MESOSCALE PRECIPITATION DISCUSSION 0421
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 AM EDT SAT JUL 01 2017

AREAS AFFECTED...NORTH TX INTO PORTIONS OF THE RED RIVER VALLEY

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 010645Z - 010945Z

SUMMARY...CONVECTION TRAINING OVER AREAS THAT RECEIVED EARLIER
HEAVY RAINFALL COULD PRODUCE FLASH FLOODING EARLY THIS MORNING.

DISCUSSION...THE INITIAL ROUND OF CONVECTION ACROSS THE RED RIVER
VALLEY HAS BECOME COLD POOL DOMINATED AND HAS ACCELERATED INTO
NORTHEAST TX AND FAR SOUTHEAST OK. ADDITIONAL CONVECTION IS
FORMING ON THE WESTERN EDGE OF AN AXIS OF 1000-2000 J/KG OF
MLCAPE. THE LOW LEVEL AIRMASS HAS BEEN MODIFIED BY THE EARLIER
CONVECTION...AND MODEL SOUNDINGS SHOWED SOME LOW LEVEL CIN ALONG
THE CENTRAL AND EASTERN RED RIVER VALLEY.

THE NEWLY DEVELOPING CONVECTION IS PRODUCING BURSTS OF COLD CLOUD
TOPS... INDICATING STRENGTHENING UPDRAFTS AND INCREASING RAINFALL
RATES. THE KTLX RADAR SHOWED HOURLY RAINFALL RATES APPROACHING
1.50 INCHES WITH THE NEWLY FORMED CONVECTION...BUT MESONET
OBSERVATIONS WERE NOT QUITE AS ROBUST AS THE RADAR OUTPUT.

THE KTLX RADAR SHOWED LOCAL 2.00 TO 4.00 INCH RAINFALL AMOUNTS
FROM THE EARLIER CONVECTION...AND THIS IS REFLECTED IN THE LATEST
HRRR SOIL SATURATION OVER THE WESTERN RED RIVER VALLEY. THIS SETS
THE STAGE FOR A FLASH FLOOD THREAT...AS THE NEW CONVECTION TRAINS
OVER THIS AREA.

IN THE NEAR TERM...THE TRAINING POSES A FLASH FLOOD THREAT...WITH
LOCAL 1.00 TO 2.00 INCH RAINFALL AMOUNTS POSSIBLE WITH THE
SCATTERED CONVECTION. THESE AMOUNTS ARE BASED MAINLY ON THE LATEST
HRRR...AND ASSUMES THAT TRAINING WILL OCCUR. THE ADDITIONAL
RAINFALL AMOUNTS COULD PRODUCE FLASH FLOODING OVER NEARLY
SATURATED SOILS.

AFTER 08Z...THERE IS A STRONG SIGNAL IN THE HIGH RESOLUTION
GUIDANCE THAT THE NEW CONVECTION PRODUCES A COLD POOL THAT HELPS
THE CONVECTION ACCELERATE TO THE SOUTHEAST...REDUCING THE FLASH
FLOOD THREAT.

HAYES

ATTN...WFO...FWD...LUB...OUN...SJT...

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

LAT...LON   34549846 34459764 33959738 33309765 33019906
            32970141 33850177 34240113