FXUS64 KLIX 301031
AFDLIX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
431 AM CST MON NOV 30 2009
.SHORT TERM...
NO SURPRISES EARLY THIS MORNING. REGIONAL RADARS CLEARLY DEPICT
LOCATION OF COLD FRONT ACROSS NORTHERN AND WESTERN LA. THE MAJORITY
OF SHOWERS AND STORMS ARE POST FRONTAL. THE BOUNDARY WILL CONTINUE
SOUTHEASTWARD AND SHOULD REACH NWRN PORTIONS OF THE CWA LATER THIS
MORNING. A FEW LIGHT ECHOS HAVE BEGUN SHOWING UP ON RADAR JUST NORTH
OF MCB. WILL LIKELY HAVE MORE LIGHT SHOWERS DEVELOP OUT AHEAD OF THE
BOUNDARY BEFORE IT MOVES IN. THE RAIN WILL SHIFT SOUTH AND EASTWARD
DURING THE AFTERNOON WITH ONLY CHNC POPS ALONG NORTHERN ZONES AFTER
18Z. A GENERAL COVERAGE OF ONE HALF INCH WILL BE MOST COMMON ACROSS
THE AREA BUT LOCALIZED HIGHER AMOUNTS ARE LIKELY. DEVELOPMENT OF
THUNDERSTORMS WILL BE FAIRLY LIMITED DUE TO LACK OF SIGNIFICANT
INSTABILITY. LITTLE TO NO CAPE AND LI/S NOT MUCH LOWER THAN 0. THE
BEST SHOT FOR STORMS WILL BE OFFSHORE LATER THIS AFTERNOON.
HIGH TEMP FORECAST IS RATHER DIFFICULT TODAY. DENSE CLOUDCOVER AND
RAIN ASSOCIATED WITH THE COLD FRONT WILL LIMIT INSOLATION IN
NORTHERN ZONES WHILE SOUTHERN HALF SHOULD HAVE MORE TIME TO WARM
INTO THE LOWER 70S. ITS ALL ABOUT TIMING AND HAVE GONE WITH MODEL
CONSENSUS ON FROPA TO ADJUST HIGHS.
THE COLD FRONT WILL CONTINUE SOUTHWARD INTO THE NORTHERN
GULF...LIKELY PAST COASTAL WATER ZONE AREAS. SHOWERS WILL BE
CONFINED MAINLY TO COASTAL LA PARISHES AND COASTAL WATERS OVERNIGHT.
SHOULD SEE A 10 TO 15 DEGREE DROP FROM PREVIOUS NIGHTTIME LOWS AS
COOLER AIR MOVES IN BEHIND THE FRONT.
.LONG TERM...
A MORE COMPLEX WEATHER SCENARIO TO DEVELOP EARLY THIS WEEK. UPPER
LOW CURRENTLY CUT OFF JUST SOUTH OF AZ WILL SHIFT EASTWARD TOWARDS
THE AREA AS AN UPPER TROUGH DIPS SOUTHWARD JUST EAST OF THE ROCKIES.
