MESOSCALE PRECIPITATION DISCUSSION 0275
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1056 AM EDT FRI JUN 26 2015
 
AREAS AFFECTED...NORTHEAST MISSOURI....CENTRAL ILLINOIS...CENTRAL
INDIANA...SOUTHWEST OHIO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 261455Z - 262055Z
 
SUMMARY...DEVELOPMENT ALONG WARM FRONT/ DEFORMATION ZONE LIKELY TO
LEAD TO LONGER DURATION FLOODING. LOW FLASH FLOOD GUIDANCE AND
INCREASING CONVECTIVE DEVELOPMENT HAS POSSIBILITY OF SOME POCKETS
OF FLASH FLOODING. 

DISCUSSION...DEVELOPING UPPER LOW BEGINNING TO DEEPEN ACROSS
NORTHERN MISSOURI PER WATER VAPOR LOOP...WITH BROAD SHEAR AXIS
EXTENDING EASTWARD. THIS DEFORMATION AXIS IS COINCIDENT THROUGH A
DEEP LAYER JUST NORTH OF THE SURFACE WARM FRONT WHICH IS ANALYZED
FROM N MO TO KIND TO NEAR KCVG.  THE STRONG PVA NEAR THE UPPER LOW
AND WEST-SOUTHWESTERLY LOW LEVEL FLOW ACROSS SOUTHERN MISSOURI
INTO SOUTHERN ILLINOIS HAS A LONG AREA OF MAXIMIZED MOISTURE
CONVERGENCE ALONG THE FRONT FOR ENOUGH LIFT TO SUPPORT SOME
INITIAL CONVECTIVE DEVELOPMENT NEAR THE UPPER LOW INTO CENTRAL IL
AT THIS TIME. THESE CELLS ARE TAPPING WEAK TO MODERATE INSTABILITY
FOR CONVECTIVE GROWTH BUT CONSIDERING IT IS IN THE 500 J/KG RANGE
IT COULD BE EXHAUSTED OVER THE NEXT FEW HOURS. STILL INITIAL RATES
OF 1-1.5"/HR ARE LIKELY AND GIVEN THE VERY SLOW MOTIONS ALONG THE
DEFORMATION ZONE...TOTALS COULD COMPILE QUICKLY ENOUGH FOR SOME
SPOTS OF FLASHY CONDITIONS PARTICULARLY GIVEN THE LOW GUIDANCE AND
SATURATED SOILS HAVING 150-200 PERCENT ABOVE NORMAL RAINFALL OVER
THE PAST WEEK OR SO.  EVENTUALLY... THE LINE WILL CONGEAL AND LOSE
VERTICAL DEPTH AND FLOOD THREAT WILL DEVOLVE TO A LONGER DURATION
FLOOD THREAT. 

FURTHER EAST INTO INDIANA/SOUTHWEST OHIO...HI-RES CONVECTIVE
ALLOWING MODELS INDICATE A BIT MORE INSTABILITY BUT WITH LESSENED
UPPER LEVEL SUPPORT CELLS SHOULD DEVELOP MORE ISOLATED IN NATURE. 
SOME WEAK/ADDITIONAL SURFACE HEATING HAS ALLOWED FOR INCREASED
INSTABILITIES OF 1000-1500 J/KG PER RECENT RAP ANALYSIS...THIS
SHOULD MAKE FOR MORE EFFICIENT CELLS WITH 1.75" TPWS/NEARLY
SATURATED PROFILES...EXPECT RATES IN THE 1.75-2"/HR RANGE.  CELL
MOTIONS SHOULD BE SLOW TOWARD THE EAST NORTH OF THE WARM FRONT. 
GIVEN THE TRACK OF THE SURFACE CYCLONE/NEARLY UNIDIRECTIONAL FLOW
IN THE CLOUD BEARING LAYER PARALLEL TO THE FRONT...SOME TRAINING
IS ALSO LIKELY ALONG AND JUST NORTH OF THE FRONT INCREASING FLASH
FLOOD THREAT. 

GALLINA

ATTN...WFO...DVN...EAX...ILN...ILX...IND...IWX...LOT...LSX...

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

LAT...LON   40759050 40678767 40198491 39578423 39258456 
            39128585 39058727 39168893 39339057 39649169 
            40109252 40429193