A shortwave trough acted on residual monsoon moisture to fuel scattered showers and thunderstorms across west-central Colorado. Some stratiform showers produced wind gusts in excess of 58 mph in Garfield County, which met high wind criteria.
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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.
A shortwave trough acted on residual monsoon moisture to fuel scattered showers and thunderstorms across west-central Colorado. Some stratiform showers produced wind gusts in excess of 58 mph in Garfield County, which met high wind criteria.
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 4, 10:05 AM MST, 1 minute earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 1105 AM MDT Mon Sep 4 2023 .SHORT TERM...(Today through Tuesday) Issued at 351 AM MDT Mon Sep 4 2023 Satellite imagery shows the low is moving through the Great Basin centered about over Elko NV tracking east. It looks to have mostly opened to the north over Idaho with the center core still closed off. The jetstreak associated with the upper-level low is starting to shift to the eastern flank to turn the trough motion more to the northeast across northern Utah into southern Wyoming by late this afternoon. Radar shows a band of showers and thunderstorms extending from the Salt Lake area southwest along I-15 to a bit south of Cedar City pretty much tracking to the northeast under the jet streak. The left exit region of the jetstreak looks to track along the Colorado- Wyoming Border early this morning where most of the convective activity occur. By late morning, the right entrance region moves over central eastern Utah and the Grand Valley with models indicating isolated to scattered showers and thunderstorms will initiate on terrain (the La Sals and the Uncompahgre Plateau) with more coverage north of the I-70 corridor along the Tavaputs and Roan Cliffs. With the upper-level support, some of these storms may move over the lower valleys, but the rain totals look to be on the low end as these storms will move quickly ahead of the frontal boundary. Expect stronger west winds gusting to 40 mph as dry air and clear skies moves in to the region behind the front. The front will move west to east through the Grand Valley around noon today, pushing east of the Divide by evening. Cloud cover, evaporative cooling and cool air advection will all combine to keep temperatures on average five to ten degrees below normal today across the region with the . cooler temperatures to the north. Clear skies overnight and tomorrow will begin a warming trend as temperatures return to near normal across the central and southern areas. .LONG TERM...(Tuesday night through Sunday) Issued at 351 AM MDT Mon Sep 4 2023 High pressure will be expanding across the Southwest CONUS border from midweek onward and effectively cutting off the monsoon source region.Therefore a dry forecast is on the books for the week. This will bring mostly clear skies and at times afternoon breezes which could lead to localized areas of critical fire weather conditions. Some moisture will be getting entrained in the Southwest flow around the high pressure cell by Saturday but this appears to be related to a tropical system moving out to sea in the E.Pac. So this dry and warm forecast easing into Fall looks to bring highs each day generally 4 to 8 degrees above normal for early September. If the limited tropical moisture materializes then some small chances of thunderstorm activity is possible by Sunday. This is showing up in the blended model solution but confidence in this is extremely low. Any better chances do not look to arrive until the middle of next week when a southerly wave enters the Southwest and picks up some moisture as it head to the 4 Corners. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 1102 AM MDT Mon Sep 4 2023 A system currently moving through the area has resulted in gusty winds, which will be common at most sites. Also, a band of showers is moving eastward along and north of I-70. Minimal impacts are expected from these showers. Skies are clearing behind the frontal band with the exception of an isolated shower or storm this afternoon. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...DB LONG TERM...15 AVIATION...TGJT
Hazardous Weather Outlook National Weather Service Grand Junction CO 349 AM MDT Mon Sep 4 2023 COZ001>014-017>023-UTZ022>025-027>029-051000- 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- 349 AM MDT Mon Sep 4 2023 This Hazardous Weather Outlook is for northwest Colorado, southwest Colorado, west central Colorado, east central Utah, northeast Utah and southeast Utah. .DAY ONE...Today and tonight. A frontal boundary moves through the region west to east from mid morning to late afternoon with isolated to scattered showers and thunderstorms ahead of it. Gusty outflow winds in excess of 40 mph and lightning will be the main threat from storms. Expect west winds gusting to 40 mph for a few hours behind the front as dry air and clear skies move into the region. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Dry breezy conditions continue through the end of the week. In the drier regime localized near critical fire weather conditions may develop Wednesday onward. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
A peak wind gust of 59 MPH was measured by the automated weather station at the Rifle Garfield County Airport.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2023Every state in 2023This day in weather historyWarnings in Colorado, September 2023
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: 1117828.