MESOSCALE PRECIPITATION DISCUSSION 0765
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
355 AM EDT WED AUG 30 2017

AREAS AFFECTED...PORTIONS OF THE CENTRAL GULF COAST

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

VALID 300754Z - 301354Z

SUMMARY...THE THREAT FOR TRAINING AND FLASH FLOODING WILL INCREASE
OVER THE NEXT 3-6 HOURS ACROSS PORTIONS OF THE CENTRAL GULF COAST.
3-5 INCHES OF RAIN WILL BE POSSIBLE THROUGH 14Z.

DISCUSSION...AS REFERENCED IN MPD #762 FOR THE CENTRAL GULF
COAST...THE TOTAL PRECIPITABLE WATER AXIS POINTING INTO THE
CENTRAL GULF COAST HAS BEEN NARROWING OVER THE PAST 6-12
HOURS...AND CURRENTLY INTERSECTS THE MISSISSIPPI/ALABAMA COASTS.
850-700 MB FLOW MEASURED NEAR 25 KT AT 06Z BY THE KMOB VAD WIND
PLOT...LOCATED WITHIN THE HIGHEST MOISTURE OBSERVED WITHIN THE
NARROW SOUTH-NORTH MOISTURE AXIS...PWATS NEAR 2.3 INCHES PER
RECENT GPS DATA. HIGHER 850-700 MB WIND SPEEDS...CLOSER TO 40
KT...WERE OBSERVED AT KLIX. REGIONAL RADAR IMAGERY AS OF 0730Z
SHOWED 3-4 NARROW BANDS ORIENTED FROM SOUTH TO NORTH CONTAINING
HEAVY RAIN WITH EMBEDDED MINI-SUPERCELL STRUCTURES EXTENDING FROM
NEAR LAKE PONTCHARTRAIN TO THE WESTERN FLORIDA PENINSULA.

AS TROPICAL STORM HARVEY CONTINUES TO TRACK NORTHEASTWARD INTO
SOUTHWESTERN LOUISIANA OVER THE NEXT 6 HOURS...STRONGER 850-700 MB
FLOW WILL EDGE EASTWARD ALONG THE CENTRAL GULF COAST...ENHANCING
MOISTURE TRANSPORT NORTHWARD ATOP A SLOW MOVING WARM FRONT
STRETCHED WEST TO EAST ALONG THE GULF COAST AT 07Z. THE SOUTH TO
NORTH MOISTURE AXIS MAY CONTINUE TO NARROW...BUT IS NOT EXPECTED
TO SHIFT MUCH TO THE EAST OR WEST THROUGH 15Z.

AXES OF HEAVY RAINFALL ARE EXPECTED TO TEMPORARILY HANG UP/TRAIN
NEAR THE CENTRAL GULF COAST/WARM FRONT IN THE SHORT TERM...BUT AS
INCREASED MOISTURE TRANSPORT ARRIVES THROUGH 12Z...ONE OR TWO MORE
ROBUST RAINFALL AXES MAY DEVELOP IN THE VICINITY OF THE
MISSISSIPPI/ALABAMA COASTLINE WITH TRAINING OF 2-3 IN/HR RAINFALL
RATES EXPECTED. FLASH FLOODING WILL BE POSSIBLE...ESPECIALLY WITH
ANY OVERLAP FROM HEAVY RAINFALL FROM THE PAST 24 HOURS.

OTTO

ATTN...WFO...BMX...JAN...LIX...MOB...TAE...

ATTN...RFC...LMRFC...SERFC...

LAT...LON   32028666 31958575 31518541 30398623 29948700
            29218863 29158873 29048955 29379023 30359036
            31118992 31298866