Strong winds with a line of showers and thunderstorms moving across Carbon County early in the morning of the 13th producing 50 MPH wind gusts at many locations. 62 MPH wind gust reported along Interstate 80 at Walcott Junction east of Rawlins.
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The episode as NWS CYS wrote it up.
Strong winds with a line of showers and thunderstorms moving across Carbon County early in the morning of the 13th producing 50 MPH wind gusts at many locations. 62 MPH wind gust reported along Interstate 80 at Walcott Junction east of Rawlins.
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 Sep 13, 2:22 AM MST, 40 minutes earlier.
Area Forecast Discussion National Weather Service Cheyenne WY 322 AM MDT Mon Sep 13 2021 .SHORT TERM...(Today and tonight) Issued at 322 AM MDT Mon Sep 13 2021 Latest KCYS radar this morning scanning areas of showers and few rumbles of thunder across the northern and western portions of the forecast area as trough axis moves across the region. No expectation of strong to severe storms this morning though any precipitation certainly a welcome sight. The region will see cold front later this morning into the afternoon move into the region from the north ushering in cooler temperatures into Tuesday. Marginal risk of strong to severe storms remain in the forecast for much of southeastern Wyoming and the Nebraska Panhandle with model solutions showing roughly around 500 J/kg of CAPE. Low level lapse rates remain fairly lackluster around 6.5 to 7 degrees C/km while more favorable middle level lapse rates reach into the 8 degree range. Questions remain on if the atmosphere can recover for convective action in the afternoon with the continued precipitation and cloud cover this morning. The NAMNEST struggles to get convection going again this afternoon while the HRRR shows solutions of precipitation this afternoon along and south of the I-80 corridor from KRWL moving eastward. Gusty winds likely the most potent severe threat today with gusts up to 60 mph in strongest to perhaps form though some small to perhaps 1 inch hail cannot be ruled out. Influence of the front and minor low pressure across the western portion of the forecast region will advance southeastward ahead of building high pressure with chance for an isolated shower or two across the Panhandle in the morning hours with a few afternoon formation across the Laramie Range and WY/CO possible though confidence remains low. Highs today reaching into the low to middle 80s across the NE Panhandle while middle 70s to low 80s on the WY side. Overnight lows into Tuesday from the middle 40s into the middle 50s. Highs Tuesday cooler with most places reaching into the low to middle 70s. .LONG TERM...(Wednesday through Sunday) Issued at 302 AM MDT Mon Sep 13 2021 This part of the forecast will remain dry until the end of the period. A couple upper level short wave troughs are still forecast to move through the Northern Great Basin region, giving a glancing blow to the forecast area during the latter half of the work week. Models have come into better agreement with the upper level pattern for the weekend, with both showing southwest flow moving in ahead of the next trough. soundings show a dry environment over the forecast area, so am not expecting any precipitation despite the passage of the troughs. There is still disagreement regarding how strong the trough moving onshore will be. However the ECMWF has trended toward the GFS in placing the ridge axis over the Central Plains instead of the lee of the Rockies. Also, both models move the trough east, unlike last night when the ECMWF had the ridge in place and the GFS had the ridge absorb the trough. The GFS does move the trough faster to the east than the ECMWF. Confidence is still low that this trough will actually occur, but if models continue to show the weather pattern, the forecast area could have another rain event for the beginning of next week. Temperatures for the period will be fairly consistent. The warm weather looks to continue for the Plains. There may be a slight cool down Thursday for the northern third of the forecast area when a weak cold front enters but is pushed back north Friday. Lows will change very little for the period. The days of light winds may be coming to a close for the season. 700mb winds progressively increase through Saturday, with a small decline Sunday. The current wind forecast for these days will likely be increasing in the coming days. