MESOSCALE PRECIPITATION DISCUSSION 0496
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
732 PM EDT THU SEP 17 2015
 
AREAS AFFECTED...SOUTHERN WI...NORTHERN IL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 172331Z - 180531Z
 
SUMMARY...TRAINING CONVECTION MAY PRODUCE LOCALLY HEAVY AMOUNTS OF
2-3 INCHES...WHICH MAY PRODUCE FLASH FLOODING.

DISCUSSION...A SHORTWAVE TROUGH ASSOCIATED WITH THE CONVECTION
CURRENTLY MOVING ACROSS WI AND NORTHERN IL INTO WI IS FORECAST TO
CONTINUE TO TRACK TO THE EAST ACROSS THE UPPER GREAT LAKES REGION
DURING THE EVENING HOURS.  HOWEVER CONVECTION IS EXPECTED TO
CONTINUE TO DEVELOP FURTHER UPSTREAM.  A LOW AMPLITUDE SHORTWAVE
EMBEDDED WITHIN A BROADER SCALE TROUGH IS FORECAST TO PRODUCE
MODEST HEIGHT FALLS ACROSS THE UPPER MIDWEST...ALLOWING THE COLD
FRONT CURRENTLY EXTENDING FROM EASTERN MN BACK THROUGH THE MID MO
VALLEY TO PUSH SLOWLY TO THE EAST THIS EVENING.  THE LATEST RAP
SUGGESTS THAT OUTFLOW FROM ONGOING CONVECTION ACROSS THE REGION
MAY REINFORCE A SLOW MOVING EAST-WEST ORIENTED EXTENDING FROM
EASTERN IA TO THE NORTHERN IL. MEANWHILE...30-40 KT LOW LEVEL FLOW
ACROSS THIS BOUNDARY AND AHEAD OF THE AFOREMENTIONED COLD FRONT
WILL CONTINUE TO SUPPORT HIGH PWS ACROSS THE HIGHLIGHTED REGION. 
THE LATEST MESOANALYSIS SHOWS 1.8-1.9 INCH PWS ACROSS THIS
REGION...WITH THE 21Z RAP SHOWING PWS REMAINING NEAR 2 INCHES
UNTIL THE COLD FRONT PASSES OVERNIGHT.  MODEST MUCAPE VALUES ARE
EXPECTED TO REBOUND TO OVER 1000 J/KG THIS EVENING.  THE 21Z HRRR
AND THE 12Z NSSL-WRF SHOW WEST-EAST TRAINING CONVECTION ACROSS THE
REGION...PRODUCING LOCALLY HEAVY AMOUNTS OF 2-3 INCHES BY 06Z. 
THESE AMOUNTS MAY PRODUCE FLASH FLOODING CONCERNS...ESPECIALLY
ACROSS AREAS ALREADY IMPACTED BY HEAVY RAINS.

PEREIRA

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

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

LAT...LON   43478909 43278816 43068785 42648776 42318785 
            42078856 41698946 41739003 42219017 42499026 
            42779054 43029018 43178976