MESOSCALE PRECIPITATION DISCUSSION 0924
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1043 AM EST SUN NOV 05 2017

AREAS AFFECTED...INDIANA...NRN/WRN OHIO...FAR SRN MICHIGAN

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 051542Z - 052100Z

SUMMARY...THE THREAT OF FLASH FLOODING WILL BEGIN TO INCREASE LATE
THIS MORNING AND EARLY THIS AFTERNOON...WITH THE MOST LIKELY AREA
TO EXPERIENCE HEAVY RAINFALL AND FLASH FLOODING FROM NORTHEAST
INDIANA INTO NORTHWEST OHIO. RAIN RATES PEAKING AROUND 1-2 IN/HR
WILL BE POSSIBLE.

DISCUSSION...CONVECTIVE DEVELOPMENT ALONG AND AHEAD OF A SURFACE
FRONT BECAME MUCH MORE WIDESPREAD BETWEEN 13Z AND 15Z...WITH
NUMEROUS THUNDERSTORMS ACROSS THE NORTHWEST PORTION OF INDIANA BY
15Z. THIS AREA OF CONVECTION SHOULD PERSIST INTO THE
AFTERNOON...WITH INDIVIDUAL CELL MOTIONS OFF TO THE NE/ENE...BUT
SOME BACKBUILDING ALSO POSSIBLE INTO A SWLY LOW-LEVEL JET. BETWEEN
NOW AND 21Z...NUMERICAL MODELS FOCUS THE NOSE OF A STRONG
LOW-LEVEL JET AND MOISTURE TRANSPORT MAX NEAR THE NORTHERN PORTION
OF THE INDIANA-OHIO BORDER. THIS IS ALREADY APPARENT IN REGIONAL
RADAR VWP OBSERVATIONS IN THE LOWEST 2KM AGL. THIS AREA OF MORE
FOCUSED LOW-LEVEL FORCING SHOULD ALSO COINCIDE WITH A STRONG
UPPER-LEVEL DIVERGENCE SIGNATURE ADVERTISED ON THE LATEST RAP
ANALYSIS AND 0-6HR FORECAST. THE NET RESULT SHOULD BE A PERIOD OF
HEAVY RAINFALL FROM INDIANA INTO OHIO OVER THE NEXT SEVERAL HOURS.

THE HIGHEST PROBABILITIES OF EXCEEDING 3 INCHES OF RAIN BY
21Z...ON BOTH THE 00Z HREF AND 12Z HRRR TIME LAGGED
ENSEMBLE...STRETCH FROM NEAR THE MUNCIE AND FORT WAYNE PORTION OF
THE I-69 CORRIDOR IN NORTHEAST INDIANA...TO NEAR THE FINDLAY TO
TOLEDO PORTION OF THE I-75 CORRIDOR IN NORTHWEST OHIO.
EXTRAPOLATION OF CURRENT RADAR TRENDS WOULD ALSO FAVOR THE SAME
AREA...WHICH ALSO HAS HIGHER NEAR-SURFACE SOIL MOISTURE LEVELS PER
THE HRRR ANALYSIS...AND RELATIVELY LOWER FFG VALUES AS COMPARED TO
POINTS FURTHER WEST IN INDIANA. THEREFORE...FLASH FLOODING APPEARS
MOST LIKELY FROM NE INDIANA INTO NW OHIO OVER THE NEXT SEVERAL
HOURS. HOWEVER...AS CONVECTION CONTINUES TO EXPAND AND NEW
DEVELOPMENT MAY OCCUR FURTHER WEST AND SOUTH...THE FLASH FLOODING
RISK MAY BEGIN TO EXTEND TO OTHER AREAS THIS AFTERNOON.

HI-RES MODELS SHOW RAIN RATES POTENTIALLY PEAKING AS HIGH AS 2
IN/HR...AND THIS SEEMS REASONABLE FOR CASES OF FAVORABLE CELL
MERGERS OR EXTENDED CELL TRAINING. FLASH FLOODING WOULD BE MOST
LIKELY IN AREAS THAT RECEIVE HEAVY RAIN RATES EXTENDED BEYOND 1
HOUR IN DURATION DUE TO TRAINING.

LAMERS

ATTN...WFO...CLE...DTX...GRR...ILN...IND...IWX...LOT...

ATTN...RFC...NCRFC...OHRFC...

LAT...LON   42328350 42208294 41808307 41638248 41688183
            41908123 41608112 41058146 40468265 39988365
            39568471 39238601 39248708 39398740 39868749
            40468719 41018678 41418629 41728569 41998469