Surface dew points increased across western Colorado as the ridge of high pressure slid east towards the Plains. This led to increased shower and thunderstorm coverage across the region with gusty outflow winds being the primary threat from convection.
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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.
Surface dew points increased across western Colorado as the ridge of high pressure slid east towards the Plains. This led to increased shower and thunderstorm coverage across the region with gusty outflow winds being the primary threat from convection.
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 May 30, 2:33 PM MST, 58 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 333 PM MDT Sat May 30 2020 .SHORT TERM...(Tonight through Sunday night) Issued at 333 PM MDT Sat May 30 2020 Showers and thunderstorms have been more prolific today as the lower atmosphere begins to moisten. The 12Z GJT sounding indicated precipitable water (PW) levels around 0.80 inches, which is the highest it's been this week. While gusty outflow winds in the 30s and 40s have been common with most storms, some of the stronger storms are beginning to produce brief moderate to heavy rain and even small hail. These stronger storms are exhibiting better organization but for the most part have been fairly short lived. This better organization and increase in activity is also attributed to a closed low over central California, lifting northeast through the northern Great Basin and Intermountain West. This will drag a shortwave boundary through the CWA from southwest to northeast late this afternoon into the evening, perhaps leading to an enhancement in activity and better chances the lower valleys will see some wetting rain. Storms could also last longer into the evening potentially a bit past midnight but should taper off early Sunday morning. After this low lifts northeast out of the area, drier air will be drawn in from the southwest across mainly portions of eastern Utah and northwest Colorado. A downturn in storm activity is expected on Sunday due to this drier air, with the focus shifting towards the western Colorado mountains mainly along the central and southern divide areas and some adjacent high valleys. Expect drier and breezier conditions across east-central Utah, while other areas will remain breezy with relative humidity levels just above the critical fire weather thresholds. More details in the Fire Weather section below. .LONG TERM...(Monday through Saturday) Issued at 333 PM MDT Sat May 30 2020 The ridge of high pressure will remain east of the divide with the upper level trough redeveloping over the west coast. A closed low will eventually develop off the southern California coast by Tuesday at the base of this trough and looks to remain there until Thursday. This keeps the ridge of high pressure to our east, and allows moisture to slowly advect into the region from the southwest in the persistent southwest flow. Looks reminiscent of a pattern we'd typically see in July (too soon?), but will allow for daily chances of afternoon storms, favoring the high terrain mainly over western Colorado. PW levels hover around the 0.6 to 0.7 inch mark so this should provide for enough moisture with daytime heating to produce convection. While models are coming into better agreement on the timing of when this SoCal low lifts northeast across the Great Basin and over our area, the details on placement and amount of moisture remain in question. The GFS is more amplified and wetter, while the ECMWF is the drier and less amplified solution. Regardless, the trend is for this low to lift northeast across the Great Basin and our CWA in the Thursday and Friday timeframe, with Friday looking like the more active day. Anticipate an increase in storm activity and coverage as this low lifts across the area with better chances of wetting rain on Friday if the GFS is to be believed. Temperatures will remain above normal by about 10 degrees Monday through mid week, with cooler temps expected late in the week due to increased clouds and showers. PW values come crashing down by next weekend as drier air moves in behind the passage of this trough. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1118 AM MDT Sat May 30 2020 Showers and storms will blossom with heating once again this afternoon with gusty outflow winds the main threat. VFR conditions should prevail over the next 24 hours though some sites may reach temporary ILS conditions as showers or storms pass nearby. There is the potential for these showers to last into the early morning hours especially in southwest Colorado. && .FIRE WEATHER... Issued at 333 PM MDT Sat May 30 2020 A downturn in storm activity is expected on Sunday as the latest disturbance exits the region and somewhat drier air advects in from the southwest. While winds will be gusty on Sunday, the main concern was relative humidity values being a bit too high across the region, limiting fire weather concerns. The area that looks to see better chances of critical fire weather conditions is east- central Utah, including Moab, so upgraded Utah Fire Zone 490 to a Red Flag Warning. Elected to cancel the Fire Weather Watch for the remaining zones as the relative humidity levels have come in a bit higher and conditions look localized or brief at best. Storm chances increase each day over the coming week as more moisture slowly advects in from the southwest. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...Red Flag Warning from noon to 8 PM MDT Sunday for UTZ490. && SHORT TERM...MDA LONG TERM...MDA AVIATION...TGJT FIRE WEATHER...TGJT
Hazardous Weather Outlook National Weather Service Grand Junction CO 354 AM MDT Sat May 30 2020 COZ001>014-017>023-UTZ022>025-027>029-311000- 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- 354 AM MDT Sat May 30 2020 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Thunderstorm development will be possible throughout the day and into the early evening period. The main threat will be gusty out flow winds but a few of the stronger storms will be capable of producing small hail this afternoon. .DAYS TWO THROUGH SEVEN...Sunday through Friday Thunderstorm activity will decrease in coverage on Sunday with the better chances limited to the central and southern Colorado mountains. Thunderstorm activity will occur over the terrain each afternoon early next week. Storm coverage looks to become more widespread from mid week onward. Warming temperatures will continue to eat at the snowpack and flows will be increasing. However at this time no flooding is forecast. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected today or tonight, however spotters are encouraged to report excessive wind or any observed wind related damage to the National Weather Service in Grand Junction.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
219 PM MDT SAT MAY 30 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0215 PM HAIL 9 SSW MONTROSE 38.36N 107.91W
05/30/2020 E0.25 INCH MONTROSE CO TRAINED SPOTTER
WIND GUSTS OF 40 MPH.
