Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
488 FXUS65 KSLC 232134 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 334 PM MDT Thu May 23 2024 .SYNOPSIS...A cool, stable airmass across northern Utah will transition to a more active pattern Friday. Widespread precipitation is expected north of I-70 late Friday into Saturday evening. A cool, stable airmass will shift into the area for Sunday, followed by a warming trend early next week. && .SHORT TERM (Through 12Z Sunday)...It`s May but we are feeling very April here today in the Beehive State. A mainly dry cold front is currently across southern Utah. Afternoon upper air and satellite analysis indicates an upper level low pulling away from the area across northeastern Wyoming. Several additional shortwave troughs are noted upstream and will bring additional rounds of precipitation to the region through Saturday. The previously mentioned cold front will continue to weaken as the upper level support shifts away from the region. This front will shift northward Friday, nearing central Utah by afternoon. Meanwhile, a combination of PVA ahead of the next shortwave trough and preferential jet dynamics will support the development of convection across much of the state. Looking at the 12Z CAMS, sufficient instability is expected across the bulk of the members to support isolated convection as far south as southern Utah, with the highest likelihood from near the boundary north. The strongest potential for any impacts, and the highest potential for heavy rain will be north of I-70. By Friday night, a weak boundary will now be across portions of northern and central Utah as yet another shortwave trough will shift into the region. With a period of frontogenesis expected Saturday morning into Saturday afternoon, widespread precipitation is expected. Heaviest precipitation will again be north of I-70. By late Saturday, this shortwave trough will be lifting out of the area, bringing a cool, stable airmass into the area by Sunday morning. For those planning to venture into the higher terrain Friday into Sunday morning, expect winter-like conditions with accumulating snow above about 8500 feet, especially for the western Uinta Mountains. Be careful out there! .LONG TERM (After 12Z Sunday)... Issued 409 AM MDT Through Sunday, should see precipitation tapering off as the system from the prior day(s) departs eastward. Temperatures will warm from that of Saturday, but afternoon highs areawide will remain below seasonal normal for late May. Deterministic and ensemble model guidance continues to show good consensus in support of a building ridge from Memorial Day on into midweek. This will yield dry conditions and a warming trend, with afternoon highs likely near normal on Monday, increasing to above normal moving into the middle of the week. In comparison to prior forecasts, NBM has backed off slightly on the potential for the first 90F or higher day Wednesday afternoon (down to 22% now at KSLC). This appears to be due to potential for an amplifying trough in the PacNW to flatten the ridge or shunt the ridge axis a bit more east of the area, seemingly supported by ~50% of ensemble members. Generally would just anticipate this to result in slightly cooler (but still above normal) temperatures, though something more aggressive/amplified like what the deterministic GFS depicts would certainly be more interesting. This split in ensemble scenarios carries on into Thursday as well, though even then there is ~25% of ensemble membership which support a continued strong ridge. Overall though, looks favorable for a period of more summer-like weather with several days with highs in the low to mid 80s across much the Wasatch Front, and mid to upper 90s in Lower Washington County. While beyond the forecast period, CPC 8 to 14 day also leans in favor of warmer/drier conditions in comparison to normal, so some sort of ridge dominated pattern seems favored to largely persist. && .AVIATION...KSLC...Northwest winds are expected to gradually decrease late this afternoon and into the early evening hours. Expect a shift back to southerly by around 04z. The south winds will likely persist into the early afternoon hours Friday along with VFR conditions before showers begin to develop for the second half of the afternoon. .REST OF UTAH AND SOUTHWEST WYOMING...Generally VFR conditions with west to northwest winds will persist across the forecast area into this evening. Winds will then decouple and become more terrain-driven by late this evening though the overnight hours. Near the Idaho border, CIGS of 11-12kft MSL will continue until around 01- 02z. Friday by around 19-20z, showers are expected to begin developing across central Utah, increasing in coverage and expanding into portions of northern and southern Utah through the rest of the afternoon and into the evening hours. && .FIRE WEATHER...Warm, dry, and breezy conditions continue across southern Utah this afternoon as a cold front gradually weakens across southern Utah. This boundary will lift north Friday, with the highest potential for wetting rain near and north of the boundary across central and northern Utah. Most of the showers and thunderstorms will trend toward high-based given the dry antecedent conditions. By Saturday, another stronger trough will bring widespread precipitation across northern and central Utah with a much higher chance of wetting rain. Southern Utah will see more isolated, high-based convection. An abnormally cool airmass will be in place statewide Sunday...with a significant warm- up expected into early next week. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ Kruse/Warthen/Cheng For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity