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April 17-18 Heavy Rain Event


A-L-E-K

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First Flash Flood Warning issued in the LOT cwa.
 

FLASH FLOOD WARNINGILC031-089-097-111-172300-/O.NEW.KLOT.FF.W.0001.130417T1703Z-130417T2300Z//00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/BULLETIN - EAS ACTIVATION REQUESTEDFLASH FLOOD WARNINGNATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL1203 PM CDT WED APR 17 2013THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A* FLASH FLOOD WARNING FOR...  LAKE COUNTY IN NORTHEAST ILLINOIS...  NORTHERN KANE COUNTY IN NORTHEAST ILLINOIS...  NORTHWESTERN COOK COUNTY IN NORTHEAST ILLINOIS...  SOUTHEASTERN MCHENRY COUNTY IN NORTHEAST ILLINOIS...* UNTIL 600 PM CDT WEDNESDAY* AT 1159 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED  THUNDERSTORMS PRODUCING TORRENTIAL DOWNPOURS...WITH RAINFALL RATES  IN EXCESS OF AN INCH AND A HALF PER HOUR. KANE COUNTY EMERGENCY  MANAGEMENT REPORTS ROUTE 47 AND PLATO ROAD COMPLETELY FLOODED.  ADDITIONAL THUNDERSTORMS WITH VERY HEAVY RAINFALL WILL MOVE ACROSS  THE AREA LATER THIS AFTERNOON...FURTHER INCREASING THE FLASH FLOOD  THREAT. RAINFALL TOTALS LOCALLY IN EXCESS 3 INCHES ARE EXPECTED BY  EARLY THIS EVENING.* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO  OCCUR.
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MT @marcmorehouse: Creekside Park in IC. pic.twitter.com/VRkJEfozMk #KCRGWX

 

:yikes:  This is about 25 miles south of me.  Iowa City got hit really hard with training thunderstorms this morning.  Up here in Cedar Rapids, it has been mostly moderate rain but the training thunderstorms have stayed mostly to my south.

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.UPDATE...
ISSUED AT 1142 AM CDT WED APR 17 2013

PORTIONS OF AN MCS THAT DEVELOPED ACROSS IOWA EARLIER THIS MORNING
HAVE NOW SPREAD OVER THE SOUTHWEST HALF OF THE FORECAST AREA.
THERE IS A BACK EDGE APPROACHING INTERSTATE 35 IN NORTHERN IOWA AS
OF 16Z...REFLECTIVE OF THE SUBSIDENCE OCCURRING IN THE WAKE OF THE
MCS. HAVE ADJUSTED PRECIPITATION CHANCES TO ACCOUNT FOR THIS BACK
EDGE...LOWERING THEM FOR A DECENT PORTION OF THE EARLY TO MID
AFTERNOON HOURS. THE 17.12Z REGIONAL CANADIAN...HRRR AND 17.00Z
NSSL WRF-ARW HAVE HAD A GOOD HANDLE ON THIS MCS...WHICH CONCURS
WITH THE PRECIPITATION CHANCE ADJUSTMENTS. ALSO HAVE ISSUED AN SPS
FOR NORTHEAST IOWA AS WIND GUSTS OF 30-40 KT HAVE DEVELOPED IN THE
WAKE OF THE PRECIPITATION.

OVER SOUTHERN IOWA INTO NORTHERN MISSOURI AND NORTHERN ILLINOIS...
CONVECTION CONTINUES ALONG THE SOUTH SIDE OF THE MCS. THIS IS
WHERE A 40-45 KT 850MB JET ON PROFILER/VAD WIND DATA IS
TRANSPORTING MUCAPE VALUES OF 1000-2000 J/KG INTO THE COLD OUTFLOW
PRODUCED BY THE MCS. IN ADDITION...THE THUNDERSTORMS ARE ALONG A
LOW LEVEL FRONTOGENESIS ZONE. THE QUESTION FOR THE AFTERNOON AND
TONIGHT IS WHERE DOES THE OUTFLOW/LOW LEVEL FRONTOGENESIS ZONE SET
UP...SINCE THIS WOULD BE THE FOCUS FOR HEAVY RAINFALL AND POSSIBLE
SEVERE POTENTIAL. THE 925-850MB WINDS ARE FORECAST TO INTENSIFY AS
UPPER TROUGH LIFTS OUT OF THE SOUTHWEST. THUS...THINK THE BOUNDARY
SHOULD BE ABLE TO LIFT NORTH. THE 17.12Z REGIONAL CANADIAN AND
17.00Z NSSL WRF-ARW SEEM TO FOCUS THE HEAVY QPF AREA OVER SOUTHERN
IOWA INTO SOUTHERN WISCONSIN FOR TONIGHT INTO THURSDAY. GIVEN THEY
HAVE THE BEST HANDLE ON ONGOING CONVECTION...A WEIGHT TOWARDS
THESE MODELS IS WARRANTED. GRANT COUNTY IN OUR FORECAST AREA IS OF
THE MOST CONCERN...WHERE SOUNDINGS SUGGEST UPWARDS OF 1000 J/KG OF
CAPE IS POSSIBLE. ALTHOUGH WARM CLOUD DEPTHS ARE UNSEASONABLY
HIGH...AROUND 3500 METERS WHICH DEFINITELY FAVORS HEAVY
RAINFALL...THIS CAPE COULD RESULT IN SOME HAIL WITH THUNDERSTORMS.
WILL UPDATE THE HAZARDOUS WEATHER OUTLOOK TO ADD THE MENTION OF
HAIL. 1-6KM SHEAR IS VERY WEAK...15 KT OR LESS...WHICH SHOULD
LIMIT ANY SEVERE POTENTIAL TO ISOLATED AT BEST.

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I was just between here and Kenosha and back. A lot of street ponding is occurring and outright flooded sections in low lying spots. Ditches are overflowing - it is a mess.

 

My backyard pond is quite high now!

 

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