MESOSCALE PRECIPITATION DISCUSSION 0777
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
445 AM EST MON NOV 28 2016
 
AREAS AFFECTED...NORTHEAST TX...SOUTHEAST OK...WESTERN AR 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 280945Z - 281445Z
 
SUMMARY...LOW TOPPED CONVECTION DEVELOPING ALONG AN AXIS OF
INSTABILITY AND DEEPENING MOISTURE COULD TRAIN IN A UNIDIRECTIONAL
ENVIRONMENT ACROSS PORTIONS OF NORTHEAST TX/SOUTHEAST OK AND
WESTERN AR. THE TRAINING COULD RESULT IN A FLASH FLOOD THREAT THIS
MORNING.

DISCUSSION...LOW TOPPED CONVECTION CONTINUES DEVELOPING IN AN
INSTABILITY AXIS (WHERE MUCAPE VALUES RANGE BETWEEN 500-1000 J/KG)
STRETCHING ACROSS NORTHEAST TX INTO SOUTHEAST OK EARLY THIS
MORNING. THE CONVECTION IS FORMING/EXPANDING ON THE NORTHERN EDGE
OF A PRECIPITABLE WATER GRADIENT...AND THE 06Z FWD SOUNDINGS
SHOWED A STRONG QUASI UNIDIRECTIONAL WIND PROFILE THROUGH ABOUT
700 MB. 

THE KDYS RADAR SHOWED HOURLY RAINFALL RATES BETWEEN 1.50 AND 1.75
INCHES WITH THE ACTIVITY ACROSS YOUNG AND JACK COUNTIES EARLIER
THIS MORNING...THOUGH DRY AIR IN THE MID LEVELS OF THE 06Z FWD
SOUNDING SUGGESTS THAT THESE ESTIMATES COULD BE HAIL CONTAMINATED.
A SHORT WAVE OVER FAR WEST TX WILL PROVIDE INCREASING DIVERGENCE
ACROSS THE REGION DURING THE EARLY MORNING HOURS...AND THE LIFT
AND INSTABILITY SHOULD BE SUFFICIENT FOR CONVECTION TO CONTINUE
DEVELOPING NORTHEAST ALONG THE INSTABILITY AXIS. ANOTHER BAND OF
CONVECTION JUST AHEAD OF THE SHORT WAVE COULD PRODUCE A SHORT TERM
FLASH FLOOD THREAT OVER YOUNG AND JACK COUNTIES IN TX.

THERE IS A FAIRLY CONSISTENT SIGNAL IN THE HIGH RESOLUTION FOR AN
AXIS OF LOCAL 2-4 INCH RAINFALL AMOUNTS EXTENDING FROM LKUD TO
KFSM...WITH THE HIGHEST AMOUNTS EXPECTED ACROSS FAR SOUTHEAST OK
AND NEARBY WESTERN AR. GIVEN THE RAINFALL RATES ACROSS NORTHEAST
TX WITH THE ACTIVITY...THESE RAINFALL AMOUNTS SEEM PLAUSIBLE. 

THERE IS SOME UNCERTAINTY CONCERNING HOW LONG THE INSTABILITY IN
PLACE NOW (THE 06Z FWD SOUNDINGS SHOWED SBCAPE VALUES NEAR 750
J/KG...WITH A PRONOUNCED CAP AT ABOUT 23000 FEET)...AND THE LATEST
RAP SUGGESTS THAT THE INSTABILITY DROP OFF AS 14Z APPROACHES. IN
ADDITION...ONE HOUR FLASH FLOOD GUIDANCE VALUES OVER THIS AREA
GENERALLY RANGE BETWEEN 2.00 AND 3.00 INCHES...SO TRAINING IN THE
QUASI UNIDIRECTIONAL ENVIRONMENT WOULD BE NEEDED FOR A FLASH FLOOD
THREAT TO DEVELOP. 

BECAUSE OF THE UNCERTAINTIES...FLASH FLOODING IS THROUGH THE
MORNING HOURS.
 
HAYES

ATTN...WFO...FWD...LZK...OUN...SHV...TSA...

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

LAT...LON   36299334 35889299 34779392 33969550 32559775 
            32319842 32609894 33009891 33379865 35139599 
            35919436