Channel Your Inner Clark Griswold

Posted Thursday, December 6th, 2018 by Taylor McCorkle

TLDR: Tonight into early tomorrow, a quick moving system will graze the southern portion of the state. This system could result in a few inches of high elevation snow and light low elevation rain in the southern third of the state. Don’t expect much in terms of accumulations in our neck of the woods. A ridge builds in for the weekend.  Our next chance of unsettled weather arrives next Tuesday.


Sunny skies and a building inversion are whats on tap for this weekend.. Not ideal, but perhaps time to get into the holiday spirit. With only 19 days til Christmas, this quiet weather pattern might be a good excuse to drag out those decorations and channel a festive mindset more like Clark Griswold and less like the Grinch (I know no snow = no fun, but we can all try, right?).

tenor

 

Short Term Forecast (Thursday Evening – Saturday Morning):
In the overnight hours, an upper-level trough will make its way across the southern portion of Utah en route to wreak havoc on the southern plains and eastern third of the U.S.  Compared to the forecasted impacts for the rest of the country, this will be essentially a non-event for us folks in Utah give the current lack of moisture in the western U.S. Below is a forecast of available moisture in the atmosphere.  Note the greys and browns over Utah, showing very dry air, while the brighter colors over Texas show an airmass with potent moisture advancing into the southern plains.

18Z GFS Precipitable water valid Friday 5 am MST
18Z GFS Precipitable water forecast. Valid Friday 5 am MST (via models.weatherbell.com)

Winter storm advisories (purple-shaded counties) and watches (dark blue-shaded counties) cover the southern plains in anticipation of the low interacting with a moist airmass originating from the Gulf of Mexico. Flood watches have also been issued for southeast Texas where temperatures will remain above freezing throughout the duration of the event.

Current weather alerts via weather.gov
Current weather alerts (via weather.gov)

In comparison, we are looking at light precipitation across southern Utah.  Given the track of the progressing upper-level low, there won’t be much (if anything) in the way of precipitation for the northern portions of the state. Ski areas in southwestern Utah, like Brian Head, will likely pick up 3-6″ of new snow from the advancing system.  Rain at lower elevations will be light to moderate through the morning. The 18Z GFS total precipitation solution is showing measurable precipitation forecasted for the Cottonwoods, but I think that is relatively unrealistic.  I think 0-2″ is a reasonable expectation through Friday.

18 Z GFS Total Precipitation through Saturday at 5 am (via models.weatherbell.com)
18 Z GFS Total Precipitation through Saturday at 5 am (via models.weatherbell.com)

3-5 Day Forecast (Saturday – Tuesday):
Over the weekend, quiescent weather will prevail, but air quality is likely to deteriorate. The combination of snow cover, cold surface temperatures, low wind, and low sun angle will aid in the development of a dreaded temperature inversion, which will result in a build up of pollutants in the surrounding valleys. The air quality is expected to be poor enough by Saturday that sensitive groups (asthmatics, eldery, etc.) could be impacted, as forecasted by the Utah Department of Environmental Quality

Salt Lake Valley air quality forecast (via air.utah.gov)
Salt Lake Valley air quality forecast (via air.utah.gov)

Luckily, the inversions rarely impact the high elevations, so get up to the mountains and go ski the excellent early season conditions.

Our next chance of unsettled weather arrives on Tuesday which should not only flush out the valley pollutants, but drop some new snow on the mountains! Enjoy a bluebird weekend!

– Taylor

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