Moist easterly upslope winds produced a period of moderate to heavy snowfall over the southern Laramie Range. Snow amounts ranged from six to twelve inches.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS CYS wrote it up.
Moist easterly upslope winds produced a period of moderate to heavy snowfall over the southern Laramie Range. Snow amounts ranged from six to twelve inches.
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 Apr 20, 4:39 PM MST, 21 minutes earlier.
Area Forecast Discussion...UPDATED National Weather Service Cheyenne WY 539 PM MDT Thu Apr 20 2017 .SHORT TERM...(Tonight through Saturday) Issued at 223 PM MDT Thu Apr 20 2017 Clouds increasing over the CWA this afternoon with showers also increasing gradually over and near the higher mtns. This in response to digging upper shortwave now over the Pacific northwest. This system will continue to drop southeast overnight and close off an upper low over Colorado during the day Friday. Rains and higher elevation snow will increase across mainly the southwest half of the CWA overnight and continue across most of the CWA Friday before tapering off Friday night. Main difficulty will continue to be the level of accumulating snow later tonight into Friday. Still appears that will be generally above about 7000 feet so current Winter Wx Advy looks good overall though the start of the snow over the South Laramie Range may hold off until later this evening. Some snow likely to fall as well later tonight into Friday morning down to around 6000 feet or so but initial warm ground and Sun angle likely to limit accumulations late tonight and Friday. Winds modest and should not create much of a problem. Much cooler over much of the CWA Friday given clouds and pcpn with chilly conditions Friday night. System pulls away Friday night and saturday allowing for warmer weather to begin its return on Saturday. .LONG TERM...(Saturday night through Thursday) Issued at 223 PM MDT Thu Apr 20 2017 A warm and dry start to the extended forecast period w/broad upper level ridging in place. Strong subsidence beneath the ridge should preclude any risk for precipitation through Sunday evening. Expect highs in the 60s and 70s with H7 temperatures of +5 to +7 C. GFS & ECMWF both suggest a fast moving short-wave trough tracking across the central Rockies on Sunday night/Monday. Jet energy is expected to be fairly modest, but 700-300 hpa RH progs show sufficient mid/ high level moisture for scattered precipitation coverage. It looks like the overall pattern will remain rather unsettled through much of next week with numerous waves embedded w/in fast WNW flow aloft through Thursday. Medium range models suggest a deepening low over the western US mid to late week, which could have the potential to bring widespread precipitation to the CWA. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 539 PM MDT Thu Apr 20 2017 Light rain becoming more widespread around Cheyenne and Laramie with snow falling at higher elevations west of Cheyenne. Expect snow levels to drop to near 6000 ft toward morning, so have LIFR visibilities and ceilings in for Cheyenne and Laramie overnight with IFR low ceilings to the east toward morning for Scottsbluff, Sidney and Alliance with mostly light rain expected. Expect activity to remain more showery around Rawlins overnight but do think ceilings will also fall there overnight to IFR. Precipitation will continue Laramie and points east through the late morning before starting to taper off from the west in the afternoon. && .FIRE WEATHER... Issued at 223 PM MDT Thu Apr 20 2017 Wetting pcpn expected across much of the area tonight and Friday with cooler temperatures. This will keep fire weather concerns nil through at least the weekend. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Weather Advisory until 6 PM MDT Friday for WYZ112-114-116. NE...None. && SHORT TERM...RE LONG TERM...CLH AVIATION...JG FIRE WEATHER...RE
Hazardous Weather Outlook National Weather Service Cheyenne WY 423 AM MDT Thu Apr 20 2017 WYZ101-102-104>111-113-115-117>119-211030- Converse County Lower Elevations-Niobrara County- 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- Upper North Platte River Basin-Laramie Valley- South Laramie Range Foothills-Central Laramie County- East Laramie County- 423 AM MDT Thu Apr 20 2017 This hazardous weather outlook is for portions of east central Wyoming...south central Wyoming and southeast Wyoming. .DAY ONE...TODAY AND TONIGHT Widespread precipitation will develop across southeast Wyoming this evening and will continue through Friday afternoon. The snow level will be around 8000 feet this evening and lower to around 6500 feet by Friday morning. Snow accumulations outside of the mountains are generally expected to be less than 3 inches. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY Precipitation will continue across portions of southeast Wyoming through Friday afternoon and then will taper off during the evening. .Spotter information statement... Spotter activation will not be needed. WYZ103-112-114-116-211030- North Laramie Range-Sierra Madre Range-Snowy Range- South Laramie Range- 423 AM MDT Thu Apr 20 2017 This hazardous weather outlook is for portions of south central Wyoming and southeast Wyoming. .DAY ONE...TODAY AND TONIGHT Widespread snow will fall across the mountains of southeast Wyoming this evening through Friday afternoon. Snow accumulations are generally expected to be 6 to 10 inches across the Sierra Madre and Snowy Ranges and 3 to 5 inches along the Laramie Range. Winter Weather Advisories are in effect for the Sierra Madre and Snowy Ranges along with the southern Laramie Range. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY Snow will continue across the mountains through Friday afternoon and then will taper off during the evening. .Spotter information statement... Spotter activation will not be needed. NEZ002-003-019>021-054-055-095-096-211030- Dawes-Box Butte-Scotts Bluff-Banner-Morrill-Kimball-Cheyenne- North Sioux-South Sioux- 423 AM MDT Thu Apr 20 2017 This hazardous weather outlook is for portions of western Nebraska. .DAY ONE...TODAY AND TONIGHT NO hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY The probability for widespread hazardous weather is low. .Spotter information statement... Spotter activation will not be needed.
The national radar mosaic for the moment the first event began.
3 winter storm. Local standard time, as filed.
A foot of snow was measured four miles southeast of Buford.
Eight inches of snow was observed at Curt Gowdy State Park.
The Crow Creek SNOTEL site (elevation 8330 ft) estimated 12 inches of snow.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2017Every state in 2017This day in weather historyWarnings in Wyoming, April 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: 697342, 697343, 697344.