Early season High Wind event for wind prone areas of southeast Wyoming. Maximum wind gusts of 83 MPH was reported at Arlington along Interstate 80 west of Laramie.
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The episode as NWS CYS wrote it up.
Early season High Wind event for wind prone areas of southeast Wyoming. Maximum wind gusts of 83 MPH was reported at Arlington along Interstate 80 west of Laramie.
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 Cheyenne, WY wrote its last area forecast discussion before the first event at Aug 19, 9:54 PM MST, 2 hours 50 minutes earlier.
Area Forecast Discussion National Weather Service Cheyenne WY 1054 PM MDT Thu Aug 19 2021 .SHORT TERM...(This evening through Friday) Issued at 206 PM MDT Thu Aug 19 2021 Severe weather remains the primary forecast challenge in the short term period, although in a slightly tempered state. An outflow boundary/subsidence region passed through much of southeastern Wyoming this morning, and has moved out into the far western counties of Nebraska early this afternoon. This boundary was evident on satellite imagery and on surface observations. This boundary has caused a rather notable shift in surface flow, which is still mostly northerly to even northwesterly at most SE WY sites as of 20z. The net effect of this mesoscale boundary has been to greatly reduce wind shear/low-level hodograph size as well as stabilize the atmosphere over much of southeast Wyoming and western Nebraska. This will ultimately limit the thunderstorm threat for much of the day today. The one exception will be in Cheyenne and Morrill counties in western Nebraska, which remain on the warm/unstable side of the boundary. Thunderstorms near severe limits were already in progress here as of 20z, and are expected to continue eastward through the day. As the afternoon progresses, additional thunderstorm development is likely to the south of the Wyoming border. However, given the passage of the aforementioned boundary, there is considerable doubt as to whether any severe- level convection will survive north of Weld county in Wyoming/Nebraska in the currently stabilized atmosphere. Farther north and west over Wyoming and western Nebraska, expect bands of elevated shower and thunderstorm activity to last through the afternoon and evening hours as our potent trough moves through. Briefly gusty winds over 40 mph remain possible, as well as heavy downpours. The flooding threat also appears rather tempered for today, given both the stabilizing effects of the morning boundary as well as notably speedy storm motions of near 30 knots. Overnight, most CAM guidance indicates that most shower and thunderstorm activity will come to an end by around 10pm. The one exception is the HRRR, which develops an additional band of showers and possibly thunder around 8z. This activity is likely a result of the actual trough/frontal passage, so will have to keep an eye out for development after midnight. Freezing levels are still expected to drop below 11,000' overnight, and with bit of moisture lingering to the west, a dusting of snow remains in the forecast for the highest elevations of the Snowy and Sierra Madre ranges. A much drier, cooler day is in the forecast for Friday. Isolated showers and possibly a rumble of thunder or two are possible over the higher terrain of the Laramie range, however areal coverage will be extremely limited as nearly all low-level moisture will be eradicated by this timeframe. Temperatures will run 5 to nearly 10 degrees below average - a very early fall preview will be in the air. .LONG TERM...(Saturday through Wednesday) Issued at 305 AM MDT Thu Aug 19 2021 Long range models continue to show generally drier and quiet weather across southeast Wyoming and western Nebraska this weekend through the middle of next week. A few weak shortwave troughs, embedded in the near-zonal/weak southwest flow aloft, will push east across the region. Other than enhancing some thunderstorm activity, not much is expected from these systems. Temperatures will remain on the cool side Saturday, especially in the morning, with early morning lows in the 40s and some mid to upper 30s in the cooler valleys west of the Laramie Range and I-25 corridor. Highs on Saturday will be about 5 to 10 degrees warmer compared to Friday with afternoon temperatures in the mid 70s to low 80s. Models show the first upper level trough rapidly moving east across Montana and Wyoming. Due to it's progressive nature, low level moisture won't be able to return to a significant part of the high plains, so kept POP on the low side for now with the best chance for some isolated/widely scattered thunder showers in the mountains and across central Wyoming. Daytime temperatures are expected to slowly increase Sunday and Monday as 500mb heights increase towards 590dm. Highs in the mid 80s to mid 90s are expected to return to most of the area by Monday. It will be windy during the weekend with gusts up to 45 mph possible across most of southeast Wyoming, especially in and near the Wind Prone areas. The best midlevel gradient shift northward into early next week, so winds do not appear as strong as a few days ago. For later in the week, models are starting to show the return of some Monsoon moisture to the Front Range by Wednesday and Thursday next week. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1053 PM MDT Thu Aug 19 2021 Low ceilings at KSNY and KAIA are still possible through the overnight hours. Then a westerly wind begins to increase towards 12Z that will scour out all the low level moisture. Strong winds through the day Friday. These winds ease after 00Z. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...High Wind Warning until noon MDT Friday for WYZ110-116-117. NE...None. && SHORT TERM...MAC LONG TERM...TJT AVIATION...GCC
Hazardous Weather Outlook National Weather Service Cheyenne WY 540 AM MDT Thu Aug 19 2021 NEZ002-003-019>021-054-055-095-096-WYZ101>103-106>108-116>119- 201145- Dawes County-Box Butte County-Scotts Bluff County-Banner County- Morrill County-Kimball County-Cheyenne County- Northern Sioux County-Southern Sioux County- Converse County Lower Elevations-Niobrara County- North Laramie Range- Central Laramie Range and Southwest Platte County- East Platte County-Goshen County-South Laramie Range- South Laramie Range Foothills-Central Laramie County- East Laramie County- 540 AM MDT Thu Aug 19 2021 This hazardous weather outlook is for the western Nebraska panhandle...east central Wyoming and far southeast Wyoming along and east of Interstate 25. .DAY ONE...TODAY AND TONIGHT Showers and thunderstorms will redevelop late this morning and early this afternoon and quickly move northeast across the area as a Pacific storm system drifts east over the area. Some of these thunderstorms will become severe today with several rounds of thunderstorms possible into late this evening. Severe thunderstorms may contain strong winds, very heavy rainfall which may result in flash flooding, and large hail. Please monitor the latest forecasts for additional statements or severe weather watches this afternoon. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY Much cooler temperatures are expected behind the surface cold front Friday and Saturday. .Spotter information statement... Spotter activation is possible this afternoon and this evening. WYZ104-105-109-111>115-201145- Ferris/Seminoe/Shirley Mountains-Shirley Basin- Central Carbon County-Southwest Carbon County-Sierra Madre Range- Upper North Platte River Basin-Snowy Range-Laramie Valley- 540 AM MDT Thu Aug 19 2021 This hazardous weather outlook is for portions of south central Wyoming, mainly west of Interstate 25. .DAY ONE...TODAY AND TONIGHT Showers and thunderstorms will continue to redevelop this morning and quickly move northeast across the area as a Pacific storm system drifts east over the area. Some of these thunderstorms may become strong today with several rounds of thunderstorms possible into late this evening. In addition, some light snowfall is possible across the higher peaks of the Snowy Range and Sierra Madre Range tonight and early Friday morning as the colder air arrives behind the cold front. Any snow accumulations should be minimal and confined to areas above 10,000 feet. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY Much cooler temperatures are expected behind the surface cold front Friday and Saturday. Strong gusty winds are expected Friday morning across the wind prone areas. .Spotter information statement... Spotter activation is unlikely, but spotters are urged to alert the National Weather Service of any strong winds and hail. WYZ110-201145- North Snowy Range Foothills- 540 AM MDT Thu Aug 19 2021 This hazardous weather outlook is for portions of south central Wyoming. .DAY ONE...TODAY AND TONIGHT Showers and thunderstorms will continue to redevelop this morning and quickly move northeast across the area as a Pacific storm system drifts east over the area. Some of these thunderstorms may become strong today with several rounds of thunderstorms possible into late this evening. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY Locally strong west winds are forecast for the Arlington and Elk Mountain areas as the storm system pushes east of the region. West winds of 35 to 45 mph with gusts up to 65 mph are possible Friday morning. Winds are expected to diminish slightly in the afternoon. .Spotter information statement... Spotter activation is unlikely, but spotters are urged to alert the National Weather Service of any strong winds and hail.
Special Weather Statement
National Weather Service Cheyenne WY
815 PM MDT Thu Aug 19 2021
NEZ096-WYZ108-200245-
South Sioux NE-Goshen County WY-
815 PM MDT Thu Aug 19 2021
...A strong thunderstorm will impact portions of southwestern Sioux
and east central Goshen Counties through 845 PM MDT...
At 814 PM MDT, Doppler radar was tracking a strong thunderstorm near
Lingle, or near Torrington, moving northeast at 25 mph.
HAZARD...Winds in excess of 40 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Torrington and Lingle.
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.
&&
LAT...LON 4193 10429 4214 10442 4237 10411 4205 10390
TIME...MOT...LOC 0214Z 232DEG 22KT 4211 10427
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH
BrothersThe national radar mosaic for the moment the first event began.
4 high wind. Local standard time, as filed.
Multiple WYDOT sensors along Interstate 80 near Arlington reported wind gusts over 60 MPH including a maximum gust of 83 MPH at KARL - Arlington. Interstate 80 was closed to light, high-profile vehicles for 10 hours.
Wind gusts reported by UPR and WYDOT sensors including maximum gust of 66 mph at UP203 - BUFORW.
WYDOT sensor KBRX - Bordeaux along Interstate 25 reported wind gust.
Wind gusts reported by UPR sensor UP226 - emkayw.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2021Every state in 2021This day in weather historyWarnings in Wyoming, August 2021
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: 973955, 973991, 973951, 973994.