TAP…IN ADDITION TO THE AMBIENT WATER VAPOR LEFT OVER FROM THE
PREVIOUS STORMS…TO AID IN EFFICIENT PRECIPITATION PROCESS. VERY
UNSTABLE WITH 700MB TEMPERATURE NEAR -18C AND 500MB TEMPERATURE NEAR
-37C. THE DYNAMICS ARE ALSO LOOKING STRONG WITH A VERY SHARP COLD
FRONT. LAKE EFFECT WILL ALSO LIKELY BE A CONTRIBUTOR WITH COLD
CONDITIONS…BUT TOO FAR OUT TO ASSESS FLOW PATTERN. IF THIS STORM
PANS OUT AS CURRENTLY ADVERTISED…IT WILL LIKELY BE ONE OF THE BEST
STORMS OF THE SEASON THUS FAR.

Previous…

Moderate (strong for S. Utah) storm system Tuesday night – Thursday. Whether you have today off from work or not, it might be worthwhile to enjoy the relatively quiet weather we’ll have before things get active tomorrow afternoon.  Low pressure system will start dropping down the west coast tonight and then start to move inland tomorrow.  An initial flow out of the southwest tomorrow afternoon could fire up some snow showers in Northern Utah.  As we head into Tuesday night, the flow will turn southerly as the Low tracks through far southern Utah.  This is very similar to the system we had last week and the Wasatch got skunked in the southerly flow, so therefore we are going to tread carefully and only forecast a few inches of new snow by Wednesday morning.  During the day on Wednesday the flow will turn more easterly, which could favor the Wasatch Back with some heavier snow, then eventually turn northerly by Wednesday evening, and finally northwesterly Wednesday night.  The snow should intensify and become more widespread as the flow finally turns northwesterly.  My best guess right now for the Wasatch would be 6-14″ by the end of the day Thursday when the snow winds down.  This is a broader range than I usually forecast but that reflects the hard-to-predict nature of relying on wrap-around moisture and orographics for most of the snowfall.  There is also the potential for banding to occur which would dump good amounts of snow on one area while other areas see very little.  It is impossible to know exactly where those bands will set up.  GFS, NAM, and WRF are all suggesting decent snows though, so think all resorts will at least reach the 6″ mark.

Southern Utah, on the other hand, will see most of their snow on Tuesday night and Wednesday as the Low tracks over them.  This snow will be heavier and more widespread than in the Wasatch.  Eagle Point and Brian Head will likely have very good days on Wednesday with 6-12″ possible.

Thursday night – Friday night will be a bit of a break with periodic light snow likely.  The break day will be Friday but a persistent NW flow will keep moisture aimed at N. Utah so we will likely still have off and on light snow in the Wasatch but it doesn’t appear like much in the way of accumulation.

Colder, stronger storm moves in on Saturday.  This system is looking very good for potentially significant snow in both the mountains and valleys.  GFS and Euro in good agreement with the GEM particularly bullish.  Too early to forecast exact amounts but Saturday and especially Sunday could be money for powder hounds like myself.  We are talking quintessential deep Utah fluff.

Beyond next weekend, models diverge a bit.  GFS flattens the Jet and we go into a moist zonal flow.  The Euro keeps the pattern a lot more amped and brings in another very cold system around next Tuesday.  No matter what, it still looks to remain active and there is no point fretting about it now with so much active weather in the next 7 days.

Bring it!

WSF

P.S.  WSF is famous! Well, not really, but I do post these same weather forecasts for OpenSnow.com which is featured in a short article in this week’s Time Magazine about sport-specific weather sites.  OpenSnow.com is a collaborative effort to bring quality ski forecasts, made by local weather professionals, to their respective areas.  No more automated ski forecasts made by some computer in Atlanta!  Great news for myself and my colleagues who work hard to bring you the best forecast possible.





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  • Anonymous

    Very cool on the Time Magazine mention.

  • Anonymous

    Glad to see WSF is getting the recognition you deserve! Very exciting to see an active weather pattern entering the Wasatch. Right now I am planing on taking your advice and driving I80 west on Friday. That being said, what kind of travel day will Sunday shape up to be? Just trying to eek out a couple extra ski days 🙂

    • Hmmm… well the worst of Saturday storm will likely be Saturday and Saturday night and might clear out a bit on Sunday. If you were to leave on Sunday, you might have some issues getting out of Utah but conditions should improve as you head west. That’s the best guess I can make right now.

      • Laura

        thanks, I’ll assess as it gets closer.

  • Great to see you on OpenSnow. I recommended you to Joel when he was looking for a Utah forecaster. I understand a lot of other folks recommended you also. Good job.

  • Anonymous

    Hello WSF. Amazing update on the forecast today. Congrats for the recognition in Time Magazine. You guys deserve it! Quick question about the long-range forecast. When you say that the GFS flattens the jet next week and sets up a moist zonal flow what exactly does this mean? Do you see the high pressure ridge building back in to establish a prolonged period of dry and warm weather?

    • Zonal flow just means that the jet is flatter and moving more directly from west to east rather than amplified with large ridges and troughs. That is just what one model was showing. As for the ridge, it is based on long range data and if it does develop, it’s impossible to know how long it would last. Sorry for the lack of an answer but long-range forecast is far from an exact science. Stay tuned and as we get closer we’ll have better answers for you. Thank you for the kind comments!

  • Barry

    Its interesting that the CPC is predicting a below average probability for precip for the next 14 days when the models seem to show otherwise. Do you know what information they use to guide their predictions? Their “forecast” changed from extreme above average to extreme below average in 1 day!

    • Good question. I always assumed they used mostly GFS long range data, but you’re right, their 8-14 day forecast isn’t consistent with that. Maybe I’ll shoot them an email and ask. Maybe I’m just crazy, but I feel like those forecasts are not nearly as reliable as they used to be even for broad trends.