A lightning strike caused a fire which burned a haystack at a ranch near Cora.
Every event with a place to put it. 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 RIW wrote it up.
A lightning strike caused a fire which burned a haystack at a ranch near Cora.
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 May 18, 1:40 PM MST, 3 hours 20 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 240 PM MDT TUE MAY 18 2010 .SHORT TERM...TONIGHT THROUGH FRIDAY ISOLATED THUNDERSTORMS WITH SMALL HAIL ARE OCCURRING OUT WEST AS WEAK SHORTWAVE LIFTS NWD. GUSTY WINDS HAVE BEEN NOTED WITH THE ISOLD STORMS IN THE RED DESERT. BEST CAPE IS ACROSS ERN JOHNSON AND FAR ERN NATRONA BUT SO FAR THE CAP HAS HELD DUE TO THICK HIGH CLOUDS IN MOST AREAS. WATCHING ONE AREA OF TSTMS OVER WRN CONVERSE THAT ARE MOVING NNW AND SHOULD EDGE INTO NERN NATRONA AND SERN JOHNSON SHORTLY. POTENTIAL FOR A FEW STRONG TO SVR STORMS STILL EXISTS THERE FOR A FEW MORE HOURS. FORECAST FOCUS THEN SHIFTS TO THE UPPER LOW OVER NRN UTAH WHICH IS FORECAST TO TRACK ACROSS NRN CO AND SRN WYO WEDNESDAY BUT WITH A POTENTIAL H7 LOW OVER JOHNSON COUNTY. ECMWF AND GFS ARE BOTH SHOWING A DECENT BULLS-EYE OF QPF OVER THE BIGHORN MTNS WITH MID LEVEL CONVERGENCE AND ELY MID LEVEL FLOW. NAM12 SIGNATURE IS NOT AS STRONG BUT THE CIRCULATION IS STILL THERE. EVEN THE WEAKER NAM IS SHOWING .50 TO .75 INCHES OF QPF. GFS AND ECMWF ARE .75 TO 1.25 INCHES DURING THE DAY AND EARLY EVENING WEDNESDAY. LEANING ON THE GFS TODAY AND HAVE GONE WITH .50 TO 1 INCH OF QPF ACROSS BIGHORNS ON WEDNESDAY WITH GENERALLY .25 TO .50 ACROSS THE NEARBY LOWER ELEVATIONS. THE HYDROLOGIST ALSO ISSUED AN ESF FOR THE POTENTIAL RISE IN THE AREA CREEKS AND STREAMS. THIS CONVERGENT AXIS AND H6-H7 DEFORMATION AXIS WILL WEAK WEDNESDAY AFTERNOON BEFORE WEAKENING WEDNESDAY NIGHT ACROSS THE ERN ZONES. THE NEXT SHORTWAVE ALREADY CLIPS THE FAR NW AND WCNTRL ZONES BY THURSDAY AFTERNOON AS THE NEXT LONG WAVE TROUGH BEGINS TO TAKE SHAPE OVER THE WEST. THIS SYSTEM WILL AID IN A COLD FRONT DROPPING SOUTH ACROSS WRN AND NRN WYOMING THURSDAY INTO THURSDAY NIGHT AND THIS FRONT WILL SAG AS FAR SOUTH AS A LND TO CPR LINE. THIS SHALLOW UPSLOPE MAY SET THE STAGE FOR AN MOIST ISENTROPIC EVENT ACROSS THE CNTRL AND SWRN ZONES AS EARLY AS LATE THURSDAY NIGHT CONTINUING INTO FRIDAY MORNING BEFORE LIFTING NWD INTO THE NRN ZONES. THE ECMWF AND NAM HAVE A SLOWER EVOLUTION TO THIS PATTERN. FORECAST IS STILL WEIGHTED STRONGLY TOWARDS THE GFS AT THIS TIME. TEMPERATURES WILL BE TRICK THURSDAY INTO FRIDAY WITH THIS COLD FRONT AND HOW FAR SOUTH IT WILL REMAIN INTO FRIDAY. I DROPPED HIGHS ACROSS THE WEST AND NORTH WITH EXPECTED COOLER AIR BEHIND THE FRONT AND PCPN. IT COULD BE COOLER STILL IF THE GFS COMES TO FRUITION. THE ACTIVE PATTERN HAS RETURNED AND WILL CONTINUE INTO THE MEDIUM RANGE PERIOD. .LONG TERM...FRIDAY NIGHT THROUGH TUESDAY MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT IN A LARGE MERIDIONAL TROUGH AFFECTING THE WESTERN CONUS THROUGH THE EXTENDED. THIS WILL RESULT IN