083 FXUS65 KSLC 210926 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 326 AM MDT Thu Mar 21 2019 .SYNOPSIS... A pacific storm system will bring low elevation rain and mountain snow across much of Utah through Friday. After brief ridging late Friday into Saturday, another pacific storm system will bring widespread precipitation across the state for the upcoming weekend. && .SHORT TERM (THROUGH 00Z MONDAY)... With height falls and upper level diffluence associated with the approach of the storm system persisting over Utah today into tomorrow morning, precipitation chances increase significantly, especially for southern and central Utah. There is sufficient instability and lapse rates to mention the threat of thunder during this period. Snow levels look to remain above 6kft for the areas with the bulk of the precipitation. Southern and central mountains may see locally significant accumulations aided by south-southeast orographic enhancement. Most valleys look to remain rain or a rain/snow mix. Best bet for valley snow accumulations will be north of Hanksville into Price and across the western Uinta Basin. The thermal profile is marginal to support snow for Price, though heavier precipitation rates could drag down the snow level a bit further. Expanded the Winter Weather Advisory northward to include the southern Wasatch and the western Uinta mountains. While the ending time was set to match the ongoing mountain advisory, its conceivable that an extension in time into the mid afternoon Friday may be needed before the affects of the storm system sufficiently abate. Given the convective nature of precipitation, LCL lowering to near 850mb, and warm cloud depth increasing to 3-4kft, locally heavy rainfall will be possible across southern valleys, especially this morning. This is coincident with anomalously high precipitable water values ahead of the lead wave pin-wheeling into the region. Tomorrow is a transition day with the trough making its way to our northeast, encouraging building heights and warming aloft from southwest to northeast during the afternoon and evening. Tomorrow night into Saturday morning should largely be quiet across the region under a ridge, however warm advection ahead of the next quick-moving storm system may sustain showery activity across portions of the north. Diffluence aloft increases Saturday afternoon into Sunday providing for the next round of precipitation, with support from a second advancing Atmospheric River. Snow levels initially look to be rather high around 6500 feet, but may fall closer to 5000 feet Sunday. .LONG TERM (AFTER 00Z MONDAY)... Sunday's trough will be quickly pulling away from the region to start the long term forecast period. A period of shortwave ridging should bring milder temperatures to the state before another cold trough crosses the region. Much of the ensemble guidance favors a longwave trough crossing the western United States Wednesday into Thursday...potentially remaining in place into the weekend. For now the general details indicate a loosely organized trough will approach the coast Tuesday...with several waves rotating around the trough. This...colocated with a jet maxima impinging on the central Sierras. Global guidance indicates this system has the potential to be fairly cold for late March, with 700mb temperatures between -7 and -9C post frontal. For now...cooled Thursday well below temperatures earlier in the week...and if the trend continues...these temperatures will need to be cooled further. While there is a chance of snow to valley floors...confidence is not high this will occur. && .AVIATION... Southerly winds will continue at the SLC terminal. Expect a period of light rain and lowered ceilings...near 5000-6000 feet AGL between 12-18Z. Ceilings should then lift until later Thursday evening. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...Winter Weather Advisory until 6 AM MDT Friday for UTZ008>010-517- 518. Winter Weather Advisory until 6 PM MDT this evening for UTZ012- 013. WY...None. && $$ SHORT TERM...10 LONG TERM/AVIATION...Kruse For more information from NOAA's National Weather Service visit... http://weather.gov/saltlakecity For frequently asked questions about the Area Forecast Discussion visit... http://weather.gov/saltlakecity/general/afd_faqs.php