Severe Thunderstorm Warning 224, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA
230 PM CST WED DEC 22 2004

.DISCUSSION...THE MAIN FORECAST PROBLEMS CONTINUE TO BE THREAT OF
STRONG TO SEVERE WEATHER LATE THIS AFTERNOON AND THIS EVENING
FOLLOWED BY A FRIGID COLD SPELL BEGINNING THURSDAY NIGHT ALONG WITH
THE CHANCE OF A WINTRY MIX FRIDAY AND FRIDAY NIGHT. SOME FAIRLY
STRONG CONVECTION CONTINUES ACROSS THE GULF WATERS THIS AFTERNOON
ALTHOUGH MOST LAND AREAS HAVE BEEN DRY OVER THE PAST FEW AREAS. THIS
SHOULD CHANGE THOUGH IN A FEW HOURS AS THE ADVERTISED COLD FRONT
CURRENTLY MOVING THROUGH THE WESTERN HALF OF LOUISIANA PUSHES INTO
THE OUTLOOK AREA LATER THIS AFTERNOON. CONVECTION HAS BEEN FIRING
ALONG AND JUST AHEAD OF THIS BOUNDARY AS IT MOVES EAST. THE DEGREE
OF INSTABILITY THOUGH ACROSS THE CWA/PWA WILL BE THE KEY FACTOR AS
TO THE EXTENT OF THE STORM INTENSITY. IF SOME DESTABILIZATION THOUGH
DOES OCCUR AS IS EXPECTED...ESPECIALLY ACROSS THE SOUTHERN AND
COASTAL ZONES...SHEAR PROFILES DO POINT TO A RISK OF STRONG DAMAGING
WINDS AND HAIL AS THIS ACTIVITY SWEEPS THROUGH. THE FRONT SHOULD
MOVE EAST OF THE FORECAST AREA BY MIDNIGHT AS THE COOLER AIR BEGINS
TO FILTER INTO THE REGION.

THE ARCTIC AIR MASS SHOULD THEN BE ENTRENCHED ACROSS THE REGION BY
THURSDAY NIGHT WITH MORE FREEZE WARNINGS ANTICIPATED...WITH THE
EXCEPTION OF MAYBE AREAS SOUTH OF LAKE PONTCHARTRAIN LEADING TOWARD
THE SOUTHEAST LOUISIANA COASTAL SECTIONS. FREEZE WARNINGS THOUGH
WILL LIKELY BE REQUIRED FOR ALL AREAS FRIDAY NIGHT AS SOME OF THE
COLDEST TEMPERATURES OF THE SEASON IMPACT THE REGION. DANGEROUS WIND
CHILL LEVELS ARE ALSO LIKELY DURING THIS TIME FRAME WITH VALUES IN
SOME AREAS POTENTIALLY DROPPING INTO THE LOWER TEENS OR MAYBE EVEN
SINGLE DIGITS. THE FRIGID WEATHER SHOULD CONTINUE THROUGH CHRISTMAS
DAY BEFORE TEMPERATURES GRADUALLY BEGIN TO REBOUND ON SUNDAY.

THE FINAL CHALLENGE INVOLVES THE POTENTIAL FOR A WINTRY MIX FRIDAY
AND FRIDAY NIGHT. THE GFS REMAINS SOMEWHAT PERSISTENT WITH
DEVELOPING A SURFACE LOW IN THE WESTERN GULF AND THEN TRACKING THE
SYSTEM DUE EASTWARD WITH MOISTURE WORKING ITS WAY AROUND THE BACK
SIDE OF THE SYSTEM IMPACTING THE LOWER HALF OF THE CENTRAL GULF
COAST REGION. THIS MODEL THOUGH MAY BE TRENDING MORE AS AN OUTLIER
COMPARED TO THE ETA...THE UKMET AND THE ECMWF WHICH HAS DRIER AIR
FUNNELING DEEPER INTO THE NORTHERN GULF WITH LESS DEVELOPMENT OF A
SURFACE WAVE. WILL LIKELY GO WITH A BLEND OF THE ETA AND THE GFS
WHICH IS CLOSE TO THE CURRENT FORECAST RIGHT NOW...EXCEPT MAYBE TO
BUMP UP PRECIP CHANCES TO THE LOW SCT CAT ACROSS THE SOUTHERN ZONES
FRIDAY AND FRIDAY NIGHT. WHILE THE GFS THICKNESS VALUES ARE NOT
OVERLY CONDUCIVE TO ALL WINTER PRECIP...MODEL SOUNDINGS DO SUGGEST
THE POTENTIAL FOR A MIX OF LIGHT RAIN...SLEET AND/OR SNOW ACROSS THE
SOUTHERN ZONES INCLUDING METRO NEW ORLEANS AND THE MISSISSIPPI GULF
COAST. MAY ALSO SEE A FEW FLURRIES ACROSS THE NORTHERN ZONES
ALTHOUGH PRECIP CHANCES WILL REMAIN IN THE SLIGHT CHANCE CAT AT BEST.
&&

