Area Forecast Discussion
Issued by NWS Salt Lake City, UT
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Issued by NWS Salt Lake City, UT
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-- Discussion containing changed information from previous version are highlighted. --649 FXUS65 KSLC 172141 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 341 PM MDT Tue Sep 17 2024 .SYNOPSIS...-- Changed Discussion --A fall-like airmass will settle into the region Wednesday. High pressure will gradually shift into the area, bringing warming temperatures. The next threat of precipitation looks to be this weekend.-- End Changed Discussion --&& .SHORT TERM (Through 12Z Thursday)...-- Changed Discussion --A cold upper level trough continues to move across the region this afternoon, bringing everything from severe thunderstorms to northern Utah, to accumulating snow above 9000 feet across the northern mountains to critical fire weather conditions across southeastern Utah. In the wake of this system, temperatures will average around 10-15 degrees below normal across much of the region Wednesday. A few locations still in growing seasons will see temperatures approaching freezing including the Enterprise/Beryl Junction area, normally cold spots of the Wasatch Back and the Loa and Bicknell areas (which have already had several freezes). Patchy frost will be possible across the Wasatch Back as well, so those with their summer gardens still outdoors should be prepared to cover and/or bring plants indoors. An upper level low shifting south along the California Coast will continue to slowly shift southward through Thursday. The end result will be gradually amplifying upper level ridging into the region, with warming temperatures (though still below normal levels). .LONG TERM (After 12Z Thursday), Issued 418 AM MDT... Guidance has trended slightly drier and warmer for the long term period as the trough that moves into the Great Basin on Thursday begins to cut off and weaken as it moves further inland. Shortwave ridging will amplify on Thursday ahead of the trough as it`s positioned over central California. This will keep conditions mostly dry with little cloud cover on Thursday as most of the precipitation associated with the low remains over Nevada and California. Additionally, high temperatures will rebound closer to normal on Thursday with mid to upper 70s across most valleys and mid 80s for far southern Utah. As the trough shifts east on Friday the upper level low likely becomes cutoff while filling in and weakening. With the center of the low moving across northern Arizona, precipitation will be more likely across central and southern Utah, but weak ascent will limit the precipitation totals to generally less than 0.1". Temperatures will cool a few degrees across the southern half of the CWA, but remain largely unchanged across northern Utah/SW Wyoming given the further proximity to the center of the low pressure system. This low shifts further east on Saturday with a few diurnal showers possible across eastern portions of the CWA. After this low exits the region we will be left in a weak northwest flow that will keep temperatures near normal for this time of year making for optimal fall foliage peeping weather over the weekend. Given the weak northwest flow regime we will be left in, guidance is a bit indecisive on whether we introduce another trough (~23% of members) or if we move into more of a ridging pattern (~77% of members).-- End Changed Discussion --&& .AVIATION...-- Changed Discussion --KSLC...Improving conditions are expected at the KSLC terminal by 23z as the primary thunderstorm threat will shift east of the area through that time. Additional shower activity moving in from the west will remain possible through 02/03z, but will be waning over time. West to northwest winds are expected to remain in place through 03z, but brief east to northeast winds <10kts will remain possible post thunderstorm passage during the 2230-2330 window. .REST OF UTAH AND SOUTHWEST WYOMING...Shower and isolated storm potential will remain in place over the northern TAF sites through 02/03z prior to waning overnight. VFR conditions are expected to prevail for all areas, but brief reductions to MVFR conditions in those isolated thunderstorms will remain possible through that 02/03z window in the north. Clear and dry conditions will remain across southern Utah.-- End Changed Discussion --&& .FIRE WEATHER...-- Changed Discussion --A fall-like pattern will build into the region behind Tuesday`s storm system. Temperatures will average around 10 degrees below normal across much of the state Wednesday. A gradual moderation as high pressure builds into the area will bring temperatures closer to normal, but cooler than the last few weeks. The next significant chance for precipitation looks to be this weekend as an upper level low ejects across the region.-- End Changed Discussion --&& .SLC WATCHES/WARNINGS/ADVISORIES...-- Changed Discussion --UT...Red Flag Warning until 9 PM MDT this evening for UTZ489-494-498. WY...None.-- End Changed Discussion --&& $$ Kruse/Mahan/Merrill For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity