MESOSCALE PRECIPITATION DISCUSSION 0613
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
551 PM EDT SUN AUG 28 2016
 
AREAS AFFECTED...EASTERN OH AND WESTERN/CENTRAL PA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 282120Z - 290320Z
 
SUMMARY...DEVELOPING LINE OF CONVECTION EXTENDING FROM NORTH
CENTRAL PA TO NORTHEASTERN OH WILL SLOWLY SINK SOUTH THROUGH THE
EVENING AND POSSIBLY RESULT IN LOCALIZED FLASH FLOODING.

DISCUSSION...DEEP TROPICAL MOISTURE IS IN PLACE AHEAD OF THE
SURFACE COLD FRONT AND PRE-FRONTAL TROUGH MOVING SOUTH AND EAST
THROUGH THE GREAT LAKES/EASTERN OH VALLEY. THIS MOISTURE CONTENT
IS AVERAGING 1.5 TIMES ABOVE STANDARDIZED ANOMALIES AND RANGING
FROM 1.75 TO 2 INCH PWS. THE DIURNAL HEATING AND NARROW
CONVERGENCE NEAR THE PRE-FRONTAL TROUGH HAS RESULTED IN A
DEVELOPING LINE OF CONVECTION... WHILE A PERSISTING CLUSTER
DOWNSTREAM SITS OVER CENTRAL PA. THIS ACTIVITY IS EXPECTED TO
GRADUALLY DROP SOUTH AND EAST AND POSSIBLY PRODUCE 1-2 INCH PER
HOUR RAIN RATES. IN FACT IN THE ASSOCIATED GRAPHIC... 850MB WINDS
ARE GENERALLY 10 KTS OF LESS TO SUGGEST VERY SLOW MOVING
CONVECTIVE RAINS. 1 HOUR FFG VALUES HOVER AROUND 1.5 INCHES AND
THIS IS DEFINITELY ACHIEVABLE. THE HI-RES GUIDANCE HAS SOME SIGNAL
ON ISOLATED INTENSE RAINFALL AMOUNTS AND 20Z HRRR SUGGEST LATER
THIS EVENING POSSIBLE MERGING OF CELLS AND SLIGHT UNI-DIRECTIONAL
FLOW. GIVEN THE OVERALL SETUP AND TERRAIN OF HILLS AND VALLEYS
ACROSS WESTERN/CENTRAL PA... FLASH FLOODING IS POSSIBLE.


MUSHER

ATTN...WFO...CLE...CTP...ILN...PBZ...RLX...

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

LAT...LON   41857804 40857780 39947857 39628095 38958244 
            39648317 40988213 41188149 41178065