445
AWUS01 KWNH 310401
FFGMPD
MAZ000-CTZ000-NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-WVZ000-310930-
MESOSCALE PRECIPITATION DISCUSSION 0338
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1200 AM EDT SAT MAY 31 2025
AREAS AFFECTED...FAR NORTHERN MID-ATLANTIC INTO SOUTHERN NY AND
SOUTHWESTERN NEW ENGLAND
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 310357Z - 310930Z
SUMMARY...AREAS OF HEAVY RAINFALL ARE EXPECTED TO IMPACT THE FAR
NORTHERN MID-ATLANTIC REGION INTO SOUTHERN NY AND SOUTHWESTERN NEW
ENGLAND THROUGH 09Z, LIKELY RESULTING IN SCATTERED AREAS OF FLASH
FLOODING. EMBEDDED PEAK HOURLY RAINFALL OF 1 TO 2 INCHES IS
EXPECTED ALONG WITH LOCALIZED TOTALS OF 2 TO 3 INCHES (PERHAPS UP
TO 4 INCHES) THROUGH 09 TO 10Z.
DISCUSSION...0330Z RADAR IMAGERY SHOWED THE HEAVIEST RAINFALL
OCCURRING OVER SOUTHEASTERN PA/NORTHERN DE AND SOUTHWESTERN NJ,
NEAR AN APPARENT MCV LOCATED JUST NORTHWEST OF ILG. MLCAPE FROM
THE 03Z SPC MESOANALYSIS WAS 500-1000 J/KG AND PWS RANGED FROM 1.2
TO 1.5 INCHES, WITH MRMS INDICATING HOURLY RAINFALL OF 1-2 INCHES.
BACK TO THE WEST, A WELL-DEFINED MID-LEVEL SHORTWAVE AND COMMA
HEAD/DEFORMATION AXIS WAS LOCATED OVER THE WV/MD PANHANDLES.
ONGOING HEAVY RAIN IN THE VICINITY OF THE PHILADELPHIA METRO IS
EXPECTED TO CONTINUE TRACKING NORTHWARD OVER THE NEXT FEW HOURS
INTO NORTHERN NJ AND SOUTHERN UPSTATE NY, FOLLOWING THE MESOSCALE
CIRCULATION AND SOUTHERLY FLOW AHEAD OF THE POTENT
SHORTWAVE/CLOSED LOW TO THE IMMEDIATE WEST. EMBEDDED HOURLY
RAINFALL OF 1-2 INCHES WILL FOLLOW THE SWATH OF HEAVY RAIN WITH
EMBEDDED THUNDERSTORMS.
BACK TO THE WEST, THERE IS GOOD SHORT TERM MODEL AGREEMENT WITH
THE TRACK OF THE SHORTWAVE INTO NJ THROUGH 10Z. A WELL-DEFINED
COMMA HEAD/DEFORMATION AXIS WILL SWING ACROSS THE EASTERN PA/MD
BORDER CONTAINING ANOTHER ROUND OF LOCALLY HEAVY RAINFALL. RAP
FORECASTS INDICATE THE POTENTIAL FOR THIS AXIS TO OVERLAP WITH A
SMALL REGION OF WEAK CAPE, PERHAPS AS HIGH AS 500-1000 J/KG. PEAK
HOURLY RAINFALL WITH THIS SECOND ROUND OF HEAVY RAIN COULD BE NEAR
1 INCH.
TOTAL RAINFALL THROUGH 09 OR 10Z OF 1 TO 3 INCHES IS LIKELY WITH
PERHAPS EMBEDDED TOTALS NEAR 4 INCHES. THESE RAINS WILL BE FALLING
ATOP PORTIONS OF THE DENSELY POPULATED URBAN CORRIDOR OF I-95 AND
INTO THE MORE SENSITIVE TERRAIN TO THE WEST OF I-95. SCATTERED
AREAS OF FLASH FLOODING ARE CONSIDERED LIKELY.
OTTO
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...ALY...BGM...CTP...LWX...OKX...PHI...
ATTN...RFC...RHA...TAR...NWC...
LAT...LON 42447343 41887302 41297316 40557391 39887478
39617602 39457686 39277774 39557852 40187849
40617793 41277623 41747545 42317440
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