Severe Thunderstorm Warning 161, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
400 AM CST SUN NOV 25 2007

.SHORT TERM...
WARM FRONT IN THE NEAR SHORE COASTAL WATERS THIS MORNING LOCATED
FROM NEAR PORT SULPHUR TO GRAND ISLE THEN OVER TO THE MAIN SFC LOW
NEAR TX. THE WARM FRONT WILL MOVE SLOWLY INLAND THIS MORNING
MAKING FOR A QUICK AND NOTICEABLE CHANGE IN AIR MASS.

SEVERE WEATHER PROBABILITIES ARE STILL IN THE SLIGHT TO MODERATE
RISK FOR THE AREA. THE BEST LOW LEVEL SHEAR PROFILES ARE LOCATED
ALONG WITH THE WARM FRONTAL BOUNDARY. THEREFORE OUR BEST HELICITY
WILL BE THIS MORNING AND WILL DECREASE AS THE WARM FRONT MOVES
NORTH. ONCE IN THE WARM SECTOR...ALL TS BECOME SFC BASED AND
HELICITY VALUES ARE NOT GOING TO BE TOO LOW(200M2/S2). THAT IS
COMPARED TO 350 TO 400 VALUES LOCATED ALONG THE WARM FRONTS
BOUNDARY. WILL CONTINUE TO SEE THE POSSIBILITY OF ANY ONE TS GO
SEVERE WITH THE POTENTIAL TO PRODUCE A TORNADO. BUT THE MAIN
HAZARDS OUTWEIGHING THE TORNADIC THREAT WILL BE STRAIGHT LINE
WINDS AND HAIL...ESPECIALLY AS THE STRONG LINEAR SQUALL LINE
APPROACHES LATE THIS AFTERNOON WITH THE COLD FRONT.

THE UPPER TROUGH EXITS STAGE RIGHT AND COOL HIGH PRESSURE FILLS
THE VOID. WILL HAVE TO WATCH TEMPS FOR MONDAY AND MON NIGHT AS
LOW CLOUDS BEHIND THE SYSTEM MAY STAY A LITTLE LONGER THAN WHAT IS
CURRENTLY ADVERTISED.

.LONG TERM...
WITH ANOTHER REINFORCING SURGE OF DRY COOL AIR BY WED NIGHT INTO
THURSDAY...A DRY FORECAST IS IN THE OFFING THROUGH NEXT WEEKEND.

&&

.AVIATION...
IFR FOR LOWERING CEILINGS EXPECTED AS WARM FRONT
APPROACHES(11-17Z). VIS WILL RANGE ON THE LOW SIDE DOWN TO 1 TO 3
MILES AS WELL. ONCE WARM FRONT PASSES MVFR RULES SHOULD APPLY AS
CEILINGS BREAK UP SOMEWHAT. THIS IS WITH THE EXCEPTION OF
SCATTERED TS ACTIVITY AFFECTING ANY ONE TERMINAL.

&&

.MARINE...
SCA WILL CONTINUE THROUGH TONIGHT AND FOR A PORTION OF MONDAY
MORNING FOR ALL GULF COASTAL WATERS. CAUTION ADVISED ON LAKES.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  68  50  59  42 /  80  80  20   0
BTR  72  49  60  43 /  90  80  20   0
MSY  74  58  63  47 /  70  90  30   0
GPT  72  58  65  45 /  60  90  50   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO MIDNIGHT CST
     TONIGHT FOR LAZ066.

GM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR GMZ550-555-
     570-575.

MS...NONE.
GM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR GMZ555-570-
     575.

&&

17

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1015 AM CST SUN NOV 25 2007

GMZ530-550-555-570-575-LAZ034>040-046>050-056>070-MSZ068>071-077-
080>082-261200-
LAKE PONTCHARTRAIN AND LAKE MAUREPAS-
COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER
TO LOWER ATCHAFALAYA RIVER LA OUT 20 NM-
COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER OUT 20 NM-
COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER
TO LOWER ATCHAFALAYA RIVER LA FROM 20 TO 60 NM-
COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER FROM 20 TO 60 NM-POINTE COUPEE-WEST FELICIANA-
EAST FELICIANA-ST. HELENA-TANGIPAHOA-WASHINGTON-ST. TAMMANY-
IBERVILLE-WEST BATON ROUGE-EAST BATON ROUGE-ASCENSION-LIVINGSTON-
ASSUMPTION-ST. JAMES-ST. JOHN THE BAPTIST-UPPER LAFOURCHE-
ST. CHARLES-UPPER JEFFERSON-ORLEANS-UPPER PLAQUEMINES-
UPPER ST. BERNARD-UPPER TERREBONNE-LOWER TERREBONNE-
LOWER LAFOURCHE-LOWER JEFFERSON-LOWER PLAQUEMINES-
LOWER ST. BERNARD-WILKINSON-AMITE-PIKE-WALTHALL-PEARL RIVER-
HANCOCK-HARRISON-JACKSON-
1015 AM CST SUN NOV 25 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF GULF OF
MEXICO...SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI.

.DAY ONE...THIS AFTERNOON AND TONIGHT

THUNDERSTORMS...
A STRONG STORM SYSTEM WILL BRING A WARM FRONT INLAND ACROSS EAST
CENTRAL AND SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI THIS
AFTERNOON. SEVERE WEATHER WILL BE POSSIBLE NEAR THE WARM FRONT WITH
THE MAIN THREAT BEING LARGE HAIL AND ISOLATED TORNADOES. AREAS OF
HEAVY RAIN ARE EXPECTED AS WELL TODAY...MAINLY WEST OF INTERSTATE 55
AND LAKE PONTCHARTRAIN.

THUNDERSTORMS...
AN AREA OF LOW PRESSURE WILL MOVE NORTHWARD ACROSS LOUISIANA AND
MISSISSIPPI TODAY WITH A COLD FRONT EXPECTED TO MOVE ACROSS THE
OUTLOOK AREA TONIGHT. THE THREAT OF SEVERE THUNDERSTORMS WILL
CONTINUE TONIGHT AHEAD OF THE COLD FRONT WITH THE THREAT OF
DAMAGING STRAIGHT LINE WINDS...LARGE HAIL...FREQUENT CLOUD TO
GROUND LIGHTNING...ISOLATED TORNADOES...AND HEAVY RAINFALL.

RAINFALL AMOUNTS OF 1 TO 3 INCHES WILL BE COMMON WITH THE HIGHEST
TOTALS EXPECTED WEST OF INTERSTATE 55 AND LAKE PONTCHARTRAIN...
WHERE LOCALLY HIGHER STORM TOTAL AMOUNTS OF 3 TO 4 INCHES WILL BE
POSSIBLE THROUGH TONIGHT. HEAVY PONDING OF WATER ON ROADWAYS IS
POSSIBLE ALONG WITH SOME FLOODING OF LOW LYING AND FLOOD PRONE
AREAS.

MARINE...
SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED TO CONTINUE THROUGH
TONIGHT ACROSS THE GULF COASTAL WATERS AS WINDS OF 20 TO 25 KNOTS
AND SEAS UP TO 9 FEET PREVAIL.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

NO HAZARDOUS WEATHER IS EXPECTED MONDAY THROUGH FRIDAY.

.SPOTTER INFORMATION STATEMENT...
STORM SPOTTERS AND EMERGENCY MANAGEMENT PERSONNEL SHOULD REMAIN
ON ALERT FOR POSSIBLE ACTIVATION TODAY AND TONIGHT.