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 8, 9:17 PM MST, 23 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 917 PM MST Thu Dec 8 2022 .UPDATE... Issued at 916 PM MST Thu Dec 8 2022 Completed an update to mainly the overnight temperature forecast. Several locations across the north were running significantly colder than previously forecast thanks to the excellent radiational cooling conditions. Many of the locations will see their overnight minimums occur in the next couple of hours before high clouds move overhead. In contrast some valleys across the central and southern areas were not cooling as fast and dewpoints were up higher than expected. This will keep those locations from being as cold tonight. && .SHORT TERM...(Tonight through Friday night) Issued at 250 PM MST Thu Dec 8 2022 The broad longwave trough across the CONUS sags southward over the next couple days, eroding the high pressure over the Gulf of Mexico. This pattern puts the region under a mostly zonal flow aloft which will continue to drive a train of shortwave troughs and ridges through the area. Satellite imagery shows the last system that went through overnight is currently over southeastern Wyoming moving to the northeast. A weak ridge moving in over eastern Utah and Western Colorado bringing mostly clear skies to the region today will quickly move through to the east by tomorrow morning ahead of the next shortwave system that will pass to the north Friday afternoon and evening. There is still a lot of residual moisture around and can't rule out a brief, light snow shower over the higher terrain, but otherwise this storm is passed and the Winter Weather Advisory for the Park Range was dropped. With mostly clear skies and a fresh blanket of snow across much of the region, expect radiative cooling overnight to drop tomorrow morning's lows to near normal in the lower valleys and five to ten degrees below normal in the higher mountain valleys. The residual moisture in the area will help buffer the low temperatures, but also brings a chance for fog forming in the valleys overnight, especially in the Uinta Basin, and the Yampa and Gunnison Valleys. Clouds associated with the next shortwave passing to the north will move in from the northwest through the day. This fast moving system won't bring much snow to the region, likely only a inch or two to the to the high Uintas and the Park Range. Otherwise, light snow showers may extend south to the I-70 corridor, but no accumulation is expected. This system will move off to the east overnight Friday, and the next weak ridge will slide in from the west by Saturday morning, bringing mostly clear skies across the region and another cold morning, a few degrees cooler than Friday. .LONG TERM...(Saturday through Thursday) Issued at 250 PM MST Thu Dec 8 2022 This weekend will be milder and pleasant as a shortwave ridge of high pressure slides overhead on Saturday followed by increasing southwest flow on Sunday ahead of a very deep and anomalous low pressure trough deepening over the Great Basin. This will lead to decent warm air advection, especially on Sunday as H7 winds increase to 30 to 40 kts, leading to deep mixing. A bit of a dry slot sneaks in in the tight gradient ahead of the deep closed low's cold front, which could lead to periods of sun helping the warming trend. Moisture begins to move in Sunday night. Very strong dynamics are evident with this system with a 120 kt jet rounding the base of the trough and strong upper level divergence. Showers get going over the eastern Utah mountains Sunday night before moving into the Four Corners and western Colorado Monday morning and afternoon, with precipitation becoming widespread by Monday afternoon. The flow will shift from strong southwest Monday afternoon to west Monday evening and then strong northerly flow by Tuesday morning. The closed low has some vertical stacking associated with it at H7 and H5 with the center tracking across the central portions of the area across the middle of our CWA on Monday evening into Tuesday morning. This is the period when large scale ascent and lift is maximized, as well as the period when the coldest air arrives. There is a very cold air mass associated with this closed low, where H7 temps drop down to the -10C to -12C range Monday night and to the -12C to -18C range by Tuesday afternoon. This will bring snow levels down to the lowest valley floors and the central track of the closed low at H7 and H5 spells good news for receiving accumulating snowfall in the lower valleys as this is a favorable track as lift is maximized underneath this low. The southern mountains and valleys appear favored for the best snowfall as they remain under the deepest moisture and forcing with strong southwest orographics helping the numbers early in the storm. This closed low moves onto the Plains, by Tuesday afternoon and moves across the midwest through Thursday before lifting out across the northern Great Lakes region on Friday. This keeps strong northerly flow hitting our northern valleys and mountains on the back side of the system through Wednesday and Thursday under a strong northerly flow, before snow finally comes to an end Friday morning. So all in all, the warmest day of the week will be Sunday with the coldest air we've seen in a while arriving in earnest Tuesday and lasting through the end of the week as a very cold air mass remains in place with H7 temps dropping into the -12C to -18C range Tuesday through Friday, before temperatures start to moderate the following weekend as the anomalously deep closed low moves eastward and loses its influence over the region. This means that high temperatures may struggle to get above freezing from Tuesday through at least the end of the week. Temperatures could be even lower though, depending on how much snow accumulates in the valleys which could end up with deep inversions. I mean, it's mid December for crying out loud?! Another storm system waits in the wings as another low moves into the Desert Southwest late next weekend but we can cross that bridge when it gets here. As far as snow amounts with this strong closed low Sunday night through Thursday, this system is looking significant and models are staying fairly consistent with the timing, track and strength of this system. The GFS, ECMWF and even now the Canadian seem to be in better agreement and coming on board. The probability of receiving at least advisory level snowfall in the mountains remains high and confidence is increasing that the valleys will share in the accumulating snowfall with this system. The amounts as they stand right now though seem underdone given the strong dynamics, deep moisture (150-200 percent of normal precipitable water) and very cold air mass with H7 temps well in the efficient dendritic snow growth range as the low tracks overhead and behind the system (which would be a fluffier, drier snow/higher ratio). && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 429 PM MST Thu Dec 8 2022 High confidence in VFR conditions for all TAF sites through the period. Afternoon cumulus will dissipate with sunset, so the ceilings below ILS approach at KASE will disappear by mid evening. Othewrise, mid to high clouds will increase from west to east late tonight and remain overhead Friday. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && UPDATE...BM SHORT TERM...DB LONG TERM...MDA AVIATION...BM
Hazardous Weather Outlook National Weather Service Grand Junction CO 328 AM MST Thu Dec 8 2022 COZ001>014-017>023-UTZ022>025-027>029-091030- 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- 328 AM MST Thu Dec 8 2022 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Scattered rain and snow showers will continue through the morning, before dissipating during the afternoon. Light snow showers will continue for the Park Range into the evening before also coming to an end. Additional snow fall of an inch or less at lower elevations and of 4-6 inches at higher elevations of the northern mountains expected. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Generally quiet weather will persist through the weekend, with a quick additional inch or two for the Park Range possible Friday evening. The next best chance for accumulating snow will be early next week. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
627 PM MST THU DEC 8 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0600 PM HEAVY SNOW HAYDEN 40.49N 107.25W
12/08/2022 M5.0 INCH ROUTT CO CO-OP OBSERVER
24 HOUR SNOWFALL.
&&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: 1060382.