Strong west to southwest flow aloft generated strong winds in and near the Absaroka Range and in central Wyoming. The strongest winds were in the northern Absaroka Range and the adjacent foothill community of Clark where wind gusts over 90 mph were recorded.
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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.
Strong west to southwest flow aloft generated strong winds in and near the Absaroka Range and in central Wyoming. The strongest winds were in the northern Absaroka Range and the adjacent foothill community of Clark where wind gusts over 90 mph were recorded. Across central Wyoming, wind gusts of around 60 mph were common from the Granite Mountains to Casper.
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, 2:41 AM MST, 3 hours 59 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 341 AM MDT SUN SEP 29 2013 .SHORT TERM...TODAY THROUGH TUESDAY NIGHT WEST SOUTHWEST WINDS HAVE BEEN RESPONDING ALONG THE SOUTHERN WIND CORRIDOR AT PLACES LIKE FALES ROCK AND AT THE HIGH ELEVATIONS. THE FAST WESTERLY FLOW WILL BE THE DOMINANT FEATURE IN THE AREA WEATHER THROUGH TUESDAY NIGHT. THE LOW SPINNING OVER 52N/134W OFF THE BRITISH COLUMBIA COAST WILL FLING A PARADE OF SHORTWAVE TROUGHS ACROSS OUR CWA THROUGH EARLY THIS WEEK. THE FIRST SUCH FEATURE WILL CLOSE OFF OVER SASK WHICH WILL DRAG A TRAILING SHORTWAVE TOWARD WYOMING THIS AFTERNOON. AS THIS FEATURE NEARS...A MOUNTAIN TOP INVERSION WILL DEVELOP THIS EVENING BUT WILL BE LONGER LIVED IN CENTRAL WYOMING THAN IN NORTHERN WYOMING WHERE IT WILL NOT SET UP UNTIL AFTER MIDNIGHT. HOWEVER...A 14C DEGREE 700MB TEMPERATURE GRADIENT WILL SET UP FROM YNP TO THE ABSAROKAS WHICH WILL ENCOURAGE GAP FLOW IN THE CODY FOOTHILLS. WE WILL BE UNDERNEATH THE RIGHT FRONT QUAD OF THE ASSOCIATED JET MAX LATE TONIGHT/MONDAY MORNING ENCOURAGING DOWNWARD FORCING OF THE 70 TO 80 MPH 700MB OUTBOUND WINDS ALONG THE EAST SLOPE OF THE DIVIDE. HOWEVER...THERE IS LACK OF A CRITICAL LAYER TO SUPPORT A TRUE MOUNTAIN WAVE EVENT. WHAT THIS ALL SPELLS OUT IS HIGH ELEVATION WINDS AND LOWER ELEVATION GAP FLOW FOR THE EAST SLOPE OF THE WIND RIVER MOUNTAINS AS WELL AS THE ADJACENT LANDER FOOTHILLS...ESPECIALLY ON THE HIGHER HILLS...AS WELL AS DUBOIS. ALSO THE ABSAROKA MTNS AND CODY FOOTHILLS INCLUDING CLARK BECAUSE OF GAP FLOW THROUGH THE CLARKS FORK GAP. WILL HOIST A HIGH WIND WATCH FOR ZONES 002 AND 003 AS WELL AS ZONES 015...016 AND 018 VALID FOR TONIGHT AND MONDAY MORNING FROM 00Z THROUGH 18Z MONDAY. WILL ALSO ISSUE A HIGH WIND WATCH FOR THE GREEN MTNS FOR TONIGHT AND MONDAY AND FOR NATRONA COUNTY INCLUDING CASPER FOR MONDAY AS THE RIGHT FRONT QUAD OF THE JET MAX SHOVES THE STRONG 700MB WINDS TO THE SURFACE IN THOSE AREAS DURING THAT TIME FRAME. MET MOS GUIDANCE ADVERTISES 32 KNOT SUSTAINED WINDS FOR CASPER ON MONDAY. IN THE MEANTIME THIS WEATHER FEATURE WILL PRODUCE RAIN AND SNOW OVER NORTHWEST WYOMING DEVELOPING TODAY AND CONTINUING TONIGHT WITH WESTERLY UPSLOPE FLOW COMBINED WITH VORT ENERGY...MAINLY UP NORTH. NEGATIVE LIFTED INDICES ARE ALSO PROGGED FOR NW WY TONIGHT. THEN THE PARENT LOW SPLITS WITH THE SECOND LOW TRAILING ANOTHER SHORTWAVE TROUGH ACROSS OUR REGION MONDAY FOR A CONTINUATION OF WEST SOUTHWEST WINDS AND RAIN/SNOW IN THE NORTHWEST WITH THE PRECIP SPREADING SOUTH INTO FAR WEST CENTRAL WYOMING. EXPECT CLEARING TO TAKE PLACE MONDAY NIGHT IN THE WEST. TUESDAY WILL FEATURE BENIGN WEATHER WITH SLIGHTLY COOLER TEMPERATURES BEHIND MONDAYS SYSTEM AFTER A WARM UP OCCURS TODAY THROUGH MONDAY. .LONG TERM...WEDNESDAY THROUGH SUNDAY ANALYSIS OF THE HEMISPHERIC PATTERN STILL SUPPORTS OUR MIDWEEK STORM EVEN THOUGH EACH MODEL AND EACH MODEL RUN CONTINUES TO CHANGE SIGNIFICANTLY. NOT SURPRISINGLY THE 00Z ECMWF IS DIGGING THE TROUGH TO OUR WEST AND CLOSING IT OFF AS IT PASSES JUST TO OUR SW THURSDAY NIGHT. THE MAJORITY OF THE GFS ENSEMBLES WERE ALSO FURTHER SOUTH THAN THE OPERATION MODEL AND THE GEM CONTINUED WITH ITS SRN CLOSED LOW SOLUTION. BASED ON ALL OF THIS...WE ARE KEEPING THE FORECAST AS IS FOR NOW. FIRST SHORTWAVE AND FRONT MOVE THROUGH ON WEDNESDAY STILL NOT THAT DISSIMILAR TO LAST WEDNESDAY WITH A CHANCE OF SHOWERS AS IT MOVES ACROSS. THE BIGGER CHANGES ARE STILL EXPECTED FIRST IN THE WEST AND FAR NORTH THURSDAY...DROPPING QUICKLY SOUTH LATE IN THE DAY INTO THE EVENING HOURS WITH THE POTENTIAL FOR RAIN CHANGING TO SNOW IN THE CENTRAL ZONES ONCE AGAIN. CONFIDENCE NOT AS HIGH YET AS THIS PAST SYSTEM WITH CONTINUED MODEL INCONSISTENCY EVEN THOUGH THE 'BIG PICTURE' SUPPORTS ANOTHER DIGGING TROUGH. HOPEFULLY WE CAN ZERO IN ON A FEW MORE DETAILS AGAIN SUNDAY NIGHT. UNTIL THEN...LITTLE CHANGES OTHER THAN TRYING TO GET A LITTLE BETTER RAIN CHANGING TO SNOW WORDING ACROSS THE CENTRAL ZONES THURSDAY NIGHT. SYSTEM MOVES AWAY FRIDAY WITH EXPECTED SHORTWAVE RIDGING ON SATURDAY FOR A MUCH MILDER DAY. MODELS DIVERGE QUITE A BIT ON SUNDAY WITH THE ECMWF HAVING A RIDGE HOLDING TO THE WEST WHILE THE GFS PUSHES A DECENT SHORTWAVE ACROSS THE NRN ROCKIES. GOING WITH A MODEL BLEND FOR NOW WITH JUST SOME WIND AND A FEW NRN MTN SHOWERS. WE'LL SEE HOW EVERYTHING LOOKS AGAIN TONIGHT. && .AVIATION.../12Z ISSUANCE/ AREAS OF LLWS WILL BE ENCOUNTERED ACROSS MUCH OF THE REGION THIS MORNING THROUGH TONIGHT. THE LLWS WILL BE STRONGEST AND MOST WIDESPREAD ALONG THE EAST SLOPES OF THE DIVIDE VCNTY KLND-KCOD. SOME MIXING DOWN OF THE WIND TO THE SFC WILL OCCUR LATER THIS MORNING THROUGH THE AFTERNOON. WEST OF THE DIVIDE....VFR CONDITIONS WILL PREVAIL THROUGH 18Z SUNDAY. AREAS OF MVFR PRECIPITATION AND INCREASING MTN OBSCURATIONS WILL SPREAD SOUTH TO VCNTY KJAC BY 21Z SUNDAY AND INTO KPNA 00Z-03Z MONDAY. SNOW LEVELS WILL REMAIN AROUND 8-8.5KFT THROUGH SUNDAY NIGHT. EAST OF THE DIVIDE...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. && .FIRE WEATHER... WEST SOUTHWEST WINDS WILL CONTINUE ALONG THE SOUTHERN WIND CORRIDOR FOR THE NEXT COUPLE OF DAYS. WINDS COULD BECOME ESPECIALLY STRONG TONIGHT AND MONDAY MORNING ALONG ABSAROKA MOUNTAINS AND THE EAST SLOPE OF THE WIND RIVER MOUNTAINS AS WELL AS THE ADJACENT FOOTHILLS. STRONG WINDS ARE ALSO POSSIBLE IN ZONE 289 TONIGHT AND MONDAY AS WELL AS IN ZONE 280 FOR MONDAY. TEMPERATURES WILL CONTINUE THEIR WARMING TREND THROUGH MONDAY AND THEN COOLING OFF SLIGHTLY TUESDAY. PERIODS OF RAIN AND SNOW WILL OCCUR ACROSS FAR WESTERN WYOMING TODAY THROUGH MONDAY. && .RIW WATCHES/WARNINGS/ADVISORIES... HIGH WIND WATCH FROM THIS EVENING THROUGH MONDAY MORNING WYZ002-003-015-016-018. HIGH WIND WATCH FROM THIS EVENING THROUGH MONDAY AFTERNOON WYZ019. HIGH WIND WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON WYZ020. && SHORT TERM...LIPSON LONG TERM...SKRBAC AVIATION...AEM FIRE WEATHER...LIPSON
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 453 AM MDT SUN SEP 29 2013 WYZ001>020-022>030-301200- ABSAROKA MOUNTAINS-BIGHORN MOUNTAINS SOUTHEAST- BIGHORN MOUNTAINS WEST-CASPER MOUNTAIN-CODY FOOTHILLS- EAST SWEETWATER COUNTY-FLAMING GORGE- GREEN MOUNTAINS AND RATTLESNAKE RANGE-JACKSON HOLE-LANDER FOOTHILLS- NATRONA COUNTY LOWER ELEVATIONS-NORTH BIG HORN BASIN- NORTHEAST JOHNSON COUNTY-OWL CREEK AND BRIDGER MOUNTAINS- ROCK SPRINGS AND GREEN RIVER-SALT RIVER AND WYOMING RANGES- SOUTH LINCOLN COUNTY-SOUTHEAST BIG HORN BASIN- SOUTHEAST JOHNSON COUNTY-SOUTHWEST BIG HORN BASIN-STAR VALLEY- TETON AND GROS VENTRE MOUNTAINS-UPPER GREEN RIVER BASIN- UPPER GREEN RIVER BASIN FOOTHILLS-UPPER WIND RIVER BASIN- WIND RIVER BASIN-WIND RIVER MOUNTAINS EAST-WIND RIVER MOUNTAINS WEST- YELLOWSTONE NATIONAL PARK- 453 AM MDT SUN SEP 29 2013 ...HIGH WIND WATCH FOR TONIGHT AND MONDAY FOR THE EAST SLOPE OF THE CONTINENTAL DIVIDE AND ADJACENT FOOTHILLS AS WELL AS FOR THE GREEN MOUNTAINS AND NATRONA COUNTY INCLUDING CASPER... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT VERY STRONG WINDS ARE POSSIBLE ALONG THE EAST SLOPE OF THE CONTINENTAL DIVIDE TONIGHT AS WELL AS IN THE ADJACENT FOOTHILLS AND IN THE GREEN AND RATTLESNAKE MOUNTAINS. PLEASE SEE THE LATEST CYSNPWRIW STATEMENTS REGARDING THIS POTENTIAL HIGH WIND EVENT. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY VERY STRONG WINDS ARE POSSIBLE FOR THE EAST SLOPE OF THE CONTINENTAL DIVIDE AND ADJACENT FOOTHILLS AS WELL AS FOR THE GREEN MOUNTAINS AND NATRONA COUNTY INCLUDING CASPER. PLEASE SEE THE LATEST CYSNPWRIW STATEMENTS REGARDING THIS POTENTIAL HIGH WIND EVENT. A NEW STORM SYSTEM MAY BRING ANOTHER ROUND OF SNOW TO AREAS WEST OF THE DIVIDE WEDNESDAY NIGHT INTO THURSDAY BEFORE SHIFTING EAST OF THE DIVIDE LATE THURSDAY INTO THURSDAY NIGHT. STAY TUNED OVER THE NEXT FEW DAYS ON THIS POTENTIAL STORM LATE NEXT WEEK. ANOTHER COLD STORM SYSTEM LOOKS POISED TO DEVELOP OVER THE AREA ONCE AGAIN WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. THE MAIN BRUNT OF THE SYSTEM LOOKS TO AFFECT AREAS ALONG AND EAST OF THE DIVIDE THURSDAY INTO THURSDAY NIGHT WITH COLD RAIN CHANGING TO SNOW. THE STORM HAS SIMILAR CHARACTERISTICS TO OUR LAST STORM BUT SOME DETAILS ARE STILL TO BE DETERMINED. STAY TUNED FOR FURTHER STATEMENTS FROM YOUR NATIONAL WEATHER SERVICE OFFICE IN RIVERTON. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT ANY WIND GUSTS GREATER THAN 50 MPH. THANK YOU. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
4 high wind. Local standard time, as filed.
Several wind gusts of over 75 mph were recorded near Clark. The strongest recorded gust was 97 mph.
The weather sensor on Chief Joseph Pass recorded several wind gusts over 75 mph, including a maximum gust of 94 mph.
Many wind gusts over 58 mph were recorded. Some of the highest were 71 mph at Fales Rock and 63 mph at Camp Creek.
A peak gust to 60 mph was recorded at Twenty Mile Hill. The Casper Airport ASOS clocked a gust of 59 mph shortly after 1200MST.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2013Every state in 2013This day in weather historyWarnings in Wyoming, September 2013
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: 472867, 472863, 472875, 472876.