000 
FXUS64 KLIX 311344
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
844 AM CDT TUE MAR 31 2009

.SOUNDING DISCUSSION...

THE ATMOSPHERE HAS BECOME MOIST AND UNSTABLE WITH A LIFTED INDEX
VALUE OF -5.3 AND A PRECIPITABLE WATER VALUE OF 1.35 INCHES. AT
THE TIME OF LAUNCH A FEW ALTOCUMULUS CLOUDS WERE PRESENT...SINCE
THEN A STRATUS DECK HAS MOVED IN. SOUTHERLY FLOW NEAR THE SURFACE
CONTINUES TO BRING IN WARM MOIST AIR...GOOD SPEED SHEAR IS ALSO
PRESENT.

&&

.PREV DISCUSSION... /ISSUED 425 AM CDT TUE MAR 31 2009/ 

SYNOPSIS...
LATEST SURFACE ANALYSIS SHOWED A DEEP 993MB LOW OVER WEST IOWA
WITH A COLD EXTENDING SOUTH TO EAST OKLAHOMA TO CENTRAL TEXAS.
SOUTH TO SOUTHEAST WINDS WERE NOTED OVER MID AND LOWER MISSISSIPPI
VALLEY. DEWPOINT READINGS OF 60F AND GREATER WERE GENERALLY WEST
OF SHV TO MSY LINE AND DEEPER MOISTURE OVER SOUTHEAST TEXAS. 00Z
PW PLOTS SHOWED SHV...LCH AND CRP FROM 1 TO 1.2 INCHES AND GFS AND
NAM INITIALIZED WELL WITH THIS FEATURE. UPPER AIR ANALYSIS SHOWED A
CLOSED OVER CENTRAL NEBRASKA AND IR SATELLITE IMAGERY CLOUDS
STREAMING WEST TO EAST NORTH MEXICO TO NORTHWEST GULF AND
CONVECTION OVER NORTHEAST TEXAS. SOUNDING AT SLIDELL SHOWED
SIGNIFICANT VEERING WINDS IN THE LOWER LEVELS...SEVERAL DRY LAYERS
ABOVE 875MB AND WB ZERO AROUND 6500 FEET.

SHORT TERM...
WITH THE MAIN SYSTEM LIFTING TOWARD THE GREAT LAKES REGION...AREAL
ATM WILL LOSE THE LOW LEVEL SOUTHEAST COMPONENT WIND THROUGH
TODAY. AS A RESULT...VEERING WINDS WITH HEIGHT DECREASE BY MIDDAY
ACCORDING TO NAM AND GFS. SRH 0-3 DECREASES FROM NEAR 400M/S AT
12Z TO 100M/S...THUS DECREASE THE TORNADIC THREAT EXCEPT ALONG THE
FRONT WITH FRONTAL FORCING. SOME DRY AIR REMAINS IN THE MID
LAYERS AND WB ZERO HOVERS FROM 9500 TO 10KFT TODAY AND THIS
EVENING. ERGO...THE MAIN THREAT IS PROBABLY HAIL AND WINDS AND
THEN TORNADO AND HEAVY RAINFALL. ALL OF THESE THREATS UNDER A
SLIGHT RISK OF SEVERE WEATHER FOR THE TODAY. SUB-TROPICAL JET
REMAINS THE MAIN CHARTER. THE BASE OF THE TROUGH ON WATER VAPOR
SHOWED SEVERAL DISTURBANCES ALONG WITH THE SUB-JET WILL CREATE
UPPER LEVEL DIVERGENCE FROM SOUTHWEST LOUISIANA TO EAST NORTHEAST
EARLY TODAY. LOSING THE SOUTHEAST LOW LEVEL COMPONENT EARLY WILL
ALLOW THE BULK OF THE DEEP MOISTURE TO REMAIN JUST SOUTH AND EAST
OF THE FORECAST LAND AREAS AND GENERAL RAINFALL OF A HALF TO 2
INCHES MAY OCCUR. WILL HOLD OFF ON ANY FLASH FLOOD WATCHES FOR
NOW...BUT WILL KEEP CATEGORICAL RAIN CHANCES TODAY THROUGH THIS
EVENING. A LULL IN THE WEATHER IS EXPECTED WEDNESDAY.
HOWEVER...THE FRONTAL PASSAGE THIS EVENING WILL ONLY PUSH THE
MOISTURE SOUTH OVER THE NORTH GULF...WHICH WILL WAIT FOR THE NEXT
SYSTEM

LONG TERM...
GFS AND NAM CONTINUE TO SHOW THE NEXT SYSTEM DIVING SOUTHEAST
ALONG THE RED RIVER VALLEY BECOMING NEGATIVELY TILTED OVER THE
ARKLATEX REGION THURSDAY MORNING. A SIGNIFICANT AMOUNT OF DRY AIR
OVER TEXAS IS EXPECTED TO ENTRAIN ON WEST AND SOUTHWEST SIDE OF
THE LOW AND MAY DECREASE MOISTURE AND CONVECTION QUICKLY BY
LATE THURSDAY AFTERNOON. WILL MAINTAIN THE BEST CHANCE OF RAIN
ACROSS SOUTHWEST AND SOUTH CENTRAL MISSISSIPPI THURSDAY AND
DECREASE RAIN CHANCES BY THURSDAY EVENING. THIS SYSTEM WILL LIFT
NORTHEAST TOWARD THE GREAT LAKES...LEAVING THE DRY WEST FLOW ALOFT
OVER THE THROUGH SUNDAY. THE NEXT SYSTEM ON SUNDAY IS COMING IN
WEAKER AS FAR AS WEATHER ACROSS THE CENTRAL GULF COAST
SUNDAY...THUS WILL MAINTAIN JUST 20 PERCENT SUNDAY.

AVIATION...
/PRELIMINARY 12Z TAF ISSUANCE/
MVFR TO VFR CEILINGS EXPECTED TODAY...WITH ANY IFR OR LOWER  
CONDITIONS LIMITED TO AREAS OF PRECIPITATION. COLD FRONT WILL MOVE 
FROM WEST TO EAST DURING THE DAYTIME AND EVENING HOURS WITH A PERIOD 
OF THUNDER EXPECTED. POST FRONTAL...VFR CONDITIONS RETURN. 35 

MARINE...
GRADIENT HAS ACTUALLY RELAXED THIS MORNING WITH NORTHEASTERN GULF 
BUOYS...INCLUDING 42040...REPORTING WINDS AROUND 10 KNOTS. HAVE 
DROPPED THE EXERCISE CAUTION FOR MOST OF THE DAYTIME HOURS. GRADIENT 
SHOULD NOT REALLY TIGHTEN MUCH UNTIL THE FRONT GETS CLOSER LATER IN 
THE DAY. WINDS WILL MOVE INTO THE EXERCISE CAUTION RANGE THIS 
AFTERNOON...BUT DUE TO SLIGHTLY SLOWER FRONTAL MOVEMENT...ANY 
ADVISORY LEVEL WINDS EXPECTED TO HOLD OFF UNTIL AROUND SUNRISE ON 
WEDNESDAY. THEREFORE HAVE LOWERED ADVISORY TO EXERCISE CAUTION. ALL 
GUIDANCE INDICATES ANY ADVISORY LEVEL WINDS SHOULD BE FOR ABOUT 6 
HOURS OR LESS WEDNESDAY MORNING. MUCH BETTER POTENTIAL WITH STRONGER 
SYSTEM ON THURSDAY...AND ANOTHER ONE SATURDAY NIGHT OR SUNDAY. 

WITH FAST MOVING FRONTAL SYSTEMS...WINDS ARE NOT EXPECTED TO 
MAINTAIN DIRECTION FOR A LONG ENOUGH PERIOD TO SET UP A SIGNIFICANT 
SWELL TRAIN OVER THE NEXT FEW DAYS. THIS SHOULD ALLEVIATE ANY 
CONCERNS OF A LONG PERIOD OF COASTAL FLOODING. 35

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  77  50  72  58 /  80  30  10  20 
BTR  77  52  73  59 /  80  30  10  20 
MSY  77  56  71  64 /  80  60  10  20 
GPT  74  55  70  63 /  80  60  20  20 

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&

$$