840 
FXUS64 KLIX 211755
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1155 AM CST SAT NOV 21 2009

.AVIATION...
WIDESPREAD SHOWERS CONTINUE TO MOVE ACROSS THE AREA. GPT IS THE
ONLY SITE NOT SEEING RAIN...BUT SHOULDN/T BE TOO MUCH LONGER. IFR
CIGS HAVE BEEN FAIRLY SPORADIC BUT SHOULD BECOME MORE COMMON LATER
TONIGHT. SO...EXPECT OFF AND ON LIGHT TO OCCASIONALLY MODERATE
SHOWER THROUGH 00Z AND TAPERING OFF AFTER THAT. IFR CIGS AND MVFR
VIS WILL RESUME THROUGH MUCH OF THE REST OF THE PERIOD. 

&&

.PREV DISCUSSION... /ISSUED 738 AM CST SAT NOV 21 2009/ 

UPDATE...
SOUNDING DISCUSSION...

THE ATMOSPHERE HAS BECOME SATURATED FROM 815 MB TO 580
MB...PRECIPITABLE WATER VALUE IS 1.10 INCHES. AN ALTOSTRATUS CLOUD
DECK WAS PRESENT AT LAUNCH DUE TO QUITE A BIT OF STRATIFORM RAIN
MOVING ACROSS THE CWA ALONG WITH A FEW EMBEDDED STRONGER SHOWERS.
AN INVERSION IS PRESENT NEAR 3000 FEET WHILE WINDS ARE OUT OF THE
EAST AT THE SURFACE SHIFTING SOUTH THEN SOUTHWEST ALOFT.

PREV DISCUSSION... /ISSUED 403 AM CST SAT NOV 21 2009/ 

SHORT TERM...AT 9Z THE SFC LOW WAS LOCATED JUST EAST OF THE CNTRL 
TX COAST AND STILL WELL SW OF THE CWA WHILE A LARGE AREA OF SHRA ARE 
MAKING THERE WAY NORTH ONTO THE SWRN AND S-CNTRL LA COAST. THERE IS 
AN AREA OF TSRA WELL SOUTH OF THE LA COAST AND THESE WERE MAINLY 
MOVING TO THE EAST. THE MID LVL DISTURBANCE WAS STILL BACK IN ERN TX 

TODAY THROUGH TOMORROW...THERE IS STILL SOME UNCERTAINTY IN THE 
TRACK OF THE SFC LOW. EVEN THOUGH THE MDLS ARE WITHIN THE NOISE LVL 
THE GFS IS FURTHER SOUTH THAN THE ECMWF. LOOKING AT CURRENT 
FEATURES...MSAS SHOWS BEST PRESSURE FALLS EAST TO ENE OF THE SFC LOW 
ALONG WITH THE STRONGEST CONVECTION WELL INTO THE GULF MOVING EAST. 
THE GFES AND SREF ARE ALSO MORE IN LINE WITH THE GFS AND WITH ALL OF 
THIS I PREFER THE FURTHER SOUTH TRACK. THAT SAID ANY DEVIATION 
NORTH(EVEN BY JUST 50 MILES) WOULD MAKE A PRETTY GOOD DIFFERENCE IN 
STRONG/SVR RISK. WITH THE TRACK EXPECTED TO REMAIN JUST OFF THE 
COAST TODAY THE WARM SECTOR WILL REMAIN OVER THE COASTAL WATERS 
MAKING TODAY MORE OF A ISENTROPIC LIFT/WAA SHRA DAY AND THIS SHOWS 
UP REALLY WELL IN THE 290-300K LVLS FOR OUR CWA. WITH THAT SAID I 
EXPECT THE LARGE AREA OF SHRA JUST OFF TO OUR SW TO CONTINUE TO 
EXPAND TO THE NE THROUGH THE MORNING. THERE WILL EVEN BE ISLTD TO 
SCT TSRA EMBEDDED IN THIS ACTIVITY THANKS TO ELEVATED 
INSTABILITY(SHOWALTERS NEAR -3). AS FOR RAINFALL TOTALS AREA WIDE 
1-2" LOOK PRETTY GOOD. THE HEAVIEST RAIN WILL LIKELY OCCUR ALONG AND 
SOUTH OF A LINE FROM MORGAN CITY TO LUCEDALE THIS AFTN. THIS 
LOCATION LINES UP WELL WITH THE LFQ OF A 100KT SUBTROPICAL JET. 

