An upper level disturbance brought thunderstorms to parts of northeast Wyoming during the late afternoon and evening hours. Gusty winds and hail accompanied a few of the storms.
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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 UNR wrote it up.
An upper level disturbance brought thunderstorms to parts of northeast Wyoming during the late afternoon and evening hours. Gusty winds and hail accompanied a few of the storms.
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 Rapid City, SD wrote its last area forecast discussion before the first event at Apr 18, 7:35 PM MST, 25 minutes earlier.
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 835 PM MDT WED APR 18 2007 .DISCUSSION...02Z SURFACE ANALYSIS HAD LOW OVER CENTRAL WY. WATER VAPOUR SHOWED INITIAL SHORTWAVE MOVING NORTH THROUGH EASTERN WY/MT. THIS WAVE BROUGHT US OUR INITIAL TS ACTIVITY...ALONG NARROW BAND OF 500J/KG CAPE WITH MARGINAL SHEAR. UPPER LOW NEAR SALT LAKE CITY WILL SPIN THE MAIN WAVE INTO THE NORTHERN PLAINS OVERNIGHT. MODEL VERTICAL MOTIONS AS WELL AS QG FORCING RAPIDLY INCREASES OVERNIGHT...SO EXPECT BLOSSOMING RADAR RETURNS AFTER MIDNIGHT AND ESPECIALLY TOWARD MORNING. WILL DROP POPS OVER MOST OF SD FOR THIS EVENING. GRADIENT WILL SUPPORT WINDY CONDITIONS OVERNIGHT...BUT WIDESPREAD HEADLINE WIND SPEEDS ARE OVER. HAVE DROPPED WIND ADVISORY AND HIGH WIND WARNING. LOOKING AHEAD TO THURSDAY...IF WE CAN MANAGE TO NOT GET DRY SLOTTED...SHOULD BE A DECENT BLOB OF RAIN OVER THE CWA IN THE MORNING...WITH MORE SPOTTY/CONVECTIVE TYPE PRECIPITATION IN THE AFTERNOON. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && HELGESON
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RAPID CITY SD 630 AM MDT WED APR 18 2007 SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058- 071-191300- BENNETT-BUTTE-CENTRAL BLACK HILLS-CUSTER CO PLAINS-FALL RIVER-HAAKON- HARDING-HERMOSA FOOT HILLS-JACKSON-MELLETTE-NORTHEASTERN CROOK- NORTHERN BLACK HILLS-NORTHERN CAMPBELL-NORTHERN FOOT HILLS- NORTHERN MEADE CO PLAINS-PENNINGTON CO PLAINS-PERKINS-RAPID CITY- SHANNON-SOUTHERN BLACK HILLS-SOUTHERN CAMPBELL-SOUTHERN FOOT HILLS- SOUTHERN MEADE CO PLAINS-STURGIS/PIEDMONT FOOT HILLS-TODD-TRIPP- WESTERN CROOK-WESTON-WYOMING BLACK HILLS-ZIEBACH- 630 AM MDT (730 AM CDT) WED APR 18 2007 ...WIND ADVISORY IN EFFECT FROM 900 AM MDT UNTIL 900 PM MDT FOR MUCH OF WESTERN SOUTH DAKOTA... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN SOUTH DAKOTA AND NORTHEASTERN WYOMING. .DAY ONE...TODAY AND TONIGHT VERY WINDY CONDITIONS WILL DEVELOP THIS MORNING OVER NORTHEAST WYOMING AND MUCH OF WESTERN SOUTH DAKOTA. SOUTH TO SOUTHEAST WINDS WILL INCREASE TO 25 TO 40 MPH WITH GUSTS TO 50 MPH. THE WINDS WILL SLOWLY TAPER OFF THIS EVENING. AN UPPER LEVEL DISTURBANCE APPROACHING THE AREA WILL RESULT IN THUNDERSTORMS DEVELOPING OVER NORTHEAST WYOMING THIS AFTERNOON BEFORE SPREADING INTO WESTERN AND SOUTH CENTRAL SOUTH DAKOTA THROUGH THE EVENING HOURS. THOUGH WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED AT THIS TIME...A FEW OF THE STORMS OVER NORTHEAST WYOMING AND FAR WESTERN SOUTH DAKOTA MAY HAVE THE POTENTIAL TO BECOME SEVERE LATE THIS AFTERNOON INTO EARLY THIS EVENING. IF ANY DO BECOME SEVERE...LARGE HAIL AND DAMAGING WIND GUSTS WILL BE THE MAIN THREATS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THE CHANCE FOR THUNDERSTORMS WILL CONTINUE INTO THURSDAY...MAINLY OVER WESTERN INTO SOUTH CENTRAL SOUTH DAKOTA. THE STORMS ON THURSDAY ARE NOT EXPECTED TO BECOME SEVERE. THE NEXT CHANCE FOR THUNDERSTORMS WILL COME FRIDAY EVENING INTO SATURDAY AS ANOTHER UPPER LEVEL DISTURBANCE APPROACHES THE AREA. SOME OF THESE STORMS WILL HAVE THE POTENTIAL TO BECOME SEVERE ON SATURDAY...PARTICULARLY OVER SOUTH CENTRAL SOUTH DAKOTA EAST OF A LINE FROM PHILIP TO MARTIN. THE PRIMARY THREATS FROM THESE STORMS WILL BE LARGE HAIL AND DAMAGING WIND GUSTS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.
The Rapid City radar (KUDX), 170 km away, was scanning. The volume nearest the first event began at 03:01 UTC.
1 thunderstorm wind, 1 hail. Local standard time, as filed.
Strong winds blew the roof off a garage. Winds were estimated around 60 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2007Every state in 2007This day in weather historyWarnings in Wyoming, April 2007
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: 16144, 16141.