Drier air working in behind a shortwave trough across the north resulted in more surface heating to act on sufficient instability and remnant moisture to produce stronger storms. Some shear was also present across the north leading to some stronger storms that produced up to nickel size hail across Uintah County in northeast Utah.
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The episode as NWS GJT wrote it up.
Drier air working in behind a shortwave trough across the north resulted in more surface heating to act on sufficient instability and remnant moisture to produce stronger storms. Some shear was also present across the north leading to some stronger storms that produced up to nickel size hail across Uintah County in northeast Utah.
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 14, 2:47 PM MST, 43 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Grand Junction CO 347 PM MDT Wed Aug 14 2024 .KEY MESSAGES... - Scattered showers and thunderstorms will continue along and north of the I-70 corridor through the latter part of the afternoon and into the evening. Gusty outflow winds, hail, and frequent lightning are the main threats. - Storms become localized Thursday and Friday with dry weather elsewhere as the airmass dries further. - Expect near normal temperatures Thursday with afternoon readings climbing 3 to 5 degrees above normal Friday and Saturday. Increased moisture later this weekend through early next week will cause highs to return to near normal levels. && .SHORT TERM /THROUGH THURSDAY NIGHT/... Issued at 347 PM MDT Wed Aug 14 2024 Per the previous discussion, drier air began to filter into the region which, in concert with a mid-level inversion south of the I-70 corridor, has limited moist convection there. Meanwhile, scattered showers and thunderstorms fired at midday north of the I-70 corridor where deeper moisture lingered. Ensemble averaged precipitable water (PWAT) indicated levels near 0.75". 0-6 Km bulk shear of around 50 Kts combined with jet divergence in the left exit region of an 80 Kt jet streak suggests the potential for a few better organized cells. These strong storms may be capable of generating up to quarter-sized hail and outflow winds approaching 60 mph through early evening. By midnight, expect all but a few light showers will remain. Clouds decrease overnight which allows temperatures to fall to near normal levels Thursday morning. Drying continues on Thursday and model ensembles indicated PWAT levels will drop to between 0.5 to 0.6" on average across the forecast area. A transitory ridge moves over the region bringing warming at mid-levels which serves to limit afternoon CAPE values. As a result, expect afternoon/evening shower and thunderstorm activity will be more limited than in previous days with isolated to widely scattered storm coverage over the mountains and little to no chance for moist convection over the valleys. Temperatures rise a bit with increased heights aloft causing afternoon highs to peak right around normal for most locations. Showers/storms diminish early in the evening with clearing and dry weather expected during the remainder of the night. Daytime warming should carry over into the overnight lows which should be a few degrees milder than tonight's forecast lows. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Issued at 347 PM MDT Wed Aug 14 2024 Friday will start out with dry westerly flow overhead across eastern Utah and western Colorado before flow shifts to the southwest. This will be in response to the subtropical high building across the area which will cut off our access to the deeper monsoonal moisture. As a result, look for dry weather to end the week and start the weekend. Enough residual moisture will be present to lead to some passing clouds but, overall, it will be a warm and mostly sunny day. By Friday evening and into Saturday, a large trough of low pressure will be strengthening off the West Coast further enhancing southwest flow across the Western Slope in response. As the trough begins to push inland Saturday afternoon, the high overhead will be deflected back to the east. As a result, subtropical moisture will begin to gradually advect back into the region. PWATs look to quickly return to 110 to 347 percent of normal on Saturday with blended guidance projecting scattered showers and thunderstorms blossoming through the day. Since it will be the first unsettled day of this new surge, gusty outflow winds will be more likely than heavy rain. The trough remains relatively stationary going into Sunday, allowing additional moisture to advect north into the region. PWATs will reach 347 to 160 percent of normal and, additionally, we can expect a shortwave rounding the periphery of the ridge to track across the area. This will lead to more widespread shower and thunderstorm activity with gusty outflow winds, small hail, and frequent lightning expected. Since the atmosphere will be better saturated the potential for heavy rain and possibly flash flooding as well will increase. Confidence begins to decrease going into the new work week as the ridge attempts to retrograde back to the west. This would once again cut off the tap to the monsoon, but blended guidance during this time keeps numerous to widespread PoPs in the forecast. The NBM is likely honing in on a shallow trough briefly knocking down the ridge on Monday, but it's messy. We'll have to keep an eye on things to see how the upstream trough progresses, and subsequently where the center of the high ends up. Regardless, sufficient residual moisture will be present to fuel at least some convection over the mountains each afternoon. Temperatures will rebound back to several degrees above normal for Friday and Saturday as the ridge builds overhead. With the uptick in moisture late in the weekend and potentially into next week, highs will moderate back to near normal and even drop back to slightly below normal. Overnight lows will be unseasonably warm through the period. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1122 AM MDT Wed Aug 14 2024 Scattered showers and thunderstorms will re-develop this afternoon, favoring areas north of I-70. VCTS more probable at KVEL, KHDN, KRIL, KEGE as well as higher terrain sites like KASE and KTEX this afternoon into the early evening. Elsewhere, mostly to partly sunny skies with drier conditions can be expected. VFR will prevail with brief MVFR or ILS conditions in any storms (mainly across the north) with strong gusty winds and brief heavy rain possible. Showers come to an end and skies should clear shortly after sunset. Benign weather continues through Thursday morning. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...NL LONG TERM...MMS AVIATION...TGJT
Hazardous Weather Outlook National Weather Service Grand Junction CO 403 AM MDT Wed Aug 14 2024 COZ001>014-017>023-UTZ022>025-027>029-151015- 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 Wed Aug 14 2024 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Scattered to numerous storms will favor areas along and north of I-70 this afternoon into the early evening with reduced coverage for areas south of I-70 as drier air moves in. Some storms could be strong and will be capable of producing gusty outflow winds, small hail, frequent lightning and moderate to heavy rainfall. Localized flash flooding and debris flows are possible. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Drier air will be in place Thursday and Friday, resulting in a sharp reduction in storm coverage with only isolated storms possible across the northern mountains. This will be short lived as monsoonal moisture returns late this weekend into early next week. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
Preliminary Local Storm Report
National Weather Service Grand Junction CO
111 PM MDT Wed Aug 14 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0110 PM Rain 4 ESE Moab 38.54N 109.49W
08/14/2024 M1.33 Inch Grand UT Trained Spotter
Storm total rain.
&&Special Weather Statement
National Weather Service Grand Junction CO
427 PM MDT Wed Aug 14 2024
UTZ024-142300-
Eastern Uinta Basin UT-
427 PM MDT Wed Aug 14 2024
...A STRONG THUNDERSTORM WILL IMPACT CENTRAL UINTAH COUNTY THROUGH
500 PM MDT...
At 427 PM MDT, Doppler radar was tracking a strong thunderstorm near
Vernal, moving southeast 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...
Vernal, Naples, and Maeser.
This includes U.S. Highway 40 in Utah between mile markers 132 and
143, and between mile markers 148 and 153.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4036 10971 4047 10956 4031 10931 4016 10953
TIME...MOT...LOC 2227Z 312DEG 21KT 4036 10959
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH
KJSThe Grand Junction radar (KGJX), 183 km away, was scanning. The volume nearest the first event began at 22:28 UTC.
1 hail. Local standard time, as filed.
A strong thunderstorm passed over Naples area in Uintah County and produced hail up to nickel 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: 1208147.