OUR SFC LOW WILL CONTINUE TO PUSH ENE ALONG/JUST OFF THE COAST AND 
SHOULD BE ALONG THE AL COAST BY TOMORROW MORNING. THIS WILL LEAD TO 
VERY GOOD RAIN CHANCES ACROSS THE ERN HALF OF THE CWA THIS EVN WITH 
RAIN TAPERING OFF AFTER MIDNIGHT. ACROSS THE SW WE COULD SEE RAIN 
COME TO AN END QUICKLY LATE THIS AFTN/EARLY EVN AS WE SHOULD BEGIN 
TO GET DRY SLOTTED. BY TOMORROW MORNING LIGHT RAIN MAY STILL BE 
OCCURRING ACROSS THE EXTREME ERN PORTIONS OF THE CWA AND POSSIBLY IN 
OUR OUTER WATERS. SUNDAY MAY BE A DREARY COOL DAY AS THE MID LVL 
DISTURBANCE WILL BE SLOW TO LIFT OUT OF THE LOWER MS VALLEY TWRDS THE 
TN VALLEY. THE LL THERMAL TROUGH WILL REMAIN WEST OF THE AREA SO WE 
EXPECT TO SEE A GOOD BIT OF LOW CLOUDS STILL.  /CAB/

LONG TERM...NO BIG CHANGES IN THE EXTENDED. THERE AREA SOME TIMING 
DIFFERENCES B/T THE MEDIUM RANGE MDLS WITH THE PASSAGE OF THE NEXT 
FRONTAL SYSTEM BUT OVERALL THE MDLS ARE IN GENERAL AGREEMENT AND 
YOUR TURKEY DAY IS LOOKING RATHER QUIET ALONG THE N-CNTRL GULF COAST 
AND LOWER MS VALLEY. WITH MAINLY JUST TIMING ISSUES I WILL USE A 
BLEND OF THE GFS AND ECMWF WITH OUR NEXT SYSTEM

THE FIRST HALF OF THE WORK WEEK WILL BEGIN QUIET BUT ANOTHER MOSTLY 
DRY FRONTAL SYSTEM WILL APPROACH THE AREA SOMETIME TUE/TUE NIGHT/WED 
MORNING. BY MON NIGHT ANOTHER DISTURBANCE WILL DROP INTO THE 
CNTRL/NRN PLAINS WITH A SFC LOW DEEPENING JUST WEST OF THE MID/UPPER 
MS VALLEY. AS THIS SYSTEM PUSHES EAST TUE IT WILL DRAG A COLD FRONT 
ACROSS THE SRN PLAINS AND INTO THE LOWER MS VALLEY. AGAIN THERE IS 
SOME UNCERTAINTY AS TO WHEN THE FRONT WILL PUSH INTO THE CWA BUT IT 
IS LOOKING LIKE SOMETIME TUE AFTN/EVN. NOW MOISTURE RETURN WILL BE 
QUITE LIMITED AHEAD OF THIS SYSTEM THANKS TO STRONG HIGH PRESSURE 
REMAINING OVER THE SERN CONUS/NRN GULF. WITH THAT LOOK FOR ISLTD TO 
WIDELY SCT SHRA MAINLY WITH THE FRONT. AS FOR TEMPS LOOK FOR 
SEASONABLY COOL TEMPS WITH LOWS IN THE MAINLY IN THE 40S TO MID 
50S(NORTH TO SOUTH) AND HIGHS IN THE UPPER 60S/LOWER 70S MON AND TUE 
AND THEN IN THE 60S BEHIND OUR FRONT ON WED. 

YOUR TURKEY DAY LOOKS RATHER QUIET AND COOL. ANOTHER SURGE OF COOLER 
CONTINENTAL AIR WILL BE ON THE WAY DOWN AND THIS SHOULD HELP KEEP 
HIGHS IN THE UPPER 50S TO LOWER 60S. LOWS THANKSGIVING MORNING WILL 
MAINLY BE IN THE 40S THANKS TO THE SFC HIGH STILL OFF TO OUR NW BUT 
IF THE COOLER AIR IS A LITTLE FASTER THEN UPPER 30S WILL BE LIKELY 
ACROSS THE NRN 3RD. 

HIGH PRESSURE WILL DOMINATE AT THE SFC INTO THE WEEKEND AND THIS 
SHOULD HELP KEEP THINGS ON THE COOL AND DRY SIDE. /CAB/

AVIATION...
CURRENT VFR CONDITIONS LIKELY TO PERSIST THROUGH THROUGH AT LEAST 
SUNRISE...BEFORE LOWER CONDITIONS MOVE IN. CURRENT FORECAST MAY 
ACTUALLY BE A TAD ON THE PESSIMISTIC SIDE AS LOWER CEILINGS HAVE NOT 
MOVED ON SHORE YET. ONCE CONDITIONS DO FALL BELOW VFR...THEY WILL 
REMAIN AT MVFR TO IFR CONDITIONS THROUGH THE REMAINDER OF THE 
FORECAST PERIOD. CONVECTION SHOULD BE LIMITED...AND DO NOT PLAN ON 
MENTIONING THUNDER IN TERMINALS AT THIS TIME. 35 

MARINE...
MAIN CONCERN REMAINS WINDS TODAY. MOST OF THE COASTAL WATERS REMAIN 
IN EXERCISE CAUTION WIND RANGES...BUT A FEW SITES OVER THE WESTERN 
WATERS HAVE REACHED 20 KNOTS SUSTAINED. SPLL1...SOUTH OF TERREBONNE 
PARISH REPORTING 30 KNOTS...BUT THIS IS SOMEWHAT ELEVATED WITH 
ANEMOMETER AT 40 METERS...SO SURFACE WINDS LIKELY SOMEWHAT LESS. 
GRADIENT FORECAST TO RELAX DURING THE DAY...AND THIS IS SHOWN IN 
MODEL WIND GRIDS. WILL CARRY SCA IN WESTERN WATERS...AND EXERCISE 
CAUTION EAST AND TIDAL LAKES THROUGH 00Z. EXPECT THAT THE EXERCISE 
CAUTION WILL NEED TO BE CARRIED INTO THE OVERNIGHT HOURS BY THE DAY 
SHIFT. 

ONCE CONDITIONS RELAX OVERNIGHT TONIGHT...NO FLAGS EXPECTED BEFORE 
MIDWEEK. AT THAT POINT...COLD AIR ADVECTION BEHIND NEXT FRONTAL 
SYSTEM TUESDAY NIGHT OR WEDNESDAY WILL LIKELY ALLOW EXERCISE CAUTION 
CONDITIONS TO RETURN.  35

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  58  49  60  48 / 100  80  10  10 
BTR  58  50  62  48 / 100  40  10  10 
MSY  62  53  64  51 / 100  50  10  10 
GPT  60  52  65  51 / 100  80  10  10 

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 6 PM SATURDAY FOR THE FOLLOWING 
     ZONES: COASTAL WATERS FROM THE SOUTHWEST PASS OF THE 
     MISSISSIPPI RIVER TO LOWER ATCHAFALAYA RIVER LA FROM 20 TO 
     60 NM...AND COASTAL WATERS FROM THE SOUTHWEST PASS OF THE 
     MISSISSIPPI RIVER TO LOWER ATCHAFALAYA RIVER LA OUT 20 NM. 

MS...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 6 PM SATURDAY FOR THE FOLLOWING 
     ZONES: COASTAL WATERS FROM THE SOUTHWEST PASS OF THE 
     MISSISSIPPI RIVER TO LOWER ATCHAFALAYA RIVER LA FROM 20 TO 
     60 NM...AND COASTAL WATERS FROM THE SOUTHWEST PASS OF THE 
     MISSISSIPPI RIVER TO LOWER ATCHAFALAYA RIVER LA OUT 20 NM. 

&&

$$

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