A tight pressure gradient and strong mid level winds mixing to the surface brought another round of high wind to portions of Park, Natrona and Fremont Counties. The strongest winds occurred near Clark where a wind gust of 99 mph was recorded.
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The episode as NWS RIW wrote it up.
A tight pressure gradient and strong mid level winds mixing to the surface brought another round of high wind to portions of Park, Natrona and Fremont Counties. The strongest winds occurred near Clark where a wind gust of 99 mph was recorded. Elsewhere, Outer Drive south of Casper saw wind gusts to 78 mph and Fales Rock had a gust to 61 mph.
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 Dec 29, 10:21 AM MST, 2 hours 11 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1021 AM MST Thu Dec 29 2016 .SHORT TERM...Thursday through Saturday night (issued 911 AM MST Thu Dec 29 2016) All in all, this is one of the quieter days we have had in a while. Notice how I said quieter, not quiet. There is always something, especially this winter. And this is in the area where the off switch to the wind machine is constantly broken. Of course, I am taking about Clark. With the 700 millibar winds increasing to around 60 knots tonight, we have high confidence in another high wind event. So, we will upgrade the high wind watch to a warning for tonight and tomorrow morning. Otherwise, things look fairly quiet today with a sunny to partly cloudy sky and temperatures not too bad for this time of year. It will continue to be breezy at times in the usual areas, like Casper, along with a bit of blowing snow, but nothing like earlier this week. The next weather maker will be a cold front dropping southward out of Montana. The models have come into better agreement on timing as well with the front moving in late Friday in the north and into central Wyoming at night. There is some upper level support with this system in the form of the right rear quadrant of a jet streak that will enhance lift. However, with it's Canadian origin it is fairly moisture starved and with it's fast movement large amounts of snow are not expected. However, this could be a situation where there could be a brief period of moderate to heavy snow with the frontal passage. This, along with some gusty winds could make travel difficult for a brief time late Friday and Friday night, especially in the northern Big Horn Basin and northern Johnson County. The system does lose it's punch as it moves further south so southern portions of the state will likely see nothing out of the passage. All precipitation should end by Saturday morning. Most of Saturday should be dry. Temperatures will be cooler than Friday but nothing unusual for the end of December. And although we can't rule out a few snow showers in the western mountains, it should be dry most of the time. Another system will drop toward the area for Saturday night. However, the models have trended slower with it so we have trimmed POPS for Saturday night in the western mountains, leaving them in the slight category for all areas. .LONG TERM...Sunday through Thursday .Arctic Blast with some Snow Next Week... Models remain in good agreement with a strong shortwave trough pushing southeast into the Pacific Northwest by 12Z Sunday. This feature is expected to become a closed upper low, and encompass a larger area with time as it gradually shifts south into Oregon by Monday. An initial shortwave swinging around the upper low will impact Western Wyoming Sunday with snow quickly breaking out over the west and far northwest. The initial surge of Arctic air is expected to drop south across the area as early as late Sunday afternoon and sweep across the area Sunday night and Monday morning. In wake of this strong cold front, models are showing isentropic lift along with periodic shortwaves in the southwest flow pushing across the forecast area Sunday night through Monday evening. This will allow for snow over the west Sunday to spread quickly east of the Divide late Sunday afternoon into Sunday Night. The 00Z operational runs of the ECMWF and GFS show the potential for the shortwave on Monday to have a weak 700mb circulation reflection as it crosses central/southern Wyoming which would enhance lift. Could also see some left front quad jet dynamics come into play as well. Models have increased their quantitative precipitation output to between 0.15 and 0.30 of an inch which is up about 0.10 from yesterday. Also the heaviest precip amounts have shifted east of the Divide. The limiting factors for significant snowfall is overall moisture will be on the low side with precipitable water values between 0.10 and 0.15 of an inch, as well as there will be little time for optimal snow growth since the system is so cold. However the duration of the event and the upper level forcing could overcome the limited moisture. Have plenty of time to watch the system unfold. Tuesday through Thursday, models have varying solutions for location of any snowfall across the region. The forecast area could be impacted by systems ejecting out of the aforementioned upper low as it movies south into California/Great Basin area, systems diving south out of Canada, or be in between both weather streams. Due to this uncertainty have gone with only slight mountain PoPs for now. Temperatures, if we must talk about it, will be MUCH BELOW average in wake of the Arctic cold front Sunday night and remain bitterly cold through the ENTIRE WEEK. A deep snow pack across much of the area will melt away any thoughts of warmth. Temperatures will be 15 to 30 degrees below average for much of the week. The coldest days are expected to be Tuesday and Wednesday with 1000-500mb thicknesses ranging between 505dm and 515dm. Some record lows and record coolest highs will be in jeopardy especially Tuesday and Wednesday. .AVIATION.../18Z ISSUANCE/ West of the divide...KBPI/KJAC/KPNA/KRKS Terminals VFR conditions will prevail through the period. Ridgetop west winds will increase this evening, resulting in areas of LLWS developing vicinity KJAC, KBPI, KPNA along with areas of blowing snow partially obscuring higher terrain. East of the divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals VFR conditions will prevail across the area through 18z Friday. A lee side surface trough will strengthen today with southwest winds at 20-30kt gusts over 40kts prevailing from 50SM NE KRKS to vicinity KCPR through 18z Friday. This will also result in areas of blowing snow and partial terrain obscurations. Ridgetop winds will increase in the vicinity of the Continental Divide this evening with areas of LLWS developing vicinity KCOD- KDUB-KLND. Some of these stronger winds will likely mix down to the surface with some gusts over 50 kts possible in the vicinity of KCOD through Friday morning. .FIRE WEATHER... Dry conditions will dominate the state today with possible inversions in the deeper valleys and valleys. A gusty wind will again blow from the Red Desert through Casper. High winds will once again be likely in the Lee of the Absarokas ahead of an advancing cold front. Mixing and smoke dispersal will remain fair to poor for most areas. A cold front will move into northern Wyoming late Friday and across central Wyoming Friday night and could bring some snow although amounts are expected to be light. && .RIW WATCHES/WARNINGS/ADVISORIES... High Wind Warning from 5 PM this afternoon to 11 AM MST Friday for WYZ003-019-020. && SHORT TERM...Hattings LONG TERM...WM AVIATION...LaVoie FIRE WEATHER...Hattings
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 923 AM MST THU DEC 29 2016 WYZ001>020-022>030-301630- 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- 923 AM MST THU DEC 29 2016 ...HIGH WIND WARNING IN EFFECT FOR THE CODY FOOTHILLS...NATRONA AND SOUTHERN FREMONT COUNTIES THIS EVENING THROUGH TOMORROW MORNING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT HIGH WIND LIKELY IN THE CODY FOOTHILLS...NATRONA AND SOUTHERN FREMONT COUNTIES THIS EVENING THROUGH TOMORROW MORNING. PLEASE SEE HIGH WIND WARNING AND FORECASTS FOR DETAILS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY FRIDAY MORNING...HIGH WIND LIKELY IN THE CODY FOOTHILLS. FRIDAY NIGHT...A BRIEF PERIOD OF SNOW IS POSSIBLE ACROSS NORTHERN AND CENTRAL WYOMING. SUNDAY AND MONDAY...SNOW BREAKING OUT OVER WEST SUNDAY...SPREADING ACROSS THE ENTIRE AREA SUNDAY NIGHT...AND LASTING THROUGH THE DAY MONDAY. SOME AREAS COULD SEE SIGNIFICANT SNOWFALL. AN ARCTIC COLD FRONT WILL SURGE ACROSS THE AREA SUNDAY NIGHT...BRINGING IN EXTREMELY COLD TEMPERATURES. TUESDAY AND WEDNESDAY...BITTERLY COLD TEMPERATURES WITH HIGHS IN SOME LOCATIONS STRUGGLING TO GET ABOVE ZERO. .SPOTTER INFORMATION STATEMENT... SPOTTER ARE ENCOURAGED TO REPORT SNOWFALL AMOUNTS AND ANY WIND DAMAGE. THANK YOU. THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY .SPOTTER INFORMATION STATEMENT...
The national radar mosaic for the moment the first event began.
3 high wind. Local standard time, as filed.
There were many wind gusts past hurricane force near Clark. The strongest gusts included 99 mph 5 miles west-northwest of Clark and 78 mph 8 miles south of Clark.
The RAWS site at Fales Rock had a maximum wind gust of 61 mph.
Strong winds occurred once again along Outer Drive south of Casper. There were many gusts past 58 mph with a maximum of 78 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2016Every state in 2016This day in weather historyWarnings in Wyoming, December 2016
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: 666087, 666088, 666089.