MESOSCALE PRECIPITATION DISCUSSION 0076
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
402 PM EDT MON MAR 20 2017

AREAS AFFECTED...IN...KY...OH...WV

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 202001Z - 210201Z

SUMMARY...ELEVATED CONVECTION CONTINUES TO EXPAND THIS AFTERNOON
ACROSS CENTRAL IN AND MAY POSE AN ISOLATED FLASH FLOOD RISK AS THE
THUNDERSTORM COMPLEX MOVES SOUTHEASTWARD INTO THIS EVENING.

DISCUSSION...THE COMBINATION OF VERY STEEP MID LEVEL LAPSE RATES
AND INCREASING LOW LEVEL MOISTURE TRANSPORT IS COMBINING TO
PRODUCE A VERY FAVORABLE ENVIRONMENT FOR ELEVATED CONVECTION THIS
AFTERNOON ACROSS CENTRAL IN. MODEL SOUNDINGS SHOW THAT THIS
ACTIVITY IS LIKELY ROOTED AROUND 800 MB...WITH THE RAP ALSO
SHOWING AN INCREASE IN MOISTURE TRANSPORT/CONVERGENCE AT THIS
LEVEL. MOISTURE TRANSPORT/CONVERGENCE AT THIS LEVEL IS EXPECTED TO
MAINTAIN IN INTENSITY...OR EVEN SLIGHTLY INCREASE...SHIFTING
SOUTHEASTWARD WITH TIME. WESTERLY MID LEVEL FLOW WILL ALSO LIKELY
CONTINUE TO ADVECT STEEP MID LEVEL LAPSE RATES SOUTHEASTWARD. THUS
WOULD EXPECT THIS CONVECTIVE COMPLEX TO MAINTAIN ITSELF AS IT
MOVES SOUTHEAST ACROSS SOUTEHRN OHIO AND INTO PORTIONS OF SOUTHERN
WV. THEREAFTER WOULD EXPECT TO SEE WEAKENING AS THE ACTIVITY MOVES
INTO VA AND AWAY FROM THE STEEPER LAPSE RATES AND BETTER ELEVATED
INSTABILITY.

INDIVIDUAL CELL MOTION CONTINUES TO BE PRETTY PROGRESSIVE. HOWEVER
CELL MOTIONS ARE EXHIBITING A LARGE COMPONENT PARALLEL TO THE 800
MB MOISTURE CONVERGENCE AXIS...WHICH IS ALLOWING FOR SOME
NORTHWEST TO SOUTHEAST TRAINING TO OCCUR. THIS SHOULD ALLOW FOR
POCKETS OF RAINFALL TOTALS APPROACHING 1-1.5" IN AN HOUR...WHICH
MAY BEGIN TO LOCALLY EXCEED THE RELATIVELY LOW FLASH FLOOD
GUIDANCE OVER PORTIONS OF THE AREA. OVERALL THIS IS NOT AN IDEAL
BACKBUILDING SETUP...AND THE CONVECTIVE COMPLEX IS PROGRESSIVE AS
A WHOLE. THUS CURRENTLY NOT ANTICIPATING SIGNIFICANT FLASH FLOOD
ISSUES...HOWEVER THE LOW FFG AND MARGINAL TRAINING SETUP DOES OPEN
UP THE POTENTIAL FOR A FEW FLASH FLOOD ISSUES AS WE HEAD THROUGH
THE AFTERNOON HOURS.

CHENARD

ATTN...WFO...ILN...IND...IWX...JKL...RLX...

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

LAT...LON   40658578 40208391 39848306 39558205 39038115
            38228089 37618120 38128277 38608411 39188536
            39818641 40208681 40578673