MESOSCALE PRECIPITATION DISCUSSION 0852...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
619 AM EDT MON OCT 02 2017

CORRECTED FOR TYPO IN AREAS AFFECTED

AREAS AFFECTED...FAR SERN LA INTO SRN MS

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

VALID 021015Z - 021615Z

SUMMARY...AN INCREASE IN CONVECTION IS EXPECTED TO DEVELOP IN AND
AROUND THE MISSISSIPPI DELTA IN THE NEXT COUPLE OF HOURS. RAINFALL
RATES NEAR 2 IN/HR ALONG WITH TRAINING MAY LEAD TO LOCALIZED FLASH
FLOODING.

DISCUSSION...EXPERIMENTAL GOES 16 SHORTWAVE IR IMAGERY SHOWED THE
NRN END OF A LOW LEVEL INVERTED TROUGH PROPAGATING WWD ALONG THE
CNTRL GULF COAST AT 10Z. VAD WIND PLOTS AT 850 MB MATCH RECENT RAP
850 MB WIND DEPICTIONS WITH SELY FLOW OF 20-30 KT EAST OF THE
TROUGH AXIS AND ELY FLOW OF 10-15 KT WEST OF THE TROUGH. A
QUASI-STATIONARY FRONT WAS ANALYZED ROUGHLY EAST TO WEST...JUST
OFFSHORE OF THE CNTRL GULF COAST WITH A SHARP GRADIENT IN MLCAPE
DEPICTED ALONG THE BOUNDARY VIA RECENT DATA FROM THE SPC
MESOANALYSIS PAGE. MLCAPE VALUES SOUTH OF THE FRONT WERE ESTIMATED
TO RANGE FROM 500-1500 J/KG AT 09Z. A MAX IN PRECIPITABLE WATER
VALUES WAS REFLECTED ON LOOPS OF BLENDED TPW IMAGERY MOVING TOWARD
THE WEST IN THE NRN GULF OF MEXICO WITH GPS DATA NOTING INCREASING
VALUES ALONG THE MISSISSIPPI DELTA WITH 2.1 TO 2.3 INCHES REPORTED
AT 09Z.

WHILE THE SATELLITE PRESENTATION ON EXPERIMENTAL GOES 16 10.3
MICRON CLEAN WINDOW IR IMAGERY TO THE EAST OF THE MISSISSIPPI
DELTA WAS NOT TOO IMPRESSIVE AS OF 10Z WITH ONLY A FEW SMALL
CLUSTERS OF COLDER CLOUD TOPS...THERE IS POTENTIAL FOR A RAPID
INCREASE IN COVERAGE EARLY THIS MORNING POST SUNRISE WITH THE
ONSET OF DIABATIC HEATING AND AS INSTABILITY IS ADVECTED TO THE
NORTH ATOP THE STATIONARY FRONT. AS THE LOW LEVEL TROUGH AXIS
CONTINUES WEST OF THE NEXT FEW HOURS...AN ELONGATED FETCH OF SELY
LOW LEVEL FLOW IS EXPECTED TO FOCUS INTO SERN LOUISIANA AND SRN
MISSISSIPPI...WHERE ISENTROPIC ASCENT ATOP THE QUASI-STATIONARY
BOUNDARY IS EXPECTED TO FOCUS ONE OR TWO AXES OF HEAVY RAIN.
FORECAST SOUNDINGS SUGGEST TRAINING OF CELLS FROM SOUTHEAST TO
NORTHWEST AND THE ENVIRONMENT WILL BE SUPPORTIVE OF RAINFALL RATES
NEAR 2 IN/HR WITH LOCALIZED 6 HOUR TOTALS OF 3-5 INCHES EXPECTED.
THIS MAY BE ESPECIALLY PROBLEMATIC NEAR AND SOUTH OF NEW ORLEANS
OVER NRN JEFFERSON/PLAQUEMINES PARISHES WHERE FLASH FLOOD GUIDANCE
IS LOWERED FROM RECENT HEAVY RAIN.

OTTO

ATTN...WFO...JAN...LIX...MOB...

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

LAT...LON   31088966 30538862 30068828 29548817 28938844
            28758960 29059055 29899074 30879038