MESOSCALE PRECIPITATION DISCUSSION 0126...CORRECTION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
807 PM EDT WED APR 19 2017

...CORRECTED FOR TYPO IN SUMMARY...

AREAS AFFECTED...SERN MN/NERN IA/SWRN WI

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

VALID 200004Z - 200600Z

SUMMARY...CONFIDENCE IS INCREASING REGARDING THE POTENTIAL FOR
FLASH FLOODING ACROSS PARTS OF SERN MN/NERN IA/SWRN WI. TRAINING
RAIN RATES OF 0.75-1.50 IN/HR ARE EXPECTED THROUGH 06Z.

DISCUSSION...00Z SURFACE OBSERVATIONS PLACED A 1006 MB SURFACE LOW
ALONG THE CNTRL NE/IA BORDER WITH A WELL DEFINED WARM FRONT
EXTENDING ESE...BECOMING STATIONARY ACROSS N-CNTRL IL. REGIONAL
RADAR IMAGERY SHOWED THAT ELEVATED CONVECTION WAS BECOMING MORE
NUMEROUS ACROSS SERN MN WITHIN AN AREA OF WEAK
INSTABILITY...100-500 MUCAPE...AND ESTIMATED PRECIPITABLE WATER
VALUES JUST OVER AN INCH PER A RECENT IAAM GPS GROUND SITE IN
N-CNTRL IA.

AS A MID-UPPER LEVEL SHORTWAVE APPROACHES FROM THE DAKOTAS EARLY
TONIGHT...THE SURFACE LOW WILL TRACK NEWD INTO NERN IA DRAGGING
THE WARM FRONT WITH IT. SWLY FLOW IN THE 850-700 MB LAYER OF 40-50
KT PER KDMX VAD WIND PLOT JUST AHEAD OF THE SURFACE LOW SHOULD
ALLOW FOR A MODEST INCREASE IN LOW LEVEL MOISTURE FOR THE
MISSISSIPPI VALLEY...INCREASING INSTABILITY TO NEAR 1000 J/KG
ACROSS THE SRN MN/WI BORDER BY 03Z...COMBINING WITH INCREASING
UPPER LEVEL DIFFLUENCE AND DIVERGENCE WITHIN THE RIGHT ENTRANCE
REGION OF A DEVELOPING JET STREAK FORECAST BY THE RAP. GIVEN
UNIDIRECTIONAL FLOW...TRAINING OF RAINFALL IS EXPECTED TO PRODUCE
RAINFALL RATES OF 0.75 TO 1.5 IN/HR. GIVEN LOW FLASH FLOOD
GUIDANCE VALUES OF 1-2 IN/HR AND 1.5 TO 2.5 INCHES IN 3 HOURS
ACROSS THIS REGION...SOME FLASH FLOODING IS EXPECTED. A GENERAL
MOVEMENT OF THE TRAINING REGION FROM WEST TO EAST SHOULD LIMIT
TOTAL RAINFALL TO SOME DEGREE.

OTTO

ATTN...WFO...ARX...DMX...GRB...MPX...

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

LAT...LON   45249061 45038966 44388958 43229105 42889256
            43029348 43969348 44999189