MESOSCALE PRECIPITATION DISCUSSION 0482
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
459 AM EDT THU JUL 19 2018

AREAS AFFECTED...SOUTHWEST MN & VICINITY

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

VALID 190858Z - 191458Z

SUMMARY...A MESOSCALE CIRCULATION APPEARS TO BE SPINNING UP
QUICKER THAN INDICATED BY SOME OF THE GUIDANCE NEAR THE SOUTHERN
MN/SD BORDER.  HOURLY RAIN TOTALS TO 2" WITH LOCAL AMOUNTS TO 4"
ARE EXPECTED.

DISCUSSION...A MESOSCALE CIRCULATION FORMED IN SOUTHEAST SD A FEW
HOURS AGO WHOSE CONVECTIVE PATTERN HAS BEEN SOMEWHAT BROADENING AS
OF LATE, WITH VERY RECENT CLOUD TOP COOLING SINCE 0830Z.  RECENT
RAP MASS FIELDS HAVE A GOOD OF THE DEVELOPMENTS IN THIS AREA.  THE
FLOW AT 850 HPA IS BECOMING MORE CENTERED AROUND THIS CIRCULATION
PER VAD WIND PROFILES, WITH SPEEDS OF 35 KTS IN THE SIOUX FALLS SD
PROFILE -- AT LEAST DOUBLE THE MEAN 850-400 HPA WIND -- AND
WEAKENING WINDS AT ABERDEEN SD.  THUNDERSTORM ACTIVITY TO THE
NORTH NEAR THE SD/ND BORDER HAS BEEN IN SLOW DECLINE. 
PRECIPITABLE WATER VALUES OF 1.5-1.7" LIE HERE PER GPS VALUES.  MU
CAPE VALUES ARE ON THE RISE AS OF LATE, 500-1000 J/KG AROUND THE
CIRCULATION.  EFFECTIVE BULK SHEAR IS 20-30 KTS HERE PER RECENT
SPC MESOANALYSES.

RECENT RAP, HRRR, 06Z NAM CONEST, AND A SOUTHWARD ADJUSTED 00Z
CANADIAN REGIONAL MODEL SEEM TO HAVE AN IDEA OF WHAT IS GOING ON
CONVECTIVELY IN THIS REGION.  AS THE SYSTEM GROWS UPSCALE, IT
SHOULD BE ACCOMPANIED BY GREATER AMOUNTS OF 850 HPA INFLOW AND
BULK SHEAR, MAKING MORE EFFECTIVE USE OF THE INSTABILITY IN ITS
ENVIRONMENT ON A BROADER SCALE.  CONVECTION MAY PERIODICALLY FORM
CURVED BANDS AROUND THE SYSTEM, WHICH COULD LEAD TO SOME TRAINING.
 WHILE THE 00Z HREF PROBABILITIES OF 1"+ AN HOUR PEAK IN THE
13-14Z PERIOD, SUCH RATES HAVE ALREADY OCCURRED IN SOUTHEAST SD
AND SHOULD CONTINUE INTO THE MORNING HOURS.  HOURLY RAIN TOTALS TO
2" WITH LOCAL AMOUNTS TO 4" ARE EXPECTED, BOTH TO THE EAST OF THE
SYSTEM AND WITHIN ITS COMMA HEAD.

ROTH

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

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

LAT...LON   46079437 45729353 44609334 43949405 43859575
            44229677 44849677 45709583