MESOSCALE PRECIPITATION DISCUSSION 0017
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1012 AM EST THU JAN 12 2017
 
AREAS AFFECTED...NRN OHIO/NRN PA INTO CNTRL NY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 121511Z - 122100Z
 
SUMMARY...ADDITIONAL TRAINING OF RAINFALL FROM NRN OH INTO NRN PA
AND CNTRL NY WITH RAINFALL RATES UP TO ROUGHLY 0.5 IN/HR SHOULD
CONTINUE TO POSE A FLASH FLOOD THREAT THROUGH ABOUT 21Z.
ADDITIONAL RAINFALL TOTALS THROUGH 21Z ARE EXPECTED TO RANGE FROM
1-2 INCHES.

DISCUSSION...15Z SURFACE OBSERVATIONS PLACED A LOW JUST EAST OF
FDY...WITH A WAVY COLD FRONT EXTENDING SW TO NE THROUGH THE LOW
CENTER. FARTHER BACK TO THE WEST...A COMBINATION OF ILX AND SGF
12Z RAOB DATA AND HRRR ANALYSES INDICATED ELEVATED INSTABILITY OF
ROUGHLY 500+ J/KG LOCATED FROM SERN MO INTO SRN IL/IN JUST AHEAD
OF THE COLD FRONT. UNIDIRECTIONAL FLOW FROM THE WSW WAS SUPPORTING
AN AXIS OF MODERATE TO LOCALLY HEAVY RAINFALL FROM NRN OH INTO
NWRN PA. VAD WIND PLOTS SUPPORTED 850-700 MB WINDS OF ROUGHLY 50
KTS ACROSS THE AREA OF TRAINING WITH 60-65 KTS UPSTREAM WITHIN THE
HIGHER INSTABILITY AXIS. 

AS A SHORTWAVE NOTED TO BE APPROACHING LOWER MI AT 15Z CONTINUES
TO ADVANCE ENEWD OVER THE NEXT 6 HOURS...WEAK UPPER DIFFLUENCE
WILL OVERSPREAD PORTIONS OF NRN PA INTO NY AS THE COLD FRONT
ADVANCES EAST ACROSS THE LOWER OH VALLEY. STRONGER LOW LEVEL FLOW
UPSTREAM IS FORECAST TO APPROACH PA/NY IN THE 18-21Z TIME FRAME.
ELEMENTS OF TRAINING ARE EXPECTED TO CONTINUE IN THE SHORT TERM
ACROSS THE OH/PA STATE LINE...WHILE MOVING DOWNSTREAM ALONG THE
NY/PA BORDER OVER THE NEXT 2-3 HOURS. 

HRRR AND EXPERIMENTAL HRRR FORECASTS HAVE  TRENDED WETTER OVER
THEIR PAST 4 CYCLES...AND INDICATE A QUICK MOVING LINE OF SHOWERS
WILL EXPAND ALONG THE COLD FRONT THROUGH 17Z...WITH THESE RAINS
MOVING OVER SOME OF THE SAME LOCATIONS WHICH RECEIVED HEAVIER
RAINFALL EARLY THIS MORNING OVER OH/PA. GIVEN FLASH FLOOD GUIDANCE
IS AN INCH OR LESS IN 3 HOURS ACROSS MUCH OF THE MPD THREAT
AREA...CONTINUED FLASH FLOODING IS POSSIBLE UNTIL THE COLD FRONT
PASSES THROUGH MUCH OF THE REGION BY 21Z.

OTTO

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

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

LAT...LON   42807499 41897468 41117737 40307882 39967994 
            39948079 40018172 40258250 40668266 41168246 
            42068008 42227889 42597664