Some weak showers produced a few dry microbursts over parts of the Nebraska panhandle.
Every event with a place to put it; 1 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.
Some weak showers produced a few dry microbursts over parts of the Nebraska panhandle.
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 May 12, 1:26 PM MST, 3 hours 17 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
226 PM MDT TUE MAY 12 2009
.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT...
SOME SHOWERS AND THUNDERSTORMS HAVE FORMED SINCE 1830Z MAINLY TO THE
EAST OF THE LARAMIE RANGE. THE STRONGEST STORM AS OF 1930Z WAS NEAR
KBFF BUT HAS WEAKENED SOME SINCE 19Z. POTENTIAL STILL EXISTS FOR
STRONGER AND EVEN SEVERE STORMS ESPECIALLY ALONG AND EAST OF A LINE
FROM KHRS TO KSNY. THAT AREA HAS BEEN RECOVERING FROM THE PASSAGE
OF THE SHORTWAVE TROUGH THIS MORNING WITH BOUNDARY LAYER WINDS
RETURNING TO MORE SOUTHERLY AND SURFACE DEW POINTS IN THE MID 40S.
THE NAM AND SREF CONTINUE TO INDICATE A MORE UNSTABLE AND MOIST
ENVIRONMENT THAN THE GFS THROUGH THE EARLY EVENING. THE STRONGER
ACTIVITY WILL FOCUS ALONG THE SURFACE LOW PRESSURE TROUGH CURRENTLY
EXTENDING BACK INTO THE EAST PART OF THE CWA FROM NORTH CENTRAL
NEBRASKA. THE ACTIVITY WILL ALSO MOVE QUICKLY OFF TO THE EAST AND
SHOULD BE EAST OF THE CWA BY 03Z. STRONG WIND GUSTS AND HAIL ARE
STILL THE MAIN WEATHER THREAT FROM THE STRONGER STORMS. AN
ENERGETIC SHORTWAVE TROUGH WILL MOVE ACROSS THE CWA TONIGHT AND
WEDNESDAY MORNING WITH THE ASSOCIATED SURFACE COLD FRONT MOVING
THROUGH THE ENTIRE CWA BY 06Z. SOME SHOWERS WERE OVER NORTHERN
WYOMING EARLY THIS AFTERNOON AND THOSE MAY CLIP THE FAR NORTH PART
OF THE CWA INTO WEDNESDAY MORNING. OTHERWISE...WEDNESDAY WILL BE
COOLER AND WINDY...BUT GENERALLY DRY OVER THE CWA. THE 700 MB WINDS
ARE BETWEEN 40 AND 50 KNOTS UP THROUGH MID AFTERNOON WEDNESDAY AND
SO WILL GO AHEAD AND ISSUE A WIND ADVISORY FOR THE WESTERN NEBRASKA
PANHANDLE FOR WEDNESDAY. WINDS MAY DIMINISH SOME AFTER 21Z OVER
THE CWA AS THE SURFACE PRESSURE GRADIENT RELAXES. THE SURFACE HIGH
WILL MOVE OVER THE HIGH PLAINS BY 12Z THURSDAY AND WILL PRODUCE A
MOSTLY CLEAR AND COOL NIGHT WEDNESDAY NIGHT.
.LONG TERM...THURSDAY THROUGH MONDAY.
TEMPERATURES SHOULD REBOUND RATHER QUICKLY AFTER WEDNESDAY WITH
HIGHS IN THE LOWER 70S. WESTERLY UPPER LEVEL FLOW WILL REMAIN
ACROSS THE AREA ON THURSDAY. THE ECMWF SHOWS A WEAK UPPER LEVEL
SHORTWAVE MOVING ACROSS MONTANA ON LATE THURSDAY INTO FRIDAY.
TEMPERATURES ON FRIDAY MAY BE SLIGHTLY COOLER COMPARED TO THURSDAY
SINCE THE UPPER LEVEL FEATURE WILL NOT MOVE THROUGH SOUTHEASTERLY
WYOMING UNTIL THE AFTERNOON. THUS EXPECT HIGHS IN THE UPPER 60S
TO AROUND 70. THERE WILL ALSO BE A SLIGHT CHANCE OF THUNDERSTORMS
ON FRIDAY AFTERNOON AND INTO THE EARLY EVENING. SATURDAY WILL BE
COOLER AFTER THE PASSAGE OF THE WEAK DISTURBANCE WITH HIGHS IN THE
MID TO UPPER 60S. THE REMAINDER OF THE WEEKEND AND INTO EARLY NEXT
WEEK WILL BE WARM AND MOSTLY DRY AS HIGH PRESSURE BUILDS OVER THE
WESTERN UNITED STATES. BY MONDAY...THE TEMPERATURES WILL WARM TO
THE LOWER TO MID 70S. WITH THE WARMER TEMPERATURES THROUGH EARLY
NEXT WEEK...THERE MAY BE SOME HYDROLOGY CONCERNS PARTICULARLY
WITH THE ADDITIONAL SNOWMELT. THERE ARE SOME UNCERTAINTY IN THE
FORECAST AFTER MONDAY AS THE ECMWF SHOWS A WEAK BACKDOOR COLD
FRONT MOVING ACROSS EASTERN PORTIONS OF WYOMING.
&&
.AVIATION...
SOME SHOWERS AND THUNDERSTORMS WILL MOVE EAST OVER THE EAST PART OF
THE CWA THROUGH 03Z. BRIEF MVFR CEILINGS AND VISIBILITIES WILL BE
ASSOCIATED WITH THE ACTIVITY. OTHERWISE...VFR CONDITIONS CAN BE
EXPECTED THROUGH 12Z THURSDAY. STRONG WESTERLY WINDS WILL BE THE
MAIN WEATHER CONCERN THROUGH EARLY THIS EVENING AND THEN AGAIN LATE
TONIGHT AND WEDNESDAY. AT THE SURFACE WEST WINDS WILL GUST AS
HIGH AS 45 KNOTS. WITH THE JET STREAM OVER THE CWA LATE TONIGHT AND
WEDNESDAY...MOUNTAIN WAVE ACTIVITY WILL BE POSSIBLE MAINLY ON THE
LEE OF THE SNOWY RANGE.
&&
.FIRE WEATHER...
THE WARM...DRY AND WINDY CONDITIONS WILL CONTINUE OVER MUCH OF THE
SOUTHEAST WYOMING PART OF THE CWA THROUGH THE EARLY EVENING. IN
FACT...SOME RELATIVE HUMIDITIES WILL STILL BE IN THE TEENS IN PARTS
OF SOUTHEAST WYOMING THROUGH 01Z. THE FUELS OVER THE CWA ARE STILL
ON THE GREEN SIDE DUE TO THE TIME OF YEAR AND RECENT PRECIPITATION.
A COLD FRONT WILL MOVE ACROSS THE CWA THROUGH 06Z WITH COOLER
TEMPERATURES AND RESULTING HIGHER RELATIVE HUMIDITIES EXPECTED FOR
TONIGHT AND WEDNESDAY. WEST WINDS WILL STILL GUST AS HIGH AS 50
MPH OVER THE CWA FOR MUCH OF WEDNESDAY...BUT FIRE WEATHER CONCERNS
WILL BE LESS THAN THOSE OF TODAY DUE TO THE COOLER TEMPERATURES.
&&
.HYDROLOGY...
WATER LEVELS ON THE LITTLE SNAKE RIVER BETWEEN SAVERY AND BAGGS WILL
REMAIN HIGH FOR THE NEXT SEVERAL DAYS. THE COOLER TEMPERATURES
EXPECTED SHOULD LOWER SNOWMELT RATES AND RUNOFF. FORECASTS FOR THE
RIVER GAGE AT DIXON KEEPS THE STAGE A FOOT OR 2 BELOW ACTION STAGE
THROUGH THE WEEKEND. WITH THE WARMER WEATHER RETURNING FOR EARLY
NEXT WEEK...RIVER LEVELS SHOULD RISE ONCE AGAIN.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...WIND ADVISORY FROM 8 AM WEDNESDAY TO 6 PM WEDNESDAY FOR NEZ001-
NEZ002-NEZ003-NEZ019-NEZ020-NEZ021-NEZ054-NEZ055.
&&
SHORT TERM/AVIATION...WEILAND
LONG TERM....MGHAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHEYENNE WY 500 PM MDT TUE MAY 12 2009 NEZ001>003-019>021-054-055-WYZ059>070-131230- SIOUX-DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL- CHEYENNE-CONVERSE-NIOBRARA-SOUTHWEST CARBON-NORTH CARBON- SNOWY RANGE-NORTH LARAMIE RANGE-LARAMIE VALLEY-LARAMIE RANGE- PLATTE-GOSHEN-CHEYENNE FOOTHILLS-PINE BLUFFS- 500 PM MDT TUE MAY 12 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA PANHANDLE AND SOUTHEAST WYOMING. .DAY ONE...THIS AFTERNOON AND TONIGHT A FEW THUNDERSTORMS ARE POSSIBLE INTO EARLY THIS EVENING MAINLY OVER THE NEBRASKA PANHANDLE. BRIEF STRONG AND GUSTY WINDS ARE POSSIBLE FROM THESE STORMS. GUSTY WESTERLY WINDS TO 45 MPH WILL ALSO OCCUR ACROSS SOUTHEAST WYOMING INTO EARLY THIS EVENING. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THERE WILL BE A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS MAINLY ON FRIDAY. NORTHWEST WINDS WILL GUST AS HIGH AS 50 MPH OVER MUCH OF THE AREA ON WEDNESDAY. A WIND ADVISORY IS IN EFFECT FOR THE WESTERN NEBRASKA PANHANDLE FOR WEDNESDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED THIS AFTERNOON AND TONIGHT. && THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT... HTTP://WEATHER.GOV/CHEYENNE RE
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CHEYENNE WY 1231 PM MDT TUE MAY 12 2009 WYZ061>066-130100- SOUTHWEST CARBON-NORTH CARBON-SNOWY RANGE-NORTH LARAMIE RANGE- LARAMIE VALLEY-LARAMIE RANGE- INCLUDING THE CITIES OF...RAWLINS...HANNA...MEDICINE BOW... CENTENNIAL...GARRETT...LARAMIE...BUFORD...HORSE CREEK 1231 PM MDT TUE MAY 12 2009 ...STRONG WINDS WILL CONTINUE OVER AND ALONG THE LARAMIE RANGE THROUGH THE EARLY EVENING... WEST WINDS WILL GUST BETWEEN 45 AND 55 MPH AT TIMES IN MANY LOCATIONS ALONG AND WEST OF THE LARAMIE RANGE THROUGH THE EARLY EVENING. AT 1210 PM...ARLINGTON REPORTED A WIND GUST OF 56 MPH. THE STRONG WINDS WILL CREATE HAZARDOUS TRAVEL CONDITIONS MAINLY FOR THOSE WITH LIGHTWEIGHT OR HIGH PROFILE VEHICLES IN THAT PART OF WYOMING THROUGH THE EARLY EVENING. WEILAND
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CHEYENNE WY 312 PM MDT TUE MAY 12 2009 NEZ003-122215- BOX BUTTE- INCLUDING THE CITY OF...ALLIANCE 312 PM MDT TUE MAY 12 2009 ...STRONG THUNDERSTORM OVER SOUTHERN BOX BUTTE COUNTY... A STRONG THUNDERSTORM IS MOVING EAST AT 30 MPH ACROSS SOUTHERN BOX BUTTE COUNTY. THE STORM SHOULD BE IN THE VICINITY OF ALLIANCE BY 320 PM. GUSTY WINDS AND MAYBE SOME SMALL HAIL MAY OCCUR IN ASSOCIATION WITH THIS STORM.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CHEYENNE WY 342 PM MDT TUE MAY 12 2009 NEZ003-122215- BOX BUTTE- INCLUDING THE CITY OF...ALLIANCE 342 PM MDT TUE MAY 12 2009 ...STRONG THUNDERSTORM OVER SOUTHERN BOX BUTTE COUNTY... A STRONG THUNDERSTORM IS MOVING EAST AT 35 MPH ACROSS SOUTHERN BOX BUTTE COUNTY. THE STORM WILL BE IN THE VICINITY OF ALLIANCE BY 345 PM BUT SHOULD PASS MAINLY SOUTH OF TOWN. GUSTY WINDS AND MAYBE SOME SMALL HAIL MAY OCCUR IN ASSOCIATION WITH THIS STORM. RE
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
408 PM MDT TUE MAY 12 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0350 PM HAIL ALLIANCE 42.10N 102.87W
05/12/2009 E0.25 INCH BOX BUTTE NE LAW ENFORCEMENT
0400 PM HAIL 6 E ALLIANCE 42.10N 102.76W
05/12/2009 E0.25 INCH BOX BUTTE NE TRAINED SPOTTER
&&
BCHAPMANSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CHEYENNE WY 522 PM MDT TUE MAY 12 2009 NEZ002-130030- DAWES- INCLUDING THE CITY OF...CHADRON 522 PM MDT TUE MAY 12 2009 ...STRONG WIND GUSTS MOVING THROUGH THE AREA... AN AREA OF WEAK SHOWERS IS PRODUCING BRIEF BUT STRONG WIND GUSTS ACROSS PORTIONS OF DAWES COUNTY. SOME GUSTS IN EXCESS OF 50 MPH HAVE BEEN NOTED. LITTLE IF ANY RAIN IS EXPECTED FROM THESE SHOWERS AND THEY SHOULD BE CLEAR OF DAWES COUNTY BY 615 PM. RE
The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
Dry microburst at the Scotts Bluff county airport. A few power lines were knocked down.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nebraska in 2009Every state in 2009This day in weather historyWarnings in Nebraska, May 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 2026-09-24. Each event’s entry at NCEI: 162116.