MESOSCALE PRECIPITATION DISCUSSION 0541
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1013 PM EDT WED AUG 10 2016
 
AREAS AFFECTED...EASTERN SD/EXTREME SOUTHEASTERN ND/SOUTHERN
MN/WEST-CENTRAL WI... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 110212Z - 110627Z
 
SUMMARY...AN INITIAL COMPLEX MOVING THROUGH SOUTHERN MN ALREADY
HAS A HISTORY OF DROPPING 2 TO 3 INCHES OF RAIN THE PAST FEW
HOURS. AS THIS CONVECTION SINKS SOUTH...ADDITIONAL THUNDERSTORM
ACTIVITY UPSTREAM WILL LIKELY SPREAD EASTWARD INTO AREAS RECENTLY
HIT. EXPECT THE POSSIBILITY OF FLASH FLOODING TO INCREASE
OVERNIGHT AS THE COMPLEX FURTHER EXPANDS AS THE NOCTURNAL LLJ
INTENSIFIES. 

DISCUSSION...A RATHER ROBUST AREA OF CONVECTION HAS BEEN DUMPING
HEAVY RAINFALL OVER THE SOUTHERN HALF OF MN THIS EVENING. THIS HAS
BEEN IN RESPONSE TO THE LEAD SHORTWAVE NOTED ON WATER VAPOR
IMAGERY TRACKING THROUGH THE UPPER MIDWEST. RECENT MESONET
OBSERVATIONS SHOW HOURLY RATES AS HIGH AS 1.61 INCHES ACROSS
CENTRAL MN WITH A FLASH FLOOD REPORT NOTED WEST OF MINNEAPOLIS/ST.
PAUL MN. THIS LEAD ACTIVITY SHOULD GRADUALLY SINK SOUTH AND EAST
ROLLING INTO SOUTHEASTERN MN/WESTERN WI.

FARTHER UPSTREAM...THE NEXT ROUND OF CONVECTION IS ALREADY ONGOING
OVER MUCH OF CENTRAL SD...MUCH OF IT FOCUSING JUST AHEAD OF THE
SURFACE WAVE. THE NORTHERN HALF OF THIS BATCH OF CONVECTION HAS
BEEN RATHER SLOW-MOVING WITH SOME REGENERATION NOTED OVER
NORTH-CENTRAL SD. THE 00Z RAOB FROM ABERDEEN SD INDICATED A RATHER
UNSTABLE AIR MASS IN PLACE WITH OVER 2000 J/KG OF MUCAPE OBSERVED.
PWATS SHOULD CONTINUE TO INCREASE OVERNIGHT AS A PLUME OF GULF
MOISTURE LIFTS NORTHWARD ACROSS EASTERN NE/WESTERN IA UP TO THE
DAKOTAS/UPPER MIDWEST REGION. EXPECT THE ACTIVITY CURRENTLY OVER
SD TO SLIDE EASTWARD OVERNIGHT INTO THE RAIN-COOLED AIR OVER MN.
IN SPITE OF THIS STABILIZING FACTOR...RECENT RAP OBJECTIVE
ANALYSES SHOWED AN IMPRESSIVE ELEVATED INSTABILITY PROFILE WHICH
SUGGESTS THE UPSTREAM ACTIVITY MAY NOT WEAKEN MUCH.
ADDITIONALLY...STRONG DYNAMICS VIA THE LLJ COUPLED WITH UPPER
DIFFLUENCE ALOFT SHOULD SUPPORT THIS HEAVY RAINFALL THREAT WELL
INTO THE OVERNIGHT HOURS.

REGARDING MODEL CHOICES...THE LATEST HRRR/HRRR-PARALLEL WERE
HANDLING THE CURRENT CONVECTION MOST ACCURATELY. OTHER RECENT
MODELS HAVE BEEN DISPLACED TOO FAR NORTHWARD.


RUBIN-OSTER

ATTN...WFO...ABR...ARX...BIS...DLH...FGF...FSD...MPX...UNR...

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

LAT...LON   46499218 46059136 44839107 44339158 43929290 
            43899470 43709772 43319951 43690082 45260061 
            46169849 45769654 45879515 46439395