MESOSCALE PRECIPITATION DISCUSSION 0258
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 PM EDT SUN JUN 21 2015
 
AREAS AFFECTED...NORTHERN TX...SOUTHERN OK 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 211844Z - 212200Z
 
SUMMARY...VERY SLOW-MOVING SHOWERS AND THUNDERSTORMS TO CONTINUE
TO IMPACT PORTIONS OF THE RED RIVER VALLEY. ADDITIONAL SHORT-TERM
FLASH FLOODING IS LIKELY THIS AFTERNOON.

DISCUSSION...A WELL-DEFINED AND VERY SLOW MOVING VORT ACROSS
NORTHEAST TX HAS BEEN INTERACTING WITH A VERY MOIST AND UNSTABLE
AIRMASS OVER THE LAST SEVERAL HOURS AND HAS BEEN PRODUCING A
COMPACT CLUSTER OF VERY INTENSE SHOWERS AND THUNDERSTORMS.
EXTREMELY HIGH RAINFALL RATES REACHING OVER 3 INCHES/HR HAVE BEEN
NOTED WITH THE ACTIVITY...AND THIS HAS BEEN RESULTING IN SOME VERY
HIGH STORM TOTALS SO FAR THAT ARE LOCALLY APPROACHING 8 INCHES
BASED ON DUAL-POL ESTIMATES.

SATELLITE AND RADAR IMAGERY SHOWS THE OVERALL VORT TRACKING SLOWLY
TO THE WEST...AND THIS SHOULD DRIVE THE STRONGER CORES OF
COLD-TOPPED CONVECTION GRADUALLY OFF TO THE WEST OVER THE NEXT FEW
HOURS. THE LAST COUPLE OF RUNS OF THE HRRR HAVE NOT DONE WELL IN
HANDLING THE ONGOING CONVECTION AS THEY HAVE INSISTED ON THE
CONVECTION FOCUSING FARTHER EAST AND WEAKENING RAPIDLY.
SUBSTANTIAL WEAKENING OF THE CONVECTION HAS NOT OCCURRED YET...AND
WITH NEW INSTABILITY DRIVEN CONVECTION DEVELOPING AROUND THE
PERIPHERY OF THE COMPACT MCS FEATURE...IT APPEARS AS THOUGH THE
CONVECTION WILL PERSIST THROUGH THE AFTERNOON.

PWATS ARE NEAR 2 INCHES AND THERE IS A PERSISTENT 25 TO 30 KT FEED
OF SOUTHERLY 850MB FLOW INTO THE CONVECTIVE CORES NEAR THE VORT
CENTER. THIS WILL CONTINUE TO PROMOTE VERY INTENSE RAINFALL
RATES...AND ADDITIONAL RAINFALL AMOUNTS OF 3 TO 5 INCHES LOCALLY
WILL BE POSSIBLE THROUGH THE REMAINDER OF THE AFTERNOON.

ORRISON

ATTN...WFO...FWD...OUN...

ATTN...RFC...ABRFC...LMRFC...WGRFC...

LAT...LON   34459756 33979644 33829555 33289546 32389612 
            32129718 32259813 32569857 33119880 33809845