Residual low level moisture in the wake of a departing upper level disturbance allowed dense fog to form in the Upper Yampa River Basin.
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The episode as NWS GJT wrote it up.
Residual low level moisture in the wake of a departing upper level disturbance allowed dense fog to form in the Upper Yampa River 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 Sep 1, 2:24 AM MST, 2 hours 51 minutes earlier.
Area Forecast Discussion National Weather Service GRAND JUNCTION CO 324 AM MDT Fri Sep 1 2017 .SHORT TERM...(Today through Saturday) Issued at 236 AM MDT Fri Sep 1 2017 The upper level trough will continue to drag across the southern half of the area, making slow progress to the east and south. WV satellite imagery shows frontolysis occurring at all levels so uplift from the trough is minimal. Isolated to scattered showers and a few thunderstorms are expected over the San Juan mountains this afternoon and evening. Further north and west cooler temperatures and more stable conditions will continue spreading over the area. After midnight tonight the trough should be south of the CO and UT borders and closed high pressure will once again take hold over the Great Basin. Expect drier and more stable conditions Saturday. .LONG TERM...(Saturday night through Thursday) Issued at 236 AM MDT Fri Sep 1 2017 The strong ridge over the Great Basin will remain the dominant weather feature over the western U.S. through Monday. Monday night the GFS drops a cold front and strong upper trough down the front range and this pushes the Great Basin ridge to the west. Scattered storms should develop along the Continental Divide Tuesday. Wednesday and Thursday the western ridge takes over again though the trend seems to call for moderately strong troughs to move out of the PACNW and into the northern Rockies. These trough will push the ridge south and west and carry moisture into the area toward the end of the week. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) Issued at 236 AM MDT Fri Sep 1 2017 VFR conditions will prevail at all the TAF sites for the next 24 hours. Isolated to scattered showers and thunderstorms are expected over the San Juan mountains through about 05z. KDRO has a small chance for outflow wind gusts to about 35 mph && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...CC LONG TERM...CC AVIATION...CC
Hazardous Weather Outlook National Weather Service GRAND JUNCTION CO 234 AM MDT Fri Sep 1 2017 COZ001>014-017>023-UTZ022>025-027>029-020845- 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- 234 AM MDT Fri Sep 1 2017 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight A disturbance will continue moving through the southern half of the area today and tonight bringing isolated to scattered showers and a few thunderstorms to mainly the San Juan mountains. The main threat from these storms will be cloud to ground lightning and outflow winds to 40 MPH. .DAYS TWO THROUGH SEVEN...Saturday through Thursday High pressure and drier conditions will move back into the area with only isolated mountain showers and thunderstorms expected each afternoon. .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 occurred across portions of the Upper Yampa River Basin along Colorado Highway 40, as well as the the Steamboat Springs Airport where the visibility dropped down to a quarter mile.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2017Every state in 2017This day in weather historyWarnings in Colorado, September 2017
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: 713038.