858 FXUS65 KSLC 120342 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 942 PM MDT Sat May 11 2019 .SYNOPSIS... High pressure will build across the region through the weekend, and remain the dominant weather feature into the first half of upcoming week. Cool and unsettled weather will return by late next week. && .DISCUSSION...A few persistent showers this evening continue to creep southward through Kane County and should be into Arizona within the hour. The state will then remain precipitation free for the overnight period. Some high clouds continue to stream over the Uinta mountains and along the spine of the mountains through central and southern Utah. The forecast this evening was updated just to be more consistent with current conditions, however largely it is in great shape with no updates needed. Many locations today topped out in the upper 60s and low 70s (outside of St George reaching 77F). Weather to finish out the weekend and start the work week off will be under high pressure with mostly clear skies and warming temperatures. The first 80+F degree day is forecast for Salt Lake City for Monday. The average date of the first 80F degree day for Salt Lake City is May 3rd. .PREVIOUS DISCUSSION (issued 302 PM MDT)... Ridging will prevail across the region Sunday through Tuesday, with the thermal ridge axis cresting the forecast area by mid-week. The result will be a welcome stretch of quiescent weather across the region, combined with day-to-day warming. High and low temperatures will both trend to 10-15F above normal by Tuesday under sunny to mostly sunny skies. While this will accelerate snowmelt runoff, with area stream and rivers running cold, high and fast, the current forecasts keep them within bankfull with little flood threat at this time. A downstream ridge position coupled with amplification of the next pacific long wave trough off the pac coast will maintain a mild southwesterly flow aloft across the area through Thursday, becoming increasingly moist and strengthening with time. Western valleys look quite breezy Thursday afternoon in advance of the first ejecting short wave moving into the central great basin at that time...with H7 flow boosting into the 30-35kt range and some surface gradient support likely. Some diffluence aloft locally coupled with a net increase of both mid/upper moisture continues to support isolated to scattered convection during the peak heating hours as well. The short wave trough will trend negatively tilted overhead (possibly closed) by Friday, and with ample moisture/lift continue to anticipate fairly widespread precip thereafter into (through) Saturday as the trough slowly lifts across the area. Although some differences in amplitude of this trough exist in deterministic globals, the big picture solution continues to lean on the higher confidence side regarding sensibly weather outcome. The long term begins with temps running some 10 degrees above normal and largely dry, but will end with temps back below climo...unsettled with some mtn snow once again. && .AVIATION... Winds are becoming light and beginning to shift to the southeast, expecting the shift to finish by 05z. Mostly clear skies will prevail with no aviation concerns through the valid TAF period. && .FIRE WEATHER...High pressure will build from the Pacific Northwest today across the region through mid next week. An isolated shower or thunderstorm is possible across southern Utah this afternoon and again Sunday afternoon, although this low threat with otherwise dry weather prevailing. The building high pressure will mainly bring a warming and drying trend, with temperatures 10-15 degrees above average by midweek. Cool and unsettled weather will return by late next week. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ Dewey For more information from NOAA's National Weather Service visit... http://weather.gov/saltlakecity For frequently asked questions about the Area Forecast Discussion visit... http://weather.gov/saltlakecity/general/afd_faqs.php