Graphic for MPD #0814

MESOSCALE PRECIPITATION DISCUSSION 0814
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
928 PM EDT TUE SEP 19 2017

AREAS AFFECTED...NEAR THE SD/ND/MN BORDER JUNCTION

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

VALID 200127Z - 200727Z

SUMMARY...SHOWERS AND THUNDERSTORMS CONTINUE TO BLOSSOM ACROSS THE
REGION.  HOURLY RAIN TOTALS TO 2" WITH LOCAL AMOUNTS TO 5" ARE
POSSIBLE.

DISCUSSION...SHOWERS AND THUNDERSTORMS CONTINUE TO TRAIN ACROSS
SOUTHEAST ND, ANCHORED BY AN APPARENT OUTFLOW BOUNDARY NEAR THE
EASTERN BORDER OF THE DAKOTAS.  ACTIVITY WITH AN APPARENT
MESOCYCLONE IS SPREADING HIGH RAIN RATES INTO WESTERN MN AT THE
PRESENT TIME.  NEW CONVECTION IS FIRING NEAR THE OCCLUDED FRONT
CLOSER TO THE INTERNATIONAL BORDER WHILE SIGNS OF CAP WEAKENING
ARE APPARENT IN THE RAP GUIDANCE AND RECENT RADAR IMAGERY IN
EASTERN SD.  PRECIPITABLE WATER VALUES ARE 1-1.5" PER 00Z
SOUNDINGS AND GPS DATA.  INFLOW AT 850 HPA IS SOUTHERLY AT 40-50
KTS PER VAD WIND PROFILES.  EFFECTIVE BULK SHEAR IS 40-60 KTS.  MU
CAPE VALUES OF 1000-3000 J/KG ARE SEEN ACROSS THE REGION.

THE MESOSCALE GUIDANCE SHOWS A BIT OF DISPERSION REGARDING AMOUNTS
AND PLACEMENT -- A ROUGH AVERAGE OF THEIR OUTPUT SUPPORTS LOCAL
AMOUNTS OF 5" THROUGH 07Z.  HOURLY RAIN TOTALS UP TO 2" SHOULD
REMAIN POSSIBLE.  CIN ACROSS THE REGION SHOULD START REDEVELOPING
SOON, TAPPING INSTABILITY ALOFT AND BECOMING INCREASINGLY
ELEVATED.  THE LOW-LEVEL INFLOW PEAKS AT ~70 KTS AROUND 05Z; UNTIL
THEN BACKBUILDING SHOULD REMAIN POSSIBLE.  THE EFFECTIVE BULK
SHEAR CONTINUES TO FAVOR MESOCYCLONES EMBEDDED WITHIN THE
ACTIVITY, WHICH WOULD ALSO FAVOR HIGH RAIN RATES.  THE PROGRESSIVE
OCCLUSION/COLD FRONT SHOULD END ACTIVITY FROM WEST TO EAST WITH
TIME AND AFTER ~05Z THERE SHOULD BE SOME EAST-WEST CONTRACTION TO
THE PRECIPITATION PROFILE AS THE STORMS BECOME INCREASINGLY
FORWARD PROPAGATION WHICH SHOULD LOWER TOTALS WITH TIME.

ROTH

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

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

LAT...LON   48989901 48909675 48219433 46609339 45259376
            44319448 43839540 43719682 44519817 45869894
            47339923 47689925


Last Updated: 928 PM EDT TUE SEP 19 2017