Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
152 FXUS65 KSLC 292205 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 405 PM MDT Sun Sep 29 2024 .SYNOPSIS...A weak and dry cold front will cross northern Utah and southwest Wyoming tonight into Monday, bringing some brief relief from the hot temperatures to northern Utah. A dry and somewhat mild airmass will remain in place for much of the remainder of the upcoming week. && .SHORT TERM (Through 12Z/6AM Tuesday)...Early Sunday afternoon, a plume of mid-level moisture had advected into Utah ahead of a weakening closed low located over SoCal. PWATs have increased into the 100-150% of normal range, and combined with weak large-scale ascent, just enough moisture, lift and instability (SBCAPE is analyzed at 250-500J/kg) to produce isolated showers and thunderstorms. Moist advection has not manifest at the surface, with a very dry, well-mixed environment in place with healthy DCAPE values greater than 1500J/kg. As a result, multiple, decaying cells have produced wind gusts in the 45-55 mph range, with a couple of higher gusts observed. A dry cold front will move southward through northern Utah this evening, moving through the Wasatch Front between from north to south between 9PM and 12AM, per the HREF mean. This front will bring a cooldown of 5F-15F across northern Utah for Monday, but temperatures will remain well above normal. Just enough moisture is forecast to linger across southern Utah to support an isolated shower Monday afternoon/evening, otherwise dry conditions are forecast across the area by the model suite. .LONG TERM (After 12Z/6AM Tuesday), Issued 310 AM MDT... There is good model agreement on a ridge off the Pacific coast that will be largely stationary through Wednesday. Southwest Wyoming and Utah will have a dry zonal to northwest flow. Temperatures will range from around 5-15 warmer than normal. The ridge will track inland Thursday, with minimal changes through at least Friday. There is more disagreement with ensemble guidance into the weekend, with almost an equal number of ensemble members on a cold front associated with a trough to the north tracking into southwest Wyoming and Utah and on a ridge through the week. There is good confidence that a cold front would be a rather dry boundary. Temperatures would decrease to slightly warmer than normal throughout southwest Wyoming and northern Utah, with slight cooling in southern Utah. && .AVIATION...KSLC...VFR conditions will persist for the period across the KSLC terminal. High based convection with gusty and erratic winds will dissipate after sunset with winds returning to light southerly flow. A dry cold front overnight will bring light northerly winds ~06Z. .REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will persist for the airspace through the period. High based convection across the area this afternoon will keep winds gusty and erratic before convection dissipates after sunset. A dry cold front will move through the north with light northerly flow developing. Light and variable winds will persist elsewhere. && .FIRE WEATHER...Just enough mid-level moisture has worked into the area ahead of an upper low in Southern California to support the development of isolated showers and thunderstorms across much of the state early Sunday afternoon with gusty, erratic microburst winds. A dry cold front will move through northern Utah this evening and through the early overnight hours, bringing an abrupt wind shift to the north. As a result of this front, pockets of critical fire weather conditions are in place late Sunday afternoon across northeast Utah, thanks to gusty winds and low humidity. Pockets of critical fire weather conditions will develop once again Monday afternoon here as well, although temperatures will be 5F to 15F cooler Monday behind the cold front. Tuesday through Friday, high pressure ridging will build back into the area, ensuring a continuation of dry conditions and very warm temperatures for the time of year, with highs 10F to 20F above normal. In addition, overnight humidity recovery will be poor, especially across central and southern Utah. Another weak dry cold front may swing through northern Utah next Saturday. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...Red Flag Warning until 7 PM MDT Monday for WYZ277. && $$ ADeSmet/Wilson/Mahan For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity