MESOSCALE PRECIPITATION DISCUSSION 0118
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
302 AM EDT SAT JUN 22 2013
 
AREAS AFFECTED...SOUTHERN MN...NORTHERN IA...SOUTHERN
WI...NORTHERN IL...SOUTHWEST MI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 220701Z - 221131Z
 
SUMMARY...A LONG BAND OF CONVECTION FROM THE IA/MN BORDER EASTWARD
TOWARDS THE WI/IL BORDER AND THE LOWER PENINSULA OF MI WILL LEAD
TO FLASH FLOODING.

DISCUSSION...A MESOSCALE BETA-SIZED BAND OF THUNDERSTORMS
STRETCHES ALONG A WINDING ROUTE FROM THE SD/IA/MN BORDER EASTWARD
ALONG THE IA/MN BORDER TOWARDS THE WI/IL BORDER AND IS ATTEMPTING
TO CROSS LAKE MICHIGAN INTO THE SOUTHWEST SECTIONS OF THE LOWER
PENINSULA OF MI.  IT IS FOCUSED JUST POLEWARD OF A WARM FRONTAL
BOUNDARY.  INFLOW AT THE 850 HPA LEVEL IS GENTLY CONVERGING WITH
WIND SPEEDS OF 45-50 KNOTS JUST AHEAD OF A SURFACE LOW NEAR THE
NE/SD/IA BORDER, WITH LESSER INFLOW THE FARTHER YOU GO EAST. 
SIGNIFICANT INSTABILITY REMAINS IN THE WARM SECTOR ACROSS IA, WITH
SATELLITE-DERIVED CAPE VALUES CONTINUING TO EXCEED 5000 J/KG. 
THIS STRONG LOW-LEVEL INFLOW AND INSTABILITY SHOULD KEEP THE
CONVECTIVE AREA ORGANIZED INTO THE MORNING HOURS.  THE AREA HAS
BROAD DIVERGENCE AHEAD OF AN UPPER LOW MOVING TOWARDS THE ID/MT
BORDER.  PRECIPITABLE WATER VALUES REMAIN IN THE 1.75-2 INCH
RANGE, WHICH IS OVER TWO STANDARD DEVIATIONS ABOVE THE NORM FOR
JUNE.  MUCH OF THIS REGION HAS EXPERIENCED RECENT RAINFALL OVER
THE PAST DAY OR SO, INCLUDING THE PAST SEVERAL HOURS, DEPRESSING
FLASH FLOOD GUIDANCE VALUES DOWN TO AROUND 2 INCHES/3 HOURS, WHICH
CONTINUED CELL TRAINING WILL EXCEED.  ADDITIONAL LOCAL RAINFALL
AMOUNTS OF 3-6 INCHES ARE POSSIBLE, WHICH WILL LEAD TO FLASH
FLOODING.

ROTH

ATTN...WFO...IWX...GRR...GRB...LOT...MKX...DVN...ARX...MPX...
DMX...FSD...

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

LAT...LON   42449649 43719622 44679341 44178975 43378764 42278603
            41278729 42399081 42979363 42449649