MESOSCALE PRECIPITATION DISCUSSION 0392
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
916 PM EDT TUE JUN 28 2016
 
AREAS AFFECTED...NORTHERN NJ...SOUTHEAST NY STATE 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 290115Z - 290515Z
 
SUMMARY...CONVECTION OVER NORTHERN NJ AND SOUTHEAST NY STATE WILL
TRACK EASTWARD... PRODUCING VERY HEAVY RAINFALL AND A SHORT TERM
FLASH FLOOD THREAT THROUGH THE LATE EVENING.

DISCUSSION...CONVECTION HAS BECOME REINVIGORATED IN AN AXIS OF
1.60 INCH PRECIPITABLE WATER AIR STRETCHING FROM EASTERN MD INTO
SOUTHEAST NY STATE. KDIX RADAR INDICATED HOURLY RAINFALL RATES
NEAR 2.00 INCHES WITH THE ACTIVITY MOVING ACROSS NORTHERN NJ
(THOUGH THERE HAVE BEEN SOME HAIL REPORTS WITH THE CONVECTION).
THE CONVECTION TAPPED INTO A RIBBON OF 500-1000 J/KG OF MLCAPE IN
A LOW LEVEL SOUTHERLY FLOW. 

A SHORT WAVE APPROACHING NEW ENGLAND IS PROVIDING LARGE SCALE
ASCENT FOR THE CONVECTION...WHICH SHOULD CONTINUE INTO THE LATE
EVENING/EARLY MORNING HOURS...BASED ON THE INSTABILITY AXIS
DEPICTED BY THE LATEST RAP. THIS SHOULD CONTINUE THE THREAT FOR
THUNDERSTORMS WITH HOURLY RAINFALL RATES THROUGH AT LEAST 04Z
ACROSS PORTIONS OF NORTHEAST NJ INTO NEARBY SOUTHEAST NY STATE. 

THE 23Z HRRR INDICATED THE POTENTIAL FOR LOCAL 2-3 INCH RAINFALL
AMOUNTS...AND BASED ON THE CURRENT DUAL POL RADAR RAINFALL
ESTIMATES...THESE AMOUNTS SEEM PLAUSIBLE. FOR THE MOST PART...ONE
AND THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE GENERALLY GREATER
THAN 2.00 INCHES. HOWEVER...ACROSS PORTIONS OF NORTHEAST NJ...ONE
AND THREE HOUR FLASH FLOOD VALUES AREAS AS LOW AS 1.00
INCHES...AND THIS POSES A FLASH FLOOD THREAT...GIVEN THE UPSTREAM
ACTIVITY. 

HAYES

ATTN...WFO...ALY...BGM...OKX...PHI...

ATTN...RFC...MARFC...NERFC...

LAT...LON   41697402 41557369 41187351 40757358 40527395 
            40467412 40417498 40977496 41097492 41367484 
            41657446