Temperatures were above normal and precipitation was below normal across much of Colorado during the month of August. As a result, drought conditions in southwest and west-central Colorado either persisted or worsened with the drought expanding north to encompass much of the western slope by the end of the month.
Every event with a place to put it; 21 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.
Temperatures were above normal and precipitation was below normal across much of Colorado during the month of August. As a result, drought conditions in southwest and west-central Colorado either persisted or worsened with the drought expanding north to encompass much of the western slope by the end of the month.
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 Jul 31, 10:37 PM MST, 1 hour 23 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 1137 PM MDT Fri Jul 31 2020 .SHORT TERM...(Tonight through Saturday night) Issued at 240 PM MDT Fri Jul 31 2020 U/A hand analysis is showing ridging extending from the subtropics to the arctic circle over western NOAM. The anomalous heights under the ridge will be stubborn to break down and an extended period of hot...northwest flow is in store for the CWA. This northwest flow can throw a wicked curveball at times...especially when and where convection will fire. Sometimes unexpectedly in the middle of the night thanks to the jet placement aloft. For now the central and southern Colorado and northeast Utah mountains will be favored for orographic flow to initially release the instability and pop storms. Valleys close to the terrain may see some storms roll off as they drift south. Doubtful much rain will be seen in the next few days with gusty outflow winds the main threat. New fire starts also a concern. Hot temperatures will be another concern with highs likely to reach the triple digits over much of the lower desert valleys. Luckily the drier atmosphere will allow radiational cooling to drop lows at least into the lower 70s so heat headlines not planned attm. No relief in this pattern through early next week. .LONG TERM...(Sunday through Friday) Issued at 240 PM MDT Fri Jul 31 2020 High pressure is going to dominate the pattern for the week. Some subtle disturbances riding over the top of the ridge will bring weather to the Front Range, and trigger some moisture to wrap around in our CWA. Pockets of 0.75 inch PW associated with this little splash of extra moisture will keep a low chance of showers and thunderstorms in the forecast, mainly along the Great Divide. Otherwise, the rest of the CWA will be hot and dry, with the lower valleys flirting with triple digit afternoon highs. Models are still hinting at a pattern change mid to late next week, with the high pressure being pushed east with a trough moving into the Pacific Northwest. As the high settles over the Southern Plains, another trough will develop off the California coast, setting the stage for a potential subtropical moisture surge. PW values are forecast to increase into the 0.75-1.00 inch range, which, along with increasing dew points, will lead to higher shower and thunderstorm activity. There are still discrepancies between models, especially in the positioning of the ridge and trough driving the moisture plume, but each subsequent model run has been showing some variation of this pattern, so confidence is growing. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1131 PM MDT Fri Jul 31 2020 Scattered mid level clouds will generally dissipate over the western slope tonight into Saturday morning. After a mainly clear start to the day, scattered afternoon thunderstorms will develop in the higher terrain and generally drift southeastward. It is unlikely that any terminals will be affected as the showers should remain in higher elevations however a very brief shower is possible at GUC, ASE, TEX and possibly DRO. Expect clearing and drying in the evening. VFR conditions will dominate the day. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...15 LONG TERM...BGB AVIATION...MAC
Hazardous Weather Outlook National Weather Service Grand Junction CO 403 AM MDT Fri Jul 31 2020 COZ001>014-017>023-UTZ022>025-027>029-011015- 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- 403 AM MDT Fri Jul 31 2020 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Expect isolated thunderstorms to develop this afternoon over the mountains of the Continental Divide. This activity is expected to diminish early this evening, fully dissipating by sunset. Gusty winds will be the primary threat with developing storms. .DAYS TWO THROUGH SEVEN...Saturday through Thursday High pressure will continue to bring warmer and drier conditions. An exception will be along the Continental Divide where isolated to scattered thunderstorms will be possible each afternoon. A monsoonal surge of moisture is possible beginning Thursday portending greater thunderstorm coverage for the end of the coming week. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
855 PM MDT FRI JUL 31 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0350 PM HAIL 6 SSW PAGOSA SPRINGS 37.19N 107.06W
07/31/2020 E0.70 INCH ARCHULETA CO TRAINED SPOTTER
&&
GJTThe national radar mosaic for the moment the first event began.
21 drought. Local standard time, as filed.
The extreme (D3) drought persisted across the entirety of the forecast zone through the end of August.
The extreme (D3) drought persisted across the eastern and central portions of the zone and expanded to include the entirety of the forecast zone by the end of August.
Extreme (D3) drought conditions persisted across the western half of the zone and expanded to include the entirety of the forecast zone by the end of August.
The extreme (D3) drought persisted across the entirety of the forecast zone through the end of August.
The extreme (D3) drought persisted across the far southeastern portion of the zone and expanded to include the entirety of the forecast zone by the end of August.
The extreme (D3) drought persisted across the majority of the forecast zone and expanded to include the few remaining portions of the zone by the end of August.
The extreme (D3) drought continued across the eastern and central portions of the zone and expanded to include the entirety of the forecast zone by the end of August.
The extreme (D3) drought persisted across the majority of the forecast zone and expanded to include the few remaining portions of the zone by the end of August.
The extreme (D3) drought continued across the eastern and central portions of the zone and expanded to include the entirety of the forecast zone by the end of August.
The extreme (D3) drought persisted across the far western portion of the zone and expanded to include the entirety of the forecast zone by the end of August.
The extreme (D3) drought persisted across the far eastern portion of the zone and expanded to include the entirety of the forecast zone by the end of August.
The extreme (D3) drought persisted across the far southern portion of the zone and expanded to include the entirety of the forecast zone by the end of August.
Moderate (D1) to severe (D2) drought conditions worsened to the extreme (D3) category across the entirety of the forecast zone by the end of August.
Moderate (D1) to severe (D2) drought conditions worsened to the extreme (D3) category across the entirety of the forecast zone by the end of August.
Moderate (D1) to severe (D2) drought conditions worsened to the extreme (D3) category across the entirety of the forecast zone by the end of August.
Moderate (D1) to severe (D2) drought conditions worsened to the extreme (D3) category across the entirety of the forecast zone by the end of August.
Moderate (D1) drought conditions worsened to the extreme (D3) category across the majority of the forecast zone by the end of August and to the severe (D2) category across the far northwest portion of the zone.
Moderate (D1) drought conditions worsened to the extreme (D3) category across the entirety of the forecast zone by the end of August.
Abnormally dry (D0) to moderate (D1) drought conditions worsened to the extreme (D3) category across the southern and central portions of the forecast zone by the end of August and to the severe (D2) category across the northern tier of the zone.
Abnormally dry (D0) to moderate (D1) drought conditions worsened to the extreme (D3) category across the southern and central portions of the forecast zone by the end of August and to the severe (D2) category across the northern tier of the zone.
Abnormally dry (D0) drought conditions across the far northeast portion of the zone and moderate (D1) to severe (D2) conditions across the remainder of zone worsened to the extreme (D3) category across the entirety of the area by the end of August.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2020Every state in 2020This day in weather historyWarnings in Colorado, August 2020
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: 909860, 909861, 909862, 909863, 909865, 909866, 909867, 909868, 909870, 909871, 909872, 909873, 909874, 909875, 909876, 909877, 909878, 909879, 909880, 911009, 911011.