Low level moisture remained trapped across the region in the wake of a departing system. This led to the development of dense fog across the Eastern Uinta Basin.
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The episode as NWS GJT wrote it up.
Low level moisture remained trapped across the region in the wake of a departing system. This led to the development of dense fog across the Eastern Uinta Basin.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Grand Junction, CO wrote its last area forecast discussion before the first event at Dec 10, 4:42 PM MST, 4 hours 48 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 442 PM MST Sat Dec 10 2022 .SHORT TERM...(Tonight through Sunday night) Issued at 249 PM MST Sat Dec 10 2022 Skies are mostly clear across eastern Utah and Western Colorado today with the exception of some low stratus and fog trapped in the Uinta Basin under an inversion. The fog has lifted in the past hour, but the low stratus will continue hanging around. For this reason, the Dense Fog Advisory was allowed to expire. A band of high clouds moving in from the west will stifle chances for the stratus to burn off. This band of clouds will move past the Uinta basin by late evening, allowing the basin to radiatively cool overnight under mostly clear skies. Look for the dense fog to reform through the evening and last until about noon Sunday before burning off. Satellite imagery indicates the models are running a few hours faster than the low is tracking as it descends off the coast of Washington State. Models still prog the low to make landfall mid day Sunday in Northern California, but on the latest run, are tracking the low farther north by Monday morning into southern Idaho. This trajectory is reducing the expected storm total precip/snow amounts across the region with this system. By Monday morning, the frontal boundary aloft at 700 mb looks to be meridionally aligned over central Utah poised to enter the region from the west. Jet support for this puts the left exit region moving over northeastern Utah and northwestern Colorado as early as Sunday afternoon, possibly kicking off a few early snow showers in the Uinta Mountains ahead of the system. Tomorrow will be a warm day under mostly clear skies. Tomorrow's highs will run about ten degrees above the seasonal normal. Enjoy the warmth while you can, because the rest of the week will be much colder. With the tight southeasterly pressure gradient ahead of the low, expect breezy southwesterly winds Sunday gusting 15 to 25 mph in the valleys and 30 to 35 mph over the higher terrain. Showers will move into the region from the west over night Sunday ahead of the front with some light snow accumulation possible in the lower valleys and a few inches on the higher terrain. At this time, icy roads conditions are not expected for the commute Monday morning at the lower elevation due to the generally warm temperatures overnight ahead of the cold front. Position and timing of the frontal passage will be something to watch over the next 24 hours to plan accordingly. Stay tuned for the latest updates. .LONG TERM...(Monday through Saturday) Issued at 249 PM MST Sat Dec 10 2022 The general overview of the long term forecast includes widespread precipitation with an initial cold front and daily high/low temperatures plummeting below normal through the end of the week. These winter weather conditions are tied to a deep low pressure system, which is expected to cross the region within the first 24 hours of the long term period. This nearly stacked, closed-low is progged to shift into northwestern Utah Monday morning, with a surface cold front just nosing into the CWA along our SLC WFO border. Strong southerly winds in prefrontal conditions not only maintain gusty conditions Monday morning but will also be pumping Pacific moisture up from the Four Corners region. Therefore, mountain snow showers ahead of the front will be well defined by mid morning, favoring south-southwest facing terrain. As the day progresses, 700mb trough axis advances across the Western Slope, swinging a line of showers along with. SBCAPE and low level frontogenesis maximize Monday afternoon, which also carries the threat for banding and snow squall-like conditions. Potential energy values aren't overly impressive in winter storms, but 100+ J/kg of CAPE combined with dynamic lift create sufficient ingredients to develop enhanced precipitation rates and drive snow levels down to valley floors. One caveat with desert valley snow actually accumulating, would be the timing of the front's passage. Terrain encompassed by this boundary during early to mid afternoon (likely the Grand Valley and stretching upstream the Gunny and Colorado River