...TODAY/S TOPIC IS..PART 6..STRAIGHT-LINE THUNDERSTORM WINDS... ------------------------------------------------------------------- ...SIGNATURE OF STRAIGHT-LINE WINDS... STRAIGHT-LINE WINDS ARE OFTEN RESPONSIBLE FOR MOST OF THE WIND DAMAGE ASSOCIATED WITH A THUNDERSTORM. THESE WINDS ARE OFTEN CONFUSED WITH TORNADOES BECAUSE OF SIMILAR DAMAGE AND WIND SPEEDS. HOWEVER THE STRONG GUSTY WINDS ASSOCIATED WITH STRAIGHT-LINE WINDS ARE UNLIKE THE ROTATING WINDS OF A TORNADO. IF YOU WERE TO SURVEY THE DAMAGE PATTERN LEFT BY STRAIGHT-LINE WINDS...YOU WOULD SEE DEBRIS...SUCH AS UPROOTED TREES...LAID OUT IN NEARLY PARALLEL ROWS. ...DOWN-BURST BASICS... DOWN-BURSTS ARE ONE EXAMPLE OF DAMAGING STRAIGHT LINE WINDS. A DOWN-BURST IS A SMALL AREA OF RAPIDLY DESCENDING RAIN AND RAIN-COOLED AIR BENEATH A THUNDERSTORM. WIND SPEEDS IN SOME OF THE STRONGER DOWN-BURSTS CAN REACH 100 TO 150 MILES PER HOUR WHICH IS SIMILAR TO THAT OF A STRONG TORNADO. THE WINDS PRODUCED FROM A DOWN-BURST OFTEN TRAVEL IN ONE DIRECTION...AND THE WORST DAMAGE IS USUALLY ON THE FORWARD SIDE OF THE DOWN-BURST. ...DERECHOS... ANOTHER CATEGORY OF STRAIGHT-LINE WINDS COMMON TO THE MIDWEST ARE KNOWN AS DERECHOS. DERECHOS USUALLY OCCUR IN THE MIDWESTERN STATES IN THE LATE SPRING AND SUMMER.
IN FACT...SOUTHERN MINNESOTA AND SOUTHERN WISCONSIN HAVE THE
GREATEST NUMBER OF DERECHOS IN THE COUNTRY...A DERECHO ALLEY.
DERECHOS ARE CREATED BY THE MERGING OF MANY THUNDERSTORM CELLS INTO A CLUSTER OR SOLID LINE EXTENDING FOR MANY MILES. THE WIDTH OF SUCH A STORM CAN RANGE FROM 20 TO 65 MILES...AND THE LENGTH CAN REACH 100 MILES OR MORE. THEY MAY TRAVEL FOR 500 TO 600 MILES.
IN EXTREME CASES THESE STORMS CAN CREATE MAXIMUM WIND GUSTS AROUND 150 MPH. NOT ONLY CAN A DERECHO CONTAIN INCREDIBLY STRONG STRAIGHT-LINE WINDS...IT IS ALSO CAPABLE OF PRODUCING SMALL TORNADOES. AS A RESULT THESE TYPES OF STORMS CAN BE EXTREMELY DANGEROUS AND INCREDIBLY DAMAGING.
...HURRICANE-FORCE THUNDERSTORM WIND FREQUENCY... ON AVERAGE...WISCONSIN EXPERIENCES HURRICANE-FORCE THUNDERSTORMS 5 DAYS PER YEAR. ON AVERAGE...WISCONSIN EXPERIENCES A 100 MPH THUNDERSTORM WIND EVENT ONE DAY EVERY OTHER YEAR.
...EXAMPLES OF POWERFUL DOWNBURSTS... ON JULY 1, 2012, A POWERFUL SQUALL LINE RIPPED THROUGH NORTHWESTERN WISCONSIN IN THE BURNETT COUNTY AREA WITH GUSTS OF 100 TO 120 MPH. THOUSANDS OF TREES WERE LEVLED AND NUMEROUS POWER-LINES WERE KNOCKED OVER. VEHICLES...CAMPER TRAILERS...AND BOATS WERE FLIPPED OVER OR DAMAGED BY TREE DEBRIS. SEVERAL HOMES SUSTAINED SIDING OR ROOF DAMAGE.
ON JUNE 21, 2011, A SQUALL LINE TORE NORTHEAST THROUGH WAUKESHA COUNTY WITH WIND GUSTS OF 80 TO PERHAPS 100 TO 110 MPH. THOUSANDS OF TREES WERE UPROOTED OR DAMAGED. ONE TRUCK ON I-94 WAS BLOWN OVER, ONE PERSON WAS INJURED BY FLYING DEBRIS.
ON SEPTEMBER 2, 2011 A POWERFUL CLUSTER OF STORMS RAKED CENTRAL AND EAST-CENTRAL WISCONSIN WITH WINDS OF 80 TO 95 MPH. NUMEROUS BUILDINGS WERE DAMAGED AND OVER 60,000 CUSTOMERS LOST ELECTRICITY. APPLETON WAS HIT THE HARDEST WITH OVER $5.3 MILLION IN DAMAGE.
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ALWAYS KEEP IN MIND THAT MAJOR DAMAGE TO A HOME...BUILDING OR ANY PERSONAL PROPERTY CAN BE CAUSED BY A VARIETY OF DIFFERENT STRAIGHT- LINE WIND EVENTS. ALWAYS TAKE COVER WHEN STRONG THUNDERSTORM WINDS THREATEN. AS WITH ANY SEVERE WEATHER STAY TUNED TO NOAA WEATHER RADIO ALL-HAZARDS OR YOUR LOCAL TV OR RADIO STATIONS FOR THE LATEST FORECAST AND SEVERE WEATHER WARNINGS. FOR ADDITIONAL SEVERE WEATHER INFORMATION AND UP TO DATE FORECASTS AND WARNINGS PLEASE VISIT OUR WEB SITE AT: https://weather.gov/mkx
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