An upper level disturbance moved across the region and resulted in scattered to numerous showers and thunderstorms during the afternoon and evening hours, some of which produced strong outflow winds.
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The episode as NWS GJT wrote it up.
An upper level disturbance moved across the region and resulted in scattered to numerous showers and thunderstorms during the afternoon and evening hours, some of which produced strong outflow 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 Aug 10, 6:09 PM MST, 2 hours 11 minutes earlier.
Area Forecast Discussion National Weather Service GRAND JUNCTION CO 709 PM MDT Thu Aug 10 2017 .UPDATE... Issued at 704 PM MDT Thu Aug 10 2017 Quick update to the grids to drive pops up a bit through this evening as convection continues to expand in coverage across east- central and northeast Utah. Additional showers driving east near the I-70 corridor in western Colorado. HiRes models keep showers going into the late-night hours, likely ending between 2 and 4 am tonight. && .SHORT TERM...(Tonight through Friday night) Issued at 314 PM MDT Thu Aug 10 2017 Storms have fired this afternoon over the higher terrain, with the northern and central areas seeing the best coverage. This is due to a weak disturbance moving through the westerly flow on the northern periphery of an area of high pressure sitting well to our south. A weak 60-70 kt upper level jet is laid across the central CWA from west to east, providing some upper level support for storm development in the left exit region where the northern half of the CWA is located. Storms are moving along at a pretty good clip thanks to this upper level support, with some locally heavy rain and small hail reported with the stronger cells. Expect most activity to wind down this evening with some lingering showers overnight. This area of high pressure is expected to slide eastward over Texas on Friday, thanks to an upper level trough moving inland along the Pacific Northwest coast. This will help turn the flow ever so slightly to southwesterly, allowing a bit better moisture into the region with precipitable water (PW) values in the 0.75 to 1.0 inch plus range across much of the area. A weak shortwave will also move into the Four Corners region Friday morning and progress through the area Friday afternoon and evening, leading to an increase in storm activity and coverage. Increased PoPs as a result. Temperatures should still be near to slightly above normal during the daytime through Friday as this better moisture begins to infiltrate the atmosphere. .LONG TERM...(Saturday through Thursday) Issued at 314 PM MDT Thu Aug 10 2017 Saturday through Monday are looking to be more active days as deeper moisture works across the region in southwesterly flow with several embedded shortwave disturbances moving through the flow. These shortwaves will come from two low pressure systems, one over the Pacific Northwest and another over the northern Great Lakes and eastern Canadian Prairies. The Pacific low will be the primary driver for our sensible weather, while the eastern low will mainly impact the Front Range, with some boundaries trailing back into our area. Bottom line is that the weekend into early next week looks more active with widespread coverage of showers and thunderstorms each afternoon and evening. Due to the embedded shortwaves and deeper moisture in place, storms have good potential to continue through the overnight hours. PW values will be approaching 1.25 inches in some areas during this period. Therefore, increased PoPs enough for all areas to see some coverage of storms Saturday through Monday evening/Tuesday morning. The most active of these periods looks to be Monday through Tuesday morning as a stronger shortwave moves through. Drier air will slowly begin to infiltrate into the area from the southwest beginning Tuesday, as this upper Pacific Northwest low carves out a trough that will dive into the Desert Southwest. Enough moisture will remain on Tuesday with PW values of 0.75 and above, which is sufficient for decent storm coverage given more surface heating taking place. Wednesday and beyond appears to be the days where this drying will be most noticeable. Confidence on this drying trend remains low, however, as models want to dry things out too quick after each monsoonal moisture surge. Still kept afternoon showers and storms favoring higher terrain in the forecast for Wednesday and beyond. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 549 PM MDT Thu Aug 10 2017 Scattered thunderstorms continue across much of northern Utah and Colorado. Impacts to aviation interests are most probable along the I-70 corridor from KRIL to KEGE. Heavy rain showers from these storms will cause temporary lowering of vsby to mvfr/ifr along with possible wind gusts to 40 mph. KVEL and KASE could also be impacted by storms but confidence not as high. Late night showers and storms may also continue to drift across the region but coverage will generally be isolated. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && UPDATE...JDC SHORT TERM...MDA LONG TERM...MDA AVIATION...TGJT
Hazardous Weather Outlook National Weather Service GRAND JUNCTION CO 228 AM MDT Thu Aug 10 2017 COZ001>014-017>023-UTZ022>025-027>029-110830- 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- 228 AM MDT Thu Aug 10 2017 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Isolated to scattered showers and thunderstorms are expected again today and tonight across eastern Utah and western Colorado, with best coverage over central and northwest Colorado and northeast Utah. Locally heavy rain, small hail and gusty winds to 40 mph are all possible with the strongest storms, and there is the possibility for local minor flooding as well. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Isolated to scattered showers and thunderstorms are expected Friday with gusty outflow winds, small hail and locally heavy rain possible. The chance of storms will increase this weekend into the beginning of next week as monsoon moisture is expected to return. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
The Grand Junction radar (KGJX), 137 km away, was scanning. The volume nearest the first event began at 03:21 UTC.
1 thunderstorm wind. Local standard time, as filed.
The automated station at the Canyonlands Regional Airport measured a peak wind gust of 66 mph from a strong thunderstorm.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2017Every state in 2017This day in weather historyWarnings in Utah, August 2017
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: 713033.