Accumulating snowfall in the higher elevations of the North Laramie Range overnight on the 8th into the morning of the 9th with northerly upslope flow totaled near 10 inches of accumulation above 8000 feet elevation.
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The episode as NWS CYS wrote it up.
Accumulating snowfall in the higher elevations of the North Laramie Range overnight on the 8th into the morning of the 9th with northerly upslope flow totaled near 10 inches of accumulation above 8000 feet elevation.
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 May 8, 3:49 PM MST, 4 hours 11 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Cheyenne WY 449 PM MDT Wed May 8 2024 .KEY MESSAGES... - Precipitation chances increase later today and overnight with accumulating mountain snowfall expected. Scattered showers continue into the day Thursday. - Warming trend likely headed into the weekend with the return of above normal temperatures for mid-May. && .SHORT TERM /THROUGH THURSDAY/... Issued at 323 PM MDT Wed May 8 2024 The low pressure center spinning around in the Dakotas that was responsible for the windy last few days, has begun to retrograde back to the southwest, leading to another round of precipitation for the CWA. As the upper-level low pushes into the CWA this evening, precipitation chances across the area will increase. Clouds have steadily been increasing across the CWA based on visible satellite imagery. Regional radar and observations also show some light rain beginning to creep into the northern tier of the CWA. As the low continues its trek across the CWA overnight, winds will turn more northerly leading to upslope flow and enhanced snowfall amounts on north-facing slopes. The North Laramie Range will see the best enhancement and highest snowfall totals. A Winter Weather Advisory is already in place here. Did go ahead and expand the Advisory until noon tomorrow as the newest Hi-Res guidance suggests persistent, steady precipitation at least through the morning hours. Northern slopes of the Snowy Range could also pick up a quick 6 inches of snow tonight into Thursday morning. Another area to watch will be Laramie and Rawlins. GFS and ECMWF ensembles show about 1 to 3 inches of snow in these cities tonight into tomorrow morning. Decided to keep totals lower than this as the HRRR show mostly scattered and quick moving showers. However, if accumulation does occur, this could lead to some slippery roads for the morning commute. Most locations east of the Laramie Range will sustain warmer temperatures overnight, leading to rain showers, with the chance for a few flakes to mix in. Widely scattered rain and snow showers will continue into the day Thursday as a final vorticity max behind the upper-level low lingers across the CWA. The mountains could pick up an additional inch or two during the afternoon hours, but warmer temperatures should keep most of the snow out of the valleys and plains. Some rumbles of thunder could also be possible as non-zero CAPE values exist across much of the area. Showers will become less numerous Thursday night as the low parks itself over the Four Corners region. Headed into Friday, expect a warmer and less active day. A few isolated showers could be possible over the high terrain as the low over the Four Corners sends weak disturbances northward. Weak southerly flow will allow 700 mb temperatures to rebound back to around 0C. This will lead to high temperatures near to slightly below average for this time of year. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... Issued at 323 PM MDT Wed May 8 2024 An unsettled long term pattern is expected across southeast Wyoming and western Nebraska. An upper-level low will continue to rotate around the Four Corners Region and points northwest throughout evening Friday and into the day Saturday. By Sunday, this upper- level low will be caught up into the upper-level jet and will rapidly progress to the east and finally leave this region of the CONUS. Prior to this, with the low rotating around the Four Corners Region, a vorticity lobe will traverse from northern Wyoming southward through much of the CWA. This vorticity lobe will provide some synoptic lift for the CWA during the afternoon hours Saturday. With this synoptic lift, but minimal assistance at the 700mb level, some showers and potentially thunderstorms will be possible across the region. Modest MLCAPE values around 400 J/kg will be present across the region, further supporting a thunderstorm or two on Saturday. Behind this system, upper-level ridging will build across the western CONUS and slowly migrate east throughout the day Sunday and into the early morning hours Monday. The ridge axis will not be directly overhead on Sunday, but temperatures will increase into the mid-60s and mid-70s across the area. Once again, with vorticity lobes moving overhead as they traverse through the ridge, synoptic lift will be present across the region along with the potential for modest MLCAPE values once again. The region could see isolated showers Sunday in the afternoon. A similar setup is expected for Monday, but the upper-level ridge axis will be closer to the region, allowing temperatures to warm into the mid-60s to upper-70s across the region. A pattern shift is expected by mid-week as an upper-level trough begins to dive into the northern CONUS on Tuesday. As this trough moves just north of the CWA, height gradients will increase slightly leading to the potential for elevated winds Tuesday. As of now, these winds only look to be elevated and not near high wind criteria. A cold front will move across the region Tuesday into Wednesday leading to slightly cooler temperatures Wednesday across the region. Behind the front, northwesterly winds will pick up once more and continue the potential for elevated winds throughout the day. With this cold front pushing through, rain showers and thunderstorms will be possible again on Tuesday into Wednesday. They do not look likely to be severe at this time, as MLCAPE values only approach the 400 J/kg level. Overall, enjoy a warm week in the forecast with nearly daily chances for isolated showers and the potential for some thunderstorms. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 443 PM MDT Wed May 8 2024 A tricky aviation forecast will begin to take shape this evening through Thursday morning. VFR CIGs will transition to MVFR/IFR fluctuations due to -SHRA/-SHSN, which will also create VIS reductions at times. Winds are anticipated to be below 12 knots overnight for all terminals, before picking up in the NE Panhandle to 20-25 knots. Please see individual TAFs for further information. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Weather Advisory until noon MDT Thursday for WYZ103. NE...None. && SHORT TERM...SF LONG TERM...AM AVIATION...BW
Hazardous Weather Outlook National Weather Service Cheyenne WY 156 PM MDT Wed May 8 2024 NEZ002-003-019>021-054-055-095-096-WYZ101>119-092000- 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- 156 PM MDT Wed May 8 2024 This hazardous weather outlook is for portions of panhandle Nebraska...east central Wyoming...south central Wyoming and southeast Wyoming. .DAY ONE...THIS AFTERNOON AND TONIGHT Strong winds continue this afternoon, mainly for the southeast Wyoming wind-prone areas before weakening this evening. Precipitation chances increase this afternoon and overnight with accumulating mountain snowfall expected. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY Scattered showers are expected throughout the day Thursday. A rumble of thunder is also possible. Warmer and drier weather expected for the end of the week. .Spotter information statement... Spotter activation will not be needed.
The national radar mosaic for the moment the first event began.
1 winter weather. Local standard time, as filed.
Numerous SNOTEL sites estimated 7 to 10 inches of snowfall across the North Laramie Range, mainly above 8000 feet elevation.
After NWS Directive 10-1605, the rules offices file Storm Data by.
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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: 1168192.