MESOSCALE PRECIPITATION DISCUSSION 0370
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
649 PM EDT THU JUN 22 2017

AREAS AFFECTED...SOUTHEAST LA...SOUTHEAST MS...SOUTHWEST AL

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

VALID 222250Z - 230400Z

SUMMARY...NARROW CONVERGENCE BAND WITHIN SHEARING WARM CONVEYOR
WILL SUPPORT AMPLE MOISTURE AND CHANNEL FOR TRAINING OVER FLOODED
AREAS LIKELY TO CONTINUE FLASH FLOODING CONDITIONS.

DISCUSSION...GOES-16 WV LOOPS SHOW A NARROW RIBBON OF DEEPEST
MOISTURE ACROSS THE BIRD'S FOOT OF SE LA THROUGH THE MS COAST INTO
SW AL...AS NORTHERN BAND OF WESTERN CARIBBEAN TUTT ENCROACHES FROM
THE EAST AND THE DRY SLOT REMAINS FAIRLY STATIONARY TO THE WEST. 
TO BE EXPECTED MOISTURE DEPTH IS DECREASING BUT REMAINS AROUND
2.5" BUT GIVEN THE SQUEEZING GOING ON...CONVERGENCE IS STRONG TO
RING OUT THE REMAINING MOISTURE WITHIN DEVELOPING CONVECTION
THOUGH UPDRAFTS WILL CONTINUE TO BE GENERALLY NARROW.  FLOW
BETWEEN THE TWO SYSTEMS SUPPORTS A NARROW CHANNEL OF
UNIDIRECTIONAL FLOW THAT WILL ONLY TIGHTEN AND SLIDE SLIGHTLY
EASTWARD...AS SUCH DEVELOPING CONVECTION WILL TRAIN TOWARD THE
NNE. 

HI-RES GUIDANCE IS FAIRLY COMPLIMENTARY WITH THE MOST PREFERABLE
BEING THE RECENT ESRL EXPERIMENTAL HRRR THAT SUGGEST A POTENTIAL
FOR AN ADDITIONAL 2-4" (MAINLY NEAR THE BEST INSTABILITY SOURCE OF
THE NORTH CENTRAL GULF) ALONG THE LOWER 2 ROWS OF COUNTIES IN SE
MS COINCIDENT WITH THE LOWEST FFG VALUES AND SIGNIFICANT ONGOING
FLOODING CONDITIONS.  AS SUCH FF IS CONSIDERED LIKELY OVER THE
NEXT FEW HOURS.  THE AREA OF CONCERN IS EXPANDED A BIT TO THE WEST
TO DENOTE SOME UNCERTAINTY OF THE SLOW WESTWARD DRIFT OF THE
BOUNDARY WITH TIME AND MATCHES UP WITH ANY FFG VALUES BELOW .5" IN
3HR ACROSS SW AL/SE MS 

GALLINA

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

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

LAT...LON   33148785 32988736 30618818 29778875 29058901
            29028931 29128962 29399010 30009010 31028939
            32418858