.PRELIMINARY POINT TEMPS/POPS...
MCB 37 42 25 37 / 70 00 00 10
BTR 38 45 28 39 / 70 00 00 20
MSY 43 47 33 39 / 80 00 00 30
GPT 41 49 29 41 / 80 00 00 30
&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
MS...NONE.
SE LA AND MS COASTAL WATERS...SMALL CRAFT ADVISORY FROM PQL TO THE
ATCHAFALAYA RIVER OUT 60 NM INCLUDING TIDAL LAKES.
&&

09

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1055 AM CST WED DEC 22 2004

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-231200-
AMITE-ASCENSION-ASSUMPTION-EAST BATON ROUGE-EAST FELICIANA-HANCOCK-
HARRISON-IBERVILLE-JACKSON-LIVINGSTON-LOWER JEFFERSON-
LOWER LAFOURCHE-LOWER PLAQUEMINES-LOWER ST. BERNARD-LOWER TERREBONNE-
ORLEANS-PEARL RIVER-PIKE-POINTE COUPEE-ST. CHARLES-ST. HELENA-
ST. JAMES-ST. JOHN THE BAPTIST-ST. TAMMANY-TANGIPAHOA-
UPPER JEFFERSON-UPPER LAFOURCHE-UPPER PLAQUEMINES-UPPER ST. BERNARD-
UPPER TERREBONNE-WALTHALL-WASHINGTON-WEST BATON ROUGE-WEST FELICIANA-
WILKINSON-
1055 AM CST WED DEC 22 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL AND SOUTHEAST
LOUISIANA AND EXTREME SOUTHWEST...SOUTH CENTRAL AND COASTAL
MISSISSIPPI.

.DAY ONE...THIS AFTERNOON AND TONIGHT

...THUNDERSTORMS...
WITH MOISTURE AND INSTABILITY IN PLACE AND A UPPER LEVEL DISTURBANCE
MOVING ACROSS LOUISIANA AND MISSISSIPPI THIS AFTERNOON AND THIS
EVENING...WIDESPREAD THUNDERSTORMS ARE EXPECTED LATER THIS AFTERNOON
AND THIS EVENING. A SURFACE LOW OVER SOUTH TEXAS WILL MOVE NORTHEAST
ACROSS SOUTHWEST LOUISIANA THIS AFTERNOON TO NORTH ALABAMA THIS
EVENING. THE ASSOCIATED COLD FRONT WILL ALSO MOVE THROUGH SOUTHEAST
LOUISIANA AND SOUTH MISSISSIPPI WEDNESDAY AFTERNOON AND EVENING.
COPIOUS AMOUNTS OF MOISTURE AND INSTABILITY WILL LIKELY COVER MOST
OF THE AREA. STRONG TO ISOLATED SEVERE STORMS ARE EXPECTED...MAINLY
LATE THIS AFTERNOON AND THIS EVENING. THE MAIN HAZARDOUS WEATHER
THREAT WILL BE DAMAGING WINDS...LOCALLY HEAVY RAINFALL...AND
POSSIBLY HAIL. HEAVY RAIN COULD CAUSE HEAVY PONDING OF WATER ON
ROADS AND MINOR FLOODING OF SMALL STREAMS...BUT SIGNIFICANT FLOODING
APPEARS UNLIKELY.

...MARINE HAZARDS...
A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE TIDAL LAKES AND THE
SOUTHEAST LOUISIANA AND MISSISSIPPI COASTAL WATERS THROUGH TONIGHT.
SOUTHERLY WINDS WILL SHIFT TO THE SOUTHWEST AND INCREASE TO 20 TO 25
THIS AFTERNOON. AFTER THE FRONTAL PASSAGE THIS EVENING...WINDS WILL
SHIFT TO THE NORTHWEST AROUND 20 TO 25 KNOTS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

...FREEZING TEMPERATURES...
THURSDAY NIGHT THROUGH CHRISTMAS...FREEZING TEMPERATURES AND VERY
COLD WIND CHILLS ARE EXPECTED THURSDAY NIGHT...FRIDAY NIGHT...AND
AGAIN SATURDAY NIGHT. LOW TEMPERATURES THURSDAY NIGHT ARE EXPECTED
TO DROP INTO THE MID TO UPPER 20S NORTH OF INTERSTATE 10...LAKE
PONTCHARTRAIN...AND THE MISSISSIPPI COAST...WITH A LIGHT FREEZE NEAR
32 DEGREES POSSIBLE SOUTH OF LAKE PONTCHARTRAIN...INLAND FROM THE
COAST. WIND CHILL READINGS WILL FALL INTO THE SINGLE DIGITS ACROSS
SOUTH MISSISSIPPI AND EAST CENTRAL LOUISIANA AND TEENS FOR SOUTHEAST
LOUISIANA THURSDAY...FRIDAY AND SATURDAY NIGHT. A HARD FREEZE IS
LIKELY FRIDAY NIGHT OVER MOST AREAS EXCEPT NEAR THE SOUTHEAST
LOUISIANA COAST AND THE SOUTH SHORE OF LAKE PONTCHARTRAIN. LOWS IN
THE LOWER TO MID 20S WILL BE COMMON.

COMPUTER MODELS INDICATE THE POTENTIAL FOR A LOW PRESSURE AREA TO
FORM IN THE WEST CENTRAL OR SOUTHWEST GULF OF MEXICO THURSDAY
NIGHT WITH MOVEMENT TO THE EAST ACROSS THE CENTRAL OR SOUTH
CENTRAL GULF FRIDAY AND SATURDAY. COLD TEMPERATURES ALONG WITH
INCREASED MOISTURE ACROSS THE AREA COULD BRING A LIGHT WINTRY MIXTURE
OF SNOW...SLEET AND RAIN ON FRIDAY AND FRIDAY NIGHT...MAINLY FROM THE
SOUTHEAST LOUISIANA COAST...FROM WEST AND SOUTHWEST OF LAKE
PONTCHARTRAIN...TO JUST NORTH OF LAKE PONTCHARTRAIN...TO THE
MISSISSIPPI COAST. PRECIPITATION AMOUNTS ARE EXPECTED TO BE LIGHT
WITH VERY LITTLE ACCUMULATION OF SNOW OR SLEET. RELATIVELY WARM
GROUND AND AIR TEMPERATURES ABOVE FREEZING DURING THE PRECIPITATION
SHOULD PREVENT ROADS FROM ICING OVER. HOWEVER...BRIDGES AND
OVERPASSES COULD BE ICY AND TREACHEROUS FRIDAY NIGHT.

...MARINE HAZARDS...
A SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT MAINLY FOR THE GULF
COASTAL WATERS THROUGH SATURDAY. STRONG NORTHERLY WINDS AROUND 20 TO
30 KNOTS ARE EXPECTED TO CONTINUE INTO SATURDAY.

.SPOTTER INFORMATION STATEMENT...

THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS AND EMERGENCY
MANAGEMENT PERSONNEL...IN SUPPORT OF SEVERE WEATHER OPERATIONS...MAY
BE REQUESTED THIS AFTERNOON AND THIS EVENING.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1124 AM CST WED DEC 22 2004

LAZ069-221805-
LOWER PLAQUEMINES-
1124 AM CST WED DEC 22 2004

...THUNDERSTORM WITH STRONG WIND GUSTS HEADING TOWARDS LOWER
   MISSISSIPPI RIVER DELTA...

AT 1121 AM CST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 15 MILES SOUTHWEST OF VENICE...MOVING NORTHEAST
AT 30 KNOTS.

THESE STORMS WILL AFFECT AREAS IN AND AROUND VENICE...BOOTHVILLE...
AND PILOTTOWN THROUGH NOON.

THE PRIMARY THREATS FROM THESE STORMS ARE DANGEROUS CLOUD TO GROUND
AND CLOUD TO WATER LIGHTNING...TORRENTIAL RAINFALL...AND WIND GUSTS
OF 40 TO 50 MPH...WHICH COULD DOWN SMALL TREE LIMBS OR BRANCHES AND
BLOW AROUND UNSECURED SMALL OBJECTS AND BOATS. SEEK SHELTER IN A
SAFE HOME OR BUILDING UNTIL THESE STORMS HAVE PASSED. MARINERS
SHOULD SEEK SAFE HARBOR IMMEDIATELY.

STAY TUNED TO NOAA WEATHER RADIO...LOCAL TV AND RADIO FOR LATER
STATEMENTS AND POSSIBLE WARNINGS.

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