A line of thunderstorms developed over central Wyoming in an environment favorable for the production of gusty outflow wind from high-based showers and thunderstorms. An outflow boundary ahead of this line moved toward Casper where a peak wind gust of 59 mph was measured at the airport.
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The episode as NWS RIW wrote it up.
A line of thunderstorms developed over central Wyoming in an environment favorable for the production of gusty outflow wind from high-based showers and thunderstorms. An outflow boundary ahead of this line moved toward Casper where a peak wind gust of 59 mph was measured at the 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 Jul 6, 12:59 PM MST, 4 hours 19 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 159 PM MDT WED JUL 6 2016 .SHORT TERM...Tonight through Saturday ...Red Flag Warning in effect for Natrona County this afternoon and evening... Imagery shows a broad trof across the wrn CONUS with upr southwest flow and an embedded disturbance moving into/through WY from west to east. Surface has weak low pressure over WY with a couple of weak attending fronts/boundaries...one across the west and the other over the east. A few gusty high based showers/virga currently across the central mountains...Wind River Basin and Bighorn Basin. Today/Tonight, similar set-up as Tuesday except for the location of better convective chances shifts over east central to northern WY. These storms will generally produce little rain with gusty wind. Stronger isolated storms may be found over Johnson County and perhaps portions of eastern Natrona county where the environment will be a bit more conducive for both small hail and gusty wind. CAPE will range from 500 to 1000 j/kg within moderate high shear...with storms moving east northeast at 35 to 45 mph. Gusts to 50 mph will be attainable with a few storms that have any height and oomph to them. Tonight, the upper level trof begins to cross the FA pushing a front into/through northern WY and then across the area east of the Divide...to the southern border by Thursday morning with some lingering post frontal showers trailing off to the south and east through sunrise. Thursday, the upper trof moves across WY to the eastern border by mid-day with modest ridging beginning over the western portion of WY. The FA dries out with little to no chance for precipitation existing under post frontal and upper level ridging stability except for a small chance for an isolated storm over the higher peaks of the Bighorns. Friday, flat upper ridging weak surface low pressure will allow for warming to continue with warm/hot conditions at the surface along with RH values dropping into the mid teens for much of the lower elevations east of the Divide and across the south. Winds, however, look to behave for the most part with no widespread wind gusts AOA 25 mph over the zones where fuels are currently critical. Otherwise, as the ridge axis moves across eastern WY, another western CONUS trof will begin to impinge on western WY, allowing for some small increases in moisture across western/northwestern WY along with cooling temperatures aloft...with associated increasing instability. Through the day, this set-up will allow for some modest increases in shower/thunderstorm chances across mainly the northern half of Wyoming through the day and evening. Most of this activity will have little rainfall and gusty winds. Saturday will be similar to Friday in many respects only warmer and drier with a little stronger surface flow across Natrona county as surface trof/low pressure shifts further to the north. This will lead to increasing fire danger - possibly extreme fire danger - across this area. Will monitor further for possible Fire Weather Watch. Otherwise, isolated to widely scattered showers/thunder with little rain and gusty winds will be the main threat across the northern mountain and basins. .LONG TERM...Saturday Night Through Wednesday Mean trough will hold across far Western U.S. into early next week before our summer ridge expands nwwd into the Rockies once again. Main model trend since yesterday is for a little stronger, further south and a little slower with our upper low movement Sunday into Monday. End result will be potential threat of strong to severe thunderstorms in Northwest Wyoming Sunday with a good chance of showers/higher elevation snow Sunday night into Monday in the AFO to COD quadrant. Ahead of this system...which is currently over Alaska...it will be very warm to hot and windy with increased fire danger. Overnight lows could be quite warm Saturday night where the breezes hold. GFS is showing nose of cyclonically curved jet moving up into far Western Wyoming around midday Sunday with fropa in the late morning. A little slower timing is quite possible with the position of the upper low still forecast to be in Ern OR at noon on Sunday. Either way, we'll have to watch this potent upper low as it moves in for potential for strong to high winds (and associated fire danger) ahead of it and strong to potentially severe thunderstorms ahead of and with fropa in especially the northwest quadrant Sunday. Temperatures will fall rapidly behind the front with H7 temps probably falling to near or below 0C in the west Sunday night and well down into the single digits east of the divide by Monday morning. The west will start to cool off already Sunday but for the far eastern zones the cooldown from Sunday to Monday should be quite dramatic with potential to go from 90s to 70s with a few spots possibly staying in the 60s. Significant precipitation of an inch or more is quite possible in the western mtns Sunday into Monday. The will not lift north of the area until Monday night based on the latest guidance giving the western and northern zones a longer period of precipitation. Tuesday into Wednesday looks dry with gradually warming temps as heights start to recover and dry wly flow returns. && .AVIATION.../00Z ISSUANCE/ VFR conditions will prevail through 06z Thursday. Isolated to widely scattered showers and thunderstorms are possible just about anywhere into this evening. The main threat from most of these will be lightning and erratic outflow winds of 30-40kts. An upper trough will swing across the northern Rockies tonight, driving a Canadian cold front south across northern and central Wyoming early Thursday morning. Areas of MVFR ceilings may develop behind the front 08z- 16z Thursday, especially from vicinity KBYG- KCPR and vicinity KCOD. Thursday will be dry across the entire area. && .FIRE WEATHER... ...Red Flag Warning in effect for Natrona County this afternoon and evening... Ahead of a cold front that will move through Wyoming this evening and through the overnight period, southwest winds area expected to increase with gusts between 20 and 30 mph this afternoon. The winds may also be enhanced near any showers or thunderstorms with a few gusts between 40 and 50 mph possible. These conditions when combined with RH values in the mid teens (percent) and the possibility of isolated relatively dry thunderstorms will raise fire danger to extreme over Natrona county later this afternoon and early evening where fuels are currently critically dry. Behind the front, cooler and slightly more moist air mass will reside on Thursday with no rainfall expected and wind gusts remaining in check. Friday will be warmer and drier with isolated to widely scattered chances for showers/thunder across the northern half of Wyoming...most with gusty winds but little rainfall. Although RH values will drop once again into the middle teens, winds should remain in check for those areas where fuels are critically dry. Saturday will be see the next chance for Red Flag conditions over portions of central Wyoming...in particular Natrona county where RH values will mostly likely drop to or below 15 percent with winds gusting 25 to 30 mph in the afternoon. Sunday may again see extreme conditions for Natrona county. && .RIW Watches/Warnings/Advisories... Red Flag Warning until 9 PM MDT this evening for WYZ280. && SHORT TERM...Braun LONG TERM...Skrbac AVIATION...Skrbac FIRE WEATHER...Braun
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 302 AM MDT WED JUL 6 2016 WYZ001>020-022>030-071200- 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- 302 AM MDT WED JUL 6 2016 ...RED FLAG WARNING IN EFFECT FOR NATRONA COUNTY THIS AFTERNOON AND EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT ELEVATED FIRE WEATHER CONDITIONS IN CENTRAL AND SOUTHERN AREAS THIS AFTERNOON AND EVENING...ESPECIALLY IN NATRONA COUNTY...WHERE A RED FLAG WARNING IS IN EFFECT THIS AFTERNOON AND EVENING. ISOLATED...MAINLY AFTERNOON AND EVENING THUNDERSTORMS. STRONG DOWNBURST WINDS ARE THE MAIN THREAT. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THURSDAY...ELEVATED FIRE DANGER POSSIBLE ACROSS THE SOUTH. FRIDAY...ELEVATED FIRE DANGER OVER CENTRAL AND SOUTHERN SECTIONS. SATURDAY AND SUNDAY...ELEVATED TO EXTREME FIRE WEATHER CONDITIONS...MAINLY IN THE LOWER ELEVATIONS EAST OF THE DIVIDE AND SWEETWATER COUNTY. ON SUNDAY...STRONG THUNDERSTORMS ARE POSSIBLE WITH AN EMPHASIS ACROSS THE NORTHWEST. MONDAY AND TUESDAY...ELEVATED FIRE DANGER IN SOME AREAS. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE URGED TO REPORT STRONG WINDS...AND ANY HAIL. THANK YOU. TEAM RIVERTON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 118 PM MDT WED JUL 6 2016 WYZ016>018-062200- UPPER WIND RIVER BASIN-WIND RIVER BASIN-LANDER FOOTHILLS- INCLUDING THE CITIES OF...DUBOIS...RIVERTON...SHOSHONI...LANDER 118 PM MDT WED JUL 6 2016 SHOWERS OVER THE WIND RIVER MOUNTAINS ARE CAUSING GUSTY WINDS TO DEVELOP ACROSS MUCH OF THE WIND RIVER BASIN THIS AFTERNOON. THESE WINDS ARE GUSTING OUT OF THE WEST TO SOUTHWEST AT 35 TO 50 MPH AT TIMES. THESE CONDITIONS WILL CONTINUE OCCASIONALLY THROUGH THE AFTERNOON PERIOD. WYZ010-011-062200- NORTHEAST JOHNSON COUNTY-SOUTHEAST JOHNSON COUNTY- INCLUDING THE CITIES OF...BUFFALO...KAYCEE 118 PM MDT WED JUL 6 2016 SHOWERS OVER THE BIGHORN MOUNTAINS ARE CAUSING GUSTY WINDS TO DEVELOP ACROSS MUCH OF THE FOOTHILLS IN JOHNSON COUNTY. THESE WINDS ARE GUSTING OUT OF THE WEST TO SOUTHWEST AT 35 TO 45 MPH AT TIMES. THESE CONDITIONS WILL CONTINUE OCCASIONALLY THROUGH THE AFTERNOON PERIOD.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 121 PM MDT WED JUL 6 2016 WYZ016>018-062200- UPPER WIND RIVER BASIN-WIND RIVER BASIN-LANDER FOOTHILLS- INCLUDING THE CITIES OF...DUBOIS...RIVERTON...SHOSHONI...LANDER 121 PM MDT WED JUL 6 2016 SHOWERS OVER THE WIND RIVER MOUNTAINS ARE CAUSING GUSTY WINDS TO DEVELOP ACROSS MUCH OF THE WIND RIVER BASIN THIS AFTERNOON. THESE WINDS ARE GUSTING OUT OF THE WEST TO SOUTHWEST AT 35 TO 55 MPH WITH LOCALLY HIGHER GUSTS AT TIMES. THESE CONDITIONS WILL CONTINUE OCCASIONALLY THROUGH THE AFTERNOON PERIOD. WYZ010-011-062200- NORTHEAST JOHNSON COUNTY-SOUTHEAST JOHNSON COUNTY- INCLUDING THE CITIES OF...BUFFALO...KAYCEE 121 PM MDT WED JUL 6 2016 SHOWERS OVER THE BIGHORN MOUNTAINS ARE CAUSING GUSTY WINDS TO DEVELOP ACROSS MUCH OF THE FOOTHILLS IN JOHNSON COUNTY. THESE WINDS ARE GUSTING OUT OF THE WEST TO SOUTHWEST AT 35 TO 45 MPH AT TIMES. THESE CONDITIONS WILL CONTINUE OCCASIONALLY THROUGH THE AFTERNOON PERIOD.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 224 PM MDT WED JUL 6 2016 WYZ016>018-062300- UPPER WIND RIVER BASIN-WIND RIVER BASIN-LANDER FOOTHILLS- INCLUDING THE CITIES OF...DUBOIS...RIVERTON...SHOSHONI...LANDER 224 PM MDT WED JUL 6 2016 SHOWERS OVER THE WIND RIVER MOUNTAINS ARE CAUSING GUSTY DOWNSLOPE WINDS TO DEVELOP ACROSS MUCH OF THE WIND RIVER BASIN THIS AFTERNOON. THESE WINDS ARE GUSTING OUT OF THE WEST TO SOUTHWEST AT 35 TO 55 MPH WITH LOCALLY HIGHER GUSTS AT TIMES. THESE CONDITIONS WILL CONTINUE OCCASIONALLY THROUGH THE AFTERNOON PERIOD. WYZ010-011-062300- NORTHEAST JOHNSON COUNTY-SOUTHEAST JOHNSON COUNTY- INCLUDING THE CITIES OF...BUFFALO...KAYCEE 224 PM MDT WED JUL 6 2016 SHOWERS OVER THE BIGHORN MOUNTAINS ARE CAUSING GUSTY WINDS TO DEVELOP ACROSS MUCH OF THE FOOTHILLS IN JOHNSON COUNTY. THESE WINDS ARE GUSTING OUT OF THE WEST TO SOUTHWEST AT 35 TO 45 MPH AT TIMES. THESE CONDITIONS WILL CONTINUE OCCASIONALLY THROUGH THE AFTERNOON PERIOD. WYZ003>006-062300- CODY FOOTHILLS-NORTH BIG HORN BASIN-SOUTHWEST BIG HORN BASIN- SOUTHEAST BIG HORN BASIN- INCLUDING THE CITIES OF...CODY...MEETEETSE...THERMOPOLIS... WORLAND 224 PM MDT WED JUL 6 2016 SHOWERS AND THUNDERSTORMS ARE DEVELOPING OFF THE ABSAROKA MOUNTAINS AND MOVING EAST ACROSS THE FOOTHILLS AND BIGHORN BASIN CAUSING GUSTY WINDS TO DEVELOP AHEAD OF THE SHOWERS AND STORMS. THESE WINDS WILL GUST 35 TO 50 MPH AT TIMES. THESE CONDITIONS WILL CONTINUE OCCASIONALLY THROUGH THE AFTERNOON PERIOD.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 303 PM MDT WED JUL 6 2016 WYZ007-016>018-062300- OWL CREEK AND BRIDGER MOUNTAINS-UPPER WIND RIVER BASIN- WIND RIVER BASIN-LANDER FOOTHILLS- INCLUDING THE CITIES OF...DUBOIS...RIVERTON...SHOSHONI...LANDER 303 PM MDT WED JUL 6 2016 SHOWERS OVER THE WIND RIVER MOUNTAINS ARE CAUSING GUSTY DOWNSLOPE WINDS TO DEVELOP ACROSS MUCH OF THE WIND RIVER BASIN THIS AFTERNOON. THESE WINDS ARE GUSTING OUT OF THE WEST TO SOUTHWEST AT 35 TO 55 MPH WITH LOCALLY HIGHER GUSTS AT TIMES. THESE CONDITIONS WILL CONTINUE OCCASIONALLY THROUGH THE AFTERNOON PERIOD. WYZ010-011-062300- NORTHEAST JOHNSON COUNTY-SOUTHEAST JOHNSON COUNTY- INCLUDING THE CITIES OF...BUFFALO...KAYCEE 303 PM MDT WED JUL 6 2016 SHOWERS OVER THE BIGHORN MOUNTAINS ARE CAUSING GUSTY WINDS TO DEVELOP ACROSS MUCH OF THE FOOTHILLS IN JOHNSON COUNTY. THESE WINDS ARE GUSTING OUT OF THE WEST TO SOUTHWEST AT 25 TO 45 MPH AT TIMES. THESE CONDITIONS WILL CONTINUE OCCASIONALLY THROUGH THE AFTERNOON PERIOD. WYZ003>006-062300- CODY FOOTHILLS-NORTH BIG HORN BASIN-SOUTHWEST BIG HORN BASIN- SOUTHEAST BIG HORN BASIN- INCLUDING THE CITIES OF...CODY...MEETEETSE...THERMOPOLIS... WORLAND 303 PM MDT WED JUL 6 2016 SHOWERS AND THUNDERSTORMS ARE DEVELOPING OFF THE ABSAROKA MOUNTAINS AND MOVING EAST ACROSS THE FOOTHILLS AND BIGHORN BASIN CAUSING GUSTY WINDS TO DEVELOP AHEAD OF THE SHOWERS AND STORMS. THESE WINDS WILL GUST 35 TO 45 MPH AT TIMES. THESE CONDITIONS WILL CONTINUE OCCASIONALLY THROUGH THE AFTERNOON PERIOD. WYZ019-020-022-028>030-062300- GREEN MOUNTAINS AND RATTLESNAKE RANGE- NATRONA COUNTY LOWER ELEVATIONS-CASPER MOUNTAIN- ROCK SPRINGS AND GREEN RIVER-FLAMING GORGE-EAST SWEETWATER COUNTY- INCLUDING THE CITIES OF...JEFFREY CITY...CASPER...ROCK SPRINGS... GREEN RIVER...WAMSUTTER 303 PM MDT WED JUL 6 2016 SHOWERS AND THUNDERSTORMS ARE DEVELOPING ACROSS PORTIONS OF SOUTHERN AND CENTRAL WYOMING AND MOVING EAST AROUND 40 MPH CAUSING GUSTY WINDS TO DEVELOP. THESE WINDS WILL GUST 35 TO 50 MPH AT TIMES. THESE CONDITIONS WILL CONTINUE OCCASIONALLY THROUGH THE AFTERNOON PERIOD.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 514 PM MDT WED JUL 6 2016 WYZ007-016>018-070100- OWL CREEK AND BRIDGER MOUNTAINS-UPPER WIND RIVER BASIN- WIND RIVER BASIN-LANDER FOOTHILLS- INCLUDING THE CITIES OF...DUBOIS...RIVERTON...SHOSHONI...LANDER 514 PM MDT WED JUL 6 2016 SHOWERS OVER THE WIND RIVER MOUNTAINS WILL CONTINUE TO CAUSE GUSTY DOWNSLOPE WINDS ACROSS MUCH OF THE WIND RIVER BASIN INTO EARLY THIS EVENING. THESE WINDS ARE GUSTING OUT OF THE WEST TO SOUTHWEST AT 35 TO 50 MPH WITH LOCALLY HIGHER GUSTS AT TIMES. WYZ010-011-070100- NORTHEAST JOHNSON COUNTY-SOUTHEAST JOHNSON COUNTY- INCLUDING THE CITIES OF...BUFFALO...KAYCEE 514 PM MDT WED JUL 6 2016 SHOWERS OVER THE BIGHORN MOUNTAINS WILL CONTINUE TO CAUSE GUSTY WINDS ACROSS MUCH OF THE FOOTHILLS IN JOHNSON COUNTY INTO EARLY THIS EVENING. THESE WINDS ARE GUSTING OUT OF THE WEST TO SOUTHWEST AT 25 TO 45 MPH AT TIMES. WYZ003>006-070100- CODY FOOTHILLS-NORTH BIG HORN BASIN-SOUTHWEST BIG HORN BASIN- SOUTHEAST BIG HORN BASIN- INCLUDING THE CITIES OF...CODY...MEETEETSE...THERMOPOLIS... WORLAND 514 PM MDT WED JUL 6 2016 SHOWERS AND A FEW THUNDERSTORMS ACROSS THE CODY FOOTHILLS AND BIGHORN BASIN WILL CONTINUE TO CAUSE GUSTY WINDS INTO EARLY THIS EVENING. THESE WINDS WILL GUST 35 TO 45 MPH AT TIMES WITH LOCALIZED GUSTS OVER 50 MPH. WYZ019-020-022-028>030-070100- GREEN MOUNTAINS AND RATTLESNAKE RANGE- NATRONA COUNTY LOWER ELEVATIONS-CASPER MOUNTAIN- ROCK SPRINGS AND GREEN RIVER-FLAMING GORGE-EAST SWEETWATER COUNTY- INCLUDING THE CITIES OF...JEFFREY CITY...CASPER...ROCK SPRINGS... GREEN RIVER...WAMSUTTER 514 PM MDT WED JUL 6 2016 GUSTY SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO EARLY THIS EVENING. THESE STORMS WILL PRODUCE OCCASIONAL WEST WINDS OF 35 TO 50 MPH WITH LOCALLY HIGHER GUSTS. TEAM RIVERTON
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
558 PM MDT WED JUL 6 2016
WYZ020-022-070045-
NATRONA COUNTY LOWER ELEVATIONS-CASPER MOUNTAIN-
558 PM MDT WED JUL 6 2016
...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL NATRONA COUNTY UNTIL
645 PM MDT...
AT 556 PM MDT...DOPPLER RADAR WAS TRACKING A COUPLE OF THUNDERSTORMS
11 MILES WEST OF EMIGRANT GAP...WHICH IS 22 MILES WEST OF CASPER...
MOVING NORTHEAST AT 40 MPH.
WINDS IN EXCESS OF 45 MPH WILL BE POSSIBLE WITH THESE STORMS.
THIS STRONG THUNDERSTORM WILL BE NEAR...
EMIGRANT GAP AROUND 615 PM MDT.
RED BUTTE AND NATRONA COUNTY AIRPORT AROUND 620 PM MDT.
MILLS AND PARADISE VALLEY AROUND 625 PM MDT.
BAR NUNN AND HOMA HILLS AROUND 630 PM MDT.
CASPER AND EVANSVILLE AROUND 635 PM MDT.
EDNESS K WILKINS STATE PARK AROUND 640 PM MDT.
THIS INCLUDES INTERSTATE 25 BETWEEN MILE MARKERS 176 AND 203.
LAT...LON 4276 10608 4267 10673 4274 10680 4274 10684
4286 10690 4314 10615 4298 10607
TIME...MOT...LOC 2356Z 246DEG 36KT 4278 10676
MEUNIERThe Riverton/Lander radar (KRIW), 164 km away, was scanning. The volume nearest the first event began at 00:16 UTC.
1 thunderstorm wind. Local standard time, as filed.
A peak wind gust of 59 mph was measured by ASOS at the Casper/Natrona County International Airport.
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, July 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: 653947.