August 8th Severe multicell cluster - a case study

A multicell cluster of severe thunderstorms developed during the late afternoon hours of August 8th, 2005 in response to an interesting interaction of stormscale outflow boundaries and weak shortwave trough rotating out of northeast Illinois. This shortwave trough is easily seen in this Water Vapor animation...note the cyclonic circulation present over northeast Illinois which later moves into northwest Indiana.

Animation of visible satellite imagery showed the developing severe multicell cluster well especially with the upscale anvil growth and overshooting top which developed with the most severe storm in southern Elkhart county.

Conditions were quite favorable for surface based convection Monday afternoon as shown in the image which shows Convective Available Potential Energy (CAPE) and lifted index (LI) and surface observations across the area at 5 pm est August 8th, 2005.

This 0.5 degree radar reflectivity animation from the National Weather Service Doppler radar in North Webster shows the rapid development and intensification of the initial multicell storm cluster as it develops northwestward out of Allen county Indiana in the late afternoon. Note the vigorous storm development which occurs over southern Elkhart county late in the loop...this storm produced widespread large hail up to golfball size and which covered the ground in southern Goshen and rainfall amounts in excess of 3 inches in only one hour.

Additional storm reports can be found in this LOCAL STORM REPORT.

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE NORTHERN INDIANA
751 PM EST MON AUG 08 2005

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0503 PM     HAIL             FORT WAYNE              41.07N 85.14W 
08/08/2005  1.00 INCH        ALLEN              IN   AMATEUR RADIO   

            IPFW CAMPUS ON EAST SIDE OF TOWN

0506 PM     HAIL             1 E FORT WAYNE          41.07N 85.12W 
08/08/2005  0.88 INCH        ALLEN              IN   EMERGENCY MNGR  

0550 PM     HAIL             TRI-LAKES               41.22N 85.48W 
08/08/2005  1.00 INCH        WHITLEY            IN   EMERGENCY MNGR  

            NICKEL TO QUARTER SIZE 

0620 PM     HAIL             6 SE GOSHEN             41.52N 85.75W 
08/08/2005  1.00 INCH        ELKHART            IN   AMATEUR RADIO   

0628 PM     HAIL             3 SE GOSHEN             41.55N 85.79W 
08/08/2005  1.25 INCH        ELKHART            IN   AMATEUR RADIO   

0635 PM     HAIL             3 SE GOSHEN             41.55N 85.79W 
08/08/2005  1.75 INCH        ELKHART            IN   TRAINED SPOTTER 

0720 PM     FLOOD            2 SE GOSHEN             41.56N 85.81W 
08/08/2005                   ELKHART            IN   BROADCAST MEDIA 

            US 33 WATER OVER ROAD 

0730 PM     FLASH FLOOD      5 SE GOSHEN             41.53N 85.77W 
08/08/2005                   ELKHART            IN   AMATEUR RADIO   

            COUNTY ROAD 31 AND US 33 AT FAIRFIELD HIGH SCHOOL ROAD 
            IMPASSABLE IN PLACES DUE TO WATER OVER ROAD


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ASTEVENS

Page created by TH on Monday August 8, 2005 10:30 PM EST