Trapped low level moisture in the wake of a shortwave trough produced areas of dense fog in some western Colorado valleys.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS GJT wrote it up.
Trapped low level moisture in the wake of a shortwave trough produced areas of dense fog in some western Colorado valleys.
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 7, 10:36 AM MST, 4 hours 24 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 1036 AM MST Fri Dec 7 2018 .SHORT TERM...(Today through Saturday) Issued at 230 AM MST Fri Dec 7 2018 Northern fork of a split 90-100kt jet (noted in H3 fields) has sparked a band of light snow from east-central Utah across west- central Colorado in the right entrance region of this feature. Jet aligned pretty closed to what the models were showing last night and should see this activity persist through daybreak before tapering off this morning. No impactful accumulations are expected with only an inch or two for the higher elevations with less than an inch for the valleys. Now lets look at those southern mountains and valleys in Southwest Colorado. Sometimes you swing for the fences on a marginal event and knock it out of the park. Looks like I struck out with this one as more fog than snow has blanketed much of southwest Colorado so far tonight (as a result of the wet snows that fell yesterday leaving wet roads and higher low level moisture). Breaks in the cloud cover has allowed areas of fog to form with visbilities below one mile. Still have a little energy working northeast across Arizona and low/mid cloud cover will increase this morning, which should help disrupt the fog a bit and drive some light snow back into the area. However, it will be too late for significant overnight impacts/accumulations. As such, have dropped all the advisories with a mention of morning showers and fog and only light accumulations (Trace to 3 inches). Steeper lapse rates this afternoon and main trough axis sliding into the area will lead to convective showers over the San Juans with an isolated storm not out of the question. This could result in a fast drop in visibility as showers pass through, although very short duration, more like a quick snow squall. Valleys dry out tonight and Saturday as flow aloft transitions to northwesterly behind the trough. Weak orographics and lingering moisture will be enough to squeeze out a few showers through Saturday afternoon, mainly along the higher northwest facing slopes. Again, not expecting big impacts, but snow will remain in the forecast for at least another 36 hours. Temperatures will continue to moderate today with readings jumping above freezing for many of the lower valleys with a 2 to 4 degrees cooldown expected on Saturday. .LONG TERM...(Saturday night through Thursday) Issued at 230 AM MST Fri Dec 7 2018 A weak shortwave will move through the northwest flow and clip the northern mountains for brief light snow showers there Saturday night through Sunday morning. Drier air continues to move in from the northwest Sunday as a ridge of high pressure moves in from the west and slides over the region by Monday morning. High level cloud cover looks to accompany this ridge axis as another trough moves into the Pacific Northwest on Monday. This trough looks to move across the area Tuesday afternoon and evening according to the GFS, which is quicker than earlier model runs. The northern and central mountains look to be favored with this quick hitting system. What is interesting is that the GFS and ECMWF flipped on their solutions from 24 hours ago, with the ECMWF now further south with this trough, taking the snowfall chances south of the Colorado border, whereas the GFS is now the further north solution. The GFS parallel still wants to dive this system even further south through Arizona and New Mexico, similar to the system affecting the region today. Another system follows on its heels Wednesday afternoon and evening, with the GFS stronger and further south than the GFS parallel and ECMWF. There are timing differences with these disturbances also, with the ECMWF a bit slower than the GFS. These timing and placement differences lend themselves to lower confidence in the forecast for next week, so the blended model solution approach appears the best way to go with lower chance PoPs until models come into better agreement. Ridge of high pressure builds back in to close out the week, but a more active weather pattern looks in store as we look beyond the next week with more weather systems moving inland off the Pacific. Temperatures look to make a rebound this weekend with near normal levels as high pressure moves in, but will become cooler with the couple weather disturbances moving through Tuesday and Wednesday. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 1036 AM MST Fri Dec 7 2018 Drier air will continue to infiltrate eastern Utah and western Colorado from the northwest today as high pressure builds over the Great Basin. However, lingering moisture and orographics will keep some light snow showers over the Continental Divide through 00Z. Patchy fog and low stratus will also hang around the I-70 corridor, briefly reducing VIS/CIGS through 20Z. Winds will continue to be light and variable. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...JDC LONG TERM...MDA AVIATION...MMS
Hazardous Weather Outlook National Weather Service Grand Junction CO 436 AM MST Fri Dec 7 2018 COZ001>014-017>023-UTZ022>025-027>029-081300- 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- 436 AM MST Fri Dec 7 2018 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Scattered to numerous snow showers are expected over the mountains, mainly south of Interstate 70 in western Colorado, through this evening. Showers will come to an end tonight. No significant snow accumulations are expected through tonight. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Saturday: Isolated snow showers are expected over the mountains. Sunday-Monday: Dry and warmer conditions will move into the region. Tuesday-Wednesday: There will be a chance for snow showers moving in across northeast Utah and northwest Colorado by Tuesday afternoon, continuing into Wednesday. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
945 AM MST FRI DEC 7 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0900 AM SNOW 5 NW CHROMO 37.07N 106.91W
12/07/2018 M2.9 INCH ARCHULETA CO COCORAHS
COCORAHS STATION CO-AU-29, PAGOSA SPRINGS
15.0SSE.
