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May 31, 1998 - Great Lakes Derecho - Milwaukee, Wisconsin

Minnesota, Wisconsin, Michigan, Ontario and New York get blasted by one of the most powerful derechos (long lived wind storm) on record!

Severe Weather Threat High!

Saturday May 30, 1998 was the start of something that would be historic in terms of severe weather across the Midwest. Reflecting back here are detailed accounts on how everything unfolded.

By early afternoon southern Wisconsin was socked in cool and overcast conditions. The Storm Prediction Center - (SPC) had placed South Dakota, Minnesota, Iowa, Wisconsin and Michigan under a moderate risk for severe thunderstorms. By early evening some small elevated showers moved across Wisconsin with otherwise generally clear skies and temperatures in the mid 50's. The National Weather Service Milwaukee/Sullivan highlighted the potential severe weather threat with their afternoon area forecast discussion:

ZCZC MKESFDMKE TTAA00 KMKE 302017
WISCONSIN FORECAST DISCUSSION
NATIONAL WEATHER SERVICEMILWAUKEE/SULLIVAN
315 PM CDT SAT MAY 30 1998

MAIN FCST FOCUS IS ON IMMEDIATE SVR WX THREAT AND VERY COOL TEMPS FOR SUN NITE.

IN THE SHORT TERM...WITHOUT GOING INTO EXTENSIVE LISTING...MANY SVR WX PARAMETERS APPEAR TO BE COMING TOGETHER FOR A SIG SVR WX EVENT FOR WISC OVRNIGHT. ETA PROG PAINTS MOST DANGEROUS OUTCOME AS ETA PC GRIDDED DATA AND ETA BUFKIT HV EHI OVER 10...CAPE OVER 3000...HELICITY 500-700 FOR SRN WISC. AS FOR DYNAMICS...PROGD COUPLED JET WITH BEST UVV OVR WISC ARND 06Z AND EXCELLENT PROGD ISENTROP LIFT DEVELPNG OVER AREA COMPLETE SVR WX PIX. WILL CONT TO HIT SVR WX WORDING HARD IN UPCOMING FCST ESPECIALLY OVER SRN WISC IN VCNTY OF WRM FNT WHICH WOULD CREATE EXCELLENT WND PROFILE FAVORBLE FOR TORNADIC DEVELOPMENT. ONLY FLY IN OINTMNT IS TSTM COMPLEX OVER IA WHICH MAY AFFECT FINAL STABILITY NUMBERS...BUT THERE WILL BE NO DENYING INCOMING DYNAMICS LATER TNGT.

IN THE FAR TERM...STORM SWEEPS OUT QUICKLY SUN. WILL TRY TO BRING SNSH TO NW WISC WITH TIME. WILL MENTN WINDY IN ZONES DUE TO DECENT CAA IN BACKLASH OF STRENGTHNG STORM. LIKE GUID NUMBERS IN NRN WISC FOR SUN NIGHT TO DIVE INTO 30S. WILL HOLD OFF ON MENTN OF FROST TIL NEXT FCST RUN DETERMINES FINAL WIND FCST. OTRW WILL BRING IN CHCY AFTN SHWRS MON TO NORTH AS FAST LOW ALG WITH WAA MOVS TOWD AREA. GUID TEMPS NOT BAD ATTM.

THANKS TO GRB/LSE/DLH FOR INPUT

. .MKX...NONE


I attended a Milwaukee Brewer baseball game that evening with Steve and there were no signs of severe weather approaching so we decided to go. The only excitement throughout the evening was the brewer fans chanting obscenities at Marlins third baseman Todd Zeile in our section. They even went further on chanting against their player, brewer right fielder Jeromy Burnitz. "Burnitz you suck," was a common chant we heard all night. Little did we know, the trigger for severe weather initiation had begun in southeast South Dakota. A supercell produced a violent F4 tornado that struck the city of Spencer, South Dakota. The Spencer, South Dakota tornado unfortunately killed and injured many people. This storm was the start of a major weather event that would take place across the upper Midwest.

We left the brewer game around 10:00 p.m. and had a hunch the moderate risk, SPC placed across the upper Midwest, would be downgraded due to the lack of severe weather and cool conditions across the area. Not knowing, the beginning of the derecho was taking shape across central Minnesota. I checked our weather radio and to my surprise SPC still had most of the area under a moderate risk for severe weather. Steve and I stopped at my place to view the radar to confirm any convection. The storms in Minnesota looked strong, but nothing really out of the ordinary. Squall lines are a common type of severe weather across Wisconsin so we decided to stay up and monitor the storms anyway. The time was 11:00 p.m. and told Steve I was going to take a quick nap. My thermometer had a reading of 53 degrees. I feel asleep.



Heat Burst

I woke up two hours later around 1:00 a.m. and Steve still surfing the web and mentioned the storms were organizing into a more mature line across eastern Minnesota and western Wisconsin. The temperature rose from 53 degrees at 11:00 p.m. to 72 degrees at 1:15 a.m. I took a double take and noticed the wind outside had increased dramatically. We both went outside and were amazed how warm it had become. Initially I figured a warm front had moved through, but was perplexed about the strong winds gusting to over 30 mph. Looking at the radar there were some small isolated showers that developed and then quickly dissipated across most of southern Wisconsin. I was told these dissipating showers had brought down warm air above the surface along with gusty winds known as a heat burst. This caused the rapid rise in temperatures across the area. Soon the winds had died down and SPC had issued a Tornado Watch across much of the state of Wisconsin. They also mentioned thunderstorm wind gusts up to 95 mph are possible. Truly, the situation was becoming more clear the squall line would pose more of a significant damaging wind threat.

100 mph wind reports & Impact

The squall line had reached Madison, Wisconsin and we were hearing numerous reports of wind damage across Minnesota and Wisconsin. There was a report on the scanner of a 103 mph wind gust in Dodge County, Wisconsin along with injuries at a campground in Columbia County. Meteorologist Bart Adrian of Fox Channel 6 stressed to take cover immediately and realized how serious the situation had become. The NWS issued severe thunderstorm warnings for all of southeastern Wisconsin, 45 minutes well ahead of the squall line. According to the radar the squall line was close, however, I didn't see any noticeable shelf cloud. Lightning wasn't as frequent either but I finally saw the leading edge of the heavy rain. It hit with a vengeance almost knocking out power and our phone lines instantly. The wind was very strong gusting to around 45 to 50 mph. One thing we did notice was the blue and green flashes to our north. We figured this was lightning along with power flashes occurring. I spoke with other friends who watched the storm move in and saw numerous flashes of green and blue color. The intense line lasted for about 10 minutes and the rest of the storm was primarily strati-form rain and lightning. Initially we thought this storm spared us and it did across our local neighborhood.

Waukesha, Wisconsin - Storm Damage

Steve and I woke up around 9:00 a.m. to find out we still had no power. Steve called his parents via cell phone and they had no power. We drove towards his residence which was located on the western fringes of the city of Waukesha. There was not much damage across the southern part of the city, but this would change as we drove further into the central and western parts. We found numerous trees uprooted and snapped along with 90% of traffic lights without power. Half the city appeared to be in the dark with residents waking up to find trees damaged across their lawn. We discovered 10 power poles snapped and blown over on highway T (Merrill Hills Road). The most significant damage had occurred in downtown Waukesha. The post office had their windows blown out, numerous trees some over 100 years old had been uprooted and destroyed. Papa George's restaurant had been completely destroyed. Initially many residents thought a tornado caused all the damage but straight-line winds and microbursts were the culprit.

Derecho Aftermath

The derecho traveled across Minnesota, Iowa, Wisconsin, Michigan, Ontario and New York. It crossed the state of Wisconsin in only 3 hours and unfortunately injured more than 30 people and killing 1 person. Wind speeds estimated across the city of Waukesha were near 100 mph with a staggering wind gust of 128 mph in Dodge County, Wisconsin. This holds the highest measured wind speed for the state of Wisconsin. There was an 87 mph wind gust measured on a weather station 1/4 of a mile northwest of our location when the storms moved through. All in all, this was one if not the most destructive wind storms to hit the upper Midwest in decades.

May 31, 1998 Derecho Resources:


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