An unusually strong ridge of high pressure brought record high temperatures to many locations across western and central Wyoming. In addition, 4 sites had their latest occurrence of a 90 degree high temperature in history.
Every event with a place to put it; 4 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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 RIW wrote it up.
An unusually strong ridge of high pressure brought record high temperatures to many locations across western and central Wyoming. In addition, 4 sites had their latest occurrence of a 90 degree high temperature in history. The most notable site was Lander, which has records dating back to 1891.
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 Riverton, WY wrote its last area forecast discussion before the first event at Sep 29, 3:49 AM MST, 2 hours 11 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Riverton WY 449 AM MDT Sun Sep 29 2024 .KEY MESSAGES... - Elevated to critical fire weather likely across the area today along with possible record high temperatures. - Turning much cooler on Monday. - Mainly dry conditions and above normal temperatures are expected from Tuesday through most of the week. && .DISCUSSION... Issued at 153 AM MDT Sun Sep 29 2024 The only concern that we have over the next several days is fire weather and the worst conditions are expected to be today. A cold front now moving into Idaho will cross the area this evening. Ahead of the front, the pressure gradient will tighten, increasing southwest flow across the area. Wind will also be enhanced by the right front quadrant of a jet streak moving across northern Wyoming. The result will be possible record heat combined with low humidity and gusty winds. This will bring critical fire weather to most of the area. We have maintained the Red Flag Warnings as is and will also issue Fire Danger statements for areas that don't have one. The heat today looks notable as well. Buffalo tied it's latest 90 degree high yesterday and is likely to break it today. The official stations in Casper, Riverton and Lander also have a chance to break the record for the latest 90 degree high temperatures today. Just about all lower elevations will be into the 80s as well. As for precipitation, the only chance would be in southern Sweetwater County with a weak area of low pressure. Even here, the chance is less than 1 out of 5 and would more than likely just be virga showers. The front will sweep across the area tonight, ushering in much cooler temperatures. Things will also get rather windy tonight in the favored northwest flow / cold advection areas late tonight, like Buffalo. High wind is not expected, but there is greater than a 1 in 2 chance of gusts past 40 mph behind the frontal passage. Highs tomorrow will be 20 to 30 degrees cooler than today, with the greatest contrast across the northern counties. As for fire weather tomorrow, temperatures will remain above normal in southern Wyoming with a gusty wind continuing. With the low humidity, we will continue the Red Flag Warning for this day as well. Elsewhere, it looks more elevated than critical. Relative humidity is borderline. In addition, wind should be decreasing as the pressure gradient lessens behind the front. There could be some fire weather statements issued though. The rest of the period looks dry and warm, but not as warm as what is expected today. High temperatures will generally average 5 to 10 degrees above normal. The only concern, again, would be fire weather but conditions on most days are borderline. The main days of concern further out would be Wednesday with a subtle shortwave and possibly next Saturday with a wave and possible cold front. The dry pattern will continue as well, with a greater than a 4 out of 5 chance in all areas with dry weather continuing through most of next week. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 447 AM MDT Sun Sep 29 2024 Light winds continue to start the TAF period. Gusty southwest winds will increase between 16-18Z. Gusts of 20 kt will increase to 35 knots and be common across much of the forecast area after 18Z. There is some uncertainty with how long these winds will continue into the late evening and early night, though winds should begin to trend downward after 00Z/Mon. A dry cold front begins to enter northern portions between 04Z-06Z, pushing southward across areas east of the Divide and turning winds northward through the rest of the TAF period. Some upper-level smoke from the Fish Creek/Pack Trail Fire is possible for KCOD, KWRL and KJAC through the day today, although chances will be decreasing for KJAC as winds are expected to turn southerly by 16Z. This smoke will be possible for KLND and KRIW toward the end of the TAF period as the cold front approaches. Not expecting any terminal impacts at this time. If smoke were to filter in, it would likely clear earlier than it did Saturday due to the increasing winds today. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts. && .FIRE WEATHER... Issued at 153 AM MDT Sun Sep 29 2024 A combination of record high temperatures, humidity under 15 percent and a gusty southwest wind ahead of an advancing cold front will bring elevated to critical fire weather to most of the area this afternoon. Southwest wind will gust as high as 40 to 45 mph in the afternoon. The cold front then moves through Sunday evening and night. Cooler temperatures and somewhat higher humidity should ease concerns across northern and central Wyoming on Monday. With stronger wind remaining in southern Wyoming, critical fire weather looks to continue for a second day Monday. && .RIW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 11 AM this morning to 7 PM MDT this evening for WYZ275-276-280>283-285-287-300. Red Flag Warning from 11 AM this morning to 7 PM MDT Monday for WYZ277>279-289. && DISCUSSION...Hattings AVIATION...LaVoie/Wittmann FIRE WEATHER...Hattings
Hazardous Weather Outlook National Weather Service Riverton WY 1243 AM MDT Sun Sep 29 2024 WYZ001>020-022>030-301045- Yellowstone National Park-Absaroka Mountains-Cody Foothills- North Bighorn Basin-Southwest Bighorn Basin- Southeast Bighorn Basin-Owl Creek and Bridger Mountains- Bighorn Mountains West-Bighorn Mountains Southeast- Northeast Johnson County-Southeast Johnson County- Teton and Gros Ventre Mountains-Jackson Hole- Wind River Mountains West-Wind River Mountains East- Upper Wind River Basin-Wind River Basin-Lander Foothills- Green Mountains and Rattlesnake Range- Natrona County Lower Elevations-Casper Mountain-Star Valley- Salt River and Wyoming Ranges-Upper Green River Basin Foothills- Upper Green River Basin-South Lincoln County- Rock Springs and Green River-Flaming Gorge-East Sweetwater County- 1243 AM MDT Sun Sep 29 2024 ...Red Flag Warning in effect for much of Wyoming Sunday afternoon, and for southern Wyoming Monday afternoon... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Elevated to critical fire weather likely in the afternoon for most of the area. Please see forecasts, Red Flag Warnings and statements for details. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Monday...Critical fire weather continuing for southern Wyoming. Monday night...Below freezing temperatures possible East of the Divide. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to Standard Operating Procedures.
The national radar mosaic for the moment the first event began.
4 heat. Local standard time, as filed.
The Johnson County airport had a record high temperature of 94 degrees. This was the latest occurrence of 90 degrees in station history.
The Natrona County airport had a record high temperature of 91 degrees. This was the latest high temperature in the 90s in station history.
The Lander airport had a record high temperature of 90 degrees. This was the latest high temperature in the 90s in station history.
The Riverton airport had a record high temperature of 90 degrees. This was the latest high temperature in the 90s in station history.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2024Every state in 2024This day in weather historyWarnings in Wyoming, September 2024
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: 1217276, 1217277, 1217278, 1217279.