&&
MMSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
946 AM MST FRI DEC 7 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0600 AM SNOW 2 W PAGOSA SPRINGS 37.27N 107.06W
12/07/2018 M3.0 INCH ARCHULETA CO COCORAHS
COCORAHS STATION CO-AU-28, PAGOSA SPRINGS
2.5W.
&&
MMSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
132 PM MST FRI DEC 7 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0800 AM SNOW 6 E SKYWAY 39.04N 108.00W
12/07/2018 M6.5 INCH DELTA CO COCORAHS
COCORAHS STATION CO-DL-45, CEDAREDGE
10.5NNW.
0700 AM SNOW 2 W VAIL 39.65N 106.40W
12/07/2018 M3.1 INCH EAGLE CO COCORAHS
COCORAHS STATION CO-EG-21, VAIL 0.9WNW.
0730 AM SNOW 3 NW STEAMBOAT SPRINGS 40.50N 106.87W
12/07/2018 M2.9 INCH ROUTT CO CO-OP OBSERVER
CO-OP OBSERVER STATION SBTC2, STEAMBOAT
SPRINGS.
0730 AM SNOW 3 NW STEAMBOAT SPRINGS 40.50N 106.87W
12/07/2018 M2.9 INCH ROUTT CO CO-OP OBSERVER
CO-OP OBSERVER STATION SBTC2, STEAMBOAT
SPRINGS.
0700 AM SNOW 2 N WOLCOTT 39.73N 106.68W
12/07/2018 M2.6 INCH EAGLE CO CO-OP OBSERVER
CO-OP OBSERVER STATION WCTC2, WOLCOTT 2N.
0600 AM SNOW 2 E STEAMBOAT SPRINGS 40.47N 106.79W
12/07/2018 M2.6 INCH ROUTT CO COCORAHS
COCORAHS STATION CO-RT-43, STEAMBOAT SPRINGS
1.9E.
0700 AM SNOW 3 N MESA VERDE NATL PAR 37.20N 108.49W
12/07/2018 M2.5 INCH MONTEZUMA CO CO-OP OBSERVER
CO-OP OBSERVER STATION MVPC2, MESA VERDE
NAT'L PARK.
0700 AM SNOW 11 E COLONA 38.29N 107.55W
12/07/2018 M2.5 INCH GUNNISON CO COCORAHS
COCORAHS STATION CO-GN-47, CIMARRON 11.2S.
0700 AM SNOW 1 ESE STEAMBOAT SPRINGS 40.48N 106.81W
12/07/2018 M2.5 INCH ROUTT CO COCORAHS
COCORAHS STATION CO-RT-53, STEAMBOAT SPRINGS
0.7ESE.
0700 AM SNOW 4 N TIFFANY 37.09N 107.53W
12/07/2018 M2.3 INCH LA PLATA CO CO-OP OBSERVER
CO-OP OBSERVER STATION IGCC2, IGNACIO 8E.
0700 AM SNOW 1 NE STEAMBOAT SPRINGS 40.48N 106.81W
12/07/2018 M2.2 INCH ROUTT CO COCORAHS
COCORAHS STATION CO-RT-16, STEAMBOAT SPRINGS
1.1E.
0700 AM SNOW 2 NW ARRIOLA 37.45N 108.68W
12/07/2018 M2.0 INCH MONTEZUMA CO CO-OP OBSERVER
CO-OP OBSERVER STATION CRZC2, CORTEZ 11NW.
0700 AM SNOW 5 SE HESPERUS 37.23N 107.97W
12/07/2018 M2.0 INCH LA PLATA CO COCORAHS
COCORAHS STATION CO-LP-72, HESPERUS 4.9SE.
0700 AM SNOW 3 S VALLECITO 37.34N 107.61W
12/07/2018 M2.0 INCH LA PLATA CO COCORAHS
COCORAHS STATION CO-LP-35, BAYFIELD 7.0N.
0700 AM SNOW 1 NNW STEAMBOAT SPRINGS 40.49N 106.82W
12/07/2018 M2.0 INCH ROUTT CO COCORAHS
COCORAHS STATION CO-RT-28, STEAMBOAT SPRINGS
0.6NNW.
0700 AM SNOW 4 NE PHIPPSBURG 40.26N 106.87W
12/07/2018 M2.0 INCH ROUTT CO COCORAHS
COCORAHS STATION CO-RT-63, 3 ENE PHIPPSBURG.
0700 AM SNOW 4 W CATTLE CREEK 39.44N 107.31W
12/07/2018 M1.7 INCH GARFIELD CO COCORAHS
COCORAHS STATION CO-GF-73, GLENWOOD SPRINGS
7.2S.
0700 AM SNOW 1 W EDWARDS 39.65N 106.62W
12/07/2018 M1.5 INCH EAGLE CO CO-OP OBSERVER
CO-OP OBSERVER STATION EDRC2, EDWARDS 1WNW.
0730 AM SNOW 3 WSW SHOSHONE 39.57N 107.23W
12/07/2018 M1.5 INCH GARFIELD CO CO-OP OBSERVER
CO-OP OBSERVER STATION GWDC2, SHOSHONE.
0700 AM SNOW 1 W EDWARDS 39.65N 106.62W
12/07/2018 M1.5 INCH EAGLE CO COCORAHS
COCORAHS STATION CO-EG-3, EDWARDS 1.3WNW.
0700 AM SNOW 3 ESE GYPSUM 39.63N 106.90W
12/07/2018 M1.5 INCH EAGLE CO COCORAHS
COCORAHS STATION CO-EG-47, GYPSUM 2ESE.
0700 AM SNOW 4 E CATTLE CREEK 39.46N 107.18W
12/07/2018 M1.5 INCH GARFIELD CO COCORAHS
COCORAHS STATION CO-GF-49, CARBONDALE
4.6NNE.
0700 AM SNOW 7 NNW ROCKWOOD 37.60N 107.83W
12/07/2018 M1.5 INCH LA PLATA CO COCORAHS
COCORAHS STATION CO-LP-79, ROCKWOOD 6.9NNW.
0700 AM SNOW 5 WSW DURANGO 37.25N 107.95W
12/07/2018 M1.4 INCH LA PLATA CO COCORAHS
COCORAHS STATION CO-LP-61, DURANGO 4.8WSW.
0720 AM SNOW 1 WNW EL JEBEL 39.40N 107.11W
12/07/2018 M1.3 INCH EAGLE CO COCORAHS
COCORAHS STATION CO-EG-37, CARBONDALE 5.7E.
0900 AM SNOW 5 SW COLONA 38.22N 107.81W
12/07/2018 M1.3 INCH OURAY CO COCORAHS
COCORAHS STATION CO-OR-19, COLONA 5SW.
0700 AM SNOW 2 NW GLENWOOD SPRINGS 39.57N 107.35W
12/07/2018 M1.2 INCH GARFIELD CO COCORAHS
COCORAHS STATION CO-GF-40, GLENWOOD SPRINGS
1.7NW.
0700 AM SNOW CARBONDALE 39.40N 107.22W
12/07/2018 M1.2 INCH GARFIELD CO COCORAHS
COCORAHS STATION CO-GF-47, CARBONDALE 0.5W.
0800 AM SNOW 4 NE MILNER 40.52N 106.96W
12/07/2018 M1.2 INCH ROUTT CO COCORAHS
COCORAHS STATION CO-RT-48, STEAMBOAT SPRINGS
7.9WNW.
0700 AM SNOW 2 SSW GYPSUM 39.62N 106.96W
12/07/2018 M1.1 INCH EAGLE CO COCORAHS
COCORAHS STATION CO-EG-29, GYPSUM 1.9SSW.
0700 AM SNOW GLENWOOD SPRINGS 39.54N 107.33W
12/07/2018 M1.1 INCH GARFIELD CO COCORAHS
COCORAHS STATION CO-GF-1, GLENWOOD SPGS
0.64S.
0700 AM SNOW 5 S VALLECITO 37.31N 107.60W
12/07/2018 M1.0 INCH LA PLATA CO CO-OP OBSERVER
CO-OP OBSERVER STATION BYFC2, BAYFIELD 7N.
0707 AM SNOW OURAY 38.03N 107.67W
12/07/2018 M1.0 INCH OURAY CO CO-OP OBSERVER
CO-OP OBSERVER STATION URYC2, OURAY.
0700 AM SNOW 3 SSE GLENWOOD SPRINGS 39.51N 107.32W
12/07/2018 M1.0 INCH GARFIELD CO COCORAHS
COCORAHS STATION CO-GF-60, GLENWOOD SPRINGS
2SSE.
0700 AM SNOW 4 S VALLECITO 37.32N 107.60W
12/07/2018 M1.0 INCH LA PLATA CO COCORAHS
COCORAHS STATION CO-LP-98, 3 S VALLECITO.
0707 AM SNOW OURAY 38.03N 107.67W
12/07/2018 M1.0 INCH OURAY CO COCORAHS
COCORAHS STATION CO-OR-2, OURAY 0.23NNW.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
135 PM MST FRI DEC 7 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0700 AM SNOW 4 NNW MOUNT CRESTED BUT 38.97N 106.98W
12/07/2018 M6.0 INCH GUNNISON CO CO-OP OBSERVER
CO-OP OBSERVER STATION GTHC2, GOTHIC.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
137 PM MST FRI DEC 7 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0700 AM SNOW 2 N WOLCOTT 39.73N 106.68W
12/07/2018 M2.6 INCH EAGLE CO COCORAHS
COCORAHS STATION CO-EG-8, WOLCOTT 2.3N.
&&The national radar mosaic for the moment the first event began.
2 dense fog. Local standard time, as filed.
Dense fog occurred across portions of the Central Yampa River Basin as visibilities dropped below a quarter mile, including at the Meeker Coulter Field Airport.
Dense fog occurred across the Four Corners area as visibilities dropped below a quarter mile, including at the Cortez Municipal Airport.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2018Every state in 2018This day in weather historyWarnings in Colorado, December 2018
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: 790357, 790358.