MESOSCALE PRECIPITATION DISCUSSION 0316
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
251 PM EDT MON JUN 12 2017

AREAS AFFECTED...PORTIONS OF MN...IA...WI

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

VALID 121850Z - 130050Z

SUMMARY...EXPANDING CONVECTION AND RESULTANT CELL MERGERS WILL
POSE AN ISOLATED TO SCATTERED FLASH FLOOD RISK OVER THE NEXT
SEVERAL HOURS ACROSS PORTIONS OF SOUTHEAST MN...FAR NORTHEAST IA
AND SOUTH CENTRAL WI.

DISCUSSION...AS OF 18Z A CONVECTIVE COMPLEX CONTINUES TO PROGRESS
NORTHEASTWARD AT A DECENT CLIP ACROSS SOUTHERN MN. THIS ACTIVITY
IS MOVING NEAR AND JUST NORTH OF A WEST TO EAST BOUNDARY
STRETCHING ACROSS THE AREA. RECENT RUNS OF THE HRRR SEEM TO HAVE
FINALLY CAUGHT ON TO THIS ACTIVITY...WITH THE EVOLUTION SEEN IN
RECENT HRRR RUNS SEEMING REASONABLE. SHOULD SEE ADDITIONAL
CONVECTION FORM OUT AHEAD OF THIS COMPLEX ALONG AN AXIS OF 850MB
MOISTURE CONVERGENCE JUST NORTH OF THE SURFACE BOUNDARY. THIS
SCATTERED ACTIVITY AHEAD OF THE MAIN CONVECTIVE LINE SHOULD EXTEND
FROM SOUTHERN MN INTO PORTIONS OF SOUTEHRN/CENTRAL WI. MEANWHILE
THE LINE OF STORMS OVER SOUTH CENTRAL MN AS OF 18Z WILL CONTINUE
TO MOVE EAST NORTHEAST ALONG/NEAR THE MLCAPE GRADIENT. MEAN WIND
FIELDS AND CORFIDI VECTORS SUGGESTS THIS LINE SHOULD EVENTUALLY
TURN MORE EASTWARD AS IT APPROACHES WI.

IN GENERAL THE PROGRESSIVE NATURE OF THE CONVECTIVE LINE SHOULD
LIMIT THE MAGNITUDE OF FLASH FLOOD THREAT. HOWEVER SOME CONCERN
THAT AS THE CONVECTIVE LINE MERGES WITH THE SCATTERED CONVECTION
THAT SHOULD CONTINUE TO FORM OUT AHEAD OF IT...THAT ENOUGH CELL
MERGERS AND SHORT TERM TRAINING COULD OCCUR TO LOCALLY ENHANCE
AMOUNTS ENOUGH FOR SOME FLASH FLOOD GUIDANCE EXCEEDANCE. THUS
ISOLATED RAINFALL TOTALS OF 2-5" ARE POSSIBLE WITHIN THE MPD AREA
WHERE CELL MERGERS OCCUR...WHICH MAY RESULT IN AN ISOLATED TO
SCATTERED FLASH FLOOD THREAT.

CHENARD

ATTN...WFO...ARX...GRB...MKX...MPX...

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

LAT...LON   44848834 44328756 43568759 43218831 43319098
            43439282 43789350 44349366 44629336 44779221
            44829038