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Excessive Rainfall Discussion
 
(Caution: Version displayed is not the latest version. - Issued 0130Z Apr 21, 2015)
 
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Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
930 PM EDT MON APR 20 2015

...VALID 03Z TUE APR 21 2015 - 00Z WED APR 22 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


...NORTHERN NEW ENGLAND...

A BROAD UPPER TROUGH REMAINS CENTERED ALONG THE MS VALLEY WITH A
DEEP UPPER LOW POSITIONED NEAR THE SOUTHERN MANITOBA/ONTARIO
BORDER.  A SURFACE LOW...ANCHORING A LARGE OCCLUDED
FRONT...CONTINUES TO LIFT INTO NORTHERN MICHIGAN.  WARM ADVECTION
PRECIPITATION MOVING ACROSS SOUTHERN NEW ENGLAND THIS AFTERNOON IS
EXPECTED TO CONTINUE SPREADING TO THE NORTH AND EAST AS SEVERAL
SHORTWAVES EMBEDDED WITHIN THE LEADING EDGE OF THE LARGER TROUGH
LIFT THROUGH THE EASTERN U.S.  MODERATE TO LOCALLY HEAVY RAINS ARE
EXPECTED TO DEVELOP ALONG THE NORTHERN NEW ENGLAND COAST BACK INTO
THE OROGRAPHICALLY FAVORED INTERIOR REGIONS LATER TODAY AS STRONG
SOUTHEASTERLY FLOW DEVELOPS AHEAD OF A TRIPLE POINT LOW DEVELOPING
NEAR THE NORTHERN MID-ATLANTIC/SOUTHERN NEW ENGLAND COAST THIS
EVENING. COINCIDING WITH 50+ KT 850 MB WINDS...PWS EXCEEDING AN
INCH ACROSS SOUTHERN NEW ENGLAND AND ALONG THE NORTHERN NEW
ENGLAND COAST ARE EXPECTED TO SUPPORT MODERATE TO LOCALLY HEAVY
RAINS.  VERY LIMITED INSTABILITY HOWEVER IS EXPECTED TO HAMPER
RAINFALL RATES AND THEREFORE THE THREAT FOR WIDESPREAD RUN OFF
CONCERNS.  HOWEVER...GIVEN THE POTENTIAL FOR RAINFALL
ACCUMULATIONS OF 1-2 INCHES BY TUE MORNING...COMBINED WITH MELTING
SNOWS OVER THE MOUNTAINS...LOCALIZED RUNOFF CONCERNS CANNOT BE
RULED OUT...ESPECIALLY  ALONG THE NORTHERN NEW ENGLAND COAST BACK
INTO THE MOUNTAINS OF NEW HAMPSHIRE AND MAINE. 

PEREIRA