MESOSCALE PRECIPITATION DISCUSSION 0345
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1112 PM EDT SAT JUL 11 2015
 
AREAS AFFECTED...SOUTHERN IOWA...NORTHEAST MISSOURI...WESTERN AND
SOUTHERN ILLINOIS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 120312Z - 120745Z
 
SUMMARY...ONGOING TRAINING CELLS LIKELY TO CONTINUE FLASH FLOOD
THREAT IN NEAR TERM.  FLOODING SITUATION BECOMES MURKIER PAST 07Z. 

DISCUSSION...INCREASING SURFACE AND DEEP MOISTURE CONVERGENCE
ACROSS NORTHERN MISSOURI INTO SOUTHERN IOWA...ALONG WITH UPPER
LEVEL DIFFLUENT FLOW NEARING THE TOP OF THE APPROACHING
SUBTROPICAL RIDGE IS ALLOWING FOR CONTINUED CONVECTIVE GROWTH AND
EXPANSION FURTHER NORTH AND WEST ALONG THE FRONTAL ZONE INTO
SOUTHERN IOWA WHERE LAST NIGHTS EVENT LOWERED FLASH FLOOD
GUIDANCE.  THIS MAY BE ABLE TO TAP THE AREA OF EXTREMELY HIGH
INSTABILITIES WITH 3000+ J/KG CAPES.  CELL MOTION VECTORS COMBINED
WITH PROPAGATION...SHOULD ALLOW FOR CELLS TO TRAIN TOWARD THE
SOUTHEAST ALONG THE FRONTAL BOUNDARY.  GIVEN LOW LEVEL 850MB
TRANSPORT IS NEARLY PERPENDICULAR TO THE FRONT IN THE NEAR TERM...
THESE CELLS MAY GET AN EXTRA BOOST TO MAINTAIN EFFICIENT RAINFALL
RATES DUE TO THE INCREASED FLUX.   ALL ANALYSIS SIGNS POINT TO THE
POTENTIAL FOR CONTINUED FLASH FLOOD THREAT TO BE LIKELY ACROSS
THIS REGION OVER THE NEXT 2-4HRS... WITH A POTENTIAL OF
SIGNIFICANT FLASH FLOODING IF THE UPSTREAM EDGE OF THE CONVECTION
CAN REMAIN CONVECTING ACROSS SOUTHERN IOWA/NE MISSOURI THROUGHOUT
THE MORNING.

HI-RES CONVECTION ALLOWING MODELS NEARLY UNILATERALLY SUGGEST THAT
UPSTREAM CONVECTIVE REDEVELOPMENT WILL BE LESS LIKELY BEYOND 07Z
AS ONE LAST CONVECTIVE CLUSTER TO TREK SOUTHEAST THROUGH THE EARLY
MORNING HOURS. THOUGHTS ON THIS DECREASING TREND FOCUSES ON THE
REDUCTION OF UPPER LEVEL DIVERGENCE AND SLACKING MID-LEVEL FLOW
(700-500MB) AS APEX OF SUBTROPICAL RIDGE REACHES EASTWARD...THIS
APPEARS MORE LIKELY A SCENARIO BUT GIVEN UNCERTAINTY OF THE
EVOLUTION THIS MPD WILL BE LIMITED FOR 4 HOUR DURATION FOR THE
MOST LIKELY TIME FRAME OF FLASH FLOODING...WHILE REASSESSING THE
SITUATION AND NEW HI-RES MODEL RUNS TOWARD THE 06-07Z TIME FRAME. 
 

GALLINA

ATTN...WFO...DMX...DVN...EAX...ILX...LSX...

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

LAT...LON   41159260 40638991 39908848 39228832 38608900 
            38509011 39589174 40779338