MESOSCALE PRECIPITATION DISCUSSION 0677
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1215 AM EST SUN DEC 13 2015
 
AREAS AFFECTED...ERN TX...SERN OK...NWRN AR...SWRN MO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 130515Z - 131100Z
 
SUMMARY...HEAVY RAIN MAY REINVIGORATE OVER THE NEXT FEW HOURS OVER
EAST CENTRAL AND NORTHEASTERN TEXAS. ADDITIONAL HEAVY RAINS ARE
EXPECTED TO CONTINUE FARTHER NORTHEAST ACROSS PORTIONS OF SERN
OK...NWRN AR...AND SWRN MO AS A PLUME OF VERY MOIST AIR WITH HIGH
PWAT VALUES STREAMS INTO THE REGION. AN ADDITIONAL 1-4 INCHES OF
RAIN IS POSSIBLE THROUGH 11Z ACROSS THE OUTLINED AREA. FLASH
FLOODING IS LIKELY.

DISCUSSION...A BAND OF MODERATE TO HEAVY RAINFALL IS CURRENTLY
ONGOING ACROSS MUCH OF EASTERN TEXAS EXTENDING NORTHWARD INTO
PORTIONS OF OKLAHOMA AND ARKANSAS. PWAT VALUES OF GREATER THAN 2
INCHES ARE INDICATED BY THE LATEST RAP RUN STREAMING NORTHWARD
INTO THE REGION ON AN IMPRESSIVE 50-60 KT LOW-LEVEL JET. THIS
EASTERN AREA OF ACTIVITY APPEARS TO BE FOCUSED BY A LEADING
UPPER-LEVEL VORTICITY MAX AND THE CONVERGENCE OF TWO LOW-LEVEL
MOISTURE STREAMS...ONE FROM SOUTHWEST OF THE REGION AND ANOTHER
FROM THE GULF OF MEXICO. INSTABILITY IS LIMITED...WITH MUCAPE
VALUES GENERALLY IN THE 500-1000 J/KG AHEAD OF THE COLD FRONT. A
SQUALL LINE IS CURRENTLY ONGOING ALONG THE COLD FRONT...AND THIS
WILL MOVE EASTWARD TOWARD THE OUTLINED MPD AREA OVER THE NEXT
COUPLE HOURS.

UPPER-LEVEL SUPPORT IS FORECAST TO IMPROVE OVER THE NEXT FEW HOURS
AS AN IMPRESSIVE 150+ KT UPPER-LEVEL JET STREAK NORTHWEST OF THE
OUTLINED AREA IMPROVES UPPER-LEVEL DIVERGENCE. THIS...ALONG WITH
IMPRESSIVE HEIGHT FALLS...AND THE LIMITED INSTABILITY WILL RESULT
IN SUSTAINED OR INCREASED CONVECTION ACROSS EAST CENTRAL AND
NORTHEASTERN TEXAS. THIS IS SUPPORTED BY MULTIPLE RECENT RUNS OF
THE HRRR...WHICH REINVIGORATE THE HEAVY RAINFALL THREAT OVER
EASTERN TEXAS DURING THE 06-09Z TIME FRAME. THE 03Z HRRR...00Z
NSSL WRF...AND THE 03Z RAP ALL INDICATE THE POTENTIAL FOR 1-4
INCHES OF ADDITIONAL RAINFALL ACROSS THIS AREA THROUGH 11Z. THIS
ACTIVITY IS FORECAST TO SPREAD NORTHEASTWARD INTO SOUTHEASTERN
OKLAHOMA IN THE 08Z-11Z TIME FRAME.

FLASH FLOOD GUIDANCE VALUES ARE LOWERED OVER PORTIONS OF THE
OUTLINED AREA DUE TO EARLIER HEAVY RAINS. WITH ADDITIONAL HEAVY
RAINS EXPECTED...FLASH FLOODING IS LIKELY.

RYAN

ATTN...WFO...EWX...FWD...HGX...LZK...OUN...SGF...SHV...TSA...

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

LAT...LON   36969455 36849316 36209297 34969350 33579444 
            31779485 30109552 29489721 30159826 31759790 
            33559738 35059662 36389559