Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
074 FXUS65 KSLC 152131 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 331 PM MDT Sat Jun 15 2024 .SYNOPSIS...Gusty southerly winds will bring critical fire weather conditions to portions of southern Utah through Monday. A strong cold front will cross the area Monday afternoon into Monday night, bringing an atypically cold airmass to Utah. Temperatures will rebound through midweek, with another round of potential critical fire weather conditions Thursday into Friday across southern Utah. && .SHORT TERM (Through 00Z Wednesday)...A mainly dry cold front crossed northern and parts of central Utah this morning, bringing a slightly cooler airmass to the region this afternoon...and relatively gusty northerly winds. Afternoon upper air and satellite analysis indicates another shortwave trough rounding the base of the longwave trough across the Pacific Northwest into Montana. This shortwave trough will eventually eject into southern Canada this evening. The associated weak cold front may slide into far northern Utah this evening into tonight, bringing an increase to the gusty northwesterly winds across the area. The longwave trough will gradually shift south and east as the next shortwave trough digs southeastward across the Pacific Northwest Sunday into Monday. This will be the impetus for increasing southwesterly flow across southern Utah bringing critical fire weather conditions to areas with critical fuels through Monday evening. A weakening, somewhat stationary boundary across central Utah will keep northerly flow across the northern half of Utah Sunday into early Monday. The airmass associated with the shortwave trough is anomalously cold, with 700mb temperatures near the 0.5 to 1 percentile for this time of year over the Pacific Northwest. While this airmass will modify to a degree over the Great Basin, 700mb temperatures will be nearing the minimum in the climatology for the EPS for the time of year as the cold front crosses Utah Monday. The best forcing/moisture for precipitation will stay north of the region Monday afternoon and evening as the trough gradually shifts across the northern Rockies, however a portion of the ensemble systems indicate some threat for convection Monday afternoon and evening, mainly north of SLC. As this anomalously strong cold front crosses northern Utah Monday afternoon, strong and gusty post-frontal winds will be possible. Right now, guidance has a low (10% or so) chance of wind gusts in the wind advisory range (45 mph or higher) behind the cold front. Conceptually, this seems to be low and will need to continue to monitor for potential wind advisories in future shifts. With a strong cold front and abrupt wind shift, Red Flag Warnings were extended across the zones with critical fuels to better time with the front. With such a cold airmass in place behind the front Monday night into Tuesday morning, patchy frost will be possible for outlying areas of the Cache, Wasatch Back and other normally cold high valleys of northern Utah. There is about a 10 percent chance of temperatures less than 32 degrees for outlying areas of the Cache and closer to 30% for the normally cold Rush Valley. Temperatures Tuesday afternoon will average 5 to 15 degrees below normal across northern and central Utah, closer to 5 degrees below normal across southern Utah. .LONG TERM (After 00Z Wednesday), Issued 413 AM MDT... For the remainder of the workweek, heights will rebound quickly over the Central Rockies as the mean trough axis retrogrades back to the West Coast. By late in the workweek, increased mid-level moisture will advect in just to our east, supporting some threat of showers/thunderstorms over eastern Utah. That said, unless the trough position sets up farther west than currently placed in ensemble means, our area is likely to remain on the hot/dry/breezy side of the trough, meaning that those conditions are expected to return by the end of the week. && .AVIATION...KSLC...VFR conditions and prevailing northwest winds are expected at the terminal through the valid TAF period. A secondary boundary crossing the terminal between 03-05z will maintain the northerly winds tonight, but a 40% chance exists that a period of light and variable winds will occur between 09-13z Sunday morning. .REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions are expected across the airspace through the valid TAF period. Moderately gusty southwesterly winds are expected during the afternoon/evening hours in the southern portions of the airspace , while modest northerly surface winds are expected to dominate in the northern portions. && .FIRE WEATHER...Winds have already increased across the Grand Staircase this afternoon, with gusts over 40 mph and humidities near 8% being reported at Telegraph Flat. Near critical fire weather conditions are being reported across zone 497. Poor overnight recoveries are expected tonight across southern Utah...with winds increasing further by late Sunday morning. Critical fire weather conditions are expected across fire weather zones 496 below 7000 feet, 495, 497 and 498 Sunday afternoon and evening. Another night of poor RH recoveries is expected Sunday night into Monday morning. As a strong cold front crosses into northern Utah Monday afternoon, winds will increase further across the critical zones. This abrupt wind shift to the northwest will reach zones 495 and 496 Monday evening, 497 and 498 Monday evening into the first half of Monday night. A somewhat cooler airmass will build in behind this front for Tuesday. By Thursday, winds will increase ahead of the next system and the potential will increase for another round of critical fire weather conditions Thursday afternoon and evening and again Friday afternoon and evening in areas of critical fuels across southern Utah. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...Red Flag Warning from noon Sunday to 9 PM MDT Monday for UTZ495- 496. Red Flag Warning until 3 AM MDT Tuesday for UTZ498. Red Flag Warning from noon Sunday to midnight MDT Monday night for UTZ497. WY...None. && $$ Kruse/Merrill/Van Cleave For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity