A tight pressure gradient at the surface created very strong winds in the wind corridor of Carbon County.
Every event with a place to put it; 2 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 CYS wrote it up.
A tight pressure gradient at the surface created very strong winds in the wind corridor of Carbon County.
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 Cheyenne, WY wrote its last area forecast discussion before the first event at Oct 30, 5:14 PM MST, 1 hour 46 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHEYENNE WY 614 PM MDT FRI OCT 30 2009 .DISCUSSION...WINDS SHOULD SLOWLY DIMINISH OVER THE CWA THROUGH EARLY TONIGHT. SINCE 23Z...BLOWING SNOW HAS DECREASED OVER AND NEAR THE MOUNTAINS. HAVE WENT AHEAD AND CANCELED THE WINTER WEATHER ADVISORY FOR BLOWING SNOW AS OF 00Z. THERE WILL STILL BE A PERIOD FOR THE NEXT FEW HOURS OF STRONG WINDS AT KARL AND KVDW. AT 00Z KARL HAD A GUST TO 60 MPH...BUT NOT MUCH BLOWING SNOW. && .PREVIOUS DISCUSSION.../ISSUED AT 309 PM MDT FRI OCT 30 2009/... SHORT TERM...TONIGHT THROUGH SUNDAY...WINDS WILL CONTINUE ACROSS THE AREA THROUGH THIS EVENING. MAX IN WIND SPEEDS OCCURRED EARLIER THIS AFTERNOON AND WILL CONTINUE TO EASE THROUGH THE LATER AFTERNOON AS THE LOW LEVEL PRESSURE GRADIENT RELAXES. EVEN THOUGH THE GRADIENT DIMINISHES SOMEWHAT...IT WILL REMAIN IN PLACE THROUGH THE NIGHT. THUS BREEZY WESTERLY WINDS WILL CONTINUE WITH GUSTS 20 TO 30 MPH MAINLY AT ARLINGTON...AND LOCATIONS NEAR THE LARAMIE RANGE. CURRENT SATELLITE IMAGERY SHOWS A FEW BREAKS IN THE CLOUDS ACROSS THE CWA WHICH HAS ALLOWED TEMPERATURES TO JUMP INTO THE MID TO UPPER 30S. WEBCAMS SHOW MANY LOCATIONS TO HAVE MINIMAL BLOWING SNOW...EVEN THOUGH WINDS ARE STILL ON THE STRONG SIDE SO EXPECT THAT THE TOP LAYER OF SNOW HAS BEGUN TO MELT AND/OR ICE OVER. THUS WILL CONSIDER DROPPING THE ADVISORY EARLIER THAN ANTICIPATED FOR MOST ZONES EAST OF THE LARAMIE RANGE. EXPECT OROGRAPHIC SNOW SHOWERS TO CONTINUE THROUGH THE NIGHT UNDER STRONG NW FLOW ALOFT. SHORTWAVE RIDGE WILL MOVE OVERHEAD TOMORROW BRINGING WARMER AND DRIER CONDITIONS TO THE AREA. STILL UNDERCUT GUIDANCE FOR MAX TEMPS DUE TO SNOWPACK BUT WILL LIKELY SPIKE INTO THE UPPER 30S AND 40S AS HEIGHTS INCREASE ALOFT AND H7 TEMPS JUMP ABOVE FREEZING. WINDS WILL BE BREEZY THROUGH THE DAY WITH H7 WINDS AT 30 TO 40 KTS AND THE SFC PRESSURE GRADIENT REMAINING IN PLACE...BUT WILL NOT BE AS STRONG AS TODAY. A SHORTWAVE WILL APPROACH THE CWA FROM THE NORTHWEST ON SUNDAY WITH A WEAK COLD FRONT MOVING THROUGH EASTERN ZONES IN THE LATE AFTERNOON. WILL SEE RAIN SHOWERS INCREASE IN COVERAGE IN THIS AREA THROUGH THE AFTERNOON AS THE FRONT PASSES THROUGH...AND WILL CHANGE OVER TO A RAIN/SNOW MIX LATER IN THE EVENING AS TEMPERATURES DROP OFF. LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...A COLD FRONT WILL BE ON THE DOORSTEP...MOVING INTO NRN WYOMING AT TO BEGIN THE PERIOD. PROGS HAVE BEEN TRENDING STRONGER AND WETTER WITH THIS FRONT...SO HAVE BOOSTED PRECIPITATION CHANCES NORTH OF A MUDDY GAP TO KIMBALL LINE. NOT EXPECTING MUCH PRECIPITATION OUT OF THIS SYSTEM...THOUGH A QUICK DUSTING IS NOT OUT OF THE QUESTION. THIS COLD FRONT WILL MOVE OUT ONTO THE PLAINS BY MONDAY...GIVING WAY TO DRY NORTHWEST FLOW ACROSS THE INTERMOUNTAIN WEST AS THE WEST COAST RIDGE DEVELOPS. THE ECMWF HAS SUGGESTED A STRENGTHENING WEST COAST RIDGE IN ITS OUTPUT OVER THE PAST SEVERAL RUNS...AND GFS PROGS CONTINUE TO TREND IN THAT DIRECTION AS WELL. SO CONFIDENCE IN A DRY AND WARMING TREND IS BUILDING. AFTER A COOLER DAY BEHIND THE FRONT ON MONDAY...TEMPERATURES WILL SLOWLY WARM BACK INTO THE UPPER 50S TO LOW 60S FOR TUESDAY THROUGH THURSDAY BENEATH DRY CONDITIONS. BY LATE THURSDAY/FRIDAY BOTH THE ECMWF AND GFS HAVE A CLIPPER SHORTWAVE DIVING INTO THE NRN ROCKIES/NRN PLAINS. PLACEMENT IS A BIT IN QUESTION...WITH THE GFS FURTHER WEST WITH THE ENERGY...WHICH WOULD HAVE MORE IMPACT ON THE CWA. WHILE THE ECMWF KEEPS THE WAVE OVER THE DAKOTAS...LIMITING IMPACT. FOR NOW...WILL CONTINUE TO SIDE WITH THE ECMWF...WHICH WOULD MAINTAIN BENIGN CONDITIONS. AVIATION...WINDS WILL SLOWLY SUBSIDE BY LATE EVENING...REDUCING THE IFR VISIBILITIES IN BLOWING SNOW OVER AND NEAR THE MOUNTAINS. OTHERWISE...VFR CONDITIONS WILL BE COMMON TONIGHT WITH THE EXCEPTION OF KRWL. LOW CIGS ARE ANTICIPATED TO WORK INTO KRWL THIS EVENING AND CONTINUE THROUGH THE OVERNIGHT HOURS. ALTHOUGH WINDS WILL NOT BE AS STRONG AS TODAY...EXPECT THAT THEY WILL BE ENOUGH TO KEEP THE LOW CLOUDS OFF THE SFC. THESE LOW CIGS WILL BURN OFF BY MID- MORNING ON SATURDAY. WINDS ARE AGAIN EXPECTED TO INCREASE ON SATURDAY...BUT AGAIN SHOULD BE WEAKER THAN THOSE OF FRIDAY. FIRE WEATHER...NO FIRE WEATHER CONCERNS THROUGH SUNDAY. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && SHORT TERM/FIRE WEATHER...RJM LONG TERM/AVIATION...HAHN UPDATE...WEILAND
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHEYENNE WY 622 PM MDT FRI OCT 30 2009 NEZ002-003-019>021-054-055-095-096-WYZ101>119-312200- DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE- NORTH SIOUX-SOUTH SIOUX-CONVERSE COUNTY LOWER ELEVATIONS- NIOBRARA COUNTY-NORTH LARAMIE RANGE-SHIRLEY BASIN- CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY- EAST PLATTE COUNTY-GOSHEN COUNTY-CENTRAL CARBON COUNTY- NORTH SNOWY RANGE FOOTHILLS-SOUTHWEST CARBON COUNTY- SIERRA MADRE RANGE-UPPER NORTH PLATTE RIVER BASIN-SNOWY RANGE- LARAMIE VALLEY-SOUTH LARAMIE RANGE-SOUTH LARAMIE RANGE FOOTHILLS- CENTRAL LARAMIE COUNTY-EAST LARAMIE COUNTY- 622 PM MDT FRI OCT 30 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA PANHANDLE...EAST CENTRAL WYOMING...SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING. .DAY ONE...TONIGHT WEST WINDS OF 25 TO 35 MPH WITH GUSTS TO NEAR 50 MPH WILL CONTINUE OVER SOME LOCATIONS IN AND NEAR THE LARAMIE AND SNOWY RANGES THROUGH EARLY TONIGHT. THIS INCLUDES INTERSTATE 80 AT ARLINGTON AND THE SUMMIT BETWEEN LARAMIE AND CHEYENNE. THE WINDS WILL PRODUCE AREAS OF BLOWING AND DRIFTING SNOW AND REDUCED VISIBILITIES DURING THAT TIME. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY SOUTHWEST WINDS WILL INCREASE TO 20 TO 30 MPH WITH GUSTS TO 40 MPH NEAR THE SNOWY AND LARAMIE RANGES ON SATURDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TONIGHT. && THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT... HTTP://WEATHER.GOV/CHEYENNE WEILAND
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</html>SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CHEYENNE WY 734 PM MDT FRI OCT 30 2009 WYZ103-105-106-110-116-117-310500- NORTH LARAMIE RANGE-SHIRLEY BASIN- CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY- NORTH SNOWY RANGE FOOTHILLS-SOUTH LARAMIE RANGE- SOUTH LARAMIE RANGE FOOTHILLS- INCLUDING THE CITIES OF...MEDICINE BOW...BORDEAUX...ARLINGTON... ELK MOUNTAIN...VEDAUWOO...BUFORD...PUMPKIN VINE...HORSE CREEK... HARRIMAN...WHITAKER 734 PM MDT FRI OCT 30 2009 ...STRONG WINDS WILL CONTINUE THROUGH 11 PM OVER AND NEAR THE SNOWY AND LARAMIE RANGES... WEST WINDS WILL GUST BETWEEN 45 AND 55 MPH THROUGH 11 PM IN MANY LOCATIONS OVER AND NEAR THE SNOWY AND LARAMIE RANGES. THE WINDS WILL CONTINUE TO SLOWLY DIMINISH THROUGH THAT TIME. AT 710 PM...ARLINGTON HAD A GUST TO 58 MPH AND VEDAUWOO REPORTED A WIND GUST OF 44 MPH. THE STRONG WINDS WILL PRODUCE AREAS OF BLOWING AND DRIFTING SNOW THROUGH 11 PM...ESPECIALLY OVER AND NEAR THE SOUTHERN LARAMIE RANGE. TRAVEL WILL BE HAZARDOUS THROUGH 11 PM ON THE INTERSTATE 80 SUMMIT BETWEEN CHEYENNE AND LARAMIE WITH SLICK ROADS AND REDUCED VISIBILITIES. WEILAND
The national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
Wyoming Department of Highways equipment (KARL) recorded sustained and gusts reaching high wind criteria for several hours with a peak gust of 71 mph at 1251 AM on 10/31/2009.
Wyoming Department of Highways equipment (KBDX) measured sustained and gusts reaching high wind criteria between 6 and 8 AM with a peak gust of 65 mph at 650 AM.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2009Every state in 2009This day in weather historyWarnings in Wyoming, October 2009
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 2026-09-30. Each event’s entry at NCEI: 196837, 196838.