&&
TGJTPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
236 PM MDT SAT MAY 30 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0228 PM TSTM WND GST 2 NW MONTROSE 38.50N 107.90W
05/30/2020 M48 MPH MONTROSE CO ASOS
ASOS STATION KMTJ MONTROSE RGNL AIRPORT.
&&
TGJTSpecial Weather Statement National Weather Service Grand Junction CO 239 PM MDT Sat May 30 2020 COZ011-014-017-302115- Upper Gunnison River Valley CO-Uncompahgre Plateau/Dallas Divide CO- Central Gunnison and Uncompahgre River Basin CO- 239 PM MDT Sat May 30 2020 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL DELTA AND NORTH CENTRAL MONTROSE COUNTIES UNTIL 315 PM MDT... At 239 PM MDT, Doppler radar was tracking a strong thunderstorm over Olathe, or 8 miles northwest of Montrose, moving north at 10 mph. Half inch hail and wind gusts up to 50 mph will be possible with this storm. Locations impacted include... Montrose, Delta and Olathe. This includes U.S. Highway 50 in Colorado between mile markers 72 and 90. LAT...LON 3850 10787 3852 10806 3874 10808 3872 10780 TIME...MOT...LOC 2039Z 189DEG 8KT 3858 10796 KJS
Special Weather Statement National Weather Service Grand Junction CO 243 PM MDT Sat May 30 2020 COZ002-005-013-302130- Flat Tops CO-Upper Yampa River Basin CO-Central Yampa River Basin CO- 243 PM MDT Sat May 30 2020 ...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL ROUTT COUNTY UNTIL 330 PM MDT... At 243 PM MDT, Doppler radar was tracking a strong thunderstorm 10 miles southwest of Hayden, or 16 miles southeast of Craig, moving north at 10 mph. Half inch hail and wind gusts up to 50 mph will be possible with this storm. Locations impacted include... Hayden. This includes U.S. Highway 40 in Colorado between mile markers 97 and 116. LAT...LON 4028 10721 4032 10745 4054 10745 4049 10711 TIME...MOT...LOC 2043Z 189DEG 8KT 4035 10732 KJS
Special Weather Statement National Weather Service Grand Junction CO 303 PM MDT Sat May 30 2020 COZ003-006-017-302145- Roan and Tavaputs Plateaus CO-Uncompahgre Plateau/Dallas Divide CO- Grand Valley CO- 303 PM MDT Sat May 30 2020 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN MESA COUNTY UNTIL 345 PM MDT... At 303 PM MDT, Doppler radar was tracking a strong thunderstorm 8 miles south of Fruita, or 9 miles southwest of Grand Junction, moving north at 10 mph. Half inch hail and wind gusts up to 50 mph will be possible with this storm. Locations impacted include... Grand Junction, Fruita, Loma, Glade Park and Redlands. This includes the following highways... Interstate 70 in Colorado between mile markers 13 and 29. Colorado 139 between mile markers 1 and 6. LAT...LON 3897 10862 3900 10885 3927 10885 3923 10852 TIME...MOT...LOC 2103Z 186DEG 10KT 3902 10874 KJS
Special Weather Statement National Weather Service Grand Junction CO 423 PM MDT Sat May 30 2020 COZ008-010-013-302245- Central Colorado River Basin CO-Flat Tops CO- Gore and Elk Mountains/Central Mountain Valleys CO- 423 PM MDT Sat May 30 2020 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN GARFIELD COUNTY UNTIL 445 PM MDT... At 422 PM MDT, Doppler radar was tracking a strong thunderstorm near Glenwood Springs. This storm was nearly stationary. Half inch hail and winds in excess of 40 mph will be possible with this storm. Locations impacted include... Glenwood Springs, Shoshone and Cattle Creek. This includes the following highways... Interstate 70 in Colorado between mile markers 115 and 126. Colorado 82 between mile markers 1 and 9. PRECAUTIONARY/PREPAREDNESS ACTIONS... Heavy rainfall is also occurring with this storm, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. This storm may intensify, so be certain to monitor local radio stations and available television stations for additional information and possible warnings from the National Weather Service. && LAT...LON 3941 10729 3947 10740 3967 10731 3956 10711 TIME...MOT...LOC 2222Z 218DEG 4KT 3949 10731 Stearns
The Grand Junction radar (KGJX), 67 km away, was scanning. The volume nearest the first event began at 22:29 UTC.
1 thunderstorm wind. Local standard time, as filed.
The automated weather station at the Rifle Garfield County Airport recorded a peak wind gust of 64 MPH from a severe thunderstorm.
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, May 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: 885987.