Severe Thunderstorm Warning 49, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
342 PM CST THU FEB 21 2008

.SYNOPSIS...
WARM FRONT CONTINUES TO MOVE NORTHWARD...AS DEPICTED BY EAST-WEST
BAND OF CONVECTION ACROSS SOUTHERN MISSISSIPPI. SOUTH OF THIS
BOUNDARY...TEMPS GENERALLY HAVE WARMED INTO THE 70S...AND LOWER
CLOUDS HAVE THINNED OUT TEMPORARILY. THIS MAY ALLOW REDEVELOPMENT
OF CONVECTION...SO WILL LEAVE TORNADO WATCH 70 UP WHERE IT IS AT.
&&

.SHORT TERM...
CURRENT WARM FRONTAL CONVECTION SHOULD MOVE NORTH OF THE CWA IN
THE NEXT FEW HOURS. NEXT IMPULSE APPEARS TO BE LIFTING THROUGH
SOUTH TEXAS AT THIS TIME. THIS SHOULD REACH OUR AREA WELL AFTER
00Z. SEVERE WEATHER PARAMETERS STILL IN PLACE...ALTHOUGH ANY
SOUTHWESTERLY COMPONENT OF SURFACE WINDS WOULD REDUCE TORNADO
THREAT...AS FORECAST SOUNDINGS ABOVE 2000 FEET PRETTY MUCH
UNIDIRECTIONAL. WILL CONTINUE MENTION OF SEVERE IN THE ZONES FOR
TONIGHT...SINCE IT WAS ALREADY IN THERE. WITH MOST AREAS BEING DRY
THIS EVENING...HAVE LOWERED POPS INTO THE LIKELY RANGE. LOW
TEMPERATURES WILL BE A BATTLE TONIGHT. IF SURFACE WAVE DRAGS
MOISTURE BOUNDARY THROUGH...AS FORECAST...CURRENT LOW TEMPERATURE
FORECAST SHOULD HOLD. IF BOUNDARY REMAINS WEST OF THE AREA...MOST
TEMPS WOULD REMAIN IN THE UPPER 60S.

MAIN PRECIPITATION AREA SHOULD SHIFT EAST OF THE CWA DURING THE
MORNING HOURS...AND WILL CARRY CHANCE POPS...AS THERE IS SOME
POTENTIAL FOR PRECIPITATION TO BE ENTIRELY OUT OF THE AREA BEFORE
12Z. THIS WILL NOT BE A COLD FRONTAL PASSAGE...AS THAT WOULD NOT
PASS THROUGH UNTIL NORTHERN STREAM TROF PASSES TO THE EAST. THIS
SHOULD OCCUR FRIDAY NIGHT. A VERY SMALL CHANCE OF PRECIPITATION
FOR EASTERN PORTIONS FRIDAY NIGHT. DRY WEATHER FOR REMAINDER OF
WEEKEND AFTER NORTHERN STREAM PASSAGE.

COOLER AIR WILL REMAIN NORTH AND WEST OF THE AREA THROUGH THE DAY
ON FRIDAY...WITH ABOVE NORMAL TEMPERATURES. MAV TEMPS ARE
REASONABLE AND ACCEPTED. HAVE TRENDED TOWARD THE COOLER GUIDANCE
FOR FRIDAY NIGHT INTO SUNDAY. 35
&&

.LONG TERM...
ONLY ONE PRECIP EVENT IN THE EXTENDED AND THIS APPEARS TO BE
MONDAY NIGHT AND TUESDAY. STRONG NORTHERN STREAM TROF TO MOVE
ACROSS THE OHIO VALLEY DURING THIS PERIOD AND SURFACE PRESSURE
FORECAST WOULD BRING FRONT THROUGH DURING THE DAYTIME HOURS ON
TUESDAY. ECMWF AND GFS FAIRLY SIMILAR ON TIMING OF PASSAGE. WILL
CARRY CHANCE OF THUNDERSTORMS DURING THIS TIME PERIOD. WILL NOT GO
LIKELY AT THIS TIME UNTIL CONFIDENCE IS HIGHER ON A PARTICULAR 12
HOUR TIME PERIOD FOR THE PRECIPITATION EVENT. TEMPERATURES WILL BE
NEAR OR SLIGHTLY ABOVE NORMAL THROUGH FRONTAL PASSAGE...THEN ABOUT
10 DEGREES BELOW NORMAL FOR ABOUT 24 HOURS...THEN BACK TO NEAR
NORMAL FOR THE END OF THE WEEK. 35
&&

.AVIATION...
WARM FRONT APPEARED TO EXTEND FROM WEST CENTRAL LA TO JUST NORTH OF
KBTR TO JUST INLAND ON THE MS COAST. NORTH OF THE WARM FRONT...LOW
STRATUS AND/OR FOG CONTINUED TO AFFECT KMCB AS OF 21Z. FRONTAL
BOUNDARY SHOULD CONTINUE TO LIFT NORTH ACROSS SOUTH MS...HOWEVER...
LOW STRATUS AND LIGHT FOG IS LIKELY TO CONTINUE AROUND KMCB. LOSS OF
DAYTIME HEATING AND WARM MOIST AIR MOVING OVER COOL WATER MAY CAUSE
FOG AND LOW STRATUS TO FORM ALONG THE COAST AND OVER LAKE
PONTCHARTRAIN WHICH WILL IMPACT THE TERMINALS AT KHUM...KMSY...
KNEW...KASD...KGPT...AND KPQL MAINLY LATE TONIGHT. SHOWERS AND
THUNDERSTORMS HAVE BEEN LIFTING NORTH WITH THE WARM FRONT...SO THE
MAIN SHOWER AND THUNDERSTORM THREAT WILL BE LATE TONIGHT INTO FRIDAY
MORNING AS THE COLD FRONT APPROACHES. 22

&&

.MARINE...
SOUTHERLY WINDS NEAR 15 KNOTS MAY INCREASE TO 15 TO 20 KNOTS OVER
THE COASTAL WATERS AS THE SURFACE LOW MOVES INTO THE LOWER MS
VALLEY. SHOWERS AND THUNDERSTORMS HAD MOVED WELL INLAND THIS
AFTERNOON...BUT ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS...SOME
POSSIBLY SEVERE...IS EXPECTED TO IMPACT THE MARINE AREA LATE TONIGHT
INTO FRIDAY MORNING. THE COLD FRONT WILL MOVE THROUGH LATE FRIDAY
INTO FRIDAY NIGHT. NORTHERLY WINDS BEHIND THE FRONT ARE ONLY
EXPECTED TO TOP OUT AROUND 15 KNOTS FOR A FEW HOURS ACROSS THE
COASTAL WATERS SATURDAY MORNING. OTHERWISE...WINDS WILL BE GENERALLY
10 KNOTS OR LESS THIS WEEKEND. 22

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  61  75  50  65 /  70  40  10  10
BTR  64  76  53  70 /  70  30  10  10
MSY  65  76  55  68 /  70  50  20  10
GPT  62  75  54  68 /  70  50  20  10

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
357 PM CST THU FEB 21 2008

GMZ530-550-555-570-575-LAZ034>040-046>050-056>070-MSZ068>071-077-
080>082-222200-
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-
357 PM CST THU FEB 21 2008

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

.DAY ONE...THIS AFTERNOON AND TONIGHT
A TORNADO WATCH IS IN EFFECT FOR THE BATON ROUGE AREA UNTIL 9 PM
CST.

SEVERE THUNDERSTORMS WILL BE POSSIBLE ACROSS SOUTHEAST
LOUISIANA...SOUTHERN MISSISSIPPI AND THE ADJACENT COASTAL WATERS
OVERNIGHT. LOW PRESSURE WILL BE MOVING NORTHEAST ACROSS TEXAS AND
NORTHERN LOUISIANA OVERNIGHT...AND WILL BRING AN AREA OF
THUNDERSTORMS ACROSS THE AREA. DAMAGING WINDS...PENNY SIZE
HAIL...FREQUENT LIGHTNING AND ISOLATED TORNADOES WILL BE POSSIBLE.
VERY HEAVY RAINFALL WILL BE POSSIBLE WITH 1 TO 3 INCHES OF RAIN
POSSIBLE...WITH LOCALLY HIGHER AMOUNTS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY
STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE EARLY FRIDAY
MORNING AS TONIGHTS THUNDERSTORMS MOVE OUT OF THE AREA.

ANOTHER FRONT WILL MOVE THROUGH THE AREA ON TUESDAY. SOME
THUNDERSTORMS ASSOCIATED WITH THIS FRONT COULD BE STRONG.

.SPOTTER INFORMATION STATEMENT...
EMERGENCY MANAGEMENT AND PUBLIC SAFETY OFFICIALS ARE ALREADY
ACTIVE IN THE BATON ROUGE AREA...AND MAY NEED TO BE ACTIVATED
ELSEWHERE OVERNIGHT.