271 
FXUS64 KLIX 020831
AFDNEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
230 AM CST THU DEC 2 1999

A RATHER DIFFICULT FORECAST PACKAGE SETTING UP THIS AM AT LEAST 36 
HR OUT AND BEYOND.  MODELS IN GOOD AGREEMENT INITIALLY BUT BEGIN TO 
DIFFER SOMEWHAT STARTING 24 HR AS THE NGM SHOWS BETTER DYNAMICS 
SETTING UP JUST W OF THE STATE WHILE THE AVN BRINGS IN A BETTER 
MOISTURE FETCH ACROSS THE REGION.  THE ETA LOOKS TO BE FAIRLY 
CONSISTENT WITH THE AVN THROUGH 48 HR ALTHOUGH MAYBE A TAD SLOWER.  
LOOKING AT AVN AND NGM GUIDANCE HOWEVER ALMOST SUGGESTS THE COMPLETE 
OPPOSITE AS THE AVN WANTS TO FORECAST SIGNIFICANTLY HIGHER POPS 
THROUGH 48 HR ALTHOUGH TEMPS ARE REASONABLY CLOSE.  WHAT THE MODELS 
DO PROPOSE IS THAT THE UPPER LEVEL LOW JUST WEST OF THE CENTRAL 
PLAINS WILL TRACK NE APPROACHING THE OHIO VALLEY REGION CARRYING THE 
BETTER DYNAMICS WELL TO THE N OF THE FORECAST AREA BEFORE SHEARING 
THEM OUT.  THE MODELS EVEN HINT AT SOME ISENTROPIC DOWNGLIDE SETTING 
UP OVER MUCH OF THE SE IN RESPONSE TO THE SHEARING LOW.

SO WHATS THIS LEAVE FOR US...AS THE UPPER LEVEL RIDGE AND 
ASSOCIATED SFC HIGH PRES CONTINUE PUSHING TOWARD THE E...DO BELIEVE 
A SOLID RETURN TRANSPORT WILL SET UP OVER SE LA AND SOUTHERN MS 
STARTING TODAY.  THIS SHOULD AID IN BUILDING BL MOISTURE VALUES 
ESPECIALLY 24 HR OUT.  AS A RESULT...HAVE OPTED TO FOLLOW MORE THE 
AVN GUIDANCE AND SOLUTION.  EVEN WITH THE BETTER DYNAMICS SHIFTING 
MORE TO THE NE...THE AVN DOES HINT AT SOME MID LEVEL ENERGY EJECTING 
SE OF THE LOW WITH RELATIVELY GOOD UPPER LEVEL FLOW AS ADDED SUPPORT.  
THEREFORE...WILL INTRODUCE SOME CLOUDS STARTING TONIGHT WITH 
INCREASING COVERAGE AND THE POTENTIAL FOR PRECIP BY FRI.

INTO THE EXTENDED...WILL CONTINUE WITH MOSTLY CLOUDY CONDITIONS AND 
SCATTERED PRECIP AS THE MRF SUGGESTS WITH A SECOND UPPER LEVEL 
SYSTEM SETTING UP OVER THE CENTRAL PLAINS AND PUSHING EWD INTO MON.  
WILL HOLD OFF ON THUNDER FOR NOW AS CONVECTIVE INSTABILITY STILL NOT 
LOOKING IMPRESSIVE ENOUGH AS SUGGESTED BY THE MODELS. 

MCB 71/53/72/55 0045    BTR 73/56/74/61 0045
MSY 72/55/75/60 0035    BIX 71/55/72/62 0035

.NEW...NONE
LA...NONE
MS...NONE.

09