MESOSCALE PRECIPITATION DISCUSSION 0438
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
348 PM EDT MON AUG 10 2015
 
AREAS AFFECTED...WESTERN NEW YORK....WESTERN
PENNSYLVANIA...EASTERN OHIO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 101947Z - 110147Z
 
SUMMARY...PRE-FRONTAL ENVIRONMENT UNSTABLE ENOUGH FOR SHALLOW BUT
EFFICIENT CONVECTION WITH A TENDENCY FOR SLOW OR NEAR STATIONARY
MOTIONS.  

DISCUSSION...RADAR MOSAIC AND VIS IMAGERY  SHOW SHALLOW SCATTERED
CONVECTION DEVELOPING JUST EAST OF LAKE ERIE/ONTARIO INTO WESTERN
PA WHERE CLEARER SKIES ALLOWED FOR SOME INCREASED INSOLATION FOR
CAPES TO REACH 1000-1500 J/KG.  RAP AND SFC ANALYSIS SHOWS THE LOW
LEVEL CONFLUENCE/CONVERGENCE MAXIMIZED ALONG THE LAKES TO HELP
INITIATE THESE CELLS.  WIND FIELDS SHOULD REMAIN MAINLY FROM THE
SOUTHEAST ACROSS PA/NY AND MORE DUE SOUTH ACROSS W PA...STEADILY
INCREASING THROUGHOUT THE EARLY EVENING TO MAINTAIN THE
CONVERGENCE AND MOISTURE FLUX.  WV LOOP SHOWS MAIN UPPER LEVEL
TROF AXIS STILL REMAINS ACROSS EASTERN ONTARIO/LAKE HURON INTO THE
LP OF MICHIGAN...SO HEIGHT FALLS AND MAIN FRONTAL ZONE REMAIN
UPSTREAM...THIS ALLOWS FOR THE ENVIRONMENT FOR HUNG UP CELLS
DEPENDING ON DEPTH OF CONVECTIVE GROWTH...THOUGH MEAN FLOW THROUGH
THE MID- TROPOSPHERE SHOULD ALLOW FOR ANY CELLS NOT HUNG UP TO
PROGRESS NORTHEAST ALONG THE CONVERGENCE BOUNDARY...FOR SOME
POTENTIAL FOR TRAINING. GIVEN SHALLOW NATURE AND LIMITED MOISTURE
AT THIS TIME ACROSS NY...CELLS MAY NOT BE THE MOST EFFICIENT..BUT
STILL CAPABLE OF 1-1.5"/HR LEADING TO ISOLATED POCKETS OF FLASH
FLOODING POSSIBLE.  FURTHER SOUTH ACROSS E OH/PA...INCREASED
VERTICAL DEPTH OF MOISTURE NEARER THE MOISTURE POOL SHOULD ALLOW
FOR MORE EFFICIENCY BUT LIKELY A BIT MORE PROGRESSIVE WITH
INFLUENCE OF APPROACHING UPPER LEVEL JET.

LATER THIS EVENING...SHORTWAVE OVER SOUTHERN LP OF MI SHOULD
CONTINUE TO DEVELOP DROPPING SOUTH AND INCREASING LOW LEVEL INFLOW
AND MOISTURE FLUX. ADDITIONAL LEFT EXIT DYNAMICS SHOULD ALSO ALLOW
FOR BROADER SCALE ASCENT FOR EXPANDED AREA OF CONVECTIVE COVERAGE
AND VERTICAL DEPTH...ALL LEADING TO STRONGER CELLS AND RATES IN
THE 1.5-2"/HR RANGE PARTICULARLY OVER EASTERN OH/EASTERN PA INTO
SW NY.   

OVERALL THERE IS STRONG HI-RES MODEL CONSENSUS FOR THIS SCENARIO
WITH A NARROW STRIPE OF 2-4" TOTALS WITH POTENTIAL FOR HIGHER
POCKETS...PRESENTED EVEN IN THE SSEO MEAN QPF FIELDS BUT
REPRESENTED BY THE ARW/NMMB/12Z NAM-CONEST AND NSSL-WRF. 

GALLINA

ATTN...WFO...BGM...BUF...CLE...CTP...PBZ...

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

LAT...LON   43947613 43677556 43117580 42377684 41887765 
            40867850 40507893 40437958 40428033 40308140 
            40558182 40908184 41488195 42078065 42417972 
            42727910 43077905 43387879 43377758 43487696 
            43787632