MESOSCALE PRECIPITATION DISCUSSION 0281
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
204 PM EDT TUE JUN 30 2015
 
AREAS AFFECTED...PENNSYLVANIA...NORTHERN MARYLAND...SOUTHERN NY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 301804Z - 302304Z
 
SUMMARY...ISOLATED FLASH FLOODING POSSIBLE THIS AFTERNOON FROM OH
VALLEY INTO NORTHERN MID-ATL THIS AFTERNOON WITH DEVELOPING
CONVECTION.

DISCUSSION...VERY LOW FLASH FLOOD GUIDANCE EXISTS FROM PARTS OF
THE EASTERN OH VALLEY INTO THE NORTHERN MID-ATL REGION THIS
AFTERNOON... AS LOW AS A .25 INCH/HOUR. MEANWHILE... UPPER TROUGH
AXIS SWINGING THROUGH THE OH VALLEY AND LEE-SIDE TROUGH OVER
MID-ATL REGION IS BEGINNING TO TRIGGER CLUSTERS OF DEVELOPING
CONVECTION. THIS CONVECTION SHOULD THRIVE OVER THE NEXT SEVERAL
HOURS AND COULD BECOME MORE ORGANIZED... AS ATMOSPHERE IS RATHER
UNSTABLE SOUTH OF A QUASI-STATIONARY FRONT AND LOW LEVEL MOISTURE
CONTENT IS AOA 1.75 INCHES... ESPECIALLY EAST OF THE APPALACHIANS.
THE GREATEST CONCERN AT THE MOMENT IS FROM SWRN OH TO WESTERN PA
OR UP THE OH RIVER AND OVER EASTERN PA/NORTHERN MD... AHEAD OF THE
LEE-SIDE TROUGH. AN MCV OVER NORTHERN OH IS TRIGGERING AN INTENSE
LINE OF CONVECTION WITH THUNDERSTORM ACTIVITY EXPANDING DOWNSTREAM
INTO EASTERN OH/WESTERN PA. THIS ACTIVITY WILL SLOWLY PRESS
DOWNSTREAM AND WITHIN THE MOST CONCENTRATED CELLS... POSSIBLE
FLASH FLOODING WILL BE POSSIBLE WITH FFG VALUES AOA 1 INCH/HOUR.
ALSO... A NARROW LINE OF CONVECTION FROM BWI INTO EASTERN PA HAS
THE POTENTIAL FOR TRAINING AS FLOW FROM SURFACE TO 850/700MB IS
RATHER UNIFORM AND PARALLEL FOR THE SHORT TERM BEFORE FORWARD
PROPAGATION IS ANTICIPATED. THE FFG IS EXTREMELY LOW ACROSS THE
REGION AND THE RECIPE EXISTS FOR POTENTIAL LOCALIZED FLASH
FLOODING. 

MUSHER

ATTN...WFO...ALY...BGM...BUF...CLE...CTP...ILN...JKL...LMK...
LWX...OKX...PBZ...PHI...RLX...

ATTN...RFC...MARFC...NERFC...OHRFC...

LAT...LON   42477619 42067459 40997485 40227477 39527575 
            38977635 39667783 39677865 39188047 38538269 
            38448374 38728508 39228518 39728422 40198360 
            40968243 41438005