MESOSCALE PRECIPITATION DISCUSSION 0251
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
651 PM EDT TUE AUG 05 2014
 
AREAS AFFECTED...WRN SD...NE WY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 052251Z - 060121Z
 
SUMMARY...FOCUSED UPSLOPE HAD ANCHORED CONVECTION IN THE BLACK
HILLS. OUTFLOWS APPROACHING FROM WYOMING HAD SLOWED UPON
ENCOUNTERING STRONGER INFLOW. WITH CELL MOTIONS OF 5 TO 10 KNOTS
AND REGENERATION IN THE TERRAIN...FLASH FLOODING APPEARS LIKELY IN
THE SHORT TERM.

DISCUSSION...WITH ENVIRONMENTAL PROFILES ONLY MARGINALLY
SUPPORTIVE OF HAIL...AND GIVEN PROXIMITY OF THE STORMS TO THE KUDX
RADAR...STORM TOTAL RAINFALL THAT WAS SURPASSING 4 INCHES SOUTH OF
DEADWOOD AS OF 2240Z MAY BE ACCURATE OR NEAR ACCURATE. HIGH
RESOLUTION MODELS WERE NOT HANDLING THE LOCATION OF THIS EVENT
PARTICULARLY WELL...BUT MANY OF THEM INDICATE POTENTIAL FOR
LOCALLY INTENSE SWATHS OF RAIN IN THIS REGION THROUGH 03Z. MODEST
925-850 MB FLOW...SHOWING SOME INCREASE THROUGH EVENING...WILL
CONTINUE TO FAVOR SLOW MOVING MULTI-CELLS AND OCCASIONAL
SUPERCELLS...ESPECIALLY NEAR THE COMBINED LIFTING EFFECTS OF THE
BLACK HILLS AND SLOWLY DEVELOPING COLD POOLS IN THE VICINITY OF
THE BLACK HILLS. GIVEN THE TERRAIN AND ITS POTENTIAL TO PRODUCE
RAPID RUNOFF...SOME FLASH FLOODING APPEARS LIKELY IN THE VERY NEAR
TERM.

UNCERTAINTY INCREASES WITH TIME OWING TO THE LACK OF CONFIDENCE IN
MODEL PERFORMANCE ON SUCH A SMALL SCALE...BUT A SUPPORTING MID
LEVEL WAVE IS FORECAST TO MOVE ONLY SLOWLY EASTWARD...AND THE RAP
MODEL FORECASTS A STEADY INCREASE OF CAPE INTO SOUTHERN SD LATER
THIS EVENING...WHICH COULD SUPPORT A SLOW MOVING MCS IF ONE WHERE
TO BREAK OFF THE TERRAIN AND BECOME SELF SUSTAINING.

BURKE

ATTN...WFO...UNR...CYS...BYZ...

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

LAT...LON   44880305 45000507 44630555 43870533 43420417 43470293
            43860224 44450233 44880305