Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 200650
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
247 AM EDT MON APR 20 2015

...VALID 06Z MON APR 20 2015 - 12Z TUE APR 21 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


...EASTERN PA AND NJ NORTHEASTWARD INTO NEW ENGLAND...

SEVERAL STREAMS OF MID/UPPER LEVEL S/WV ENERGY WILL KEEP THINGS
WET THRU THE MID ATLANTIC AND NEW ENGLAND STATES THIS PERIOD..AND
ESPECIALLY SO FROM EASTERN PA/NEW JERSEY INTO NEW ENGLAND.
SOUTHERN BRANCH S/WV ENERGY NOW LIFTING INTO THE MID TO UPPER OH
VALLEY..FOLLOWED CLOSELY BY THE WELL DEFINED S/WV APPROACHING THE
CONFLUENCE OF THE MS AND OH RIVER VALLEYS..ARE BEING PRECEDED BY A
STRONG ATLANTIC INFLOW/LOW LEVEL WARM AIR ADVECTION AND MOISTURE
ADVECTION PATTERN..WHICH IS CURRENTLY SUPPORTING THE MODERATE TO
HEAVY RAINS VICINITY OF THE MID ATLANTIC STATES.  AS THESE S/WVS
CONTINUE TO LIFT NORTH-NORTHEASTWARD THRU THE LATE AFTERNOON
HOURS..THE STRONGER ATLANTIC INFLOW/MOISTURE INFLOW WILL ALSO LIFT
UP THE NORTHERN MID ATLANTIC AND NEW ENGLAND STATES..TAKING THE
MODERATE TO HEAVY RAINS WITH IT.  THIS BETTER INFLOW IS LIKELY TO
SLOW DOWN CONSIDERABLY INTO ME LATER IN THIS PERIOD..AS THE
NORTHERN STREAM H5 TROF CONTINUES TO DIG INTO THE GREAT LAKES AND
MAINTAINS A NEARLY SOUTHERLY
MID/UPPER LEVEL FLOW REGIME INTO NEW ENGLAND.  HIGHER MOISTURE
AVAILABILITY IN THE MORE PROGRESSIVE ATLANTIC INFLOW REGIME THRU
THE NORTHERN MID ATLANTIC AND SOUTHEASTERN NEW ENGLAND AREAS
SHOULD SUPPORT SOME 1-2 INCH RAINS HERE..WHILE LESS MOISTURE
AVAILABILITY AND A SLOWER INFLOW REGIME INTO PARTS OF ME SUPPORT
SIMILAR 1-2 INCH RAINS ESPECIALLY ALONG THE ME COAST.  BIGGEST
THREAT OF RUNOFF PROBLEMS WITH THIS RAINFALL PATTERN MOST LIKELY
IN THE URBAN NEW YORK CITY AREA WITH THE QUICK BURST OF HEAVY
RAINFALL THIS MORNING..OTHERWISE THE POTENTIAL 1-2 INCHES OF RAIN
EXPECTED FARTHER NORTH UP INTO ME SHOULD OCCUR OVER A LONGER
DURATION WHICH SHOULD SIGNIFICANTLY LESSEN ANY FLASH FLOOD THREAT.

TERRY
$$





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