MESOSCALE PRECIPITATION DISCUSSION 0048
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
247 PM EDT MON MAY 12 2014
 
AREAS AFFECTED...EASTERN OK...NORTHEAST AND CENTRAL TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 121846Z - 130046Z
 
SUMMARY...ORGANIZED THUNDERSTORMS WITH HEAVY RAINFALL ARE EXPECTED
TO MOVE ACROSS EASTERN OK, NORTHEAST TX, AND THE TX HILL COUNTRY
OVER THE NEXT SEVERAL HOURS.  REGIONAL FLASH FLOODING IS
CONSIDERED POSSIBLE IN THESE AREAS.

DISCUSSION...THE COMBINATION OF A SLOWLY PROGRESSIVE COLD FRONT,
PRECIPITABLE WATER VALUES OF 1.75-2 INCHES (BETWEEN THE 90TH AND
99TH PERCENTILES FOR MID-MAY), 0-3 KM WIND SHEAR OF OVER 25 KNOTS,
AND CAPE VALUES OF 2000-4000 J/KG HAS ORGANIZED A NARROW BAND OF
THUNDERSTORMS ACROSS PORTIONS OF TX AND OK, WITH A CLUSTER
CURRENTLY FORMING ACROSS SOUTHEAST OK.  WITH 850 HPA INFLOW
EXCEEDING THE 850-400 HPA MEAN WINDS ACROSS TX AND OK, HEAVY RAINS
ARE LIKELY WITH THIS ACTIVITY, ON THE ORDER OF 2" AN HOUR WITHIN
STRONGER CONVECTION.

THE MESOSCALE GUIDANCE IS IN GENERAL AGREEMENT THAT THUNDERSTORM
ACTIVITY NEAR THE MOST EXTREME CAPE, COMBINED WITH DRY AIR ALOFT,
SHOULD CAUSE A COLD POOL TO FORM IN ASSOCIATION WITH THE
NORTH-CENTRAL TX, AND POSSIBLY SOUTHEAST OK, CONVECTION AND ALLOW
IT TO BOW OUT SOMEWHAT TO THE SOUTHEAST ACROSS THE HILL COUNTRY
INTO THIS EVENING.  AS IT DOES SO, INFLOW INTO THE BAND WILL
INCREASE AND RAINFALL EFFICIENCY SHOULD INCREASE AT THE EXPENSE OF
THUNDERSTORM ACTIVITY FARTHER TO THE NORTHEAST.  HIGH FLASH FLOOD
GUIDANCE VALUES ACROSS THE REGION, ON THE ORDER OF 3-4" IN THREE
HOURS, PRECLUDED THE IDEA OF THE LIKELY CATEGORY.  LOCAL RAINFALL
AMOUNTS OF 4"+ ARE POSSIBLE ACROSS CENTRAL TX BY SUNSET, WHICH
COULD LEAD TO REGIONAL FLASH FLOODING.

ROTH

ATTN...WFO...SHV...TSA...HGX...FWD...OUN...EWX...SJT...

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

LAT...LON   33489722 34689642 35969570 35919459 33249479 30169590
            29319746 29449861 29799917 30179940 30509962 30959982
            30969981 31369929 31929846 32809763 33489722