Let’s just make it to Friday!

Posted Tuesday, December 18th, 2018 by Pete Saunders

TLDR:  A short wave trough will move through the area this evening into tomorrow morning bringing a chance of small snow accumulations in the mountains Wednesday. High pressure builds in Wednesday night through Friday morning with associated valley haze and possibly stratus/fog. Beginning Friday morning, though, a series of small disturbances are likely to move through providing us with fresh snow (especially next week) and an end to inverted valley conditions for awhile.

Today – Thursday

Clouds have been on the increase today, with short instances of the sun peaking through, as a short wave trough pushes in from the Pacific coast. Below is an example of just that from Snowbasin Resort in Huntsville.

View from John Paul Lodge at Snowbasin Resort at 1400 MST. Mostly cloudy with the sun peaking through a bit. Courtesy: snowbasin.com

Some precipitation associated with a slightly cooler mid-level airmass ahead of the trough should develop this evening in the northernmost Utah mountains (Beaver Mountain). As the southern portion of the trough moves overhead, warm advection we currently are experiencing will turn into cold advection (always good for snow as long as there is moisture available), and we will see snow showers begin to stretch south along the Wasatch Front late tonight/early Wednesday morning. Overall, though, expect very light accumulations in the 1-3″ range, with the most occurring over the northernmost ski resorts (Beaver Mountain and Powder Mountain). Below is a map showing the GFS accumulated snowfall forecast (inches) for northern Utah through tomorrow morning at 18z (1100 MST).

GFS accumulated snowfall forecast valid from this morning through Wednesday morning at 18z (1100 MST). Note the “bull’s eye” over Beaver Mountain for 2.5-3″ of snow. Courtesy: Weathernerds.org

Wednesday evening, strong high pressure moves in and we will be in (yet again) another bout of thick haze and possibly fog/stratus through Thursday night.

Friday – Sunday

By Friday morning, strong westerly flow will advance into the Intermountain West as the strong ridge moves east of our area. A short wave trough looks like it will make its way through northern Utah during this time with a fairly decent amount of moisture and lift. This should give the mountains some snow, but as this system looks like it will move fairly quickly, expect low snowfall totals in the 1-3″ range across northern Utah mountain resorts.

GFS forecast for relative humidity and wind at 700 hPa (~10,000 ft) and vorticity at 500 hPa. Note the strong westerly winds moving into the Intermountain West, along with an increase in relative humidity (green shading). There also are positive vorticity values associated with the increase in moisture, meaning we could have enough spin and lift needed for precipitation (mountain snow) given the higher relative humidity values. Courtesy: weathernerds.org

As cold advection moves in behind that trough Friday afternoon, expect it to be quite cold in the mountains during the day on Saturday with a few light snow showers and small snow accumulations. The ECMWF (below) currently is showing temperatures of -15 degrees Celsius (5 degrees Fahrenheit) for Saturday morning at 700 mb (~10,000 ft), so any snow that falls will be very low density (light and fluffy).

ECMWF 700 hPa temperature forecast for Saturday morning at 18z (1100 MST). Temperatures will be very cold (-15C) Saturday morning which means that any snow we get from cold advection/orographic showers will be low density (light, fluffy powder). Courtesy: models.weatherbell.com

Sunday should be similar to Saturday (maybe a bit warmer), with a slight chance for some light snow showers with small accumulations in the mountains. Overall, not a bad weekend to be skiing. But course we’d like to see a bit more snow than that!

Long Range Forecast

We may get our wish for more meaningful snow….next week. By early morning on Christmas Eve, the first of several small disturbances that could impact us for a few days looks like it will make its way into our area. It’s still too far out to know what this and the succeeding short waves following after it will do, but as of now it looks like we could see some decent snowfall amounts in the mountains Monday through Wednesday! Hopefully it will make for a white Christmas in the valley too…

Check back in for more details on that and an update on the weekend forecast!


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