Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
161 FXUS65 KSLC 101016 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 416 AM MDT Mon Jun 10 2024 .SYNOPSIS...A weak cold front will bring a brief cooldown across the northern half of the region today, though temperatures will remain above normal. Strengthening high pressure will then build in by the middle of the week, resulting in temperatures well above seasonal normal once again. && .SHORT TERM (THROUGH 12Z WEDNESDAY)...High pressure is situated over Colorado this morning as a split storm system moves into the Western CONUS. The northern branch trough is continuing to track east across Idaho early this morning while the southern branch wave has pinched off into a closed low off the SoCal coast (and will factor into our weather later this week). The cold front associated with the Idaho trough has moved into northern Utah and currently extends from western Juab County through the Salt Lake Valley. A few weak showers continue to linger along the Idaho border. Meanwhile, another weak disturbance is noted lifting across southeast Utah. This has produced quite a bit of weak radar returns, but so far, no measurable precipitation has been reported by any surface obs. As such, these are likely just virga or sprinkles at best. Temperatures will cool across a good portion of the area today due to the cold front, most notably across the north. Many northern Utah locales will see a 5-10 degree drop in afternoon maxes today compared to yesterday. Still, given the abnormally hot temperatures of late, this is still 5-10 degrees above climatological normals. The airmass will also continue to gradually trend drier today. However, models are still showing a pocket of up to around 0.85 inches of PWAT today. This pocket of moisture coincides with the area of highest SBCAPE values this afternoon, which is a corridor from the west deserts through Utah County. While isolated and generally weak showers and thunderstorms are still possible over many higher terrain areas today, focus will be placed on this corridor where a couple of stronger cells may be possible later this afternoon. As high pressure starts to build back into the area on Tuesday, a warming trend will return. While not quite back into headline criteria inducing heat just yet, afternoon maxes will be generally 6- 12 degrees above climatology across the state, with triple digits in the lower valleys of far southern Utah and 90s across a good portion of the remaining valley areas. .LONG TERM (After 12Z/6AM Wednesday)...A strengthening, but shallow, ridge will dominate on Wednesday and Thursday, resulting in the two hottest days of the next seven. KSLC could even see its first 100 degree day, with a roughly 40% chance on both Wednesday and Thursday. As far as heat headlines go, an Excessive Heat Watch has been issued for Lake Powell/Glen Canyon on Wednesday/Thursday due to wide coverage of "Major" HeatRisk across the zone. Luckily, the heat will not last long as a closed low situated off the coast of SoCal begins to shift inland, reaching southern/eastern UT by Friday. Highs on Friday will thus decrease by around 5-15 degrees across the area with the greatest decrease across eastern areas along the track of the low. Scattered high-based convection is also looking more likely along and east of the central spine of Utah mountains during the afternoon. Heading into the weekend, uncertainty in the longwave pattern increases. Ensemble guidance favors some sort of trough moving into the PacNW early in the weekend, though there is plenty of disagreement in how it evolves across the Intermountain West. Roughly 59% of ensemble members favor a deeper trough resulting in a greater cooldown over Utah, while the other 41% of members suggest the trough remains fairly zonal and far to our north. To quantify this uncertainty further, the 25th-75th percentiles for 700-mb temperatures range from +4C to +13C...dropping from +17C on Thursday. && .AVIATION...KSLC...Northwesterly winds will continue through the day, with some gusts to 20kts possible after 18z. Winds may transition back to light and southeasterly as early as 05z this evening, becoming variable at times after 03z. .REST OF UTAH AND SOUTHWEST WYOMING...Isolated showers and thunderstorms are likely to develop after 19z across a line roughly from just south of KENV to just south of KPVU. These showers will be capable of producing gusty outflow winds, including at KPVU. Generally, winds will favor northwesterly across the northern two thirds of UT behind a weak boundary, with areas south favoring westerly to southwesterly winds during the afternoon. && .FIRE WEATHER...A cold front which will weaken and stall over central Utah today will result in cooler temperatures today, most notably across the north. Although the airmass is gradually trending drier, some isolated showers and thunderstorms can still be expected, mainly over the higher terrain. Temperatures will start trending warmer again tomorrow, then become hot Wednesday into Thursday as high pressure builds over the area. The next storm system looks to eject across southern and eastern Utah Friday into Saturday, bringing increased moisture and cooler temperatures heading into the weekend. However, as southerly flow increases on Thursday ahead of this system, marginal/isolated critical fire weather conditions are possible across portions of southern Utah Thursday afternoon and evening. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ Cheng/Cunningham For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity