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Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
536 FXUS65 KSLC 282150 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 350 PM MDT Fri Jun 28 2024 .SYNOPSIS...High pressure will bring the return of hot and dry conditions over the weekend. Increasing winds will bring the potential for critical fire weather conditions into Monday. Moisture and instability may return to the area early next week. && .SHORT TERM (Through 12Z/6AM Sunday)...Early Friday afternoon, broad westerly flow was in place across Utah and SW Wyoming in the wake of yesterday`s shortwave trough and associated jet, which as of this writing was exiting eastward across Wyoming and the Northern Plains. The proximity of the jet remains close enough to maintain deep-layer shear of 35-45kts across eastern Utah. Low level moisture remains ample, with dewpoints in the upper 40s to mid 50s. Deep-layer moisture is much lower than Thursday, however, with PWATs checking in around 125-175% of normal across eastern Utah. Given less plentiful moisture and less forcing when compared to Thursday, convective activity is much less. However, enough shear and moisture exists to support isolated showers and thunderstorms. We can`t rule out an isolated strong thunderstorm through this evening capable of producing gusty winds, hail, dangerous lightning and briefly heavy rainfall. CAMs suggest the greatest potential exists across the Uinta Basin and the Swell. Dry conditions will largely be in place on Saturday, however, just enough low-level moisture will linger across eastern Utah, mainly over high terrain areas. Otherwise, the most noticeable change will be increasing temperatures, as Saturday`s high temperatures will rise 5F to 10F compared to Friday`s. With deep-layer southwesterly flow becoming increasingly established as we head through the day Saturday in advance of an incoming trough, gusty SW winds will develop in the afternoon, strongest across western valleys, where gusts will reach the 20-30 mph range. .LONG TERM (After 12Z/6AM Sunday), Issued 353 AM MDT... An approaching PNW trough will increase southwesterly flow aloft. A well mixed boundary layer during the day on Sunday will increase surface southwesterlies with widespread gusts 25-35 mph. High pressure centered over Texas will advect higher moisture into the southeastern portion of the CWA with drier air encompassing the remainder of the region. This will pose a fire weather risk Sunday afternoon. An isolated high based thunderstorm will be possible across the southeastern portions of the CWA. With inverted V sounding profiles, any storms that do form will be capable of producing gusty microburst winds. Temperatures will be in the mid to upper 90s for most locations with 100-107 across far southern Utah. The aforementioned trough will move through Utah on Monday with increasingly southwesterly flow and low RH once again. A dry cold front will sweep through northern Utah, dropping high temperatures ~10 degrees compared to Sunday. This cooler air likely won`t make it too far into central or southern Utah, resulting in little change in daytime highs. Moisture will stay more elevated across southeastern Utah so another isolated storm can`t be ruled out as this trough moves by. A gradual transition to a dry northwesterly flow aloft will scour out moisture across southeastern Utah and eliminate almost all chances for precipitation for the remainder of the period. Cooler air aloft across the northern CWA will keep temperatures near normal with temperatures running ~5 degrees warmer than normal across central and southern Utah. By the end of next week the ensemble members signal a bit of uncertainty regarding the overall synoptic pattern. 56% of members have high pressure building off the PNW coast with a continued dry northwesterly flow that will prevent temperatures from getting too much above normal. 25% of the members have high pressure building over the Great Basin that would keep conditions dry with hotter temperatures. The remaining 19% of members have high pressure centered to our southeast that could advect moisture into the region indicative of a monsoon type of pattern. && .AVIATION...KSLC...VFR conditions will continue tonight and tomorrow with dry weather and generally clear conditions. Northwest winds up to 10kts this afternoon will pivot to southeast between 3Z and 6Z. South to southwest winds are expected by mid-morning tomorrow, likely in the 10 to 15 knot range. There is uncertainty in the timing of stronger south to southwest winds developing, with a 50% chance of this change occurring by 15Z. .REST OF UTAH AND SOUTHWEST WYOMING...Scattered cumulus over the higher terrain east of US-89, with a few embedded showers and thunderstorms, will continue through the early evening before dissipating. Elsewhere, expect generally clear conditions with light winds. Similar conditions are expected tomorrow with a further downward trend in cumulus/shower/thunderstorm activity. Stronger southerly sustained winds of 10-20 knots with gusts to around 25 kts will develop by tomorrow afternoon. && .FIRE WEATHER...Drier air is continuing to move into Utah from the north and west this afternoon. However, isolated showers and thunderstorms are anticipated over far eastern Utah into early Friday evening. By Saturday, minimum relative humidity values are expected to drop to or below 15 percent over much of Utah, with breezy winds anticipated over a large portions of southwest and west central Utah. Winds will increase even further on Sunday, with critical fire weather conditions developing across much of Utah`s lower elevation areas especially where critical fuels, winds and humidity intersect. Winds will begin to diminish on Monday, but critical fire weather conditions will persist across southwest and south-central Utah with more isolated critical fire weather conditions across eastern valleys. From Tuesday through Friday, isolated pockets of critical fire weather conditions are expected, with most areas remaining dry. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...Fire Weather Watch from Sunday afternoon through Sunday evening for UTZ492. Fire Weather Watch from Sunday afternoon through Monday evening for UTZ495-497-498. WY...None. && $$ ADeSmet/Van Cleave For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity