MESOSCALE PRECIPITATION DISCUSSION 0192
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
620 PM EDT SAT JUL 12 2014
 
AREAS AFFECTED...EXTREME SOUTHEAST NE...CENTRAL/SOUTHERN IA...FAR
NORTHERN MO...CENTRAL/NORTHERN IL...EXTREME SOUTHEAST WI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 122210Z - 130215Z
 
SUMMARY...CONVECTION WILL DEVELOP AND INCREASE IN COVERAGE AND
INTENSITY THE NEXT FEW HOURS OVER THE MIDWEST. POTENTIAL FOR
CELL-MERGERS AND TRAINING CONVECTION WILL HEIGHTEN THE FLASH FLOOD
POTENTIAL.

DISCUSSION...THE LATEST VIS SAT IMAGERY SHOWS AN EXPANDING CU/TCU
FIELD IN THE WARM SECTOR AHEAD OF A SYNOPTIC SCALE COLD
FRONT...AND AHEAD OF LARGER SCALE HEIGHT FALLS IMPINGING ON THE
UPPER MIDWEST FROM SRN CANADA. THE BOUNDARY LYR IS VERY WARM AND
UNSTABLE WITH SBCAPE VALUES AHEAD OF THE COLD FRONT OF 4000 J/KG
TO 4500 J/KG. MID LEVEL LAPSE RATES ARE NOT PARTICULARLY
STEEP...BUT STRONGER LOW LEVEL LAPSE RATES AHEAD OF THE FRONT
COUPLED WITH IMPROVING LARGER SCALE ASCENT ALOFT SHOULD BE ENOUGH
TO ALLOW CONVECTION TO DEVELOP AND EXPAND IN A LINEAR FASHION
SW/NE ALONG AND AHEAD OF THE FRONT.

THE CONVECTIVE MODE BASED ON THE AFOREMENTIONED SBCAPE VALUES AND
EFFECTIVE BULK SHEAR VALUES OF 35 TO 45 KTS SHOULD SUPPORT AN
INCREASE IN MULTI-CELLULAR AND SUPER-CELLULAR CONVECTION THE NEXT
COUPLE OF HOURS. THE ENVIRONMENT THIS EVENING WILL INITIALLY FAVOR
CELL-MERGERS...BUT SHOULD BECOME INCREASINGLY FAVORABLE FOR
TRAINING CONVECTION...ESP AFTER 00Z GIVEN THE MEAN LAYER FLOW
PARALLELING THE COLD FRONT...AND WITH THE NOSE OF A VERY MOIST 40
KT SWLY LOW LVL JET ARRIVING BY AROUND 00Z. 

ALL OF THE GLOBAL MODELS AND THE LATEST HI-RES MODELS STRONGLY
SUPPORT MORE ORGANIZED CONVECTION DEVELOPING OVER THE NEXT FEW
HOURS...WITH A HEIGHTENED RISK OF TRAINING CONVECTIVE LINE
SEGMENTS AFTER 00Z.

FFG VALUES ARE LOCALLY RATHER LOW...AND WITH PWATS EXPECTED TO
INCREASE TO NEAR 2 INCHES THIS EVENING...RAINFALL RATES OVER 2
INCHES/HR WILL BE EXPECTED. THIS COUPLED WITH POTENTIAL FOR
TRAINING CONVECTIVE BANDS WILL ELEVATE THE RISK FOR FLASH FLOODING.

ORRISON

ATTN...WFO...LOT...ILX...MKX...DVN...DMX...EAX...OAX...TOP...

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

LAT...LON   43138789 41628762 40798887 40419184 40199336 39949525
            40089624 40489644 40999521 41529379 42079239 42059101
            42098997 42348918 43138789 
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