A tight pressure gradient ahead of an advancing trough brought high wind to Natrona County. Some of the maximum wind gusts included 66 mph along Wyoming Boulevard south of Casper, 65 mph along Hat Six Road and 60 mph at the Natrona County airport.
Every event with a place to put it; 3 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.
A tight pressure gradient ahead of an advancing trough brought high wind to Natrona County. Some of the maximum wind gusts included 66 mph along Wyoming Boulevard south of Casper, 65 mph along Hat Six Road and 60 mph at the Natrona County airport.
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 Nov 25, 10:02 AM MST, 1 hour 28 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1002 AM MST Wed Nov 25 2020 .SHORT TERM...(Today through Thanksgiving) Issued at 233 AM MST Wed Nov 25 2020 In the spirit of Thanksgiving, let's talk about the two main food groups that Wyoming has to offer this time of year. The first food group is snow, and not the kind you put in a cone with flavored syrup. As of 3 AM, light snow continues to fall at Togwotee lodge with a low-level cloud deck hanging across Yellowstone and the western valleys. This cloud deck will likely continue to spit snow through this morning. The bigger story here will be later this afternoon. Models have really come to agreement on timing with the main push of snow showers moving into Yellowstone Park around late morning. Snow will begin to fill into the western mountains during the early part of the afternoon and into the Jackson Valley during late afternoon. Snow accumulations will be near advisory amounts in the Tetons and southern Yellowstone, however, due to the lack of population in these areas, just stuck with the SPS. One thing to note, Teton Pass will likely see a fair amount of accumulating snow during the afternoon and evening, so travelers should be aware of slick potentially dangerous travel conditions over the Pass. The steadiest snow will fall during the late afternoon and evening, and will mainly end by Thanksgiving morning. Again, not looking at significant accumulations or impacts with this event. East of the Divide, could see an inch or two of snow over the northern Bighorns as the front passes through as well as less than an inch across northeast Johnson county and the Buffalo area. Impacts with this will be very minimal. Our second Wyoming food group is wind. Wind concerns today will be predominantly east of the Divide and we will focus on the area from Muddy Gap to Casper and the Cody Foothills. Winds have already begun to increase at both Cody and Casper this morning with jet dynamics becoming more favorable as the morning progresses. 700 mb winds this afternoon look to be in the area of 50kts and given the Watch and the fact that many people will be traveling today, decided to upgrade Natrona county to a High Wind Warning. Casper Airport has already gusted to 41 mph at 3 AM, and with Jet dynamics looking to become more favorable later in the day, high wind criteria certainly look possible here. As for the Cody Foothills, high wind criteria are looking less likely, despite somewhat favorable jet dynamics. Cody Airport had a peak wind gust around 3 AM of 44 mph, but have dropped back down to gusts around 25 mph. 700mb winds are barely peaking at 50kts later in the afternoon, so definitely a marginal event, but not marginal enough to pull the trigger. Went with an SPS instead. Winds will decrease after sunset and diminish significantly after 5 or 6 PM. Gusty winds will stick around for the Casper area, but should be much below high wind criteria by 6 PM. For Thanksgiving Day, mainly light winds are expected across the region. .LONG TERM...(Thursday night through Tuesday) Issued at 233 AM MST Wed Nov 25 2020 The trough will be through the region by Thursday night, with much lighter northwest flow beginning to establish with increased ridging aloft. The ridge will keep conditions tranquil through Sunday, with temperatures remaining above normal. Next clipper system races across Montana late Saturday into Sunday. Models have become much more divergent on how far south this clipper will extend into northern WY Sunday, with the GFS much farther into the state, while the EC pretty much misses WY completely. Either way, this system is quick and weak, so minimal impacts will be noted, with a slight cool down and a brief shift to northwest flow. Differences in the Sunday clipper impact the outcome of the trailing system diving into the Pacific NW early next week, so any solutions rendered by models are low confidence for the time being. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) Issued at 944 AM MST Wed Nov 25 2020 East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals The main issue through 00Z will be strong wind at KCPR. A cold front will push into northern Wyoming around 21Z, but slowly push south to near the Divide by around 06Z. Some snow showers are possible across northern Wyoming between 03Z and 09Z. Also models are showing some MVFR ceilings developing across the Bighorn Basin, Johnson County and Natrona County as early as 03Z over the north spreading south to Casper by around 09Z. These low clouds, if the do end up forming, should scatter out by 15Z to 16Z. By 18Z, mainly SKC is expected with mainly light winds. The exception for some breezy westerly winds in the Cody Foothills. West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals Snow showers are expected to break out across far western Wyoming by 21Z. The main impact from the snow will be MVFR ceilings/IFR visibility at KJAC developing between 23Z and 01Z. Also mountain obscurations are expected across northwest Wyoming. Farther southeast impacts are expected to be minimal at KBPI and KPNA with no impact at KRKS. The bulk of the snow at KJAC should end by around 05Z, but snow showers could still impact KJAC through about 15Z. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Issued AT 233 AM MST Wed Nov 25 2020 Light snow will continue across parts of the west this morning, but the bulk of the snow will come later this afternoon. Snow accumulations will be minimal with higher amounts focused across the Tetons and southern Yellowstone Park. East of the Divide, snow will be minimal and will mainly be across the northern Bighorns and northeastern Johnson County. Snow will mainly end by Thanksgiving morning. Elsewhere is expected to be dry with mostly cloudy skies. The other concern today will be wind from Muddy Gap to Casper, where a High Wind Warning is in effect, and also along the Cody Foothills. Winds will diminish after sunset and be mainly light through the night, with stronger winds lingering around the Casper area into the early part of the night. Gusty winds can be expected across Natrona county during the afternoon hours through the weekend, but the region should remain dry and quiet otherwise. && .RIW WATCHES/WARNINGS/ADVISORIES... High Wind Warning until 6 PM MST this evening for WYZ020. && SHORT TERM...Fisher LONG TERM...Straub AVIATION...Murrell FIRE WEATHER...Fisher
Hazardous Weather Outlook National Weather Service Riverton WY 429 AM MST Wed Nov 25 2020 WYZ001>020-022>030-261200- Yellowstone National Park-Absaroka Mountains-Cody Foothills- North Big Horn Basin-Southwest Big Horn Basin- Southeast Big Horn 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- 429 AM MST Wed Nov 25 2020 ...High Wind Warning for Natrona County on Wednesday... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Accumulating snowfall across the west, mainly focused across the northern Tetons and southern Yellowstone Park with some light accumulations possible in the Jackson Valley. The greatest travel impacts will be across Teton and Togwotee Passes this afternoon and this evening. Strong to high winds possible from Muddy Gap to Casper today. A High Wind Warning is in effect for this area. Strong winds are also possible for the Cody Foothills through this afternoon. .DAYS TWO THROUGH SEVEN...Thanksgiving through Tuesday. The probability for widespread hazardous weather is low. .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.
3 high wind. Local standard time, as filed.
A 60 mph wind gust was measured at the Natrona County, Wyoming airport.
A mesonet site measured 65 mph winds along Hat Six Road in Casper, Wyoming.
A measured wind gust of 66 mph was reported along Wyoming Boulevard, just south of Casper, Wyoming.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2020Every state in 2020This day in weather historyWarnings in Wyoming, November 2020
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: 930436, 930438, 923880.