Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
472 FXUS65 KSLC 281531 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 931 AM MDT Tue May 28 2024 .UPDATE...Updated forecast for aviation discussion. Otherwise, previous forecast looks on track with no changes necessitated at this time. && .SYNOPSIS...High pressure will be in place today bringing high temperatures of 5F to 10F above normal. A cold front Wednesday will bring a few showers and thunderstorms with a gusty wind threat. Temperatures will cool back down to around normal by Thursday behind the front. Another warming trend will begin in earnest by early next week. && .SHORT TERM (Through 12Z/6AM Thursday), Issued 404 AM MDT...Early Tuesday morning analysis products depicted a mid-level ridge axis centered over eastern Utah while an area of low pressure was approaching the British Colombian coastline. The ridge will move off to the east today while the low approaches the Washington coast. As a result, modest deep-layer SW flow will overspread Utah and SW Wyoming, promoting a continued warming trend (highs 5F to 10F above normal) while also opening the door to modest mid-level moist advection. Just enough moisture will be introduced to foster isolated shower and thunderstorm development this afternoon, mainly over high terrain areas of northern and central Utah. Modest deep-layer shear development by late afternoon and early evening could support updrafts that can briefly survive the trek off of the terrain. Main hazards with this activity will be isolated lightning and gusty winds in the 35-45 mph range. Convective activity will be more robust and widespread on Wednesday, however. On Wendesday, models are in good agreement with their depictions of the above-mentioned cold front moving across northern Utah and SW Wyoming during the afternoon, before settling across central Utah during the evening and overnight hours before diminishing. Thanks to continued mid-level moisture advection and large-scale ascent associated with the front, scattered showers with isolated thunderstorms will break out across northern Utah during the late morning and afternoon hours, with additional convective initiation gradually trending southward into central Utah during the evening. Ensemble mean SBCAPE values reach 1000J/Kg during the late afternoon and early evening, with superimposed deep-layer shear values in the 30-40kt range. These ingredients suggests the environment will be supportive of organized updrafts and propagating cold pools. Available ingredients are the best we`ve seen so far in what`s otherwise been a relatively quiet Spring in terms of convective activity. Main threats will once again be lightning and gusty outflow winds, with the coverage and strength of winds much greater than Tuesday, with numerous gusts in the 45-55 mph range accompanying many of the showers and storms, thanks to a dry sub-cloud environment and increasing kinematics aloft with the approaching frontal boundary. HREF max wind gust plots exceed 58 mph across portions of central Utah during the late afternoon and early evening hours (with a 10% probability contour appearing), focused between Provo and Cove Fort. Convection will gradually wane during the evening hours, but enough support owing to the presence of the cold front will be in place to support a few showers through the night, particularly across northern and central Utah. .LONG TERM (After 12Z/6AM Thursday), Issued 404 AM MDT...Thursday will begin a modest temperature drop in the wake of a cold front Wednesday. But for the end of May, temperatures are forecast to be very seasonal and very pleasant. The weather pattern headed into and through the weekend look to bring rather mild conditions to the region. Warming temperatures are forecast as southwest flow arrives by Saturday with high temperatures near the triple digit marker in St. George and in southeast Utah. High pressure is not expected to leave the region anytime in this long term forecast. In fact, there`s little variance in ensemble models until next week, where the question becomes, just how high will temperatures climb with a building ridge? && .AVIATION...KSLC...Predominantly VFR conditions expected through the period with generally light winds following typical daily trends. Afternoon cumulus development over the Oquirrhs will likely eventually lead to a thunderstorm or two with bases at or above 10k feet AGL moving northeastward into the Salt Lake Valley. Such storms will have 50% chance of gusty outflow winds reaching the terminal from about 21Z-0Z, though with only a 10-20% chance of reaching the terminal vicinity itself. Showers/thunderstorms are possible again tomorrow (30% chance). .REST OF UTAH AND SOUTHWEST WYOMING...Isolated showers/thunderstorms are expected this afternoon, generally east of I-15 and north I-70, tracking northeastward. Such storms will be capable of gusty winds. Outside of this, VFR conditions and light diurnal wind variations are forecast today and tonight. && .FIRE WEATHER, Issued 404 AM MDT...Warm, dry conditions will be in place today with temperatures around 10F above normal. Increasing mid-level moisture ahead of an approaching cold front will promote isolated high-based showers and storms across northern and central Utah`s high terrain areas this afternoon and evening. On Wednesday, the cold front will move through northern Utah during the afternoon, before dropping into central Utah by Wednesday evening. The front will promote the development of high- based showers and storms across northern and central Utah, with the greatest coverage during the afternoon and evening hours. Showers and storms will be capable of strong, gusty and erratic outflow winds. Temperatures will cool 10-15F across northern and central Utah behind the front on Tuesday. As we get into the weekend, warm, dry conditions will return to the state with temperatures increasing to near 10F above normal once again. Through the next week, little change is expected across southern Utah, with temperatures remaining 5-10F above normal along with a continuation of dry conditions accompanied by poor overnight recovery. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ Warthen/ADeSmet/NDeSmet/Van Cleave For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity