MESOSCALE PRECIPITATION DISCUSSION 0355
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
458 PM EDT WED JUN 21 2017

AREAS AFFECTED...EXT SOUTHEASTERN TX COAST...SOUTHWESTERN LA

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

VALID 212100Z - 220200Z

SUMMARY...NORTHERN INNER CONVERGENCE BAND OF TS CINDY...TRAINING
AND EFFICIENT RAINFALL MAY PRODUCE FLASH FLOODING MAINLY SOUTH OF
I-10.

DISCUSSION...GOES-16 CONUS VISIBLE IMAGERY SHOWS NUMEROUS INTERNAL
VORTICIES IN THE INNER CORE OF TS CINDY.  WV LOOP CONTINUES TO
SHOW MODEST SOUTHERLY SHEAR/DRY AIR COVERING THE SOUTHERN PORTION
OF THE CYCLONE LEADING TO TIGHTENING OF THE DOWNSTREAM CONVERGENCE
BANDS.  THIS TIGHTENING CORRESPONDS WITH DECREASING PROXIMITY TO
SHORE AS WELL.  AS SUCH STRONG LOW LEVEL EASTERLY FLOW IS BECOMING
MORE UNIDIRECTIONAL AS WELL AS HIGHLY CONVERGENT.  FAIRLY CLEAR
SKIES ALSO ALLOWED A WELL OF INCREASED/UNTAPPED INSTABILITY TO
DEVELOP ALONG THE SW LA COAST IN THE INCREASINGLY CONFLUENT
NORTHERN BAND WITH SBCAPES TO 2500 J/KG AND SATURATED PROFILES
SUPPORTING TPWS OF 2.5"+.  SO WITH THE STRONG MST
CONVERGENCE...CONVECTION SHOULD BE INCREASING WITH TIME WITH RAIN
RATES OF 2.5"/HR POSSIBLE.  ADDITIONALLY WITH SFC TO 850 CONFLUENT
FLOW STRONGER UPSTREAM TO 40KTS...PROPAGATION VECTORS SUPPORT
BACKBUILDING THROUGH VERIMILLION BAY/MARSH ISLAND.  CURRENT VIS
IMAGERY SHOWS NEXT SIGNIFICANT INNER CORE PRESSURE MESOLOW...TO
TRACK VERY NEAR THE VERMILLION/SE CAMERON PARISH COASTLINE TOWARD
00-01Z...FURTHER ENHANCING LOCALIZED WINDS/CONVERGENCE AND
THEREFORE BACKBUILDING.  AS SUCH IT WOULD NOT BE OUT OF THE REALM
OF POSSIBILITIES OF TOTALS OF 3-5" BY 02Z MAINLY SOUTH OF I-10. 

AS NOTED BY THE GOES-16 WV CHANNELS THERE MAY BE SOME DRY AIR
ENTRAINMENT ABOVE 7H BY THE SOUTHERLY SHEAR AND MAY SUPPORT SOME
CONVECTION TO BE OUTFLOW DOMINANT.  THIS WOULD REDUCE THE
EFFECTIVENESS OF TRAINING...EXPANDING THUNDERSTORMS FURTHER NORTH
THAN I-10 REDUCING FLASH FLOOD THREAT THROUGHOUT THE AREA GIVEN
AREAL EXPANSION OF RAINFALL.  AS SUCH THIS MINOR UNCERTAINTY AND
GENERALLY HIGHER FFG VALUES/RECENT DRY SPELL ONLY LEADS TO
CONFIDENCE OF POSSIBLE FLASH FLOODING TO OCCUR IN THE AREA OF
CONCERN.  THOUGH IF DRY AIR IS NOT AS EFFECTIVE...FLOODING COULD
BE SIGNIFICANT ALONG AND SOUTH OF I-10.

GALLINA

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

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

LAT...LON   30429366 30419286 30109216 29529174 29379180
            29379185 29529242 29569355 29529428 29759453
            30139420