


Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
984 FXUS65 KSLC 022142 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 342 PM MDT Wed Apr 2 2025 .SYNOPSIS...Troughing will maintain an unsettled pattern through Friday. The pattern will gradually shift towards ridge dominated moving into the upcoming week, resulting in dry and mild conditions. && .SHORT TERM (Through 12Z/6AM Friday)...A large scale mid to upper level trough remains centered more or less atop the area this afternoon. Across the northern half of the forecast region, steepened lapse rates due to increased cold air aloft is driving the development of some instability driven showers. Further south more into central Utah, the area is situated beneath something of a deformation zone given the progression of the trough, which in combination with instability is yielding showers with fairly limited motion. As daytime heating ceases later this evening, coverage of shower activity should begin to decrease in these areas. Across southern Utah, nearer the base of the trough, multiple shortwave impulses continue to ripple by within the broader scale trough. Along with with some extra support from an associated surface low, a higher coverage of shower activity pivoting around the circulation is noted accordingly. Through the remainder of the short term, the aforementioned features will slowly continue an eastward trajectory. With the pattern remaining fairly similar, albeit shifting slightly, southern Utah will continue to see higher precipitation coverage. In particular expect highest chances over the high terrain, with a higher coverage period expected during the daytime due to diurnal heating. Elsewhere across the forecast region, daytime heating will also once again trigger development of scattered shower activity. Impacts-wise, given minimal change in forecast philosophy, opted to maintain the ongoing Winter Weather Advisory covering the southern Utah mountains. Amounts remain broadly in the 6-12" range, with potential for locally higher amounts in places like the Tushar Range. In any stronger bands of snow, or where the terrain can add a favorable upslope component given how the low is pivoting through, some periods of higher snowfall rates to an inch or so an hour will be possible. Snow levels will follow a diurnal trend, generally rising to around 4500-5000 ft MSL during the day, and falling more around 3500-4000 ft MSL during the overnight. As such, some lighter lower elevation accumulations will be possible, especially across southern Utah where coverage/forcing will remain highest. Elsewhere at areas northward, any stronger diurnal cell with convective enhancement could briefly result in moderate periods of graupel/snow/rain mix, which could pose briefly hazardous to any motorists encountering them. .LONG TERM (AFTER 12Z FRIDAY)...The long term forecast period features a general trend of drier and more stable conditions as high pressure gradually builds into the area. Temperatures will trend higher during this timeframe, eventually bringing temperatures back to and above normals for this time of year. However, this period begins Friday morning with an elongated trough still over the area, with a closed low over Arizona. This will maintain moist and unsettled conditions for Utah, with showers increasing again Friday afternoon. Precipitation should remain relatively light, with around 1-3 inches of snow over the mountains, highest across southern and central Utah. With H7 temperatures continuing to trend upward (to between -6 to -9C across the forecast area), snow levels should be above 5-5.5kft most areas by afternoon. As precipitation winds down Friday evening with the loss of daytime heating, some locally gusty canyon winds will be possible. Areas of focus include both the Wasatch Front and Washington County. At this point, however, models are not in very good agreement with canyon winds of any significant strength along the Wasatch Front, but with a general east to northeasterly H7 flow and surface pressure gradient, this is something to monitor. There is more agreement with regards to gusty Washington County canyon winds, but even so, the NBM currently only has less than a 20% chance of gusts reaching 45 mph. High pressure building into the area from the northwest will then bring drier and more stable conditions to the area on Saturday, along with warmer temperatures (albeit still below normal). By Sunday, the ridge axis will be over eastern Nevada with Utah remaining under a northwesterly flow aloft. Temperatures should rise closer to climatological normals on Sunday. However, a shortwave trough is then forecast to break into the ridge. Mostly, this will just flatten the ridge, halting the warming trend and bringing a bit of an increase in moisture to the area. Some models are a bit stronger with the trough, such as the deterministic GFS. This solution would bring precipitation to at least northern Utah along with a cooling trend for the Monday/Tuesday timeframe. For now, just maintained the NBM in the forecast given model spread. By Wednesday, a broader ridge will build into the area, leading to a more prolonged period of dry and warm conditions (afternoon maxes over 70F likely at SLC Wed-Fri). && .AVIATION...KSLC...Snow showers, primarily around nearby mountainous terrain, will taper off around 01Z. There is around a 30% chance for showers at KSLC, likely as a rain and snow mix capable of MVFR conditions. Dry conditions will last through the night, although mountain obscuration is likely. Isolated to scattered showers, primarily mountain snow showers, will build after 18Z. .REST OF UTAH AND SOUTHWEST WYOMING...Showers will primarily linger around mountainous terrain for southwest Wyoming and northern Utah through around 01Z. Throughout southern Utah, it is more likely for precipitation to track into valley areas, including snow showers at KCDC and KBCE and rain showers at KSGU through 09Z. Snow showers will be capable of lowering conditions into MVFR or IFR range. Isolated to scattered showers will build after 18Z for southwest Wyoming and most of Utah, primarily around mountainous terrain. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...Winter Weather Advisory until 9 PM MDT Thursday for UTZ125. WY...None. && $$ SHORT TERM...Warthen LONG TERM...Cheng AVIATION...Wilson For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity