Southern Utah Scores Big; Central Wasatch Refresher

Posted Friday, February 22nd, 2019 by Taylor McCorkle

TLDR: Southern Utah benefitted big time from a low pressure system and lots of moisture yesterday. Central Wasatch resorts got just enough to refresh the surface of the snow pack.  A quiet weekend is on tap for the intermountain west, with our next chance of snow set for early in the work week.


A low pressure system moved north into southern Utah yesterday along with ample moisture and cold temperatures.  Along with a record-breaking day (35.9″ in 24 hr!!) of snowfall in Flagstaff, AZ, southern Utah scored with a nice snowfall that will help pad those bases. Eagle Point and Brian Head were the big winners with 10″ and 8″, respectively. Even St. George got in on the fun and had a rare snowfall! (See link to news article and photos)
As the low tracked northward in the overnight hours, even some Cottonwood resorts got a few inches of fresh snow thanks to the southwest flow and leftover moisture.
Here are the 24- and 72-hour snow totals as reported by OnTheSnow:

Resort snow reports via onthesnow.com
Resort snow reports via onthesnow.com

All this snow is keeping the entire state of Utah above normal for the current water year (Oct 1 – Present).  The water year accumulated snow water equivalent for a station at Brighton is currently tracking ahead of not only the mean, but most recent years with the exception of 2017.  Though, if our active pattern continues, I feel confident this year could pull ahead. Below is a graphical representation of current SWE (green line), mean SWE (blue) as well as years 2014-2018. Plot produced by the Colorado Basin River Forecast Center (CBRFC – click for link to site)

Accumulated Snow Water Equivalent via Colorado River Basin Forecast Center
Accumulated Snow Water Equivalent for years 2014-2019 and 33-year mean.

5-Day Forecast:
The weather should remain relatively quiet through Sunday with a ridge settling in over Northern Utah. Light wind and little mixing will result in temperatures remaining below normal at all elevations. Air quality is not expected to be a concern during this period.  Below is a plot of forecasted 700 mb temperatures just before noon on Saturday. Crest-level conditions will be frigid (~-15 Celsius), so plan accordingly.

GFS 700 mb temperature forecast valid 18Z Saturday; via tropicaltidbits.com
GFS 700 mb temperature forecast valid 18Z Saturday; via tropicaltidbits.com

Beginning Monday, moderate southwesterly flow will advect warmer air into the area and put us back in the normal range for temperatures for this time of year.  This shift in flow is due to a low pressure system that is forecasted to track to our north on Tuesday. The current forecast shows the surface low center originating over the Pacific and moving inland across central Idaho and into Montana/Wyoming. Even though the low pressure center is well to our north, we are still forecasted to get some snow. Below is a gif showing the 12 Z GFS forecasted mean sea level pressure and 6-hour precipitation rate (mm/hour)

GFS Forecasted MSLP and precip via tropicaltidbits.com
GFS Forecasted MSLP and precip via tropicaltidbits.com

As Alex mentioned yesterday, uncertainty with the track of the low remains high. This is what is causing the large spread in the ensemble forecast solutions of accumulated precipitation. Here are some scenarios: 1) If the low pressure center shifts further north, our forecasted snow totals will likely diminish to next to none. 2) If the low pressure center shifts southward, our precipitation chances increase and forecasts of accumulating snow will trend towards solutions with higher totals.

As the event nears, the models are getting a better grasp on the atmosphere and the ensembles are in slightly better agreement than they were yesterday. Recall Alex’s post with nearly a 100″ spread in total snowfall.  Here is the 12Z forecast from the NAEFS, which still has a large spread, but if we ignore the outliers, we are looking at anywhere from 5-40″ through next Wednesday.

NAEFS 12Z ensemble forecasts of accumulated snow via weather.utah.edu
NAEFS 12Z ensemble forecasts of accumulated snow via weather.utah.edu

As always, this forecast is likely to change and will become more accurate as we progress through the weekend.  Check back with us every day for the latest information.

For now, the snow is great, so enjoy your weekend!

-Taylor

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