Graphic for MPD #0687

MESOSCALE PRECIPITATION DISCUSSION 0687
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
420 AM EDT MON AUG 14 2017

AREAS AFFECTED...SOUTHEAST OK...NORTHEAST TX...CENTRAL/SOUTHERN
AR...NORTHWEST MS

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

VALID 140815Z - 141415Z

SUMMARY...DEVELOPING SHOWERS AND THUNDERSTORMS WILL TEND TO EXPAND
IN COVERAGE OVER THE NEXT SEVERAL HOURS. SOME REPEATING CELL
ACTIVITY IS EXPECTED AND THIS COUPLED WITH HEAVY RAINFALL RATES
AND WET ANTECEDENT CONDITIONS WILL FOSTER SOME FLASH FLOODING
CONCERNS.

DISCUSSION...THE LATEST RADAR IMAGERY IS SHOWING AN AXIS OF
SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS AREAS OF FAR NORTHEAST
TX...FAR SOUTHEAST OK AND ACROSS SOUTHERN AR. THE CONVECTION IS
DEVELOPING IN RESPONSE TO THE GRADUAL APPROACH OF AN UPSTREAM
SHORTWAVE TROUGH OVER THE SOUTHERN PLAINS AND ALSO THE MCV
ASSOCIATED WITH A WEAKENING MCS OVER AREAS OF SOUTHWEST OK AND
NORTHWEST TX. THE APPROACHING ENERGY IS INCREASING THE WARM AIR
ADVECTION PATTERN DOWNSTREAM OVER THE LOWER MS VALLEY AND GIVEN
THE PROXIMITY OF A QUASI-STATIONARY FRONT AND THE POOLING OF
GREATER INSTABILITY AND MOISTURE ALONG AND OVER THE FRONT IN AN
ELEVATED FASHION...CONVECTION WILL LIKELY TO TEND TO FURTHER
EXPAND IN COVERAGE THIS MORNING.

THE CONVECTION WILL TEND TO BE OCCURRING OVER AREAS WHERE THERE
HAS BEEN RECENT HEAVY RAINFALL...ESPECIALLY IN ANY AREAS INVOLVING
SOUTHEAST OK/NORTHEAST TX AND SOUTHERN AR. THE LATEST HRRRX
GUIDANCE IS SHOWING A FAIR DEGREE OF CONVECTIVE ORGANIZATION IN A
W/E FASHION THROUGH THE EARLY TO MID MORNING HOURS...WITH A RATHER
SOLID SIGNAL FOR REPEATING CELL ACTIVITY.

THE PWATS ARE QUITE HIGH WITH VALUES OF 2.2 TO 2.4 INCHES...AND
THE CIRA-LPW DATA FROM 06Z SHOWS A NARROW STRIPE OF CONCENTRATED
MOISTURE IN THE 500/300 MB LAYER OVER SOUTHERN AR. THIS WILL LEAD
TO EFFICIENT RAINFALL PROCESSES FOR ENHANCED RAINFALL RATES THAT
MAY APPROACH 2.5 INCHES/HR.

THERE IS OVERALL NOT A VERY CONFIDENT SIGNAL FOR WIDESPREAD HEAVY
RAINFALL AMOUNTS...BUT BASED ON THE LATEST SATELLITE AND RADAR
TRENDS...COUPLED WITH THE HRRRX GUIDANCE...IT DOES APPEAR THAT
SOME SOME CONCENTRATED HEAVY RAINFALL WILL OCCUR THIS MORNING WITH
AS MUCH AS 3 TO 5+ INCHES POSSIBLE. THIS WOULD RESULT IN SOME
ADDITIONAL FLASH FLOODING CONCERNS. WILL CONTINUE TO MONITOR.

ORRISON

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

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

LAT...LON   34799078 34598981 33888938 33438967 33239031
            33119125 33079217 32979331 32889481 32929588
            33029658 33409699 33919712 34399672 34619609
            34739484 34729296 34779181


Last Updated: 420 AM EDT MON AUG 14 2017