MESOSCALE PRECIPITATION DISCUSSION 0222
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
959 PM EDT TUE MAY 16 2017

AREAS AFFECTED...SOUTHEAST MN...NORTH CENTRAL IA...WEST CENTRAL WI

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

VALID 170200Z - 170700Z

SUMMARY...INCRASING CONVECTION WITH TRAINING LIKELY TO POSE
POSSIBLE FLASH FLOODING CONDITIONS IN THE EARLY OVERNIGHT.

DISCUSSION...GOES-16 AND LOCAL RADAR MOSAIC SHOWS CONVECTIVE
DEVELOPMENT ALONG THE TRAILING EDGE OF EXITING S/W FEATURE WITH
COOLING TOPS AND MERGING ANVILS.  MODEST LOW LEVEL CONFLUENCE AT
ALONG COLD FRONT FROM SFC LOW NEAR OEO WITH STEADILY INCREASING
LLJ THAT IS ADVECTING UNSTABLE AIR REPRESENTED BY MLCAPES OF
2500-3000 OVER N CENTRAL IA PER RECENT RAP ANALYSIS.  MID-LEVEL
STEERING FLOW IS GENERALLY WEAKENING IN THE ENVIRONMENT BETWEEN
THE EXITING WAVE AND THE STRONGER S/W IN NEB.  AS SUCH PROPAGATION
VECTORS ARE GENERALLY WEAK TOWARD THE EAST THOUGH MAY EVEN SUPPORT
SOME WEAK UPSTREAM DEVELOPMENT GIVEN THE 35-40KT INFLOW.  
ADDITIONAL SUPPORT ALOFT WILL BE INCREASING AS 3H JET AND NICELY
PLACED LEFT ENTRANCE REGION TO THE AREA OF CONCERN IS
STRENGTHENING OVER 100KTS IN N CENTRAL MN BY 04-05Z. 

FURTHER UPSTREAM STRONG MESO LOW/HIGH COUPLET JUST NW OF OMA IS
LOCALLY BACKING INFLOW TO INCREASE SFC MST CONVERGENCE AHEAD OF
THE BOW.  GIVEN STRENGTHENING LL FLOW AND FORWARD PROPAGATION OF
THE BOW...THE LINE IS LIKELY TO FILL IN BETWEEN LSE AND AEL/MCW
OVER THE NEXT FEW HOURS.  GIVEN THE ORIENTATION AND CONVECTIVE
COMPLEX MOTION AND POTENTIAL BACK-BUILDING TO THE COMPLEX...CELLS
HAVE A GOOD POTENTIAL FOR ALIGNING WITH MEAN FLOW TO SUPPORT
TRAINING.  GIVEN TPWS OF 1.25-1.5" AND GOOD FLUX...RAIN RATES UP
TO 1.5"/HR ARE LIKELY WITH RAIN TOTALS OF 2-3" POSSIBLE LEADING TO
POSSIBLE FLASH FLOODING CONDITIONS.  HOWEVER...GREATEST CONCERN IS
THE LINE TRACKING ACROSS SATURATED SOILS/COMPROMISED FFG VALUES
FROM YESTERDAY NIGHT 2-4" TOTALS ACROSS WINONA/WABASHA
COUNTIES...MAKING THE THREAT OF FF MORE LIKELY THERE.

GALLINA

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

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

LAT...LON   45039014 44448967 43499139 42899274 42679367
            43309425 44199316 44749169