Alert archive / Wyoming / Winter Storm Warnings in 2020
Winter Storm Warning 18, NWS Cheyenne, WY
NWS Cheyenne, WY issued this winter storm warning at Sep 7, 2020, 4:09 AM MDT for 7 counties in Wyoming; Sioux County, Nebraska. It took effect at Sep 8, 2020, 12:00 AM MDT. It was in force for 27 hr. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Sep 7, 2020, 4:09 AM MDT (10:09 UTC)
- In effect from
- Sep 8, 2020, 12:00 AM MDT
- Expired
- Sep 9, 2020, 2:31 AM MDT
- In force
- 27 hr
- Issued by
- NWS Cheyenne, WY
Counties Sioux County, NE, Albany County, WY, Carbon County, WY, Converse County, WY, Goshen County, WY, Laramie County, WY, Niobrara County, WY, Platte County, WY
The radar
The Cheyenne radar (KCYS), 115 km from the middle of the area, began a volume at 10:15 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Denver, CO (KDNR), launched 00:00Z, 10.2 hours before the alert went out and 298 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 4605 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- -7 m²/s²
- 0-3 km storm-relative helicity
- 21 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
What forecasters said that day
The local office's own words before this winter storm warning went out, 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 this winter storm warning went out at Sep 6, 11:54 PM MDT, 4 hours 15 minutes earlier.
Area forecast discussion, Sep 6, 11:54 PM MDT, 4 hours 15 minutes before
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</html>Hazardous weather outlook, Sep 6, 6:37 AM MDT, 21 hours 32 minutes before
Hazardous Weather Outlook National Weather Service Cheyenne WY 637 AM MDT Sun Sep 6 2020 WYZ103-105-106-110-115>118-071245- North Laramie Range-Shirley Basin- Central Laramie Range and Southwest Platte County- North Snowy Range Foothills-Laramie Valley-South Laramie Range- South Laramie Range Foothills-Central Laramie County- 637 AM MDT Sun Sep 6 2020 This hazardous weather outlook is for portions of south central Wyoming and southeast Wyoming. .DAY ONE...TODAY AND TONIGHT No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY An abrupt change to unseasonably cold temperatures will occur Monday night as a strong cold front blasts across the region, marking the official end to the growing season. Widespread rain will quickly change to snow on Monday night, with snow persisting through Tuesday night. Significant accumulations are possible, along with some blowing snow. Travel may be impacted due to slick, snow covered roads and low visibility. Some tree damage and power outages are also possible. Mountain recreation will be life threatening to those caught unprepared for severe winter conditions. Winter Storm Watches are in effect. Bitterly cold temperatures are expected Wednesday morning, with lows falling into the teens and single digits. There is a danger of frozen pipes due to prolonged exposure to sub freezing temperatures. .Spotter information statement... Spotters are encouraged to report significant weather to the National Weather Service in Cheyenne. NEZ002-003-019>021-054-055-095-096-WYZ101-102-104-107>109-111>114- 119-071245- Dawes-Box Butte-Scotts Bluff County-Banner County-Morrill- Kimball County-Cheyenne-North Sioux-South Sioux- Converse County Lower Elevations-Niobrara County- Ferris/Seminoe/Shirley Mountains-East Platte County-Goshen County- Central Carbon County-Southwest Carbon County-Sierra Madre Range- Upper North Platte River Basin-Snowy Range-East Laramie County- 637 AM MDT Sun Sep 6 2020 This hazardous weather outlook is for portions of panhandle Nebraska...western Nebraska...east central Wyoming...south central Wyoming and southeast Wyoming. .DAY ONE...TODAY AND TONIGHT No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY An abrupt change to unseasonably cold temperatures will occur Monday night as a strong cold front blasts across the region, marking the official end to the growing season. Widespread rain will quickly change to snow on Monday night, with snow persisting through Tuesday night. Some accumulations are possible, along with some blowing snow. Travel may be impacted due to slick, snow covered roads and low visibility. .Spotter information statement... Spotters are encouraged to report significant weather to the National Weather Service in Cheyenne.
The office that day
Everything else NWS Cheyenne, WY issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 7, 4:09 AM MDT | Winter Weather Advisory | CYS | Albany, Carbon, Goshen, Laramie | 46 hr |
| Sep 7, 1:28 PM MDT | Freeze Warning | CYS | Albany, Carbon, Converse, Goshen, Laramie, Niobrara and 1 more | 43 hr |
Nearby
Winter Storm Warnings in Wyoming, 2020Winter Storm Warnings in Nebraska, 2020Every winter storm warning in 2020
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.