MESOSCALE PRECIPITATION DISCUSSION 0481
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
633 PM EDT THU JUL 21 2016
 
AREAS AFFECTED...CNTRL AND SRN WISCONSIN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 212230Z - 220250Z
 
SUMMARY...POSSIBLE TRAINING OF HEAVY RAIN ALONG AN OUTFLOW
BOUNDARY MAY ALLOW FOR 3 HOURLY RAINFALL RATES OF 2-3 INCHES
ACROSS PORTIONS OF WRN AND SRN WISCONSIN OVER THE NEXT SEVERAL
HOURS. REPEATING CELLS MAY LEAD TO FLASH FLOODING.

DISCUSSION...TRENDS IN RADAR OVER THE PAST COUPLE OF HOURS HAVE
SHOWN A GROWING COMPLEX OF THUNDERSTORMS OVER S-CNTRL
WISCONSIN...ALONG A REMNANT OUTFLOW BOUNDARY FORMED FROM
CONVECTION EARLIER TODAY. WHILE THE NEW COMPLEX HAS BEEN
PROGRESSING TOWARD THE SOUTHEAST AT 20-30 KTS...IT HAS PRODUCED A
NEW OUTFLOW BOUNDARY WITH THE WRN EDGE OF THIS BOUNDARY LOCATED
ALONG THE MISSISSIPPI RIVER NEAR THE TRI-STATE AREA OF MN/WI/IA.
SURFACE TEMPERATURES IN THE LOWER 90S AND DEWPOINTS IN THE UPPER
70S TO LOWER 80S HAVE CONTRIBUTED TO ESTIMATED MLCAPE VALUES OF
OVER 4000 J/KG TO THE SOUTH AND WEST OF THE NEWLY FORMED OUTFLOW
BOUNDARY...ALONG WITH PRECIPITABLE WATER VALUES NEAR 2 INCHES PER
RECENT GPS SITE MEASUREMENTS.

CURRENT AND FORECAST CORFIDI VECTORS ARE TOWARD THE SOUTHEAST AT
20-30 KTS...PARALLEL TO THE WRN EDGE OF THE NEWLY FORMED OUTFLOW
BOUNDARY. AS THE CONVECTION IN WISCONSIN CONTINUES TO FORWARD
PROPAGATE TOWARD THE SOUTHEAST...THE WRN EDGE OF THE OUTFLOW
BOUNDARY MAY STALL OR BE SLOW TO MOVE FARTHER WEST...AT LEAST IN
THE SHORT TERM. GIVEN LOW LEVEL INFLOW IS FROM THE SOUTHWEST INTO
AND ACROSS THE OUTFLOW BOUNDARY...REGENERATION OF CONVECTION IS
EXPECTED TO DEVELOP IN WRN WISCONSIN ALONG THE BOUNDARY...AND
PROPAGATE TOWARD THE SOUTHEAST WHILE NEW CONVECTION FORMS
UPSTREAM. THIS REPEATING NATURE OF RAINFALL MAY LEAD TO FLASH
FLOODING WITH 3 HOUR RAINFALL RATES OF 2-3 INCHES...WHICH WOULD
MATCH OR EXCEED CURRENT FLASH FLOOD GUIDANCE VALUES ACROSS THE
REGION. CONFIDENCE IS ONLY MODERATE IN THIS SETUP GIVEN A LACK OF
CONSENSUS FROM THE LATEST CAM GUIDANCE.

OTTO

ATTN...WFO...ARX...DVN...LOT...MKX...

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

LAT...LON   44349101 44339054 43918970 43348915 42758878 
            42118839 41668884 41638950 41859028 42149099 
            42879150 43639173 44129154