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Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
046 FXUS65 KSLC 222112 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 312 PM MDT Sat Jun 22 2024 .SYNOPSIS...Lingering moisture will continue to bring the threat of thunderstorms to portions of eastern Utah through the early evening. Moisture will increase over southern Utah Sunday as northern Utah stays dry with dangerous heat expected for valley locations. Moisture will persist over southern Utah to start the work week as temperatures become slightly less hot over northern Utah. && .SHORT TERM (Through 12Z Monday)...Utah and southwest Wyoming are under a roughly zonal flow aloft this afternoon, allowing drier air from western Utah to advect into eastern Utah. As a result, seeing a steady decline in PWs, though satellite derived PWs are still around 0.7 over the majority of eastern Utah. Also seeing a bit of lingering jet support and shortwave energy from yesterday`s trough that is providing modest instability and shear. Thus, have seen isolated convection develop over eastern Utah, with some storms producing heavy rainfall, primarily over Capitol Reef National Park. The threat of storms will diminish during the early evening with the loss of daytime heating and as instability continues to move east of the area. By Sunday, high pressure will amplify over the area, giving a more southerly component to the flow aloft. This will advect deeper moisture back into southern Utah, bringing a threat of isolated to widely scattered convection capable of producing gusty winds and heavy rainfall. Meanwhile, the amplifying ridge will bring a very hot airmass over northern Utah with temperatures in the upper 90s to around 100F anticipated Sunday afternoon for the valleys of northern Utah, values up to 15F above normal for this time of year. HeatRisk data indicates these temperatures will be dangerously hot for many northern and central Utah valleys. Current suite of Excessive Heat Warnings and Heat Advisories seems to cover this threat well. .LONG TERM (After 12Z Monday), Issued 404 AM MDT...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...VFR conditions will prevail through the valid TAF period. Through 23Z, there is a very low chance (less than 10%) of convection forming over the Oquirrh Mountains, then drifting into the valley, and potentially producing gusty outflow winds. A northwest lake breeze should switch to a typical southeast drainage wind, perhaps enhanced a bit by southerly aloft, around 04Z. .REST OF UTAH AND SOUTHWEST WYOMING...Isolated convective activity will continue through the evening hours to the south and east of a KEVW to KBCE line. Any convection will be capable of producing gusty outflows winds and a brief period of reduced ceilings and visibilities. Otherwise, expect VFR conditions with typical diurnal wind patterns. && .FIRE WEATHER...Isolated showers and thunderstorms have developed over eastern Utah this afternoon, which will tend to dissipate this evening. Northern Utah will stay dry tomorrow, becoming dangerously hot. Over southern Utah, moisture will linger, allowing for additional convective development. Northern Utah will become a but less hot Monday but stay dry as moisture lingers over southern Utah. Southern Utah will dry for the middle to latter part of the week as winds increase, bringing the threat of critical fire weather conditions. && .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. && $$ SHORT TERM/FIRE WEATHER...Traphagan LONG TERM...Warthen AVIATION...Barjenbruch For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity