Changes Are Coming

Precipitation analyses for the 30-day period ending yesterday at 1200 UTC (0500 MDT) show that northern Utah has clearly gotten the shaft.  Totals are highest across the far northwest, dropping down through Wyoming and Colorado.  To our south, this week's storm has even given them something. 

Source: NWS
Things may, however, be changing for Thanksgiving week as there is a shift in the large-scale pattern expected to begin later this weekend into early next week.  GEFS forecasts valid 0000 UTC 26 November (1700 MDT Monday) predominantly favor a trough  over the west.  


As do most (but not all) forecasts valid 1200 UTC 27 November (0500 MDT Wednesday). 

Source: Penn State E-Wall
Thus, at a minimum, cooler, possibly much cooler temperatures are likely to prevail next week.  It is also likely that we will see some mountain and possibly some valley snow. 

When one here's the phrase "pattern change" there is a tendency to get excited when we've been persistently warm and dry this time of year.  I like to keep calm and carry on.  After deducting totals for today, the NAEFS ensemble forecasts through 0000 UTC 28 November (1700 MDT Wednesday) generate a mean of about 30 inches of snow at Alta Monday, Tuesday, and Wednesday, but this number is jacked up by several Canadian Members that produce huge, unrealistic totals.  The GEFS mean (red line) suggest around 18 inches, but the GEFS range is also between about 8 and 30 inches for the period.

Thus, change is coming, but exactly how much falls before the Thanksgiving holiday depends on  the structure and track of the weather systems as they enter and move across the western U.S.  There is also the potential for snow during the Thanksgiving holiday, although I'm not inclined to speculate at such long lead times about amounts as there are a wide range of possibilities. 

Comments

  1. alexunfNovember 21, 2019 at 8:50 PM

    Last year there always seemed to be one Canadian member predicting apocalyptic amounts of snow for each storm (I remember seeing 10 feet pretty regularly). Glad to see it's continuing to sway the mean this season.

    ReplyDelete
  2. aaronNovember 22, 2019 at 11:23 AM

    I love that plucky Canadian model. Keep doin' your thing, guy.

    ReplyDelete

Post a Comment

More from Wasatch Weather Weenies

A Biblical Storm Update

Image
 " The rain fell on the Earth four days and four nights " -Genesis 7:12 (paraphrased) I suppose its blasphemous to paraphrase the bible, but by the time the current storm is over tomorrow, it will be about a four-day event, so it seems appropriate.   Below are gauge-measured precipitation totals for the first 3 days of this storm (i.e., from 1500 UTC/0900 MDT Saturday to 1500 UTC/0900 MDT Tuesday). Many stations, even in valley locations, are over an inch.  2+ inches at many locations along the east bench of the Wasatch Range from Orem to Ogden.  Some statiions over 6" in the Wasatch Range.  This data hasn't been quality controlled and a few big amounts might need to be adjusted, but the normally somewhat reliable Timpanogos Divide and Snowbird SNOTEL stations are at 7.00 and 7.30 inches, respectively.   Source: Mesowest The Collins snowstake has about 8" of dense snow on it this morning.   Snowbird has 10" on theirs, giving them early b...
Read more

The Jet Stream Is Broken

Image
An upper-level trough is moving through Utah today (Thursday) and tomorrow, bringing with it some convective storms and eventually cooler temperatures.   Snow from the last storm is now almost gone.  The Mount Baldy webcam at Alta this morning shows the snow line has tretreated to nearly 10,000 feet with substantial losses even at upper elevations.  Although the Mt. Baldy summit is obscured, considerable rock and dirt is exposed in the Ballroom at center right of the photo.   Source: Alta.  Photo from about 7:45 AM 22 October 2026 Se, we are essentially starting over from here.  The situation for today and tomorrow is a bit of a crap shoot.  Today, snow levels will be too high for much in the way of accumulations.  Perhaps if we get a thunderstorm or thunderstorm complex today it can lower the snow levels down onto our highest peaks, but the RRFS ensemble shows the wet-bulb 0.5 level sitting over 11,000 feet until later this evening....
Read more

The Deluge So Far

Image
It's been an active 48 hours over northern Utah thanks to the Saturday showers and thunderstorms, remnants of Rachel, and several other precipitation drivers. The plot below shows the estimated precipitation over northern Utah for the 48-hour period ending at 1400 UTC (0800 MDT) today (Monday, October 12.  Everyoen got some, but the biggest amounts are on the Alpine Ridge above Little Cottonwood Canyon and over the south slope of the Uintas where there are local accumulations of more than 3.5 inches.  Most of the central and northern Wasatch has seen at least an inch.  The lightest accumulations are in the northwest Salt Lake Valley (<0.5").   Source: MRMS Big Cottonwood Canyon was closed for a while yesterday due to flooding on the road. 🚧 Uphill Restriction Alert 🚧 SR-190: @SLCO_OOTS @UtahDOT are restricting uphill traffic due to flooding and debris on road. 📍: traffic will be turned around at mouth. ‼️ETO to uphill traffic: UNKNOWN https://t.co/tAZHyS...
Read more