MESOSCALE PRECIPITATION DISCUSSION 0579
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
148 AM EDT FRI AUG 19 2016
 
AREAS AFFECTED...SOUTHEAST SD...SOUTHERN MN...WESTERN/SOUTHWEST WI 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 190547Z - 191130Z
 
SUMMARY...SLOW MOVING AND TRAINING CONVECTION ALONG AND NORTH OF A
QUASI STATIONARY FRONT MAY PRODUCE FLASH FLOODING WITH RAINFALL
RATES OF 1-2 IN/HR ACROSS SERN SD INTO SRN MN AND
WESTERN/SOUTHEWESTERN WI THROUGH 1130Z.

DISCUSSION...05Z OBSERVATIONS SHOWED SURFACE LOW OVER SOUTHEAST SD
ALONG A QUASI STATIONARY FRONT ACROSS SOUTHERN MN WHICH TURNS INTO
A COLD FRONT IN THE WAKE OF THE LOW.  00Z SOUNDINGS SHOWED THE
AXIS OF GREATEST INSTABILITY ALONG AND NORTH OF THE MN BOUNDARY
WITH SATELLITE DERIVED SHOWALTER VALUES RUNNING CLOSE TO MINUS 8
PER NESDIS/SAB BRIEFING.  SPC MESOANALYSIS AND THE RAP STILL
INDICATED A RELATIVELY NARROW AXIS OF STRONG UNCAPPED
INSTABILITY...MLCAPE OF 3000+ J/KG WHERE H85 DEWPOINTS WERE ON THE
ORDER OF 15 DEGS C...NEAR THE SURFACE LOW AND IN VICINITY OF THE
FRONTAL BOUDARY IN SOUTHERN MN.  

CONVECTION HAS GENERALLY BEEN FORWARD PROPAGATING WHICH WOULD
LIMIT THE POTENTIAL FOR FLASH FLOODING.  EVEN SO...CONVECTION WAS
DEVELOPING OVER PARTS OF SOUTHEAST MN AND SOUTHWEST WI IN A REGION
OF LOW LEVEL WARM ADVECTION NORTH OF THE BOUNDARY...WITH
ADDITIONAL SHOWERS AND THUNDERSTORMS APPROACHING FROM THE WEST. 
SOME LOCATIONS IN THIS REGION HAD FLASH FLOOD GUIDANCE VALUES ON
THE ORDER OF 1.5 INCHES PER 3 HOURS BEFORE TONIGHTS
CONVECTION...SO FLASH FLOODING MAY BE POSSIBLE IN REGIONS WHERE
CELLS TRAIN.  RAINFALL RATES LOOK TO BE AIDED BY WEAK BUT
PERSISTENT UPPER LEVEL DIFLUENCE THROUGH THE NIGHT. 

BANN

ATTN...WFO...ABR...ARX...FSD...MPX...

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

LAT...LON   45349438 45239290 44869156 43739043 43059077 
            43509205 43739420 43589629 43509717 44129731 
            44639680 45099612