000 
FXUS64 KLIX 172108
AFDNEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA 
310 PM CST FRI NOV 17 2000

...HEAVY RAIN EPISODE ABOUT TO UNFOLD FOR THIS WEEKEND...

INGREDIENTS COMING TOGETHER FOR A RATHER IMPRESSIVE OVER-RUNNING AND 
ISENTROPIC LIFT EVENT THIS WEEKEND. 12Z ANALYSES SHOWED A VERY 
STRONG JET STRUCTURE OVER THE TENNESSEE VALLEY WITH LOUISIANA AND 
COASTAL MISSISSIPPI PLACED UNDER THE RIGHT REAR QUADRANT OF THIS JET 
THROUGHOUT THE WEEKEND. THE STATIONARY FRONT SOUTH OF THE COASTLINE 
IS BECOMING INCREASINGLY BAROCLINIC WITH WEAK SURFACE MECHANICAL  
LOWS ATTAINING DEEPER STRUCTURES IN TIME. 

ISENTROPIC ANALYSIS FROM THE ETA AND AVN MODELS SHOW 35 TO 40 KT OF 
SOUTHERLY FLOW CONVERGING INTO A 15 KT EASTERLY FLOW ALONG THE I-10 
CORRIDOR DURING THE DAY SATURDAY. THE 300K ISENTROPIC SURFACE 
SETTLES FROM 700MB DOWNWARD TO 850MB BY SUNDAY MORNING WITH THE 
UPPER LEVEL DIVERGENCE INCREASING IN DEPTH...THEREBY INCREASING PIVA 
AND OMEGA THROUGHOUT THE PERIOD. THICKNESSES INCREASE ABOVE LOW 
LEVEL COLD AIR ADVECTION...THEREBY SHOWING WARM THERMAL WIND 
ADVECTION SATURDAY. 

BELIEVE THE ETA TO BE TOO FAST IN EJECTING THE SYSTEM EASTWARD. THE 
AVN SEEMS MUCH MORE BELIEVABLE. THE CUT-OFF LOW NEAR BAJA CALIFORNIA 
SHOULD HOLD BACK GIVEN THE AMOUNT OF SUB-TROPICAL FLOW APPROACHING 
THAT REGION ALONG WITH DIGGING TROUGH FALLING OUT OF THE UPPER 
ROCKIES. THIS WILL MOVE STEADILY EASTWARD INTO TEXAS BY LATE 
SATURDAY GIVING A DIFFERENT ORIENTATION TO THE FLOW PATTERN BECOMING 
MORE DIFFLUENT AND CONDUCIVE TO TRAIN ECHOES SATURDAY EVENING AND 
NIGHT...BEFORE BECOMING PROGRESSIVE SUNDAY. 

IN COORDINATION WITH LAKE CHARLES WILL BE GOING WITH A FLASH FLOOD 
WATCH TO ENCOMPASS THE WESTERN HALF OF OUR LA CWA. THIS WATCH AREA 
WILL BE ESSENTIALLY W OF I-55 AND EXTEND THROUGH KLCH CWA. CONSENSUS 
RAINALL FORECAST OF 2-4 INCHES WITH LOCALLY HIGHER AMOUNTS EXPECTED 
MAINLY THROUGH SATURDAY. HAVE OPTED TO GO THROUGH SUNDAY MORNING TO 
AT LEAST COVER THE ENTIRE PERIOD OF ANTICIPATED HEAVY RAINFALL. THE 
PRECIPITATION CALCULATOR OUTPUT USING 308K LIFT FROM 850 MB IN A 
STRATIFORM REGIME SHOWS A POTENTIAL OF 7.4 INCHES ACCUMULATION 
THROUGH SUNDAY MORNING. WILL NOT BE GOING WITH THIS NUMBER IN THE 
WATCH HOWEVER...THOUGH THERE WILL BE AMPLE TIME FOR REVISIONS.

TEMPERATURES WILL BE NEARLY ISOTHERMAL WITH ONLY ABOUT 3 TO 5 
DEGREES DIURNAL RANGE THROUGH SUNDAY. WILL BE MAINTAINING 
CATEGORICAL POPS MOST LOCATIONS FOR TONIGHT...SAT AND SAT 
NIGHT...THEN TAPER TO MAINLY MORNING POPS ON SUNDAY. 

ALSO GIVING CONSIDERATIONS TO COASTAL HIGH TIDES. AT THIS TIME THERE 
ARE NO EXTENUATING TIDAL SITUATIONS BUT THIS WILL HAVE TO BE 
MONITORED THROUGHOUT THE WEEKEND. AT THIS TIME...WILL BE CARRYING 
ABOVE NORMAL TIDES WORDING IN COASTAL WATERS FORECAST ALONG WITH 
SMALL CRAFT ADVISORY.

MCB 41/45/40/47 +++3       BTR 44/47/45/50 +++4
MSY 49/53/50/55 +++4       GPT 47/51/44/53 7++5

.NEW...SCA PQL TO ATCHAFALAYA BAY INCLUDING LAKES PONTCHARTRAIN AND 
MAUREPAS.
LA...FLASH FLOOD WATCH LAZ034>038-046>050-056>058-065 TONIGHT THRU 
     SUN AM.
MS...NONE.
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