A weakening shortwave trough is expected to bring light precipitation to northern Utah and southwest Wyoming tonight, according to a National Weather Service Area Forecast Discussion. While conditions are expected to remain generally dry and seasonable through Thursday, a significant Pacific storm arriving this weekend could bring an increased threat of flash flooding and lower snow levels.
Weather conditions are expected to remain fairly benign on Wednesday and Thursday under a southwesterly flow aloft. Temperatures are expected to cool slightly across northern Utah due to the cold front before rebounding for Thursday. A weakening trailing shortwave disturbance may cross Utah late Wednesday afternoon into Wednesday evening, though the associated dynamics appear insignificant with very little to no precipitation expected.
A new storm system is expected to begin spreading moisture into the area on Friday, bringing an increasing threat of flash flooding. While most of the forecast area may see no measurable precipitation, southwest Utah could experience heavier showers and isolated flooding potential. On Saturday, the storm system is expected to move inland, maintaining unsettled weather with isolated to scattered showers and thunderstorms.
The storm system is expected to cross Utah on Sunday, potentially phasing with a southern stream system associated with an atmospheric river. This could result in widespread, moderate to heavy precipitation and an increased flash flood threat. A cold front arriving Sunday is also expected to push lower snow levels into the region, with snow levels potentially dropping as low as 7500 feet by Monday morning.
Depending on the strength of the trough and precipitation amounts, snow totals could reach 3-6 inches, with locally 10 inches or more possible in higher elevation sites near Brian Head, the Tushars, the upper Cottonwoods, and the high Uintas. Precipitation is expected to mostly wind down by Monday morning, leaving a cool northerly flow in place.
The long-term pattern remains uncertain, as models diverge on how quickly the storm will progress east out of the area and whether another storm system will move into the area midweek.
