A series of disturbances moved across eastern Utah during the month of October. This led to areas of above normal precipitation for the month which resulted in some improvement of the drought across the region, most notably across the northern zones.
Every event with a place to put it; 7 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.
A series of disturbances moved across eastern Utah during the month of October. This led to areas of above normal precipitation for the month which resulted in some improvement of the drought across the region, most notably across the northern zones.
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 30, 10:37 PM MST, 1 hour 23 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 1137 PM MDT Thu Sep 30 2021 .UPDATE... Issued at 857 PM MDT Thu Sep 30 2021 Allowed the Flash Flood Watch for the Grizzly Creek burn scar to expire at 9 PM this evening. There are still a few light showers moving through the area, though rainfall rates and accumulations are expected to remain low. && .SHORT TERM...(Tonight through Friday night) Issued at 315 PM MDT Thu Sep 30 2021 Current mesoanalysis indicates the 700mb low is centered just south of the Four Corners and it's mid-level circulation is displaced to its northwest over central Utah. Strong southwesterly to southerly winds aloft have continued to pump anomalously high PWAT levels across the Western Slope. Through evening hours, the broad upper level circulation will tighten into a relatively stacked, closed low and slowly trek eastward along the CO/NM border. As a result, this transition will increase forecast PWATs between 100 to 200 percent of normal levels over Southwest Colorado and the Four Corners region. Current guidance is on track for moderate to heavy rainfall to favor this region through the evening, falling as a series of thunderstorms rippling north- northwest and then transitioning into stratiform precipitation rotating around the Four Corners overnight. WPC and ensemble guidance are in line with 0.5 to an inch of rain falling along the Foothills of the southern San Juans, with closer to 0.25 to 0.5 inches as you trek north and approach the CO/UT border. Some welcomed moisture, no doubt! However, heavier rates from convective activity may carry along additional hazards for sensitive areas (burn scars, steep complex terrain, and narrow canyons/arroyos). Moisture tied to this evening's convection will mainly stay confined south of the Hwy 40 corridor and then shift south of I-70 overnight. Increased moisture and cloud cover will keep temperatures cooler this afternoon, though moderate lows overnight. On Friday, the low slide southeast of the forecast area. Moisture tied to the east and northeast quadrant of the low should maintain storm activity along the Divide and across the San Juans Friday afternoon, thanks to moisture spilling over from the Front Range. Precipitation will be concentrated southeast of a diagonal line from the Abajos to the Uncompahgre, to the Grand Mesa, Flat Tops and tapping into the southerly tip of the Park Range. Can't rule out convective activity popping up over the Tavaputs or Uinta Mountains, however lower valleys to the northwest of this imaginary line will stay relatively dry. The eastward progression of the cold core low will result in warm air advecting into the area on Friday, and thus, allow high temps to increase a few degrees. Climbing trend will continue into the weekend, as mentioned in the long term discussion below. .LONG TERM...(Saturday through Thursday) Issued at 315 PM MDT Thu Sep 30 2021 Some residual moisture will remain across the CWA on Saturday as ridging starts to build in. Deterministic models continue to indicate that we'll receive enough daytime heating to allow some convection to fire over the San Juans and along the Divide up to Vail Pass. QPF amounts are forecast to only reach .1 inches so not much concern with rainfall with this convection. Despite the chance for convection, Saturday and Sunday both look to be nice days with plenty of sunshine as temperatures increase to near normal values and just above on Sunday. The NAM and EC both agree on a weak shortwave passing through Sunday evening allowing some convection to fire while the GFS also hints at this shortwave but doesn't produce any QPF. Will need a few more model runs to really nail down the specifics. As far as the bigger picture is concerned, guidance has been consistent with a closed low breaking off from the mean flow, just off the Baja California coast during the weekend. A long wave trough to the north will cause this closed low to move northeastward and be just on our doorstep Wednesday morning. Confidence is increasing for precip down south Wednesday morning shifting to the north through the day before ending Thursday morning. Unfortunately, the low looks to move pretty quickly so high QPF amounts aren't expected. Temperatures look to start above normal at the start of the work week and become more seasonal Wednesday as the next system moves through. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1130 PM MDT Thu Sep 30 2021 Lower cigs in this moist airmass are impacting flight conditions at the southern TAF sites under MVFR conditions. This may continue into the predawn hours with areas of terrain obscuration persisting over the next 24 hours. && .HYDROLOGY... Issued at 315 PM MDT Thu Sep 30 2021 GEFS M-Climate and EURO PWAT anomalies suggest some heavier precipitation falling over Southwest Colorado overnight. Late this afternoon into the early morning hours will be the time period of most concern. Burn scars and steep terrain will the most susceptible to excessive runoff and some minor urban flooding may occur due to storm drainage issues. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && UPDATE...NL SHORT TERM...ERW LONG TERM...TGR AVIATION...TGJT HYDROLOGY...15
Hazardous Weather Outlook National Weather Service Grand Junction CO 600 AM MDT Thu Sep 30 2021 COZ001>014-017>023-UTZ022>025-027>029-011200- 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- 600 AM MDT Thu Sep 30 2021 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Thunderstorm development will be possible this afternoon and evening. Some of these storms over southwest Colorado will contain heavy rainfall rates and lead to localized flooding. Burn scars...steep terrain and some urban areas in the San Juans and the southern valleys will be the most impacted by the heavy rainfall through sunrise on Friday. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Thunderstorm development will again be possible on Friday as this storm system moves slowly eastward. Drier conditions move in for Saturday with only isolated mountain thunderstorms expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected today or tonight, however spotters are encouraged to relay rainfall amounts or any observed flooding to the National Weather Service in Grand Junction.
The national radar mosaic for the moment the first event began.
7 drought. Local standard time, as filed.
The status of the drought remained unchanged through the month of October as extreme (D3) drought conditions persisted across the entirety of the zone.
The status of the drought remained unchanged across the zone through the month of October. The extreme (D3) drought continued over all but the far eastern portion of the zone where severe (D2) conditions remained.
The status of the drought remained unchanged through the month of October as extreme (D3) drought conditions persisted across the entirety of the zone.
The status of the drought improved across much of the zone during the month of October as the extreme (D3) drought was trimmed back to include just the far western part of the zone and improved to the severe (D2) category over the central part. Meanwhile, the severe drought improved to the moderate (D1) category across the far eastern portion of the zone.
The status of the drought improved across half of the zone through the month of October as the extreme (D3) drought improved to the severe (D2) category over the eastern portion of the zone. Meanwhile, the extreme drought continued over the western half.
The status of the drought improved across half of the zone through the month of October. The extreme (D3) drought improved to the severe (D2) category across the eastern portion of the zone. Meanwhile, the extreme drought continued over the western half.
The status of the drought remained unchanged across the zone through the month of October as extreme (D3) drought persisted across all but the far northwest corner where severe (D2) conditions continued.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2021Every state in 2021This day in weather historyWarnings in Utah, October 2021
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: 984918, 984919, 984920, 984921, 984922, 984923, 984924.