MESOSCALE PRECIPITATION DISCUSSION 0260
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
805 AM EDT MON JUN 22 2015
 
AREAS AFFECTED...NORTHERN IA...SOUTHERN MN...SOUTHWEST
WI...EXTREME NORTHWEST IL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 221200Z - 221600Z
 
SUMMARY...INTENSE MCC CONTINUES TO FOSTER VERY HEAVY RAINFALL
RATES AND WILL FAVOR AT LEAST SOME LOCALIZED FLASH FLOODING
THROUGH THE MORNING HOURS.

DISCUSSION...AN EXTREMELY COLD-TOPPED MCC WITH NUMEROUS
OVERSHOOTING TOPS AND A STRONGLY SEVERE MODE CONTINUES TO ADVANCE
RAPIDLY EAST ACROSS THE UPPER MIDWEST THIS MORNING. THERE HAS BEEN
SOME ADDITIONAL CLOUD TOP COOLING JUST OVER THE LAST HOUR...AND
THE EXPERIMENTAL GLD-LIGHTNING DENSITY PRODUCT SHOWS A CONTINUED
UPTICK IN STRIKE ACTIVITY WHICH SUGGESTS EVEN STRONGER UPDRAFT
INTENSITY/FORCING.

THIS CONVECTIVE COMPLEX IS LIKELY TO BE LONG-LIVED GIVEN THE LEVEL
OF STRONG LOW LEVEL JET ENERGY AND INSTABILITY FEEDING INTO
SOUTHWESTERN FLANK OF THE CONVECTIVE MASS. SOUTHWEST 850 MB FLOW
THE LAST COUPLE OF HOURS HAS BEEN PEAKING CLOSE TO 60 KTS OVER
WESTERN IA AND MUCAPE VALUES OF 3000 TO 4000 J/KG ARE NOTED OVER
CENTRAL/SOUTHERN IA.

OVER THE NEXT FEW HOURS...WHILE THERE WILL CONTINUE TO BE A FOCUS
ON THE SEVERE NATURE OF THE COMPLEX...THERE WILL BE SOME GROWING
CONCERNS FOR FLASH FLOODING OVER ESPECIALLY NORTHERN IA AND
SOUTHEAST MN WHERE CELL-MERGERS AND TRAINING CELLS ARE EXPECTED TO
OCCUR. RAINFALL RATES HAVE BEEN AS HIGH AS 2 TO 2.5 INCHES/HR AND
THIS WILL CONTINUE THROUGH THE MORNING.

HI RES MODEL OUTPUT VIA THE LATEST HRRR AND THE 00Z ARW SUGGESTS
RAINFALL AMOUNTS OF 3 TO 5 INCHES WILL BE POSSIBLE WITH THE EVENT
FOR PARTS OF NORTHERN IA/SOUTHEAST MN AND POSSIBLY SOUTHWEST WI
BEFORE THE MCC EXITS THE REGION. THIS COUPLED WITH SUCH INTENSE
SHORT-TERM RATES WILL FAVOR THE RISK FOR AT LEAST LOCALIZED FLASH
FLOODING.

ORRISON

ATTN...WFO...ARX...DMX...DVN...FSD...LOT...MKX...MPX...

ATTN...RFC...NCRFC...

LAT...LON   44329239 44289100 43818947 43208877 42648870 
            42228928 42339106 42349229 42239394 42339487 
            42699509 43299434 44009351