MESOSCALE PRECIPITATION DISCUSSION 944
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1013 PM EST TUE DEC 19 2017

AREAS AFFECTED...NORTHEAST TX...SOUTHERN AR...NORTHERN
LA...NORTHERN MS

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

VALID 200313Z - 200903Z

SUMMARY...MULTIPLE ROUNDS OF HEAVY CONVECTION IN THE VICINITY OF A
STATIONARY FRONT ARE EXPECTED TO RESULT IN 1 TO 3 INCHES OF
RAINFALL, WITH LOCALLY HIGHER AMOUNTS.  SOME INSTANCES OF FLASH
FLOODING WILL BE POSSIBLE DURING THE LATE EVENING AND EARLY
MORNING HOURS.

DISCUSSION...A WELL DEFINED MID-LEVEL VORTMAX, ACCOMPANIED BY A
300MB DIVERGENCE MAXIMA OVER THE ARKLATEX REGION, IS SUSTAINING A
SURFACE LOW AND SLOW MOVING FRONT.  STRONG 850MB FLOW ON THE ORDER
OF 40 KNOTS TO THE EAST OF THE SURFACE LOW IS ADVECTING ANOMALOUS
1.75 INCH PWS NORTHWARD ACROSS MUCH OF THE LOWER MISSISSIPPI RIVER
VALLEY, ALONG WITH 70F SURFACE DEWPOINTS.  THE STRONG VORTICITY
ADVECTION FROM THE WEST, ALONG WITH SUSTAINED MOISTURE CONVERGENCE
NEAR THE STATIONARY FRONT, IS EXPECTED TO KEEP THE CONVECTION
GOING THROUGH 3AM LOCAL TIME.  RAINFALL RATES WITH THE HEAVIEST
CONVECTION ARE LIKELY TO BE ON THE ORDER OF 1.5 TO 2 INCHES PER
HOUR.

THE MAJORITY OF THE LATEST HI-RES GUIDANCE, INCLUDING THE HRRR,
HRRRX, ARW, AND NAM-CONEST, DEPICT GOOD AGREEMENT OF THE AXIS AND
SUGGEST A RELATIVELY NARROW CORRIDOR OF 1+ INCH AMOUNTS WITH
EMBEDDED 3 INCH AMOUNTS BY 1AM.  THESE AMOUNTS MAY EXCEED 3 TO 6HR
FLASH FLOOD GUIDANCE VALUES AND THEREFORE FLASH FLOODING IS
CONSIDERED POSSIBLE. 

HAMRICK

ATTN...WFO...FWD...HGX...JAN...LZK...MEG...SHV...

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

LAT...LON   34719048 34638943 34038857 33408852 33008891
            32958956 32799076 32439212 32009311 31479417
            31079495 30969548 30979597 31319614 32529582
            33149532 33779420 34409224