Basins) may be too warm for accumulating snow, initially. This would, however, be ideal for icy conditions to rapidly develop in the post-frontal regime. In contrast, looking at conditions generally above 5000 to 6000 ft, sub- freezing surfaces will favor all QPF to fall as snow. In addition, Thaler's QG equation denotes omega plunging over central Colorado throughout the day, which alludes to maximized dynamic lift directly overhead. The favorable dendritic growth zone (DGZ) lowers to about 700mb in post frontal conditions, thus, areas that lie below max dynamic lift through the DGZ will have the most efficient snow ratios. Current analyses favors the Unitas falling within this dynamic duo Monday morning, then shifting to the San Juan's by Monday evening. Overnight, the 500mb low lifts into the Northern Plains, which essentially cuts off moisture supply to southern zones and mountain ranges. However, as the low pressure system deepens across the Plains, a broad plume of moisture will continue to wrap around the northern and northwestern periphery of the low. Additional moisture supplied by the Gulf of Mexico will continue to feed snow showers for the northern and central mountains. By this point, northwesterly flow in a cold, post frontal environment will maintain fluffy snowflakes and now favor the western to northwestern aspects, while the low continues to progress into northeast Nebraska. Aside from on going showers across northwestern Colorado mountains, the 24-36 hour snow accumulations look to remain within advisory level thresholds. Forecast has been fairly persistent, generating a range of 5 to 10 inches in the mountains and 2 to 4 inches for higher valleys. By Wednesday, northerly winds encompass much of the CWA. The Euro is trending towards recent GFS runs, which show another short wave dropping into northern Colorado by Friday. This may trigger additional snow showers up north, but also maintain widespread cold temperatures across the region. Sub-freezing temperatures are forecast down to valley floors through the end of the week, with an exception of the Four Corners region which peak at 40 degrees by Saturday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 438 PM MST Sat Dec 10 2022 Some broken high clouds will move overhead this evening and overnight though conditions will remain VFR for all TAF sites minus KVEL. Current ceilings and vis at KVEL are in the IFR category and this trend will continue overnight through tomorrow morning. Visibilities will likely drop to below 1/4 mile over the next 2 hours while ceilings hover between 100 to 200 feet. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...DB LONG TERM...ERW AVIATION...TGR
Hazardous Weather Outlook National Weather Service Grand Junction CO 348 AM MST Sat Dec 10 2022 COZ001>014-017>023-UTZ022>025-027>029-111100- Lower Yampa River Basin-Central Yampa River Basin- Roan and Tavaputs Plateaus-Elkhead and Park Mountains- Upper Yampa River Basin-Grand Valley-Debeque to Silt Corridor- Central Colorado River Basin-Grand and Battlement Mesas- Gore and Elk Mountains/Central Mountain Valleys- Central Gunnison and Uncompahgre River Basin- West Elk and Sawatch Mountains-Flat Tops- Upper Gunnison River Valley-Uncompahgre Plateau and Dallas Divide- Northwest San Juan Mountains-Southwest San Juan Mountains- Paradox Valley/Lower Dolores River- Four Corners/Upper Dolores River-Animas River Basin- San Juan River Basin-Southeast Utah-Eastern Uinta Mountains- Eastern Uinta Basin-Tavaputs Plateau-Arches/Grand Flat- La Sal and Abajo Mountains-Canyonlands/Natural Bridges- 348 AM MST Sat Dec 10 2022 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight No significant weather is expected today. .DAYS TWO THROUGH SEVEN...Sunday through Friday Significant snowfall is possible late Sunday night through Wednesday as a strong winter storm moves through the area. Early indications are for nearly a foot or more of new snow across the mountains and up to 4 inches in the high valleys during this timeframe. Moisture wrapping around the exiting storm system may bring an additional few inches to the northern mountains through the end of the work week. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
The national radar mosaic for the moment the first event began.
1 dense fog. Local standard time, as filed.
Dense fog was observed across the Eastern Uinta Basin including at the Vernal Regional Airport as visibility was reduced to less than one quarter of a mile for several hours overnight and into the next morning.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2022Every state in 2022This day in weather historyWarnings in Utah, December 2022
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1060384.