BELOW AVERAGE TEMPERATURES AND ABOVE AVERAGE CHANCE FOR PRECIPITATION FOR MUCH OF THE LONG TERM. ON FRIDAY THE TROUGH AXIS WILL BE ACROSS THE WEST COAST. A DECENT SHORTWAVE MOVING THROUGH THE MEAN TROUGH WILL PUSH EAST INTO THE GREAT BASIN FRIDAY...AND THEN NORTHEAST ACROSS INTERMOUNTAIN WEST/CENTRAL AND NORTHERN ROCKIES FRIDAY NIGHT AND SATURDAY. THEN MODELS ARE HINTING AT A LULL SATURDAY NIGHT/SUNDAY...BEFORE THE NEXT UPPER LOW/SHORTWAVE IN THE MEAN TROUGH AFFECTS THE REGION LATE SUNDAY THROUGH MONDAY. THE 00Z GFS IS NEGATIVELY TILTED WITH THE FIRST SYSTEM...WHILE THE 00Z ECMWF IS NEGATIVELY TILTED WITH THE SECOND SYSTEM. LOOKS LIKE THE MOST SIGNIFICANT PRECIPITATION WILL AFFECT WEST/NORTHWEST SECTIONS OF THE FORECAST AREA. SIGNIFICANT SNOWFALL COULD OCCUR OVER THE WESTERN/NORTHWESTERN MOUNTAINS. ALTHOUGH SNOW LEVELS WILL LOWER TO VALLEY FLOORS WEST OF THE DIVIDE FRIDAY NIGHT...AND THEN POSSIBLY SATURDAY NIGHT EAST OF THE DIVIDE...ONLY MINOR ACCUMULATIONS IN THE LOWER ELEVATIONS ARE EXPECTED WEST OF THE DIVIDE. TEMPERATURES...ESPECIALLY HIGHS WILL BE WELL BELOW AVERAGE THROUGH THE EXTENDED...WITH THE EXCEPTION OF HIGHS ON FRIDAY...WHICH COULD BE SEASONAL TO ABOVE AVERAGE EAST OF THE DIVIDE. MEDIUM RANGE MODELS CONTINUE TO STRUGGLE ON HOW MUCH WARM AIR WILL ADVECT NORTHWARD AHEAD OF THE FIRST STORM FRIDAY NIGHT/SATURDAY. && .AVIATION... THE THUNDERSTORM ACTIVITY THAT HAS BEEN ONGOING IN FAR WESTERN WYOMING WILL SHIFT ITS FOCUS TO NATRONA AND JOHNSON COUNTIES THIS EVENING AS A SHORTWAVE TROUGH AHEAD OF THE MAIN TROUGH OVER THE GREAT BASIN TRACKS NORTHEAST TO NORTHEAST WYOMING LATER THIS EVENING. THIS WILL RESULT IN SCATTERED MVFR AND ISOLATED IFR CONDITIONS. SOME OF THESE STORMS WILL PRODUCE LOCALLY GUSTY WINDS AND SMALL HAIL. THE MAIN TROUGH WILL TRACK EAST ACROSS WYOMING WEDNESDAY RESULTING IN NUMEROUS RAIN SHOWERS WITH SNOW ABOVE 9000 FEET ALONG AND EAST OF THE BIG HORN MOUNTAINS INCLUDING KCPR AND KBYG. RAIN SHOWERS WITH SNOW ABOVE 9000 FEET EAST OF THE DIVIDE WILL BE MORE SCATTERED ELSEWHERE EAST OF THE DIVIDE WEDNESDAY. WEST OF THE DIVIDE... LINGERING RAIN SHOWERS WITH SNOW SHOWERS ABOVE 7500 FEET CAN BE EXPECTED WEDNESDAY. && .FIRE WEATHER... ACTIVE WEATHER PATTERN HAS RETURNED WITH ONE SYSTEM LIFTING NORTH ACROSS THE AREA THIS AFTERNOON WHILE AN UPPER LEVEL LOW TRACK FROM NORTHERN UTAH INTO NORTHERN COLORADO TONIGHT. SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE OUT WEST WITH LESS SHOWER CHANCES AND ISOLATED THUNDERSTORMS EAST OF THE DIVIDE...MAINLY IN THE RED DESERT AND FAR NORTHEASTERN ZONES. STORMS MAY PRODUCE SMALL HAIL IN THE WEST AND FAR EASTERN ZONES INTO THE EARLY EVENING ALONG WITH GUSTY WIND. STRONG WIND GUSTS OVER 40 MPH ARE ALSO EXPECTED WITH STORMS ACROSS THE RED DESERT INTO THE EARLY EVENING. SHOWER CHANCES WILL INCREASE ACROSS THE EASTERN PART OF THE DISTRICT WEDNESDAY MORNING AND CONTINUE THROUGH THE AFTERNOON AND EARLY EVENING. ONE HALF TO ONE INCH OF RAIN IS POSSIBLE IN THE BIGHORN MOUNTAINS WITH ONE QUARTER TO ONE HALF INCH ACROSS THE LOWER ELEVATIONS. CONDITIONS WILL IMPROVE BRIEFLY LATE WEDNESDAY NIGHT INTO THURSDAY MORNING BUT ANOTHER SYSTEM WILL BRING MORE SHOWERS AND ISOLATED THUNDERSTORMS INTO THE NORTHWEST BY AFTERNOON. SHOWER CHANCES WILL INCREASE SIGNIFICANTLY ACROSS THE CENTRAL PART OF THE DISTRICT BY LATE THURSDAY NIGHT INTO FRIDAY MORNING AND THEN LIFT INTO THE NORTHERN HALF OF THE AREA AS THE MORNING WEARS ON FRIDAY. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM...SKRBAC LONG TERM...WM AVIATION...LIPSON FIRE WEATHER...SKRBAC
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 600 AM MDT TUE MAY 18 2010 WYZ001>020-022>030-191200- 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- 600 AM MDT TUE MAY 18 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT ISOLATED THUNDERSTORMS WILL BE POSSIBLE ACROSS MUCH OF WESTERN AND CENTRAL WYOMING THIS AFTERNOON AND EVENING. THERE IS A SLIGHT POTENTIAL FOR STRONG THUNDERSTORMS OVER NORTHERN JOHNSON COUNTY...PRODUCING SOME HAIL AND FREQUENT LIGHTNING. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THUNDERSTORMS ARE POSSIBLE OVER NATRONA AND JOHNSON COUNTIES WEDNESDAY AFTERNOON AND EVENING. A COUPLE OF STORM SYSTEMS WILL AFFECT THE AREA THURSDAY NIGHT THROUGH MONDAY. THIS SYSTEM HAS THE POTENTIAL TO BRING LIGHT TO MODERATE AMOUNTS OF MOUNTAIN SNOW AND VALLEY RAIN. THUNDERSTORMS ARE ALSO EXPECTED...ESPECIALLY FRIDAY ALONG AND AHEAD OF A COLD FRONT. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT. TEAM RIVERTON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 144 PM MDT TUE MAY 18 2010 WYZ002-182030- ABSAROKA MOUNTAINS WY- 144 PM MDT TUE MAY 18 2010 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN PARK COUNTY UNTIL 230 PM MDT... AT 140 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A SIGNIFICANT THUNDERSTORM 6 MILES SOUTHWEST OF SUNLIGHT BASIN...OR 31 MILES WEST OF CODY...MOVING NORTH AT 25 MPH. PEA SIZE HAIL IS LIKELY WITH THIS STORM...ALONG WITH BRIEF HEAVY RAIN. THIS STORM WILL BE NEAR...CRANDALL CREEK AND STATE HWY 296 MILE MARKER 10 AROUND 205 PM MDT. U.S. HWY 212 MILE MARKER 10 AROUND 220 PM MDT. LAT...LON 4499 10986 4500 10959 4463 10949 4459 10974 4499 10993 4499 10989 4499 10987 TIME...MOT...LOC 1944Z 166DEG 22KT 4471 10965 LIPSON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 244 PM MDT TUE MAY 18 2010 WYZ012-015>017-182200- TETON AND GROS VENTRE MOUNTAINS-UPPER WIND RIVER BASIN- WIND RIVER BASIN-WIND RIVER MOUNTAINS EAST- 244 PM MDT TUE MAY 18 2010 AN ELONGATED BAND OF SHOWERS AND THUNDERSTORMS ALIGNED ALONG THE HIGHWAY 26 CORRIDOR BETWEEN CROWHEART AND TOGWOTEE PASS WILL TRACKING NORTH NORTHWEST TO JUST NORTH OF HIGHWAY 26 THROUGH 4 PM. EXPECT UP TO PEA SIZE HAIL AND BRIEF LOCALLY HEAVY RAINFALL FROM SOME OF THESE STORMS. WYZ024-027-182200- SALT RIVER AND WYOMING RANGES-SOUTH LINCOLN COUNTY- 244 PM MDT TUE MAY 18 2010 SCATTERED SHOWERS AND THUNDERSTORMS WILL BE AFFECTING PORTIONS OF SOUTHERN LINCOLN COUNTY AS WELL AS THE SALT AND WYOMING RANGES THROUGH 4 PM. EXPECT UP TO PEA SIZE HAIL AND BRIEF LOCALLY HEAVY RAINFALL FROM SOME OF THESE STORMS. LIPSON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 312 PM MDT TUE MAY 18 2010 WYZ030-182215- EAST SWEETWATER COUNTY- 312 PM MDT TUE MAY 18 2010 A STRONG THUNDERSTORM WAS NEAR INTERSTATE 80 EXIT 146 MOVING NORTH AT 20 MPH. EXPECT BRIEF HEAVY DOWNPOURS...SMALL HAIL AND OCCASIONAL DANGEROUS CLOUD TO GROUND LIGHTNING WITH THIS STORM. EXPECT TO ENCOUNTER OTHER DEVELOPING SHOWERS AND THUNDERSTORMS ALONG INTERSTATE 80 THROUGH 5 P.M. WYZ026-182215- UPPER GREEN RIVER BASIN- 312 PM MDT TUE MAY 18 2010 A STRONG THUNDERSTORM WAS NEAR MILE MARKER 30 ALONG HIGHWAY 191 APPROXIMATELY SIX MILES SOUTH OF EDEN MOVING NORTH AT 20 MPH. EXPECT BRIEF HEAVY DOWNPOURS...SMALL HAIL AND OCCASIONAL DANGEROUS CLOUD TO GROUND LIGHTNING WITH THIS STORM. EXPECT TO ENCOUNTER OTHER DEVELOPING SHOWERS AND THUNDERSTORMS ACROSS THE UPPER GREEN RIVER BASIN 5 P.M. AEM
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
453 PM MDT TUE MAY 18 2010
WYZ005-007>009-017-020-022-182330-
BIGHORN MOUNTAINS SOUTHEAST WY-BIGHORN MOUNTAINS WEST WY-CASPER
MOUNTAIN WY-NATRONA COUNTY LOWER ELEVATIONS WY-OWL CREEK AND BRIDGER
MOUNTAINS WY-SOUTHWEST BIG HORN BASIN WY-WIND RIVER BASIN WY-
453 PM MDT TUE MAY 18 2010
...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN NATRONA...EASTERN
FREMONT AND SOUTHEASTERN HOT SPRINGS COUNTIES UNTIL 530 PM MDT...
AT 450 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM BEARTRAP MEADOWS
COUNTY PARK TO CASPER TO 7 MILES SOUTHEAST OF POWDER RIVER TO 6 MILES
NORTHEAST OF U.S. HWY 20/26 MILE MARKER 70 TO 10 MILES NORTH OF U.S.
HWY 20/26 MILE MARKER 90...AND MOVING NORTH AT 25 MPH.
WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THESE STORMS.
THESE STORMS WILL BE NEAR...
CASPER EVENTS CENTER...JCT I25 AND HWY 20...NATRONA COUNTY
AIRPORT...POWDER RIVER AND ARMINTO AROUND 500 PM MDT.
EASTRIDGE MALL AND I25 EXIT 191 AROUND 505 PM MDT.
U.S. HWY 20/26 MILE MARKER 30...GOLDENEYE RESERVOIR...NATRONA AND BAR
NUNN AROUND 510 PM MDT.
I25 EXIT 182 AROUND 515 PM MDT.
THIS INCLUDES INTERSTATE 25 IN WYOMING BETWEEN MILE MARKERS 177 AND
220.
REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN
RIVERTON AT 1-800-211-1448.
LAT...LON 4259 10611 4273 10636 4287 10690 4314 10750
4331 10802 4369 10809 4348 10761 4347 10748
4343 10690 4329 10635 4315 10610
TIME...MOT...LOC 2252Z 180DEG 20KT 4272 10622 4283 10636
4296 10690 4323 10750 4336 10791
MEUNIERThe Riverton/Lander radar (KRIW), 123 km away, was scanning. The volume nearest the first event began at 00:02 UTC.
1 lightning. Local standard time, as filed.
Lightning ignited a fire in a haystack near Cora around 1700MST. The fire smoldered into the early morning hours of the following day and scorched approximately 350 tons of hay. The stack was three bales high across an area 300 feet by 200 feet in size.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2010Every state in 2010This day in weather historyWarnings in Wyoming, May 2010
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: 231820.