MESOSCALE PRECIPITATION DISCUSSION 0339
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
526 PM EDT WED JUN 20 2018

AREAS AFFECTED...SOUTHEAST TEXAS

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

VALID 202125Z - 210225Z

SUMMARY...PRECIPITATION CONTINUES TO TRAIN IN A SOUTH TO NORTH
DIRECTION INTO SOUTHEAST TEXAS.  A SLOW NORTHEASTWARD SHIFT OF THE
HEAVIEST AXIS INTO AREAS THAT HAVE NOT RECEIVED A LOT OF
PRECIPITATION RECENTLY.

DISCUSSION...THERE ARE NO SIGNFICANT CHANGES TO THE  LATEST
COMPOSITE RADAR LOOPS ACROSS SOUTHEAST TEXAS.  AREAS OF
PRECIPITATION CONTINUE TO TRAIN IN A GENERAL SOUTH TO NORTH
DIRECTION.  THERE IS A GREADUAL SHIFT IN THIS AXIS TO THE
NORTHEAST...AWAY FROM AREAS THAT HAVE RECIEVED VERY HEAVY AMOUNTS
ALONG THE MID TO LOWER TEXAS COAST AND TOWARD THE UPPER TEXAS
COAST THAT HAS BEEN RELATIVELY DRIER. STILL...WITH THE LIKLIHOOD
OF TRAINING PERSISTING OVER THE NEXT FEW HOURS...THE RISK OF
RUNOFF ISSUES WILL BE INCREASING AS THE BAND MOVES TOWARD THE
HOUSTON METRO AREA.

THE LATEST CAM GUIDANCE DOES NOT APPEAR TO HAVE A VERY GOOD HANDLE
ON THE CURRENT ACTIVITY.  COMPARISON OF THE SIMULATED RADARS FROM
THE NAM CONEST...ARW AND NMMB SHOW ALL THREE OF THESE MODELS ARE
SIGNIFICANTLY UNDERDONE WITH THEIR RESPECTIVE RADAR COVERAGE
COMPARED TO CURRENT ACTIVITY. THE HRRR AND HRRX FROM 1900 UTC ARE
SHOWING THIS SOUTH TO NORTH LINE BETTER...BUT BOTH APPEAR TO BE
SLOW IN MOVING IT UP THE COAST. 

FRONTOGENESIS FROM THE 1800 AND 1900 UTC RAP RUNS SHOW A WELL
DEFINED FRONTOGENESIS MAX EXTENDING ALONG THIS SOUTH TO NORTH
TRAINING AREA AND THEN TO THE NORTHEAST ALONG THE SOUTHWEST TO
NORTHEAST ORIENTED SURFACE TROF OVER NORTHEAST TEXAS.  THE
EVOLUTION OF THIS FRONTOGENESIS FIELD IN THE RAP SHOWS THE SOUTH
TO NORTH AXIS DISSIPATING WHILE THE SOUTHWEST TO NORTHEAST AXIS
SETTLES SOUTHWARD TOWARD THE UPPER TEXAS COAST BY 2200 UTC...WHERE
IS THEN PERSISTS INTO THE EARLY HOURS OF THURSDAY. 

WITH THE LATEST GUIDANCE HAVING ISSUES DEPICTING THE ONGOING
ACTIVITY...CONFIDENCE IN THEIR RESPECTIVE QPFS GOING FORWARD IS
LOW.  AT THE MOMENT...WITH NO SIGNIFICANT SIGNS OF WEAKENING ON
THE LATEST RADAR LOOPS OF LATEST GOES 16 IR IMAGERY...BELIEVE THE
SOUTH TO NORTH TRAINING AND RESULTANT HEAVY RAIN AND INCREASING
RUNOFF THREAT WILL CONTINUE INTO THIS EVENING.  1"+ HOURLY TOTALS
POSSIBLE INTO THIS EVENING IN THE AREAS OF TRAINING. 

ORAVEC

ATTN...WFO...HGX...LCH...SHV...

ATTN...RFC...WGRFC...

LAT...LON   31789479 31789437 31499446 31239470 30889478
            30389446 29129392 28379410 27719481 27499536
            27679588 28359618 28989640 29769657 30139645
            30439638 31159563