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WPC Met Watch

 
Mesoscale Precipitation Discussion: #0270
(Issued at 844 AM EDT WED AUG 13 2014 )

MPD Selection
 


Graphic for MPD #0270
 
MESOSCALE PRECIPITATION DISCUSSION 0270...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
844 AM EDT WED AUG 13 2014
 
CORRECTED FOR GEOGRAPHICAL REFERENCE

AREAS AFFECTED......SOUTHERN NEW ENGLAND... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 131207Z - 131607Z
 
SUMMARY...TORRENTIAL RAIN HAS ENTERED A WEAKENING PHASE...WITH
REORGANIZATION AND SOME RE-INTENSIFICATION EXPECTED BY LATE
MORNING AND AFTERNOON. 

DISCUSSION...EXTREME RAINFALL RATES EXCEEDING 4 TO 5 INCHES PER
HOUR IN SOME LOCATIONS ACROSS CENTRAL LONG ISLAND AND SOUTHERN
CONNECTICUT HAVE BEGUN TO WANE IN RESPONSE TO INITIAL DEVELOPMENT
OF THE BOUNDARY LAYER WHICH IS COUPLING THE LOW LEVEL JET AND
CAUSING IT WEAKEN.  MEANWHILE...WATER VAPOR AND INFRARED SATELLITE
SHOW SLIGHTLY DRIER AIR ENTRAINING INTO THE ONCE QUASI-STEADY LINE
OF TORRENTIAL RAIN WHOSE BALANCE HAS NOW BEEN DISRUPTED CAUSING
THE RAIN RATES TO LOWER.

HI-RES AND GLOBAL GUIDANCE ARE UNANIMOUS IN ALLOWING THE LOW NEAR
NYC TO LIFT NORTHWARD INTO SOUTHERN NEW ENGLAND THROUGH 18Z WHICH
FAVORS A GRADUAL SHIFT IN THE MOST FAVORABLE CONDITIONS FOR HEAVY
RAINFALL INTO PORTIONS OF CONNECTICUT...ROAD ISLAND...AND
MASSACHUSETTS...WITH THE DEFORMATION ZONE OR INVERTED TROUGH
IMMEDIATELY NORTH OF THE LOW CONSIDERED THE MOSTLY FAVORABLE ZONE.
 GIVEN THE VERY MOIST CONDITIONS...RAIN RATES OF 1 TO 2 INCHES PER
HOUR MAY RESUME OR DEVELOP DEVELOP ELSEWHERE ACROSS PORTIONS OF
SOUTHERN NEW ENGLAND BY LATE MORNING AND AFTERNOON. 
FINALLY...SCATTERED CONVECTION IS EXPECTED TO FORM ALONG A SLOW
MOVING COLD FRONT ENTERING FROM THE WEST THIS AFTERNOON...ALTHOUGH
RAIN WITH THIS SYSTEM WILL BE LESS AND SHORTER.

JAMES

ATTN...WFO...GYX...BOX...OKX...ALY...

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

LAT...LON   40797388 41827351 42617270 43027154 42737025 41626998
            40697155 40337331 40797388 


Last Updated: 844 AM EDT WED AUG 13 2014
 

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Page last modified: Friday, 21-Feb-2014 14:24:37 GMT