MESOSCALE PRECIPITATION DISCUSSION 0538
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
535 PM EDT WED AUG 10 2016
 
AREAS AFFECTED...NORTHEAST SD...CENTRAL MN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 102135Z - 110200Z
 
SUMMARY...SLOW MOVING SUPERCELLS WITH RATES AOA 2"/HR MAY
PRODUCING FLASH FLOODING PARTICULARLY IF THERE IS TRAINING AS THE
CELLS MOVE EAST ALONG THE FRONTAL ZONE.

DISCUSSION...GOES-E VISIBLE/RADAR MOSAIC INDICATES NEAR SFC ROOTED
DEEP CONVECTION ALONG A SLOWLY NORTHWARD LIFTING WARM FRONT ACROSS
NE SD INTO SOUTH CENTRAL MN...WHICH IS BEING REINFORCED BY EARLIER
ELEVATED CONVECTION'S OUTFLOW THAT HAS DRIFTED SOUTH OUT OF MN. 
SURFACE ANALYSIS ALSO INDICATED LOW IN W SD CONTINUES TO SHOW
PRESSURE FALLS TO 1002.5MB SUPPORTING STRONG 20+ KT SFC FLOW JUST
AHEAD OF THE COLD FRONT BUT ALSO INTERSECTING DUE EASTERLY FLOW
NORTH OF THE WARM FRONT PROVIDING A LARGE AREA OF STRONG 20-30
UNIT SFC MOISTURE CONVERGENCE AS FAR WEST AS 100W...PROVIDING
POTENTIAL FOR UPSTREAM DEVELOPMENT OVER THE NEXT FEW HOURS AS WELL.

PER SPC MCD...SUPERCELL MODE FOR THESE CELLS WILL SUPPORT VERY
SLOW EASTWARD MOTIONS LESS THAN 10KTS PER RAP BUNKER'S RIGHT
MOVING CELL MOTIONS.  THE HIGH FLUX OF HIGH 60S/LOW 70S TD AIR AND
2.0" TPW VALUES SUPPORT EFFICIENT RAINFALL PRODUCTION...THOUGH
SOME MAY BE LOST TO HAIL GENERATION...RATES IN THE 2-2.5"/HR RANGE
ARE POSSIBLE ALLOWING FOR COMPOUNDED TOTALS IN THE NEXT 1-3 HOURS.
 EVENTUALLY COLD POOL GENERATION SHOULD SUPPORT FORWARD
PROPAGATION TOWARD THE E/ESE ALONG THE FRONTAL ZONE WHICH WILL
ALSO LIKELY TRACK ACROSS THE AREAS AFFECTED BY THE DOWNSTREAM
SUPERCELLS.  THIS COULD LEAD TO FLASH FLOODING CONDITIONS...EVEN
THOUGH THE CELLS APPEAR TO BE TRACKING FURTHER SOUTH THAN THE
SATURATED SOILS ACROSS SE ND INTO CENTRAL MN FROM LAST NIGHT'S
ROUND AND THE ELEVATED CONVECTION DISCUSSED IN MPD 536.

HI-RES GUIDANCE HAS BEEN SLOW TO DEVELOP CONVECTION BUT ALSO IS
DEVELOPING DIFFERENTLY...WITH THE EXCEPTION OF THE LAST FEW HOURS
OF THE OPERATIONAL HRRR (THOUGH IT APPEARS NORTH OF REALITY TOO).
SO THINKING THE RANGE OF TOTALS ON THE HRRR AND HRRR PARALLEL SEEM
OK WITH SOME LOCATIONS PICKING UP 3-5" EXCEEDING LOCAL FFG VALUES
EVEN SOUTH OF THE LOWER VALUES.

GALLINA

ATTN...WFO...ABR...FGF...MPX...

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

LAT...LON   45879792 45849561 45719418 45409332 44479407 
            44789575 44999979 45839984