Graphic for MPD #0766

MESOSCALE PRECIPITATION DISCUSSION 0766
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
907 AM EDT WED AUG 30 2017

AREAS AFFECTED...FAR EASTERN TX....WESTERN LA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 301300Z - 301900Z

SUMMARY...VERY HEAVY RAINS ASSOCIATED WITH T.S. HARVEY WILL
CONTINUE THROUGH MIDDAY WITH ADDITIONAL FLASH FLOODING LIKELY.

DISCUSSION...T.S. HARVEY IS MOVING FARTHER INLAND ACROSS SOUTHWEST
LA THIS MORNING AND CONTINUES TO PRODUCE VERY HEAVY RAINFALL
AROUND THE NORTHWEST FLANK OF THE CENTER OF CIRCULATION WHICH AT
12Z WAS LOCATED 25 MILES WEST-NORTHWEST OF LAKE CHARLES. THE
SYSTEM IS MOVING DUE NORTH CURRENTLY AT ABOUT 9 KTS.

FORTUNATELY...THE CONVECTIVE CLOUD PATTERN ASSOCIATED WITH HARVEY
HAS BECOME LESS IMPRESSIVE OVER THE LAST 2 TO 3 HOURS WITH THE
NON-OPERATIONAL GOES-16 10.3 MICRON/IR DATA SHOWING A WARMING OF
CLOUD TOPS TEMPERATURES ASSOCIATED WITH THE CONVECTIVE MASS NEAR
AND NORTHWEST OF THE CIRCULATION CENTER. THIS HAS RESULTED IN SOME
DECREASE IN THE RAINFALL RATES WHICH HAVE COME DOWN TO GENERALLY 1
TO 2 INCHES/HR BASED ON RECENT SURFACE OBSERVATIONS. THE GOOD NEWS
IS THAT THE HEAVY RAINS ARE ALSO PULLING AWAY FROM THE
BEAUMONT/PORT-ARTHUR AREA...INCLUDING THE JACK BROOKS REGIONAL
AIRPORT WHICH REPORTED AN ASTONISHING 22.33 INCHES OF RAIN IN A 24
HOUR PERIOD GOING BACK TO 12Z YESTERDAY. THIS SAME LOCATION
RECORDED 26.03 INCHES JUST FOR THE CALENDAR DAY ON TUESDAY ALONE.

MOVING FORWARD THROUGH THE REMAINDER OF THE MORNING AND EARLY
AFTERNOON...THE MAIN FOCUS OF HEAVY RAIN SHOULD BE ACROSS FAR
EASTERN TX AND WESTERN LA...WITH A FOCUS ALONG THE TX/LA BORDER
AND ADJACENT AREAS. THERE STILL REMAINS A CORRIDOR OF ENHANCED
SURFACE CONVERGENCE NEAR AND NORTH OF THE CENTER OF HARVEY WHICH
SHOULD MAINTAIN A HIGHLY FORCED ENVIRONMENT FOR HEAVY RAINS TO
CONTINUE TO DEVELOP AND SLOWLY ADVANCE NORTH.

HOWEVER...GOES-WV IMAGERY IS SHOWING A SIGNIFICANT AMOUNT OF DRY
AIR WRAPPING AROUND THE CIRCULATION CENTER AND THIS ENTRAINMENT OF
DRY AIR COUPLED WITH AN INCREASING DETACHMENT OF OF THE SYSTEM
FROM MORE FAVORABLE INSTABILITY OFF TO THE SOUTHEAST WILL WILL
TEND TO ALLOW RAINFALL RATES TO POTENTIAL COME DOWN A BIT MORE
OVER THE NEXT FEW HOURS. RAINFALL RATES SHOULD GENERALLY BE ON THE
ORDER OF 1 TO 2 INCHES PER HOUR AT MOST...WITH ADDITIONAL STORM
TOTALS THROUGH 18Z OF 2 TO 4 INCHES.

THESE TOTALS WILL STILL PROMOTE ADDITIONAL FLASH FLOODING AND WILL
AT LEAST EXACERBATE ONGOING EXTREME FLOODING CONCERNS OVER PARTS
OF EASTERN TX AND FAR SOUTHWEST LA.

ORRISON

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

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

LAT...LON   33069327 32819242 32129240 31399264 30899278
            30029302 29799343 29789381 30159457 31019484
            31869462 32749393


Last Updated: 907 AM EDT WED AUG 30 2017