A high pressure system centered over the Upper Midwest the previous two days produced very dry conditions over the area. This allowed the minimum relative humidity to fall into the 25 to 35 percent range, as reported by the automated weather observing equipment at the La Crosse and Viroqua airports in the afternoon hours of April 18th and 19th.
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 ARX wrote it up.
A high pressure system centered over the Upper Midwest the previous two days produced very dry conditions over the area. This allowed the minimum relative humidity to fall into the 25 to 35 percent range, as reported by the automated weather observing equipment at the La Crosse and Viroqua airports in the afternoon hours of April 18th and 19th. The combination of the dry conditions and local wind effects enabled a control burn to become uncontrollable on the La Crosse County and Vernon County line on April 19th. The wildfire burned around 10 acres of grass.
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 La Crosse, WI wrote its last area forecast discussion before the first event at Apr 19, 2:44 AM CST, 9 hours 52 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 344 AM CDT MON APR 19 2010 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT MAIN FORECAST CONCERN IS IF PRECIPITATION CAN DEVELOP DURING THE AFTERNOONS OF TUESDAY AND WEDNESDAY. CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWS DEEP TROUGHING ACROSS THE GULF OF ALASKA...RIDGING OVER THE WESTERN U.S. INTO SASKATCHEWAN...A WEAKENING SHORTWAVE TROUGH OVER THE DAKOTAS AND RIDGING OVER THE UPPER MISSISSIPPI RIVER VALLEY REGION. ALSO TO NOTE ON WATER VAPOR IS A SHORTWAVE TROUGH IN NORTHEAST MANITOBA. AHEAD OF THE WEAKENING DAKOTAS SHORTWAVE TROUGH...PLENTY OF UPPER LEVEL MOISTURE EXISTS ON WATER VAPOR... WHICH IS MANIFESTING ITSELF AS CIRRUS ON IR IMAGERY. OVER THE FORECAST AREA...MAJORITY OF THE CIRRUS IS WEST OF THE MISSISSIPPI RIVER. PLENTY OF DRY AIR EXISTS BELOW THE CIRRUS...AS SEEN ON THE 00Z MPX SOUNDING WHICH STILL HAS A PRECIPITABLE WATER VALUE OF 0.25 INCHES. NOTE TOO THAT THE SOUNDING MIXED UP TO 750MB. DESPITE THE CIRRUS...TEMPERATURES HAVE STILL COOLED TONIGHT...DUE TO THE DRY AIR AND LIGHT WINDS FROM A SURFACE HIGH PRESSURE RIDGE IN PLACE. READINGS ARE IN THE 30S AND 40S... COOLEST FROM SPARTA NORTHEAST UNDER THE CLEARER SKIES. AIRMASS OVERALL CONTINUES TO WARM... THOUGH...NOTED BY 00Z 850MB TEMPS OF 2C AT GRB...6C AT MPX AND 8C AT BIS. TODAY THROUGH TUESDAY...THE UPPER LEVEL RIDGING OVER THE FORECAST AREA IS EXPECTED TO BREAK DOWN OVER THE NEXT 24-36 HOURS...DUE TO A COMBINATION OF THE SHORTWAVE TROUGHS IN THE DAKOTAS AND NORTHEAST MANITOBA DROPPING SOUTHEAST. IN ADDITION...AS THE NORTHEAST MANITOBA TROUGH DIVES DOWN INTO NORTHERN ONTARIO TOMORROW...LOOK FOR A COLD FRONT TO ACCOMPANY IT. THIS COLD FRONT IS PROGGED TO REACH CENTRAL WISCONSIN TOWARDS 00Z. DUE TO A LACK OF MOISTURE AND FORCING AHEAD OF THE FRONT...THERE ARE NO PRECIPITATION CONCERNS WITH IT. IN FACT...THE ONLY PRECIPITATION CONCERN DURING THIS PERIOD IS TUESDAY AFTERNOON OVER NORTHEAST IOWA AND SOUTHWEST WISCONSIN. THE 19.00Z NAM...LIKE PREVIOUS RUNS OF THE NAM...CONTINUES TO SHOW SOME LIGHT DIURNAL SHOWERS POPPING UP IN THIS AREA. SOUNDINGS FROM THE MODEL SHOW IT IS A RESULT OF THE BMJ DEEP CONVECTION SCHEME...AND THEREFORE SOMEWHAT SUSPECT. PREFER THE DRIER LOOK OF THE GFS... ECMWF...AND OUR LOCAL WRF-ARW RUN. INSPECTING OUR LOCAL WRF-ARW RUN AT 21Z TUESDAY ALSO REVEALS STARTLING DIFFERENCES COMPARED TO THE NAM...WITH MIXING HEIGHTS 50-75MB HIGHER AND SURFACE DEWPOINTS 5-10F LOWER. EITHER WAY...AN INCREASE IN DAYTIME CUMULUS IN NORTHEAST IOWA AND SOUTHWEST WISCONSIN LOOKS LIKELY TUESDAY AFTERNOON. AS FAR AS TEMPERATURES GO...EXPECT A CONTINUED SLOW RISE FOR HIGHS EACH DAY AS 850MB TEMPS HIT 4-6C TODAY AND 6-8C ON TUESDAY. THE CIRRUS CLOUD COVER LOOKS TO HAVE A NEGLIGIBLE IMPACT FOR HIGHS...AND SHOULD START CLEARING OUT ON TUESDAY. LOWS TONIGHT STILL LOOK COOL...BUT THE CIRRUS OVER MUCH OF THE AREA SHOULD KEEP READINGS UP A FEW DEGREES COMPARED TO CURRENTLY. TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...FORECAST AREA IS PROGGED TO REMAIN IN NORTHWEST FLOW ALOFT DURING THIS PERIOD...CREATED BY THE SHORTWAVE THAT DROPPED INTO NORTHERN ONTARIO ON TUESDAY. IN FACT... THE TROUGHING OVER SOUTHEAST CANADA THAT DEVELOPS DURING THIS PERIOD SEEMS MORE DOMINANT THAN MODELS INDICATED LAST NIGHT. AS SUCH...THEY ALLOW A LITTLE MORE SURFACE RIDGING TO DROP DOWN INTO THE AREA ON WEDNESDAY BEHIND A COLD FRONTAL PASSAGE TUESDAY NIGHT. SINCE MORE HIGH PRESSURE IS BUILDING IN...ALONG WITH DRIER AIR FLOWING SOUTH INTO THE AREA...HAVE KEPT THIS PERIOD DRY. SIMILAR TO TUESDAY... CONCERN DOES EXIST FOR PRECIPITATION IN NORTHEAST IOWA AND SOUTHWEST WISCONSIN DURING HEATING ON WEDNESDAY AFTERNOON...BUT THIS TIME FROM THE ECMWF. THE ECMWF SHOWS PRECIPITATION FORMING ALONG THE COLD FRONT WHICH FALLS APART IN NORTHEAST IOWA AND SOUTHWEST WISCONSIN. HOWEVER...WITH THE GFS AND NAM DRY...AND MOST OF THE ECMWF PRECIPITATION OUTSIDE OF THE FORECAST AREA...HAVE MAINTAINED THE DRY FORECAST. REGARDING TEMPERATURES...850MB TEMPS RESPOND TO THE COLD FRONTAL PASSAGE BY DROPPING TO 2C OVER TAYLOR COUNTY ON WEDNESDAY. HOWEVER...MUCH OF NORTHEAST IOWA AND SOUTHWEST WISCONSIN SEE LITTLE COOLING DUE TO THE THE COLD FRONT FALLING APART THERE...SO 850MB TEMPS ARE STILL 6-8C. AS SUCH...EXPECT A DECENT RANGE OF LOW TEMPERATURES TUESDAY NIGHT AND HIGHS ON WEDNESDAY... COOLEST IN TAYLOR AND CLARK COUNTIES. COOLER TEMPERATURES EVERYWHERE ARE PLANNED FOR WEDNESDAY NIGHT AS A LITTLE MORE CANADIAN AIR ENTERS THE AREA...COMBINED WITH MOSTLY CLEAR SKIES AND LIGHT WINDS ALLOWING FOR GOOD RADIATIONAL COOLING. .LONG TERM...THURSDAY THROUGH MONDAY SIMILAR TO THE PAST FEW DAYS...MAIN CONCERN IS ON THE PRECIPITATION EVENT MODELS HAVE BEEN SHOWING TO DEVELOP OVER THE REGION IN THE FRIDAY TO SATURDAY TIME PERIOD. THE FORECAST PRECIPITATION EVENT IS CONNECTED TO AN EJECTING UPPER TROUGH COMING OUT OF THE SOUTHERN CALIFORNIA...WHICH MODELS SHOW FORMING TUESDAY NIGHT AND WEDNESDAY. THE 18.12Z ECMWF DECIDED TO THROW UNCERTAINTY INTO THE PRECIPITATION EVENT...BY SHOWING A SLOWER EJECTION OF THE UPPER TROUGH AND KEEPING THE BULK OF PRECIPITATION MAINLY SOUTH OF I-90. THE 19.00Z SUITE HAS PICKED UP ON A SIMILAR TREND...EXCLUDING THE GFS. SOME OF THIS HAS TO DO WITH THE SOUTHEAST CANADA TROUGH HAVING MORE INFLUENCE OVER THE AREA AS MENTIONED IN THE SHORT TERM DISCUSSION. MAIN ADJUSTMENTS SO FAR TO THE FORECAST WERE TO DECREASE CLOUD COVER AND RAISE HIGHS SLIGHTLY ON THURSDAY...AS WELL AS LOWER DEWPOINTS (AGREED UPON BY ALL MODELS). HAVE LEFT THURSDAY NIGHT DRY...UNDER THE IDEA THAT THE GFS IS TOO PROGRESSIVE SPREADING PRECIPITATION NORTHWARD INTO THE DRY AIRMASS OVER THE AREA. BOTH THE 19.00Z ECMWF AND CANADIAN ARE DRY DURING THIS TIME PERIOD. IN FACT...DECREASE CLOUD COVER AND LOWERED LOW TEMPERATURES A FEW DEGREES TO STAY WITH THE CONSENSUS. FRIDAY IS THE TRICKY DAY. IF THE 19.00Z ECMWF IS CORRECT...THE DAY IS DRY WITH PLENTY OF SUNSHINE...ALLOWING FOR HIGHS IN THE MID 70S AT LEAST DUE TO 850MB TEMPS AROUND 12C. ON THE OTHER HAND...THE CANADIAN AND GFS HAVE PRECIPITATION. THEREFORE... FOR NOW LEFT HIGH TEMPERATURES ALONE...BUT RESPECTED THE TRENDS IN THE LAST TWO ECMWF RUNS BY LOWERING PRECIPITATION PROBABILITIES BY 5 PERCENT. FRIDAY NIGHT AND SATURDAY PRESENT SIMILAR DIFFICULITIES... ESPECIALLY NORTH OF I-90 WHERE THE ECMWF IS MAINLY DRY. NO ADJUSTMENTS WERE MADE BEYOND FRIDAY DUE TO MODEL UNCERTAINTY. IT DOES APPEAR THAT FOR SUNDAY AND MONDAY...THE SOUTHEAST CANADA TROUGH WILL SLIDE SOUTHWEST INTO THE FORECAST AREA...BRINGING WITH IT COOLER CONDITIONS. && .AVIATION...TODAY AND TONIGHT DRY HIGH PRESSURE WILL REMAIN OVER THE TAF SITES THROUGH TUESDAY... MAINTAINING VFR CONDITIONS AND LIGHT WINDS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && SHORT/LONG TERM...AJ AVIATION..........AJ/DAS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LA CROSSE WI 500 AM CDT MON APR 19 2010 IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-032>034- 041>044-053>055-061-201200- ADAMS-ALLAMAKEE-BUFFALO-CHICKASAW-CLARK-CLAYTON-CRAWFORD-DODGE- FAYETTE-FILLMORE-FLOYD-GRANT-HOUSTON-HOWARD-JACKSON-JUNEAU-LA CROSSE- MITCHELL-MONROE-MOWER-OLMSTED-RICHLAND-TAYLOR-TREMPEALEAU-VERNON- WABASHA-WINNESHIEK-WINONA- 500 AM CDT MON APR 19 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST MINNESOTA...NORTHEAST IOWA AND SOUTHWEST INTO CENTRAL WISCONSIN. .DAY ONE...TODAY AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THERE IS A CHANCE OF THUNDERSTORMS FRIDAY THROUGH SATURDAY NIGHT. AT THIS TIME IT IS TOO EARLY TO DISCERN ANY SEVERE WEATHER POTENTIAL FROM THE THUNDERSTORMS. .SPOTTER INFORMATION STATEMENT... NO ACTION IS NEEDED. .EMERGENCY MANAGEMENT COORDINATION... NO CALL IS SCHEDULED. AJ
The national radar mosaic for the moment the first event began.
2 wildfire. Local standard time, as filed.
A controlled burn of garbage quickly became out of control and burned 10 acres of grass.
A controlled burn of garbage quickly became out of control and burned 10 acres of grass.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2010Every state in 2010This day in weather historyWarnings in Wisconsin, April 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: 222033, 222034.