A 70 to 80 knot jet streak moved over eastern Utah with deep layer shear and CAPE between 1000 to 1500 J/kg, resulting in a few strong storms that produced hail dime to penny size.
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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 70 to 80 knot jet streak moved over eastern Utah with deep layer shear and CAPE between 1000 to 1500 J/kg, resulting in a few strong storms that produced hail dime to penny size.
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 Aug 25, 1:16 PM MST, 2 hours 14 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Grand Junction CO 216 PM MDT Sun Aug 25 2024 .KEY MESSAGES... - All the ingredients will be in place for another day of showers and thunderstorms. Some storms may reach severe criteria. Strong wind gusts and hail will be possible with the strongest storms. - Heavy rain also remains possible especially if any training occurs. Localized flash flooding is possible in susceptible areas. - Dry air moves in Monday and Tuesday. Some showers and storms may return Wednesday onwards over the southern half of the forecast area. && .SHORT TERM /THROUGH MONDAY/... Issued at 141 PM MDT Sun Aug 25 2024 The day started early with a wave of fast moving thunderstorms traversing eastern Utah and northwestern Colorado southwest to northeast under the right entrance region of a 95 kt jetstreak. Storm motion was 50 to 60 mph with brief heavy rain, a foreboding of what's coming this afternoon and evening. Behind this wave skies cleared to allow the sun to warm the region and fill the tank to feed the later thunderstorms. With the jet overhead, expect southwest winds this afternoon gusting 25-35 mph in the valleys and over 50 mph at the higher elevations. This mornings sounding had a pwat of 0.84 inches, and a conservative projection of surface temps along with mixing out dewpoints revealed CAPE of 500 to 1000 J/kg with the level of free convection approaching 250 mb concurring with the overshooting top temps on the current storms. With the very dry air above 500 mb, DCAPE exceeded 800 J/kg making severe outflow winds likely later today. Models are showing 30 to 50 kts shear through the afternoon and evening across eastern Utah extending across the border into Western Colorado which also points to more severe thunderstorms. Hoisted the Flash Flood Watch for southeastern Utah this morning based on possibility of training storms which looks to be a good call as thus far the storms have been training. WPC has hoisted a Severe Thunderstorm Watch through 8 PM today for eastern Utah and most of Western Colorado for large hail and damaging winds from the afternoon and early evening thunderstorms. Temperatures today will remain five to ten degrees below normal for late August due to the precipitation and clouds in the region. Models are in good agreement with satellite imagery showing the low centered over Nevada beginning to lift to the northeast. As the low over the Great Basin ejects to the northeast into southeastern Idaho and western Wyoming through this afternoon and overnight, the high over Kansas shifts farther east into the Midwest and the jetstreak slides east more over Western Colorado pushing high dry air into eastern Utah and Western Colorado generally north of the San Juans with pwats falling below 0.50 inches across much of the region by Monday morning. With the right entrance region of the jet still over the Colorado mountains through early Monday morning, expect convection to continue well into the overnight period. With the dry airmass over the region and the upper level dynamics pushed east out onto the Plains Monday, showers and thunderstorms will be mostly isolated over the southern Colorado mountains with a few stragglers in the central mountains and the northern mountains along the Divide. Look for temperatures to remain five to eight degrees below normal Monday as the trough passes over the region. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Issued at 152 AM MDT Sun Aug 25 2024 Due to the high operational tempo, the long-term forecast has not been updated since early this morning. As noted above, monsoonal moisture will continue to stream up from the south but the low pressure moving across the northern Plains States will shunt this moisture eastward. This is evident with forecast PWATs only reaching 0.4 inches Monday night and staying right around there through Wednesday. Enough residual moisture and instability may linger over the highest terrain of the San Juans to allow some weak afternoon convection to fire both Tuesday and Wednesday. Elsewhere, partly cloudy skies will be the rule tending towards more sunny skies than not. The San Juans may see more clouds but that'll be about it. High temps will reach right around the usual late August values. Wednesday, a deep area of low pressure will be tracking just north of the Canadian/US border. A cold front will drop down from this low and will move across northern portions of the CWA Wednesday evening. Do not anticipate much besides a wind shift. However, both the EC and GFS are indicating that this will open the door, somewhat, for moisture to move in from the south. Forecast PWATs will reach around 0.8 inches and this moisture will only reach as far north as the I-70 corridor. So while it's not a massive surge (median values around those dates area usually .65 inches), moisture will increase nonetheless. The NBM solution for 40 to 50% chance PoPs (slight chance to chance) for showers and thunderstorms for the southern half of the forecast area looks reasonable for each afternoon and evening from Wednesday through Saturday. As one would expect, increased cloud cover will also make an appearance in the same area so daytime highs will be about 5 degrees cooler than seen over the last few days. Areas north will see temps run a few degrees above seasonal values. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1151 AM MDT Sun Aug 25 2024 Deep moisture and a series of disturbances aloft will generate numerous showers and thunderstorms across eastern Utah and western Colorado. Strong southwest winds aloft will drive storms forward at 35 to 40 mph or higher leading to localized strong winds. Potential is high for thunderstorms to impact all TAF sites this afternoon/evening with MVFR visibility a strong possibility. Storms are likely to continue overnight across the north as a trough encroaches on the area late. && .HYDROLOGY... Issued at 629 AM MDT Sun Aug 25 2024 PWAT came in at 0.84 this morning which is a bit lower than seen recently. Having said that, showers and storms have already fired early this morning with already impressive instantaneous rainfall rates. Convection will be ongoing through the day with the strongest expected from noon onwards. Slot canyon country and steep terrain may be affected by these rainfall rates and as these areas did experience some flash flooding a few days ago, felt it prudent to issue a Flash Flood Watch again today. While this convection will be moving quickly, the possibility of training cells was enough to go ahead and issue said product. The Watch is in effect from noon through midnight tonight. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...Flood Watch until midnight MDT tonight for UTZ022-027>029. && SHORT TERM...DB LONG TERM...TGR AVIATION...NL HYDROLOGY...TGJT
Hazardous Weather Outlook National Weather Service Grand Junction CO 232 AM MDT Sun Aug 25 2024 COZ001>014-017>023-UTZ022>025-027>029-261230- 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- 232 AM MDT Sun Aug 25 2024 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Showers and thunderstorms, some strong, will move across the area today. Strong outflow winds and larger hail will be possible under the strongest thunderstorms. Some localized flash flooding is also possible especially if any training occurs with these storms. Convection will continue overnight. .DAYS TWO THROUGH SEVEN...Monday through Saturday Dry air moves in Monday and Tuesday keeping convection to a minimum though a stray shower or quick storm can't be ruled out over the San Juans. Modest moisture may return Wednesday onwards and cause an uptick in convection for the southern half of the forecast area. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected today or tonight, however spotters are encouraged to relay rainfall amounts, strong winds, or any observed flooding to the National Weather Service in Grand Junction.
Special Weather Statement
National Weather Service Grand Junction CO
400 PM MDT Sun Aug 25 2024
COZ019-021-022-252230-
Animas River Basin CO-Southwest San Juan Mountains CO-
Four Corners/Upper Dolores River CO-
400 PM MDT Sun Aug 25 2024
...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN MONTEZUMA AND WEST
CENTRAL LA PLATA COUNTIES THROUGH 430 PM MDT...
At 400 PM MDT, Doppler radar was tracking a strong thunderstorm 17
miles north of Shiprock, moving northeast at 45 mph.
HAZARD...Wind gusts up to 50 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Mancos and Mesa Verde Natl Park.
This includes U.S. Highway 160 in Colorado between mile markers 50
and 59, and between mile markers 61 and 62.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
A Severe Thunderstorm Watch remains in effect until 800 PM MDT for
southwestern Colorado.
&&
LAT...LON 3704 10872 3742 10830 3722 10807 3700 10842
3700 10868
TIME...MOT...LOC 2200Z 226DEG 40KT 3703 10858
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH
NLSpecial Weather Statement
National Weather Service Grand Junction CO
417 PM MDT Sun Aug 25 2024
COZ001-002-013-252230-
Flat Tops CO-Lower Yampa River Basin CO-Central Yampa River Basin CO-
417 PM MDT Sun Aug 25 2024
...STRONG THUNDERSTORMS WILL IMPACT CENTRAL MOFFAT COUNTY THROUGH 430
PM MDT...
At 416 PM MDT, Doppler radar was tracking a cluster of strong
thunderstorms 30 miles northwest of Meeker, or 36 miles west of
Craig, moving northeast at 35 mph.
HAZARD...Wind gusts up to 40 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Maybell, Juniper Springs, and Sunbeam.
This includes the following highways...
U.S. Highway 40 in Colorado between mile markers 38 and 72.
Colorado 64 between mile markers 42 and 43.
Colorado 318 between mile markers 40 and 60.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Heavy rain is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
A Severe Thunderstorm Watch remains in effect until 800 PM MDT for
northwestern Colorado.
&&
LAT...LON 4042 10788 4016 10844 4087 10842 4100 10814
4100 10783
TIME...MOT...LOC 2216Z 224DEG 31KT 4040 10823
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH
DBSpecial Weather Statement
National Weather Service Grand Junction CO
419 PM MDT Sun Aug 25 2024
COZ002-003-007-252245-
Roan and Tavaputs Plateaus CO-Debeque to Silt Corridor CO-
Central Yampa River Basin CO-
419 PM MDT Sun Aug 25 2024
...A STRONG THUNDERSTORM WILL IMPACT SOUTH CENTRAL GARFIELD AND SOUTH
CENTRAL RIO BLANCO COUNTIES THROUGH 445 PM MDT...
