MESOSCALE PRECIPITATION DISCUSSION 0029
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1135 AM EST THU FEB 22 2018

AREAS AFFECTED...NORTHEAST TX....SOUTHEAST OK...SOUTHWEST AR

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

VALID 221635Z - 222130Z

SUMMARY...SHOWERS AND THUNDERSTORMS WILL TEND TO GROW IN
ORGANIZATION OVER THE NEXT FEW HOURS. GIVEN THE WET ANTECEDENT
CONDITIONS...SOME FLASH FLOODING WILL BE POSSIBLE.

DISCUSSION...A SHORTWAVE TROUGH EJECTING NORTHEAST OUT ACROSS THE
SOUTHERN PLAINS WILL BE FACILITATING THE EXPANSION OF CONVECTION
OVER THE NEXT SEVERAL HOURS ACROSS AREAS THAT HAVE BEEN QUITE WET
OF RECENT AND WITH NEARLY SATURATED SOIL CONDITIONS. ALREADY
SATELLITE AND RADAR IMAGERY CONFIRMS THE EXPANSION OF CONVECTIVE
ACTIVITY OVER AREAS OF NORTHERN AND NORTHEAST TX ALONG WITH
ADJACENT AREAS OF SOUTHERN OK.

THE ENERGY WILL BE INTERACTING WITH AN AXIS OF ELEVATED
INSTABILITY SURGING NORTH OVER A FRONT WELL TO THE SOUTH ACROSS
SOUTHEAST TX. MEANWHILE...WARM AIR ADVECTION WILL BE IN THE
INCREASE AHEAD OF THE SHORTWAVE AND THIS COUPLED WITH INCREASING
MOISTURE TRANSPORT SHOULD FAVOR GREATER CONVECTIVE ORGANIZATION
AND AN INCREASE IN RAINFALL RATES.

THESE RATES WITH THE DEGREE OF AVAILABLE ELEVATED INSTABILITY MAY
APPROACH 1 TO 1.5 INCHES/HR...AND WITH COMPROMISED SOIL
CONDITIONS/LOW FFG VALUES...THERE WILL BE CONCERNS FOR LOCALLY
ENHANCED RUNOFF AND/OR FLASH FLASH FLOODING.

THERE IS NO ONE HIRES MODEL THAT IS HANDLING THE ONGOING
CONVECTION ACROSS NORTHERN TX AND SOUTHERN OK PARTICULARLY WELL AT
THIS TIME...BUT A CONSENSUS GENERALLY OF THE 12Z ARW/NMMB AND 12Z
NAM-CONEST WOULD FIT THE ANTICIPATED CONVECTIVE EVOLUTION
RELATIVELY WELL AND WOULD SUPPORT ADDITIONAL RAINFALL TOTALS OF AS
MUCH AS 1.5 TO 2 INCHES THROUGH 21Z. HOWEVER...THESE TOTALS MAY BE
SOMEWHAT UNDERDONE LOCALLY BASED ON CURRENT AND EXPECTED RAINFALL
RATES...AND ALSO WITH THE POTENTIAL FOR SOME LOCALIZED TRAINING OF
CONVECTIVE ELEMENTS OVER THE NEXT SEVERAL HOURS. WILL CONTINUE TO
MONITOR.

ORRISON

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

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

LAT...LON   34849286 34659216 34019225 33319333 32789451
            32469575 32489653 32719681 33119669 33649610
            34359486 34759386