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Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
777 FXUS65 KSLC 221004 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 404 AM MDT Sat Jun 22 2024 .SYNOPSIS...Lingering moisture will continue to bring the threat of thunderstorms to portions of eastern Utah today. Additional moisture will be pulled north ahead of the next system impacting the Pacific...bringing the threat of additional showers and thunderstorms to central and southern Utah Sunday. Very hot temperatures can be expected across the northern valleys Sunday. && .SHORT TERM (Through 12Z Monday)...A much quieter day will be in store for the region Saturday, as the best forcing/moisture has shifted east of the region. Early morning upper air and satellite analysis indicates the best a pronounced band of moisture near the 4-Corners area, streaming into the Plains. Somewhat zonal flow is building into northern Utah. While net drying is noted across eastern Utah, sufficient instability and moisture remain in place for another round of convection this afternoon, though nothing similar to the coverage and severity of Friday afternoon. SBCAPE values near 1000 J/kg plus 25-30 kts of deep layer shear should support at least an isolated severe threat (mainly gusty winds and small hail) for eastern Utah...though cant rule out a thunderstorms in the Salt Lake Valley off the Oquirrhs. By Sunday, an upper level trough crossing the Pacific Northwest may draw additional moisture into southern Utah. CAMS nearly universally support additional convection across portions of central and southern Utah Sunday afternoon and evening. Meanwhile, across northern Utah, very hot temperatures are expected Sunday. Upgraded the Excessive Heat Watch to a Warning and added the Tooele Valley as temperatures have been trending fairly close to the Salt Lake Valley. Added Heat Advisories to Utah Valley, eastern Juab/Millard and the Sanpete and Sevier Valleys. .LONG TERM (After 12Z Monday)...On Monday, a trough passing through north of the region will help flatten the ridge and help nudge temperatures down very slightly, but the overall pattern persists into midweek. Broad ridging will extend from the southern Plains into the Desert Southwest, resulting in H7 temps locally around 15C to 19C. At the surface, this will yield continued anomalous heat, with daily afternoon high temperatures around 5F to 15F above climatological normal for late June, and overnight lows around 10F to 15F above normal. In comparison to yesterday`s guidance, temperatures have trended downward very slightly, such that HeatRisk no longer is as bullish on the necessity of subsequent heat headlines. That said, if guidance heads back the other way with things ultimately trending nearer the 75th percentile or so, headlines may yet need to be considered. In any case, the point remains that it will be quite hot for the vast majority of locations in the forecast area, with limited overnight cooling/recovery. Heat related safety should still be kept in mind, especially for those working or recreating outdoors. Stay hydrated and take frequent breaks if at all possible, and ideally wear light and loose fitting clothing. Aside from the heat, enough moisture continues to push into the region around the ridge to result in daily diurnal convection through midweek. Coverage of this convection will tend to be maximized from southern to central Utah, primarily firing off terrain and drifting into adjacent valleys. While convection will be fairly isolated to scattered in nature, those recreating in rain sensitive places such as slot canyon, typically dry washes, or slickrock areas should remain weather aware. Coverage looks to spread a little further northward on Wednesday, up into the Uintas or so. Thursday into Friday guidance continues to maintain some moderate consensus that a deepening Pacific trough will shift inland, flattening the trough, and depending on the amplitude, potentially shoving a cold frontal boundary southward at least into portions of the forecast region. As a result, precipitation chances increase Thursday afternoon (particularly along/east of the I-15 corridor), and temperatures are forecast to fall nearer to climatological normal. && .AVIATION...KSLC...Generally a quieter weather day anticipated at the terminal with southerly winds expected to switch to the northwest ~19Z-21Z Saturday, and return to a southerly direction between ~03Z-05Z thereafter. There is a fairly low chance (less than 20%) of convection forming off nearby terrain and drifting into the valley, which if it were to occur may produce some gusty outflow winds and briefly reduced conditions at the terminal. Otherwise, just some limited mid level cloud cover is expected. .REST OF UTAH AND SOUTHWEST WYOMING...Less active weather expected at area terminals, with only low chances (~10-20%) of convection primarily east of the I-15 corridor and south of the I-80 corridor. If any convection forms near terminals, some gusty erratic outflow winds would be possible. Otherwise, largely expect terminals to follow something near a diurnally typical wind pattern, with some mid level cloud cover filtering through. && .FIRE WEATHER...A very dry airmass remains across western Utah today, with another round of single digit to low teens humidities. Meanwhile, moisture will decrease across eastern Utah, but isolated showers and thunderstorms remain a possibility. While another round of showers and thunderstorms will develop across central and southern Utah Sunday, humidities will remain quite low across western Utah. Isolated convection will continue to be possible across the higher terrain through much of the week. Significant humidity improvement across the western half of the state is not forecast for the next 7 days, with eastern Utah remaining quite dry after Saturday. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...Excessive Heat Warning from 9 AM to 9 PM MDT Sunday for UTZ101>105. Heat Advisory from 9 AM to 9 PM MDT Sunday for UTZ106-116-118- 119. WY...None. && $$ Kruse/Warthen For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity