MESOSCALE PRECIPITATION DISCUSSION 0176
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
337 AM EDT FRI JUL 04 2014
 
AREAS AFFECTED......EASTERN MD/DE/NJ/SOUTHEAST NY/WESTERN CT 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 040737Z - 041337Z
 
SUMMARY...THE RISK FOR FLASH FLOODING WILL INCREASE THROUGH THE
LAST NIGHT AND EARLY/MID MORNING AS HURRICANE ARTHUR INTERACTS
WITH MULTIPLE FRONTAL BOUNDARIES.

DISCUSSION...A COLD FRONT ALONG THE PA/NJ BORDER AND AN INVERTED
FRONT EXTENDING SOUTHWARD FROM THE CHESAPEAKE BAY ARE EXPECTED TO
SLOWLY MERGE AND THEN CONSOLIDATE WITH A STRENGTHENING STATIONARY
FRONT ALONG THE NJ SHORE BETWEEN THE LATE NIGHT AND EARLY/MID
MORNING AS HURRICANE ARTHUR APPROACHES.

RADAR SHOWS RAINFALL TO BE HEAVIER AND MORE PERSISTENT THAN MOST
HI-RES GUIDANCE.  OTHER THAN THE HWRF RUNS GENERATED FOR
ARTHUR...OTHER HI-RES GUIDANCE IS AS MUCH AS 15 TO 30 MB TOO WEAK
WITH ARTHUR'S PRESSURE...AND THUS ARE LIKELY TOO WEAK WITH ITS
ASCENT AND INTERACTION WITH THE FRONTS.  THE KDOX RADAR SHOWS THE
SUBTLE BUT SLOWLY DEVELOPING FRONT NEAR THE NJ SHORE WITH A
SHALLOW COLD POOL AT THE SURFACE AND STEADY BACKING WINDS THROUGH
A DEEP LAYER ABOVE.  GIVEN THAT ARTHER IS EXPECTED TO CONTINUE
MOVING TOWARD AN ALREADY FAVORABLE REGION FOR HEAVY
RAINFALL...FLASH FLOODING SHOULD BECOME INCREASINGLY PROBABLE AS
THESE SYSTEMS INTERACT.

THE NEARLY SATURATED ENVIRONMENT AND SLIGHTLY VEERING WIND
PROFILES FAVOR TRAINING DEVELOPMENT...WITH HOURLY RATES POSSIBLY
NEARING 1.5 TO 2 INCHES AND LASTING FOR 2 OR MORE HOURS.

JAMES

ATTN...WFO...OKX...ALY...PHI...AKQ...LWX...

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

LAT...LON   37867695 38857656 40057575 41057465 42027386 41897304
            40477330 38967397 37817498 36897612 36907685 37867695