MESOSCALE PRECIPITATION DISCUSSION 0020
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1202 AM EST MON JAN 16 2017
 
AREAS AFFECTED...NORTHEAST TX...SOUTHEAST OK 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 160500Z - 160900Z
 
SUMMARY....CONVECTION STREAMING NORTH AHEAD OF A WEAKENING SQUALL
LINE OVER NORTHEAST COULD POSE THREAT FOR TRAINING AND LOCALIZED
FLASH FLOODING INTO THE EARLY MORNING HOURS. 

DISCUSSION...A WEAKENING SQUALL LINE MOVING ACROSS NORTHEAST TX
(WHICH RESULTED IN FLASH FLOODING IN THE DALLAS/FT WORTH AREAS
EARLIER) CONTINUES TO PUSH EAST. AHEAD OF THE SQUALL
LINE...CONVECTIVE CELLS SOUTH OF A STATIONARY FRONT ACROSS
NORTHEAST TX CONTINUE TO STREAM NORTHEAST. THE CELLS ARE FORMING
IN AN AIRMASS WITH 500 J/KG OF MOSTLY ELEVATED INSTABILITY...
WHILE A 35 TO 45 KNOT LOW LEVEL JET PUMPS 1.40 INCH PRECIPITABLE
WATER AIR ACROSS NORTHEAST TX IN NEARBY SOUTHEAST OK.  

WHILE THE MAIN THREAT WITH THE WEAKENING SQUALL LINE REMAINS
SEVERE WEATHER...THE CONVECTIVE CELLS MERGING WITH THE SQUALL LINE
ACROSS PORTIONS OF NORTHEAST TX INTO NEARBY SOUTHEAST OK COULD
RESULT IN A FLASH FLOOD THREAT. WHILE MUCH OF THE HIGH RESOLUTION
GUIDANCE IS ALREADY SLOWER THAN REALITY WITH THE TIMING OF THE
SQUALL IN ACROSS NORTHEAST TX...THERE IS A MULTI MODEL SIGNAL
(INCLUDING THE LATEST HRRR/RAP...AS WELL AS THE 00Z WRF ARW3) FOR
A STRIPE OF 2.00 TO 3.00 INCHES OF RAINFALL WHERE CELL MERGER
OCCUR.

AS THE CONVECTION MOVES INTO SOUTHEAST OK...FLASH FLOOD GUIDANCE
VALUES ARE LOWER (AS LOW AS 1.50 INCHES IN SPOTS). GIVEN THE LOWER
FLASH FLOOD GUIDANCE VALUES...AS WELL AS THE MULTI MODEL SIGNAL
FOR RAINFALL AMOUNTS NEAR OR EXCEEDING 2.00 INCHES...FLASH
FLOODING IS POSSIBLE THROUGH ABOUT 08Z OR SO. AFTER THAT
TIME...THE LATEST RAP SUGGESTS THAT THE INSTABILITY THIS FAR NORTH
WILL HAVE BEEN CONSUMED...AND A WEAKENING TREND IN THE CONVECTION
IS EXPECTED. 

HAYES

ATTN...WFO...FWD...OUN...SHV...TSA...

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

LAT...LON   34929571 34639511 33839494 32859537 32719547 
            32029623 31369759 32049757 32429738 32849715 
            33489697 34139676 34689644