MESOSCALE PRECIPITATION DISCUSSION 0063
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1019 PM EDT SUN MAR 18 2018

AREAS AFFECTED...CENTRAL LA...FAR SOUTHWEST MS...EXT EASTERN TX

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

VALID 190220Z - 190655Z

SUMMARY...POTENTIAL TRAINING THROUGH AREAS OF LOWERED FFG
VALUES/SATURATED SOILS SUGGESTS POSSIBLE FLASH FLOODING THREAT
THROUGH 07Z.

DISCUSSION...GOES-16 10.3 EIR LOOP AND LIGHTNING NETWORK DATA
DETECT RECENT UPTICK IN CONVECTIVE DEVELOPMENT ACROSS THE PINEY
REGION OF EAST TX STARTING TO ADVANCE INTO WEST CENTRAL LA.  WV
SUITE SUGGEST A WEAK SHORTWAVE PROVIDING SOME ENHANCED DPVA WITHIN
A WEAKLY DIFFLUENT UPPER LEVEL PATTERN TO MAINTAIN CONVECTION.  IN
THE LOWER LEVELS INSTABILITY HAS BEEN MAINTAINED WITH UPPER 60S
TDS IN THE UPSTREAM ENVIRONMENT WITH ONSHORE CONFLUENT STREAMLINES
SUPPORTING MODEST MOISTURE CONVERGENCE.  3.9UM SWIR DETECTED AN
OLD LINGERING BOUNDARY ORIENTED FROM THE COMPLEX ESE TOWARD LAKE
PONTCHARTRAIN LIKELY SET BY EARLIER MORNING CONVECTION AND APPEARS
TO EFFECTIVE POOLING OF INSTABILITY WITH MUCAPES REMAINING AROUND
THE 1500-2000 J/KG RANGE.  LOW LEVEL SHEAR HAS BEEN RECENTLY
SUPPORTING ROTATING UPDRAFTS AND STRONG HAIL SIGNATURES...BUT
GIVEN MST FLUX AND TPWS UP TO 1.5" THERE IS LIKELY TO BE MODERATE
TO HEAVY RAINFALL ASSOCIATED WITH THESE CORES AS WELL WITH RATES
UP TO 1.5"/HR.

A CURRENT LIMITING FACTOR IS RELATED TO THE STRENGTH OF THE FLOW
WHERE EASTERLY FORWARD MOTIONS UP TO 25-30KTS ARE LIKELY TO LIMIT
OVERALL RAINFALL TOTALS FROM ANY GIVEN CELL TO AT OR BELOW 1.0" IN
ANY GIVEN SPOT.  HOWEVER...SUPERCELLS WOULD LIKELY BE A BIT SLOWER
AND LIKELY TURN RIGHT TOWARD THE BOUNDARY AND POTENTIALLY GIVEN
CURRENT TREND/ORIENTATION POSE A THREAT FOR CELLS TO BECOME
FAVORABLY ANGLED FOR SOME  ISOLATED TRAINING.  TO MAKE MATTERS
MORE CONCERNING FOR THE POTENTIAL FOR FLOODING...CURRENT CELL
TRACK APPEARS TO BE NEAR/JUST SOUTH OF THE MORNING CONVECTION'S
TRACK WHERE FFG VALUES HAVE BEEN COMPROMISED WHERE EVEN 3HR VALUES
ARE AOA 1.0-1.25" FROM THE VIC OF KPOE TO KHDC.  AS SUCH THERE IS
A POSSIBLE THREAT FOR FLASH FLOODING THROUGH THE LAST HOURS OF
SUNDAY INTO MONDAY MORNING.

GALLINA

ATTN...WFO...JAN...LCH...LIX...SHV...

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

LAT...LON   31749248 31499074 30678995 30079075 30329197
            30559288 30879381 31289401 31669368