MESOSCALE PRECIPITATION DISCUSSION 0495
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
900 AM EDT THU SEP 17 2015
 
AREAS AFFECTED...SOUTHEASTERN MN/WESTERN WI... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 171300Z - 171700Z
 
SUMMARY...TRAINING CONVECTION IS ALREADY ONGOING ACROSS THE TWIN
CITIES WITH THE POTENTIAL SLIDING EASTWARD GIVEN FAVORABLE WIND
PROFILES. RECENT MESOSNET DATA SUGGESTED HOURLY RATES APPROACHING
2 INCHES IN SOME OF THE MORE CONCENTRATED AXIS OF CONVECTION. THIS
MAY CAUSE ADDITIONAL THREATS FOR FLASH FLOODING THROUGH THE
MORNING.

DISCUSSION...AN IMPRESSIVE AREA OF TRAINING IS OCCURRING ACROSS
THE TWIN CITIES AREA ALONG A PRONOUNCED NOCTURNAL LLJ. VWP DATA
ACROSS THE UPPER MIDWEST SHOWED 30 TO 35 KNOTS OF UNIDIRECTIONAL
SOUTH-SOUTHWESTERLY FLOW IN THE 925-700 MB LAYER. THE 12Z MPX RAOB
SUPPORTS THIS OBSERVATION WITH ABUNDANT BUOYANCY IN PLACE PER THE
SOUNDING AND OBSERVED CG LIGHTNING DATA. IT APPEARS THIS INITIAL
BURST OF CONVECTION ACROSS SOUTHEASTERN MN HAS WEAKENED A BIT VIA
THE CIMSS OVERSHOOTING TOP ALGORITHM. HOWEVER...THE RAP OBJECTIVE
ANALYSIS STILL SHOWS AN ABUNDANCE OF INSTABILITY NOT YET ERODED
AND MOIST/UNIDIRECTIONAL FLOW FOCUSED ACROSS EASTERN MN/WESTERN
WI. CORFIDI VECTORS IN THE AREA OF INTEREST REMAIN NEAR ZERO
DURING THE NEXT FEW HOURS WHICH SUPPORTS THE IDEA OF SLOW
MOVING/TRAINING CONVECTION UNTIL AT LEAST 16Z.

CAMS HAVE SHOWN HINTS AT THE EVOLUTION THIS MORNING BUT THERE WAS
NOT A LOT OF CONSISTENCY IN THEIR SOLUTIONS. THUS...TRUSTING
CURRENT RADAR/SATELLITE TRENDS AND OBSERVATIONAL DATA. FOR MORE
INFORMATION ON THE SATELLITE PERSPECTIVE OF THIS EVENT...PLEASE
VIEW THE LATEST SPENES FROM NESDIS/SAB. 

RUBIN-OSTER

ATTN...WFO...ARX...DLH...GRB...MPX...MQT...

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

LAT...LON   46899136 46789000 46058939 45398939 44778955 
            43959048 43569157 43649310 44319337 45119316 
            46059239