748 FXUS65 KSLC 122232 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 332 PM MST Thu Jan 12 2023 .SYNOPSIS...High pressure will maintain stable conditions area-wide through Friday. After a brief period of inactive weather, the next storm system arrives Saturday. && .SHORT TERM (THROUGH 00Z MONDAY)...Dry weather conditions will prevail through tomorrow evening under a ridge of high pressure. Mid to high based clouds are noted and likely to increase tomorrow afternoon ahead of the next shortwave arriving in from the west. This shortwave is forecast to bring the next chances for precipitation to portions of Utah as early as Saturday afternoon, much of which will be confined the the higher terrain as snow. This shortwave, part of a broader area of low pressure off the west coast, will pack a slightly different punch compared to the last few weather events recently. The last several have had abundant atmospheric river moisture associated with it. This time, the river of moisture is tracking ever so slightly southward and more across southern California/Arizona. Since this moisture plume is ever so close to southern Utah, we are still noting moisture to arrive in with the highest likelihood for heavy snow to the southern mountains, such as Brian Head and the Tushar Mountains in the overnight period Saturday into early Sunday morning. Precipitation is forecast to expand statewide into a valley rain/mountain snow event by early Sunday. By Sunday morning, more of a rain/snow mix is forecast across the northern Utah valleys with around a 30% likelihood for snow and 70% chance for rain. Heavy snow is more probable in the northern Utah mountains Sunday morning. Snowfall amounts in the across Utah mountains range from 8 to 12 inches with local higher amounts. .LONG TERM (After 00Z Monday)...Most locations won't see much of a break in between the weekend storm and the first trough of the long- term period. This next storm will bring widespread precipitation late Monday into Tuesday, mainly snow, with an emphasis on southern Utah. A brief period of ridging on Wednesday will then give way to another trough and more precipitation. With the main jet dynamics and vort max passing over AZ, southern Utah will see the brunt of this first system early next week. Most ensemble members (90%) suggest the trough axis reaches Utah Tuesday afternoon, but there are still 10% of members that favor the trough stalling along the west coast. The most likely scenario favors lighter precipitation lingering through Monday morning, with precipitation ramping up in rates and coverage by Monday afternoon and continuing through Tuesday. Valley snow is most likely with this system, though periods of transition to a wintry mix are not out of the question, especially Monday evening. Despite 700-mb temperatures nearing -12C by Tuesday morning, the push of remnant low-level atmospheric river moisture could cause some precipitation type issues given the "warm" nature of ARs. Lower Washington County is expected to see all rain. Uncertainty in the forecast increases as we move into the second storm system. Ensemble members disagree whether or not there is much of a break between the two storms. Roughly 35% of members suggest a break in precipitation on Wednesday, while another 48% favor a much shorter break as the second system moves in quickly late Wednesday. The last 17% don't favor much of a break either, with precipitation lingering from the first storm. This second storm is expected to have the biggest impact on northern Utah, unlike the first. Additionally, with even colder air advecting into the area, valley snow (except Lower Washington County) is even more likely. The 25th-75th percentiles for H7 temperatures over northern Utah are -12 to -15C by Wednesday night. By the end of the work week, models are favoring a ridge developing over the northeast Pacific, but with the potential for shortwave troughs moving over the ridge and into our area, precipitation is still possible for our forecast area moving into the end of the long- term period. && .AVIATION...KSLC...Ridging holds through Thursday, with the ridge axis beginning to slip east of the region overnight into Friday. As a result, will see high clouds build back in as the ridge slips away and the next trough begins to approach. With the approaching trough, guidance largely suggests winds stay southerly through Friday. Cloud base will also lower, but anticipating VFR conditions to hold through Friday. .REST OF UTAH AND SOUTHWEST WYOMING...Ridge axis begins to shift east overnight into Friday, with a trough and associated moisture approaching in turn. Primarily anticipating an increase in high base clouds overnight, persisting thereafter and gradually lowering. That said, generally expecting VFR conditions to hold at area terminals, with one exception being LGU (or other sheltered terminals with good lingering snow pack) where there is some signal for BR formation overnight. For winds, anticipating most terminals see diurnally normal to variable winds with fairly light magnitudes, with some potential for a bit more southerly component during Friday. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ SHORT TERM...NDeSmet LONG TERM...Cunningham AVIATION...Warthen For more information from NOAA's National Weather Service visit... http://weather.gov/saltlakecity