At 418 PM MDT, Doppler radar was tracking a strong thunderstorm 20
miles northwest of De Beque, or 36 miles north of Grand Junction,
moving northeast at 35 mph.
HAZARD...Wind gusts up to 40 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
This storm will remain over mainly rural areas of south central
Garfield and south central Rio Blanco Counties.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Heavy rain is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
A Severe Thunderstorm Watch remains in effect until 800 PM MDT for
northwestern and west central Colorado.
&&
LAT...LON 3947 10837 3960 10854 3987 10827 3968 10802
TIME...MOT...LOC 2218Z 228DEG 29KT 3959 10839
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH
DBSpecial Weather Statement
National Weather Service Grand Junction CO
420 PM MDT Sun Aug 25 2024
COZ002-003-013-252245-
Roan and Tavaputs Plateaus CO-Flat Tops CO-
Central Yampa River Basin CO-
420 PM MDT Sun Aug 25 2024
...STRONG THUNDERSTORMS WILL IMPACT CENTRAL RIO BLANCO COUNTY THROUGH
445 PM MDT...
At 420 PM MDT, Doppler radar was tracking a cluster of strong
thunderstorms 18 miles west of Meeker, or 49 miles southwest of
Craig, moving northeast at 35 mph.
HAZARD...Wind gusts up to 40 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
This storm will remain over mainly rural areas of central Rio Blanco
County.
This includes Colorado 64 between mile markers 46 and 71.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Heavy rain is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
A Severe Thunderstorm Watch remains in effect until 800 PM MDT for
northwestern Colorado.
&&
LAT...LON 3970 10838 4016 10841 4035 10800 3989 10798
TIME...MOT...LOC 2220Z 228DEG 29KT 4002 10824
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH
DBSpecial Weather Statement
National Weather Service Grand Junction CO
427 PM MDT Sun Aug 25 2024
COZ003-006-017-252300-
Roan and Tavaputs Plateaus CO-Uncompahgre Plateau/Dallas Divide CO-
Grand Valley CO-
427 PM MDT Sun Aug 25 2024
...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN MESA AND
SOUTHWESTERN GARFIELD COUNTIES THROUGH 500 PM MDT...
At 427 PM MDT, Doppler radar was tracking a strong thunderstorm 7
miles northwest of Fruita, or 16 miles northwest of Grand Junction,
moving northeast at 40 mph.
HAZARD...Wind gusts up to 40 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Fruita, Mack, and Loma.
This includes the following highways...
Interstate 70 in Colorado between mile markers 7 and 20.
Colorado 139 between mile markers 1 and 31.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Heavy rain is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
A Severe Thunderstorm Watch remains in effect until 800 PM MDT for
west central Colorado.
&&
LAT...LON 3909 10877 3916 10898 3960 10880 3949 10848
TIME...MOT...LOC 2227Z 203DEG 35KT 3921 10884
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH
DBSpecial Weather Statement
National Weather Service Grand Junction CO
429 PM MDT Sun Aug 25 2024
UTZ027>029-252315-
La Sal and Abajo Mountains UT-Arches/Grand Flat UT-
Canyonlands/Natural Bridges UT-
429 PM MDT Sun Aug 25 2024
...A STRONG THUNDERSTORM WILL IMPACT NORTHERN SAN JUAN AND SOUTH
CENTRAL GRAND COUNTIES THROUGH 515 PM MDT...
At 429 PM MDT, Doppler radar was tracking a strong thunderstorm near
Spanish Valley, or 10 miles south of Moab, moving northeast at 25
mph.
HAZARD...Wind gusts up to 50 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Moab, Castle Valley, and Spanish Valley.
This includes the following highways...
U.S. Highway 191 in Utah between mile markers 106 and 124.
Utah 128 between mile markers 6 and 7, and between mile markers 14
and 17.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
A Severe Thunderstorm Watch remains in effect until 800 PM MDT for
southeastern and east central Utah.
&&
LAT...LON 3831 10946 3841 10964 3872 10944 3856 10916
TIME...MOT...LOC 2229Z 215DEG 21KT 3843 10950
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH
ERWThe Grand Junction radar (KGJX), 114 km away, was scanning. The volume nearest the first event began at 22:30 UTC.
1 hail. Local standard time, as filed.
A strong storm passed over Castle Valley area and produced hail dime to penny size.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2024Every state in 2024This day in weather historyWarnings in Utah, August 2024
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: 1208149.