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1123 PM MDT Sun Sep 12 2021 Isolated showers and thunderstorms are currently moving across portions of southeast Wyoming, but are expected to dissipate in the next hour or so (by 7Z). Another wave of showers and thunderstorms is forecast to move across portions of southeast Wyoming and the Nebraska panhandle between 10Z and 18Z beginning near KRWL around 10Z, reaching KLAR by 12Z, then the Nebraska panhandle by 14Z. Visibilities and ceilings may temporarily lower to MVFR levels as these showers move through. Gusty winds to 25 knots are possible following these showers across all TAF terminals. Monday evening another wave of isolated showers and thunderstorms are possible, primarily for KCYS, KLAR, and KSNY after 00Z. Wind shifts will accompany these waves of showers and thunderstorms move through, so the TAFs may require amendments if the different waves move through either earlier or later than currently forecast. && .FIRE WEATHER... Issued at 301 AM MDT Mon Sep 13 2021 Gusty winds and continued min RHs into the 20s for most locations Monday and Tuesday ahead of yet another dry and breezy pattern beginning Wednesday through the end of the work week. Some widespread chances of precipitation continue today to limit concern. Near-critical to critical fire weather conditions possible later in the week for potential for headlines being needed. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && SHORT TERM...WM LONG TERM...JTL AVIATION...LK FIRE WEATHER...WM
Hazardous Weather Outlook National Weather Service Cheyenne WY 323 AM MDT Mon Sep 13 2021 NEZ002-003-019>021-054-055-095-096-WYZ101>119-140930- 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-Ferris/Seminoe/Shirley Mountains- Shirley Basin-Central Laramie Range and Southwest Platte County- East Platte County-Goshen County-Central Carbon County- North Snowy Range Foothills-Southwest Carbon County- Sierra Madre Range-Upper North Platte River Basin-Snowy Range- Laramie Valley-South Laramie Range-South Laramie Range Foothills- Central Laramie County-East Laramie County- 323 AM MDT Mon Sep 13 2021 This hazardous weather outlook is for portions of panhandle Nebraska...east central Wyoming...south central Wyoming and southeast Wyoming. .DAY ONE...TODAY AND TONIGHT Isolated showers and thunderstorms possible this afternoon, some may be on the strong to severe side. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY The probability for widespread hazardous weather is low. .Spotter information statement... Spotter activation likely not needed.
Special Weather Statement
National Weather Service Cheyenne WY
345 AM MDT Mon Sep 13 2021
WYZ103>105-109-110-113-114-131030-
Shirley Basin WY-Upper North Platte River Basin WY-
North Snowy Range Foothills WY-North Laramie Range WY-
Central Carbon County WY-Ferris/Seminoe/Shirley Mountains WY-
Snowy Range WY-
345 AM MDT Mon Sep 13 2021
...Strong thunderstorms will impact portions of northeastern Carbon,
northwestern Albany and western Converse Counties through 430 AM
MDT...
At 345 AM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from 7 miles southeast of Alcova to 7 miles
southwest of Teton Reservoir. Movement was east at 55 mph.
HAZARD...Wind gusts of 50 to 55 mph.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects.
Locations impacted include...
Rawlins, Hanna, Sinclair, Seminoe Campground, Shirley Basin, Seminoe
Dam, Boxelder, Little Medicine School and Teton Reservoir.
This includes Interstate 80 in Wyoming between mile markers 216 and
251.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4244 10671 4243 10608 4262 10607 4267 10581
4149 10673 4145 10745
TIME...MOT...LOC 0945Z 259DEG 46KT 4246 10664 4153 10735
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH
MokryPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
400 AM MDT MON SEP 13 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0356 AM TSTM WND GST 15 E SINCLAIR 41.74N 106.84W
09/13/2021 M62 MPH CARBON WY MESONET
MESONET STATION WY15 14.5 E SINCLAIR
(WYDOT).
&&
WMThe Cheyenne radar (KCYS), 182 km away, was scanning. The volume nearest the first event began at 10:00 UTC.
1 thunderstorm wind. Local standard time, as filed.
WYDOT mesonet station WY15 - Walcott Junction 14 miles east of Sinclair measured wind gust.
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, September 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: 977500.