FXUS64 KLIX 090542
AFDLIX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1142 PM CST TUE DEC 8 2009
.AVIATION...
LINE OF STORMS IS CURRENTLY TRACKING EAST ACROSS SOUTHERN MS. A
FEW ISOLATED SHOWERS CONTINUE TO DEVELOP OUT AHEAD OF THE BOUNDARY
IN SOUTHEASTERN LA. TSRA SHOULD BE THRU MCB SHORTLY AND NOT
EXPECTING MUCH ELSE FOR THE REMAINDER OF THE NIGHT EXCEPT POSSIBLY
A SHOWER OR TWO. CIGS WILL NOT IMPROVE AND VIS WILL DROP TO AT
LEAST MVFR AT ALL SITES OVERNIGHT. EXPECT LIFR VIS AT MSY AND BTR
WHILE GPT DROPS TO VLIFR FOR AN EXTENDED PERIOD NEAR SUNRISE. ONCE
FOG DISSIPATES AFTER SUNRISE...WINDS WILL BECOME NWRLY AND VFR
CONDITIONS PREVAIL.
&&
.PREV DISCUSSION... /ISSUED 851 PM CST TUE DEC 8 2009/
UPDATE...
AN UPDATED ZONE PACKAGE IS FORTHCOMING TO EXTEND THE TORNADO WATCH
FOR THE FOUR SOUTHERN MISSISSIPPI COUNTIES THAT WERE ALREADY IN WT
796. THE NEW WT 799 EXTENDS TO 2 AM BUT THE COUNTIES MAY BE
CLEARED SOONER ONCE THE SURFACE FRONT MOVES THROUGH. THE FRONT
APPEARS TO BE ROUGHLY FROM RUSTON LA TO LUFKIN TX AND MOVING EAST
AROUND 40 MPH. BEST DYNAMICS FOR THUNDERSTORMS APPEAR TO BE INTO
CENTRAL MS WHERE BEST LOW LEVEL CONVERGENCE AND SHEAR IS
OCCURRING. SHALLOWER CONVECTION INITIATING IN SOUTHERN LOUISIANA
AND STREAMING NORTHWARD IN PARALLEL STREAKS IN UNIDIRECTIONAL SW
FLOW WITH ABOUT 20KT OF SPEED SHEAR FROM SURFACE TO 3KFT. FRONTAL
FORCING MAY CAUSE SOME LOCALIZED BACKING OF LOW LEVEL WINDS AND
SLIGHTLY BETTER INSTABILITY STILL BUT CURRENTLY CELLS ARE FIGHTING
A COUPLE OF WARM LAYERS IN THE MID LEVELS THAT ARE INHIBITING
CONVECTIVE GROWTH. TOPS ONLY GETTING TO ABOUT 30KFT ATTM. 24/RR
PREV DISCUSSION... /ISSUED 724 PM CST TUE DEC 8 2009/
UPDATE...
.SOUNDING DISCUSSION...
NO PROBLEMS WITH THE FLIGHT THIS EVENING. A VERY MOIST SOUNDING
WITH A PW OF 1.62 INCHES. A CAP OF WARM AND DRY AIR AT 778 MILLIBARS
HAS INHIBITED THUNDERSTORM DEVELOPMENT ACROSS THE CWA. STRONG
SOUTHWEST WIND FLOW IN THE LOWER LEVELS CONTINUING TO PUMP WARM AND
MOIST AIR INTO THE REGION. WINDS ARE FAIRLY UNIFORM THROUGHOUT THE
LAYERS WHICH WILL LIKELY KEEP THE TORNADO DOWN TO A MINIMUM.
HOWEVER...THERE IS A SLIGHT CHANCE OF STRAIGHT LINE WIND DAMAGE AS
THE FRONT APPROACHES...GIVEN A STORM MOTION OF AROUND 40 KNOTS.
PREV DISCUSSION... /ISSUED 358 PM CST TUE DEC 8 2009/
SHORT TERM...
