Mostly zonal flow aloft advected some modest midlevel moisture into northern portions of eastern Utah and western Colorado in the days leading up to this event. This moisture, combined with some low-end instability, set the stage form some isolated showers and thunderstorms to form over the higher terrain.
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The episode as NWS GJT wrote it up.
Mostly zonal flow aloft advected some modest midlevel moisture into northern portions of eastern Utah and western Colorado in the days leading up to this event. This moisture, combined with some low-end instability, set the stage form some isolated showers and thunderstorms to form over the higher terrain. A passing weak shortwave trough added some extra lift and energy to the region on the 1st, resulting in some stronger showers and thunderstorms capable of producing strong, gusty winds. In addition, dry surface levels led to precipitation from these storms evaporating before reaching the surface, thus also enhancing winds.
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 Jun 1, 10:21 AM MST, 3 hours 39 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Grand Junction CO 1121 AM MDT Sat Jun 1 2024 .KEY MESSAGES... - Isolated to scattered thunderstorm development remains a threat each afternoon through early next week with gusty outflow winds more likely than wetting rainfall. - Temperatures remain above normal this weekend into early next week...an expanding ridge aloft next week suggests temperatures are likely to climb even higher by midweek. - The warmer temperatures means runoff will be well underway with most major stem rivers showing rises over the next several days. && .SHORT TERM /THROUGH SUNDAY/... Issued at 400 AM MDT Sat Jun 1 2024 Even though transitory ridging works in from the west today, the flow will stay primarily zonal with several embedded shortwaves moving through the flow this weekend. One such weak shortwave tracks across this afternoon with a more robust shortwave this evening, which should work on available moisture and instability to generate isolated to scattered showers and thunderstorms. Most activity will initially favor the high terrain but with the more robust shortwave this evening, activity could spread into the northwest Colorado valleys. Areas north of I-70 still hold the best instability with CAPE north of 500 J/kg, while areas south of I-70 are less than 200 J/kg. Storm coverage could be a bit better today than previously indicated based on these reasons as well as latest hi-res guidance which shows a bit more coverage, especially up north. Although moisture is elevated with mixing ratios upwards of 4 g/kg today, the low levels still remain dry with inverted V sounding profiles, so expect gusty outflow winds to be more of a threat than wetting rain. Not expecting much in the way of rainfall but winds could gust 40 to 50 mph with any storm outflows, especially across the north. Overall, mostly dry conditions and above normal temperatures are expected today despite any showers/storms which should be more high based and virga producing, again isolated to scattered in coverage. Some storms could linger past sunset given forcing from the shortwaves, with any remnant isolated activity likely clearing out or dissipating by midnight. Following on the heels of today's activity is another shortwave, again clipping the northern areas Sunday afternoon. Coverage looks to favor the high terrain for areas mainly north of I-70 with this shortwave with limited precipitation and more gusty outflow winds from any convection. Temperatures are expected to be warmer today than yesterday and similar on Sunday with highs 4 to 8 degrees above normal. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Issued at 400 AM MDT Sat Jun 1 2024 Flow aloft turns northwesterly Sunday night as the shortwave slides over the Front Range and out onto the Plains. Another low pressure system drops south out of the Gulf of Alaska off the BC Coast Sunday and turns east to track along the Canadian Border Sunday night into Monday. With the approach of this trough, look for gusty west winds Monday generally along and north of I-70. Though this system stays well to the north, the southern edge of the trough will brush the northern areas of eastern Utah and Western Colorado Monday night into Tuesday. Models are indicating that this trough will drag a significant patch of moisture currently south of the Aleutian Islands over the North Pacific into the Pacific Northwest and down into the region with IVT's of 300 to 400 kg/m/s along and north of the I-70 corridor, and IVT's approaching 200 kg/m/s pushing south into the Four Corners area. Pwats climb above 200% across the region with this surge. Guidance still isn't picking up on this limiting PoPs to 20% over the Uinta and Park Mountains and less than 10% elsewhere. With the left exit region of the jet passing over the northern areas Monday night, expect nocturnal thunderstorms possible generally north of the I-70 corridor. The trough also tightens the pressure gradient with linear shear values around 30 kts, and a cool front pushes south into the region to about I-70, so wouldn't be surprised to see an isolated stronger storm possible. This is definitely something to keep an eye on over the next day or two to see if the models pick up on this. As the trough and associated jet moves east, the right exit region moves in over the northern areas and ridging builds in from the southwest putting eastern Utah and Western Colorado under subsidence, clearing out the skies somewhat Tuesday allowing diurnal heating to spawn isolated orographic showers and isolated thunderstorms over the region through the afternoon. The high pressure continues to build in over Intermountain West Wednesday and even though the subsidence will tend to cap convection, expect diurnal heating to spark isolated light showers over the higher terrain with a possible isolated clap of thunder. Models are in concurrence with a Pacific low moving in off the Baja Coast Wednesday and the high pressure sliding southeast over New Mexico, Texas and northern Mexico Thursday which opens the door to a subtropical flow under the high and up into the region Thursday into next weekend. Look for afternoon and evening showers and thunderstorms becoming widely scattered across the region through the latter half of the week. Temperatures start the week at six to eight degrees above normal Monday with a slight dip Tuesday as the trough passes. Wednesday onward will see temperatures climb to 10 to 15 degrees above normal with high sitting over the region. Look for the lower desert valleys to possibly hit the century mark late in the week. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1121 AM MDT Sat Jun 1 2024 Another round of isolated to scattered showers and thunderstorms are expected this afternoon, favoring the mountains. Outside of activity, expect mostly to partly sunny skies and breezy afternoon winds to 25 mph at times. Gusty outflow winds can be expected near any shower or storm activity with gusts up to 45 mph possible. Showers diminish this evening with dry weather returning through Sunday morning. Overall, VFR will prevail through the TAF period. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...MDA LONG TERM...DB AVIATION...TGJT
Hazardous Weather Outlook National Weather Service Grand Junction CO 332 AM MDT Sat Jun 1 2024 COZ001>014-017>023-UTZ022>025-027>029-020945- 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- 332 AM MDT Sat Jun 1 2024 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight The probability for widespread hazardous weather is low. However, isolated to scattered thunderstorms are possible over the mountains especially along the Continental Divide and across northwest Colorado this afternoon through this evening. .DAYS TWO THROUGH SEVEN...Sunday through Friday Isolated to low end scattered thunderstorms are possible over the mountains of the Continental Divide and the eastern Uinta Mountains each afternoon/evening through the remainder of the coming week. Dry and much warmer conditions are possible mid to late week. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
Special Weather Statement
National Weather Service Grand Junction CO
152 PM MDT Sat Jun 1 2024
COZ004-005-013-012015-
Flat Tops CO-Upper Yampa River Basin CO-
Elkhead and Park Mountains CO-
152 PM MDT Sat Jun 1 2024
...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN ROUTT COUNTY
THROUGH 215 PM MDT...
At 151 PM MDT, Doppler radar was tracking a strong thunderstorm near
Oak Creek, or 37 miles southeast of Craig, moving east at 30 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...
Oak Creek, Yampa, and Phippsburg.
This includes the following highways...
U.S. Highway 40 in Colorado between mile markers 141 and 151.
Colorado 131 between mile markers 41 and 57, and mile marker 62 and
near mile marker 64.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4016 10664 4011 10707 4029 10713 4042 10665
4034 10665 4034 10663 4018 10663
TIME...MOT...LOC 1951Z 255DEG 28KT 4022 10696
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH
KJSThe Grand Junction radar (KGJX), 171 km away, was scanning. The volume nearest the first event began at 20:59 UTC.
1 thunderstorm wind. Local standard time, as filed.
The peak gust associated with this thunderstorm was 58 mph and was recorded at the KCAG ASOS at the Craig-Moffat County Airport at 3:31 PM MDT. Additional gusts with this storm, while strong, were generally below severe criteria.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2024Every state in 2024This day in weather historyWarnings in Colorado, June 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: 1197681.