Thunderstorms produced heavy rainfall that caused localized flash flooding and mud/debris flows near Woods Landing.
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The episode as NWS CYS wrote it up.
Thunderstorms produced heavy rainfall that caused localized flash flooding and mud/debris flows near Woods Landing.
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 Jul 12, 10:32 AM MST, 2 hours 13 minutes earlier.
Area Forecast Discussion National Weather Service Cheyenne WY 1132 AM MDT Thu Jul 12 2018 .UPDATE... Issued at 516 AM MDT Thu Jul 12 2018 Please see latest 12z Aviation Discussion && .SHORT TERM...(Today - Tonight) Issued at 429 AM MDT Thu Jul 12 2018 A few lingering showers remain intact across portions of southeast Wyoming early this morning, but most of the nocturnal activity has diminished in coverage and intensity. GOES-16 WV Satellite imagery continues to depict a deep circulation associated w/ a stacked low pressure system over central and eastern Colorado. This is helping support considerable mid/high level moisture across the CWA, which suggests the potential for another round of widespread showers and thunderstorms today. It appears convection may develop across some of our higher terrain quite early today, perhaps even prior to 10- 11 AM given cooler temperatures aloft & the proximity of the upper low. Thunderstorms should then increase in coverage across a large part of the area with increasing moist upslope & convergence along the inverted surface trough. Highs today should be around 5-10 deg cooler than yesterday with the help of ample cloud cover. There is a threat for locally heavy rainfall today in the vicinity of the Badger Creek Burn Scar. WPC has placed portions of our area in a SLGT Risk for excessive rainfall, but this appears to be more focused on the southern Laramie Range or Laramie Valley which does make sense given the position of the surface trough. We did have a discussion on a potential Flash Flood Watch, but with better over- all forcing just to the east and CAMs also showing heavier rain to the east, we decided to hold off for now. Also, we could see a few stronger storms today with dew points 55-65 F supporting CAPEs at/ around 1500-2000 J/kg. Meager shear profiles should preclude risks for a more organized severe threat this afternoon. .LONG TERM...(Friday - Wednesday) Issued at 429 AM MDT Thu Jul 12 2018 A generally active pattern can be expected through the majority of the extended forecast period beneath quasi-zonal flow aloft. A few features to note. A brief bout of short-wave ridging will send 500 mb heights back near 595 dm on Saturday, setting the stage for hot and dry conditions once again with highs in the 90s. A weak upper- level disturbance/associated cold front is progged to swing across the area Saturday night/Sunday, bringing cooler temperatures along with good chances for precipitation. Daily chances for showers and thunderstorms should exist through Wednesday. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) Issued at 1127 AM MDT Thu Jul 12 2018 VFR conditions will degrade this afternoon and evening to MVFR and IFR in some spots as scattered to numerous showers and thunderstorms develop. As of 1730z showers and storms were developing over the Laramie range and were slowly drifting southeast with cloud tops up to FL400. Storms should continue this evening and intensify across much of the area. Expect some low CIGS and possible fog at Nebraska terminals tomorrow morning as remnant moisture and cooler temperatures bring higher relative humidities. && .FIRE WEATHER... Issued at 429 AM MDT Thu Jul 12 2018 No major fire weather concerns over the next few days w/ generally cooler temperatures and good chances for wetting rains. Warmer for Saturday, but minimum RH values should remain above 15 percent and winds are likely to be well below critical thresholds. Showers and thunderstorms could become quite numerous over the high country in the mid/late morning and afternoon hours today. This activity will produce gusty/erratic surface winds and locally heavy rain. Please be alert for the possibility of flash flooding on the Badger Creek Burn Scar today. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && UPDATE...WM SHORT TERM...CLH LONG TERM...CLH AVIATION...AL FIRE WEATHER...CLH
Hazardous Weather Outlook National Weather Service Cheyenne WY 631 AM MDT Thu Jul 12 2018 NEZ002-003-019>021-054-055-095-096-WYZ101>119-131245- Dawes-Box Butte-Scotts Bluff-Banner-Morrill-Kimball-Cheyenne- North Sioux-South Sioux-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- 631 AM MDT Thu Jul 12 2018 This hazardous weather outlook is for portions of western Nebraska...east central Wyoming...south central Wyoming and southeast Wyoming. .DAY ONE...TODAY AND TONIGHT Thunderstorms are expected to develop over the higher terrain this morning, then spread across the high plains of southeast Wyoming and the western Nebraska Panhandle during the afternoon and evening. The strongest storms may produce brief heavy rainfall, gusty winds to 50 MPH, and nickel size hail. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY There will be daily chances for showers and thunderstorms across much of the region from Friday through Wednesday. Severe weather is not expected at this time. .Spotter information statement... Spotter activation will not be needed.
Special Weather Statement National Weather Service Cheyenne WY 132 PM MDT THU JUL 12 2018 WYZ103-106-122015- Central Laramie Range and Southwest Platte County WY- North Laramie Range WY- 132 PM MDT THU JUL 12 2018 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN ALBANY AND SOUTHWESTERN PLATTE COUNTIES UNTIL 215 PM MDT... At 132 PM MDT, Doppler radar was tracking a strong thunderstorm 10 miles southeast of Friend Park Campground, or 22 miles west of Wheatland, moving southeast at 20 mph. Half inch hail and winds in excess of 40 mph will be possible with this storm. This storm will remain over mainly rural areas of northeastern Albany and southwestern Platte Counties. LAT...LON 4214 10553 4222 10531 4189 10505 4178 10538 TIME...MOT...LOC 1932Z 335DEG 17KT 4212 10539 Lyons
Special Weather Statement
National Weather Service Cheyenne WY
137 PM MDT THU JUL 12 2018
WYZ116-122015-
South Laramie Range WY-
137 PM MDT THU JUL 12 2018
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN ALBANY AND
SOUTHWESTERN LARAMIE COUNTIES UNTIL 215 PM MDT...
At 137 PM MDT, Doppler radar was tracking a strong thunderstorm near
Pumpkin Vine, or 23 miles south of Laramie, moving east at 10 mph.
Nickel size hail and wind gusts up to 50 mph will be possible with
this storm.
Locations impacted include...
Pumpkin Vine, Tie Siding and Buford.
This includes Interstate 80 in Wyoming between mile markers 331 and
336.
LAT...LON 4108 10558 4115 10538 4112 10528 4100 10517
4100 10555
TIME...MOT...LOC 1937Z 248DEG 10KT 4099 10547
LyonsThe Cheyenne radar (KCYS), 102 km away, was scanning. The volume nearest the first event began at 19:43 UTC.
1 flash flood. Local standard time, as filed.
Locally heavy rain in less than 30 minutes over the Badger Creek burn scar led to mud and debris flows across Highway 230 near Woods Landing.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2018Every state in 2018This day in weather historyWarnings in Wyoming, July 2018
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: 779591.