MESOSCALE PRECIPITATION DISCUSSION 0064
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
918 PM EST WED MAR 09 2016
 
AREAS AFFECTED...SE TEXAS...N & W LOUISIANA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 100217Z - 100817Z
 
SUMMARY...PERSISTENT SOUTHERLY ONSHORE FLOW ASCENDING OVER
STATIONARY FRONTAL ZONE WILL PROVIDE ENVIRONMENT FOR REPEAT DEEP
CONVECTION FOR THE NEXT FEW HOURS COMPOUNDING TOTALS FOR LOCAL
FLASH FLOODING CONCERNS.

DISCUSSION...ANOMALOUS UPPER LOW EJECTED A WEAK MID-LEVEL WAVE
THAT JUST PASSED THROUGH MATAGORDA AROUND 01Z LIFTING
NORTH...WHILE A STATIONARY FRONTAL ZONE REMAINS STEADFAST IN ITS
LOCATION ACROSS CENTRAL LA OFFSHORE NEAR SABINE RIVER WHERE IT
PARALLELS THE COAST A 100 MILES OR SO BEFORE DROPPING DUE SOUTH
TOWARD A RAPIDLY DEVELOPING SURFACE LOW.  DEEP SOUTHERLY FLOW IS
CHANNELED IN A NARROW CORRIDOR TO THE EAST OF THE N-S LINE THAT
WILL CONTINUE TO INTERSECT THE FRONTAL ZONE JUST EAST OF THE WEAK
SURFACE INFLECTION TO SUPPORT BETTER ISENTROPIC ASCENT AND GIVEN
LIMITED INHIBITION...QUICKLY BECOMES CONVECTIVE IN A FAVORED
TRAINING ORIENTATION ACROSS SE TX...WITH NO RESPITE FOR REPEAT
DEVELOPMENT GIVEN THIS CORRIDOR OF ENHANCED LOW LEVEL FLOW.  THIS
FLOW IS ALSO QUITE MOIST WITH NEARLY SATURATED LOW LEVEL NEARLY
MOIST ADIBATIC "SKINNY PROFILES" WITH TPWS NEARING 2.0" SUPPORTING
HIGHLY EFFICIENT RAINFALL PRODUCTION WITH RATES UP TO 2"/HR.  THE
OVERALL SLOPE OF THE ISENTROPIC SURFACE IS A BIT FLATTER
SUPPORTING A BROAD SHIELD OF MODERATE PRECIPITATION EXACERBATING
ONGOING FLOODING CONDITIONS OVER E TX AND CENTRAL/N LA...THOUGH
RATES WILL NOT BE DRAMATIC IT SHOULD BE ENOUGH TO MAINTAIN FF
CONDITIONS AS IT SHOULD EASILY EXCEED THE VERY LOW FF GUIDANCE
VALUES ACROSS THE REGION. 

WV LOOP SHOWS SHORTWAVE/ASSOCIATED JET STREAK ALREADY ROUNDED THE
SOUTHEAST SIDE OF THE DEEP UPPER LOW IN MEXICO...THAT WILL SUPPORT
THE SURFACE CYCLOGENESIS WHICH IN TURN WILL INCREASE THE LOW LEVEL
FLOW WITHIN THE CORRIDOR AND WILL ADVECT INCREASED INSTABILITY PER
MUCH OF THE HI-RES CAM MODELS DRIVING 2000 J/KG PLUS CAPES TOWARD
THE SE TX COAST TOWARD 08Z...WHILE INCREASING SHORTWAVE RIDGING
ALOFT TO EXPAND UPPER LEVEL DIVERGENCE OVER CENTRAL AND SE TX FOR
SOME OVERALL SYNOPTIC ASCENT TO THE MESOSCALE DRIVEN CONVECTION. 
THIS WILL ALSO ALLOW THE FRONTAL ZONE TO BE COME MORE E-W ORIENTED
NEAR/ALONG THE TX COAST INTO SOUTH CENTRAL LA...SUPPORTING A
BROADENING AREA OF CONVECTION SIMILAR TO THE SETUP OVER SE TX. 
THIS APPEARS BEST PRESENTED BY THE 12Z ARW.  


GALLINA

ATTN...WFO...CRP...EWX...HGX...JAN...LCH...SHV...

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

LAT...LON   32729210 32209137 30699285 29999347 29409467 
            28819544 28609593 28449648 28759678 29909669 
            30939560 32589397