Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
877 FXUS65 KSLC 071034 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 334 AM MST Sun Dec 7 2025 .SYNOPSIS...Generally tranquil conditions are expected over Utah and southwest Wyoming through Monday, with just a few showers late Sunday into Monday morning near the Utah/Idaho border. Winds will increase Tuesday into Wednesday, bringing the potential of strong winds to southwest Wyoming and the western Uinta Basin. There is 25% chance that the northern Utah mountains will see warm atmospheric river moisture return by midweek, with a 75% chance that windy conditions will persist with minimal moisture. && .SHORT TERM (Through 12Z/5AM MST Tuesday)... Key Messages: - High pressure will bring generally tranquil conditions across Utah and southwest Wyoming through Monday - Flow aloft will increase out of the west to northwest Tuesday into Wednesday, with a medium chance of wind gusts exceeding 45 mph for southwest Wyoming and the Western Uinta Basin during that time. - There is a 25% chance that warm atmospheric river moisture returns to northern Utah by Wednesday, which could produce 1-2 inches of water equivalent in the mountains with high snow levels and dense snow. Otherwise, there is a 75% chance that moisture remains to our north brining minimal precipitation and otherwise windy conditions for the mountains. Eastward expansion of the Pacific ridge has pushed atmospheric river moisture and associated instability eastward out of Utah and southwest Wyoming, resulting in tranquil conditions this morning with just some high clouds for northern Utah. Temperatures will be on the mild side, with maxes averaging 5F above seasonal normals over southwest Wyoming and northern Utah, and up to 10F above climo across southern Utah. Grazing shortwave energy will bring an increase in cloud cover over northern Utah this afternoon into Monday morning, particularly near the Utah/Idaho border where there is a low chance of light mountain snow. Any accumulations will be light. Modest warm advection will bring a subtle warming trend, particularly for northern Utah where maxes will approach 10F above seasonal normals. .LONG TERM (After 12Z/5AM MST Tuesday)...The mid-week storm continues to be a tricky forecast as models struggle to pinpoint the trajectory of a landfalling atmospheric river. QPF is the main area of uncertainty by a long shot; in fact, QPF spread has increased further across the northern mountains since earlier forecasts. But first, looking at the large-scale pattern, our forecast area will be situated between a broad region of high pressure off of the west coast and a trough across the eastern US by Tuesday morning, resulting in overall northwesterly flow through at least Thursday. A landfalling atmospheric river in the PacNW will bring moisture into the Intermountain West, though the main question is how far south it`s able to reach. A reasonable low-end scenario puts only 0.00- 0.10" of QPF across the northern mountains, if that plume stays too far north. However, model guidance has a fairly high tail in the distribution, even at the 75th percentile. For example, the NBM 75th percentile QPF between Tuesday and Thursday is up to 0.30-1.30" across the northern mountains, with the highest amounts in the Bear River Range. Luckily, there is higher confidence in other aspects of the forecast. For example, snow levels will be high, rising to 8000- 9000ft by Wednesday morning with subtle warm-air advection across the area. This will result in very dense snow/low snow ratios, similar to our even lower than our last storm system. Additionally, regardless of what happens with precipitation, a strong jet to our north will produce strong winds, particularly across Uinta Co., WY. Current ensemble mean 700-mb flow is around 45kts, with guidance suggesting wind gusts well into the 40-50kt range across much of the county. NBM probabilities of 24-hour max gust exceeding 50kts reach 60-90% by Wednesday afternoon. By Friday, conditions look to dry out statewide as the aforementioned ridge builds across the western US. Temperatures will hover around 10-20 degrees above normal, with 700-mb temperatures rising to +2C to +5C by Saturday. && .AVIATION...KSLC...Southerly to southeasterly winds will continue through the TAF period, though will increase slightly to 8-12kts between roughly 18-01z. VFR conditions will prevail, though CIGs around 5000ft AGL will bring a period of mountain obscuration after ~06z Monday. REST OF UTAH AND SOUTHWEST WYOMING...Conditions will remain largely quiescent as winds continue to decrease across the area. Aside from westerly wind gusts to 20kts developing SW-WY this afternoon, winds should remain largely light and terrain-driven elsewhere. VFR conditions will prevail, with lowering CIGs/mountain obscuration heading into the evening hours, particularly after 03-06z. Expect a few light showers to develop Sunday night across far northern UT. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ SHORT TERM...Traphagan LONG TERM/AVIATION...Cunningham For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity