MESOSCALE PRECIPITATION DISCUSSION 0461
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
433 PM EDT MON JUL 10 2017
AREAS AFFECTED...CENTRAL/SOUTHEAST OH...SOUTHWEST PA...NORTHERN WV
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 102030Z - 110100Z
SUMMARY...TRAINING AND BACK-BUILDING ON SOUTHWEST EDGE OF MCS MAY
LEAD TO POSSIBLE FLASH FLOODING CONDITIONS.
DISCUSSION...GOES-16 EXPERIMENTAL WV LOOP DEPICTS STRONG MCV
CROSSING CENTRAL OH WITH TRAILING TROF EXTENDING SW. AT THE
SURFACE THE OUTFLOW BOUNDARY FROM THE MCS LAYS GENERALLY FLAT E-W
ACROSS EAST CENTRAL OH TOWARD CMH BEFORE TURNING NW INTO N CENTRAL
IND. IT IS AT THE BASE OF THE BOUNDARY THAT SFC/BOUNDARY LAYER
FLOW IS GENERALLY CONFLUENT SUPPORTING SUFFICIENT
FORCING/CONVERGENCE FOR UPSTREAM DEVELOPMENT. THIS ENVIRONMENT
HAS ALSO BECOME GENERALLY UNCAPPED WITH MLCAPES TO 1500 J/KG WITH
SFC TDS IN THE LOW 70S AND A NARROW CORRIDOR OF INCREASED MOISTURE
ALONG THE OH RIVER VALLEY PER CIRA LAYERED TPW 850-700MB.
ADDITIONALLY SATELLITE IMAGERY ALSO DEPICTS AN UPSTREAM JET STREAK
DEPICTED BY MID-LEVEL BROKEN DEBRIS WITH NW-SE AXIS DIRECTED
ACROSS SE IND...THOUGH WEAK CURVATURE IN E CENTRAL OHIO SUGGESTS
SOME DIFFLUENCE...AND WITH THIS UPSTREAM EDGE SUGGESTING
ADDITIONAL SUPPORT FOR UPSTREAM REDEVELOPMENT. THE 500-1000MB
THICKNESS FIELD BECOMES INCREASINGLY DIVERGENT ACROSS S-SE OHIO
INTO WV SUGGESTING SLACKING PROPAGATION VECTORS WITH GOOD GRADIENT
OF MEAN CLOUD BEARING CELL MOTION VECTORS SUGGESTING WESTERLY FLOW
THAT WOULD MAY SUPPORT SOME SMALL SCALE TRAINING AS WELL
PARTICULARLY ALONG THE UPSTREAM EDGE. GIVEN RAIN RATES UP TO
2.0"/HR AND SOME TRAINING/REDEVELOPMENT A STREAK OR TWO OF 2-3"
RAINFALL TOTAL SWATHS ARE POSSIBLE LEADING TO POSSIBLE FF
PARTICULARLY IN URBAN CENTERS.
OTHERWISE FURTHER DOWNSTREAM...FORWARD MOTIONS ARE STRONG ENOUGH
(30-40KTS) THAT RAINFALL TOTALS ARE LIKELY TO BE 1-2" ACROSS SE OH
INTO N WV/SW PA OVER THROUGH 00-01Z TONIGHT. AS SUCH FF THREAT IS
NON-ZERO BUT IS LIKELY TO BE HIGHLY LOCALIZED OR LIMITED TO
TRADITIONALLY PRONE LOCATIONS.
GALLINA
ATTN...WFO...ILN...PBZ...RLX...
ATTN...RFC...OHRFC...
LAT...LON 40468014 39937957 39258000 38828061 38878182
39078257 39568383 40138323 40158186
Last Updated: 433 PM EDT MON JUL 10 2017