MESOSCALE PRECIPITATION DISCUSSION 0782
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
858 AM EST SAT DEC 03 2016
 
AREAS AFFECTED...SOUTHEAST TX...SOUTHWEST LA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 031400Z - 032000Z
 
SUMMARY...HEAVY RAINFALL RATES/TOTALS LEADING TO POSSIBLE FLOODING
CONDITIONS THROUGH THE LATE MORNING/EARLY AFTERNOON

DISCUSSION...CURRENT GOES-E WV LOOP DENOTES FAIRLY SOLID UPPER
LEVEL RIDGING ACROSS E TX INTO LA AT THIS TIME WITH STRONG RIGHT
ENTRANCE TO 130 KT POLAR JET ACROSS OK/N TX WITH LARGE SCALE
ASCENT EXTENDING ALL THE WAY TO THE GULF COAST.  S/W AXIS
CURRENTLY OVER CENTRAL TX WILL CONTINUE TO LIFT NORTHEASTWARD
ALLOWING FOR THE TRAILING CONFLUENCE ZONE/TROF TO SUPPORT VEERING
LOW LEVEL WIND PROFILES ACROSS THE NW GULF WHILE CONTINUING TO
SUPPORT STRONG SELY FLOW EAST OF 94W. THIS ORIENTATION WILL ALSO
SUPPORT A MORE UNIFORM DIRECTIONAL SHEAR TO ALLOW FOR CELLS THAT
DEVELOP ALONG THE COASTAL WARM FRONT TO ORIENT FAVORABLY FOR SOME
REPEATING OF CONVECTIVE CORES.  THIS IS PARTICULARLY THE CASE
GIVEN THE UPSTREAM HEIGHT FALLS THROUGHOUT THE MORNING AND THE
VEERED LOW LEVEL FLOW SHOULD SUPPORT A BACKBUILDING REDEVELOPMENT
AREA AS FAR WEST MATAGORDA BAY. IR/VIS IMAGERY DENOTES A N-S
BOUNDARY THAT IS A GOOD MARKER OF THIS WESTERN EXTENT.  

THE SURFACE FLOW OVER THE WESTERN GULF AOA 25-30KTS FROM NEARLY
ALL SOUTHERLY DIRECTIONS...SURFACE MOISTURE CONVERGENCE IS VERY
STRONG AND SHOULD BE MAINTAINED AS WELL ENHANCING EXCELLENT
MOISTURE TRANSPORT OF MODERATELY UNSTABLE (SBCAPES TO 2000 J/KG)
AND DEEP MOISTURE WITH TDS IN THE LOW 70S AND TPWS INCREASING UP
TO 2.0".  GIVEN THE STRENGTH OF THE FORCING THIS SHOULD SUPPORT
RAIN RATES INCREASING FROM 1.5 TO 2"/HR LIKELY LOCALLY HIGHER
TOWARD 18Z.  THIS BARES SIMILARITY TO HI-RES CAMS SUCH AS THE 12Z
HRRR AND 00Z WRF-ARW BOTH FOCUSED FROM GALVESTON BAY OVER TO LAKE
CHARLES WITH 6HR ADDITIONAL TOTALS IN THE RANGE OF 3-5"; HOWEVER
IT IS NOT OUT OF THE REALM OF POSSIBILITY THE AXIS MAY BE AS FAR
NW AS THE SE HOUSTON METRO.  THOUGH FF GUIDANCE VALUES ARE HIGH
THIS SHOULD POSE SOME FLASH FLOODING CONCERNS PARTICULARLY GIVEN
THE RAINFALL THAT HAS ALREADY FALLEN THIS MORNING.  

OF NOTE: FURTHER NORTH IN THE FRONTOGENETIC FORCING ACROSS THE
CENTRAL BIG PINEY REGION OF TX INTO W CENTRAL LA...WITH LACK OF
INSTABILITY REACHING THE BEST ISENTROPIC ASCENT...VERTICAL ASCENT
MAY BE STUNTED AND RATES MAY NOT BE SUFFICIENT FOR FLASH FLOODING.
 HOWEVER...FAVORABLE TRAINING PROFILES SUGGEST SOME FLOODING
CONCERN LIKELY ON LONGER TIME SCALES.  WILL CONTINUE TO
EVALUATE/MONITOR THIS AREA FOR ANY FUTURE MESOSCALE PRECIPITATION
DISCUSSIONS.   

GALLINA

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

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

LAT...LON   30999406 30839327 30039299 29779307 29659375 
            29419444 29039499 28799532 28639605 29089571 
            29859529 30509471