HAVE DECIDED TO EXTEND THE FLASH FLOOD WATCH UNTIL 9 PM THIS
EVENING. NUMEROUS SHOWERS CONTINUE TO FORM IN SOUTHEAST LA AND
SOUTHERN. THIS IS IN AN AREA WHICH HAD STABILIZED DUE TO LAST
NIGHTS AND THIS MORNINGS HEAVY RAIN. AN UPPER LEVEL JET STREAK IN
SOUTHEAST TX IS EXPECT TO MOVE RAPIDLY EAST ACROSS THE FORECAST
AREA THIS EVENING. THIS COULD BE ENOUGH TO RAPIDLY DESTABILIZE THE
ATMOSPHERE AND PRODUCE ANOTHER ROUND OF THUNDERSTORMS BEFORE THE
COLD FRONT MOVES THROUGH LATE TONIGHT. IN ADDITION...SMALL CRAFT
ADVISORY WILL CONTINUE. WINDS REALLY WILL NOT DECREASE UNTIL THE
LARGE SURFACE LOW IN THE PLAINS LATE TODAY MOVES THROUGH THE GREAT
LAKES ON WEDNESDAY.
LONG TERM...
A SERIES A UPPER LEVEL DISTURBANCES ASSOCIATED WITH THE UPPER
WEST SOUTHWEST LEVEL JET CONTINUES TO DOMINATE THE LOWER MS
VALLEY. THE FIRST DISTURBANCE WILL CAUSE A WARM FRONT TO MOVE
TOWARDS THE LA AND MS COASTAL WATERS ON FRIDAY. THE WARM FRONT WILL
DRIFT INLAND OVER THE COASTAL PLAIN ON SATURDAY. THE THE
DISTURBANCE MOVES EAST OF THE FORECAST AREA ...THE FRONT WILL MOVE INTO
THE GULF ON SUNDAY. RETURN FLOW SHOULD DEVELOP ON MONDAY AS A
STRONG JET COMING INTO THE PACIFIC NORTHWEST CAUSES A DEEP UPPER
LEVEL TROUGH TO DEVELOP IN THE ROCKIES. THIS JET AND UPPER LEVEL
TROUGH WILL MOVE EAST ACROSS THE MS VALLEY ON TUESDAY...PUSHING
A STRONG COLD FRONT WELL INTO THE GULF OF MEXICO...AND BREAKING
RECENT UNSETTLED PATTERN.
MARINE...
THE COLD FRONT WILL MOVE THROUGH THE REGION TONIGHT. WINDS AND
SEAS WILL GRADUALLY DECREASE AS THE STRONG LOW PRESSURE AREA IN
THE PLAINS MOVES UP THROUGH THE GREAT LAKES. A BREAK BREAK IN THE
ACTION IS EXPECTED WEDNESDAY AND THURSDAY AS HIGH PRESSURE BUILDS
OVER THE AREA. HOWEVER...ANOTHER LOW PRESSURE AREA AND WARM FRONT
IS EXPECTED TO MOVE TOWARDS THE LA AND MS COAST ON FRIDAY.
EASTERLY WINDS AND SEAS WILL INCREASE ON FRIDAY. THE FRONT WILL
MOVE INLAND AS A WARM FRONT ON SUNDAY AND THEN FINALLY MOVE BACK
INTO THE GULF AS A COLD FRONT ON SUNDAY.
AVIATION...
NUMEROUS SHOWERS CONTINUE TO DOMINATE THE REGION ALONG AN NORTH OF
INTERSTATE 10 THIS AFTERNOON. SCATTERED THUNDERSTORMS ARE POSSIBLE
LATER TONIGHT AS AN UPPER LEVEL JET MOVES RAPIDLY THROUGH THE
REGION. CEILINGS ARE BELOW 1000 FEET AND VISIBILITIES ARE BELOW 3
MILES IN THE SHOWERS. UNTIL THE COLD FRONT MOVES THROUGH THE
REGION LATE TONIGHT...LOW IFR CONDITIONS ARE POSSIBLE ESPECIALLY
IF THE SURFACE WINDS DECREASE LATE TONIGHT DURING THE EARLY
MORNING HOURS AS THE LARGE...POWERFUL SURFACE LOW MOVES FURTHER
AWAY FROM LA AND MS.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 52 58 33 53 / 50 10 10 10
BTR 56 63 36 57 / 10 10 10 10
MSY 63 69 44 58 / 40 10 10 10
GPT 61 71 39 58 / 40 10 10 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&
$$