STRONG CYCLOGENESIS TO OCCUR IN THE WESTERN GULF TUESDAY. THIS
SURFACE LOW WILL APPROACH THE GULF COAST TUESDAY EVENING. SAME STORY
TODAY IN TERMS OF THE TRACK OF THIS LOW. ECMWF REMAINS IN THE MIDDLE
GROUND WITH NAM MORE NORTHERLY AND GFS TO THE SOUTH. HAVE KEPT THE
FORECAST TO GO ALONG WITH THE EURO. ABUNDANT MOISTURE WILL SURGE INTO
THE AREA WITH STRONG ONSHORE FLOW. MODEL SOUNDINGS INDICATE PWATS
REACHING 2 INCHES TUESDAY NIGHT. THIS TIME PERIOD IS WHEN MOST OF
THE ACTION WILL TAKE PLACE. MODELS HAVE BEEN STEADILY INDICATING A
SWATH OF 3-5 INCHES ALONG SOUTHERN ZONES. THE POSSIBILITY EXITS THAT
A FLOOD WATCH WILL HAVE TO EVENTUALLY BE ISSUED FOR THESE AREAS. THE
MAIN REASON FOR HOLDING OFF...AT LEAST ON THIS SHIFT...IS THE FACT
THAT CURRENT FFG NUMBERS ARE STILL QUITE HIGH AT AROUND 3 INCHES FOR
1 HR AND 5 INCHES FOR 6 HRS.
THE MAIN UPPER LOW WILL BE ABSORBED BY AFOREMENTIONED NORTHERN TROUGH
AS IT TRACKS NEWD ON WED. THIS DEEP TROUGH WILL DIG FOR IN THE
REGION. MODELS ARE INDICATING 1000-500MB THICKNESSES TO DROP VERY
LOW FOR THIS TIME OF YEAR ACROSS THE AREA...IN THE 530DM RANGE.
CURRENT FREEZE LINE ALONG AND NORTH OF I-12 COULD EVEN BE A
CONSERVATIVE ONE IF ALL STAYS THE SAME. OTHERWISE...NO RAIN EXPECTED
UNTIL POSSIBLY NEXT WEEKEND.
MEFFER
&&
.AVIATION...
SIGNIFICANT LIFR/IFR FOG WILL BE LIMITED TO KGPT THE NEXT FEW
HOURS...THEN THE MAIN ISSUE WILL BE MVFR CIGS AND LOWERED VSBYS IN
SHRA/POSSIBLE TSRA MAINLY MORNING HOURS KBTR AND KMCB...AND MID
MORNING TO EARLY AFTERNOON KMSY AND KGPT. CONDITIONS WILL QUICKLY
IMPROVE BACK TO VFR MID TO LATE AFTERNOON KBTR-KMCB...AND LATE
AFTERNOON TO EARLY EVENING KMSY-KGPT. 22/TD
&&
.MARINE...
LIGHT SOUTH WINDS EARLY THIS MORNING WILL VEER TO SOUTHWEST AND
INCREASE SLIGHTLY THIS MORNING. A COLD FRONT WILL PUSH THROUGH THE
COASTAL WATERS THIS AFTERNOON AND EARLY EVENING. OFFSHORE FLOW WILL
INCREASE BEHIND THIS FRONT TONIGHT AND WINDS WILL BE CLOSE TO SMALL
CRAFT ADVISORY CRITERIA. LOW PRESSURE DEVELOPING IN THE NORTHWEST
GULF OF MEXICO TONIGHT IS FORECAST TO STRENGTHEN AND MOVE TOWARD THE
NORTHERN GULF COAST LATE TUESDAY THROUGH EARLY WEDNESDAY MORNING.
WINDS ARE EXPECTED TO INCREASE SIGNIFICANTLY AS THIS FEATURE
APPROACHES...AND CONFIDENCE IS NOW HIGH THAT GALES WILL DEVELOP
TUESDAY AFTERNOON AND PERSIST THROUGH TUESDAY NIGHT AND POSSIBLE
EARLY WEDNESDAY MORNING.
HAVE SEVERAL HEADLINES IN THE EARLY MORNING MARINE FORECAST...SMALL
CRAFT EXERCISE CAUTION 3 TO 6 PM TODAY...SMALL CRAFT ADVISORY
TONIGHT AND TUESDAY MORNING...AND A GALE WATCH TUESDAY AFTERNOON
THROUGH WEDNESDAY MORNING. BEYOND THIS TIME...STRONG WINDS ON THE
BACK SIDE OF THE DEPARTING STRONG LOW PRESSURE SYSTEM...DUE TO
CONTINUED STRONG PRESSURE GRADIENT AND COLD AIR ADVECTION...MAY
INCREASE TO NEAR GALE...AT LEAST IN GUSTS...AGAIN LATE WEDNESDAY
AFTERNOON AND EVENING. SINCE THIS IS WELL BEYOND 48 HOURS...WILL LET
LATER SHIFTS EVALUATE THE NEED TO EXTEND THE GALE HEADLINES ONCE
THEY ARE CONVERTED TO WARNINGS. 22/TD
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 61 41 55 47 / 80 10 60 70
BTR 65 46 57 48 / 80 20 70 70
MSY 72 49 58 49 / 80 30 80 80
GPT 72 45 58 55 / 80 10 70 90
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...COASTAL FLOOD WATCH FROM NOON TUESDAY TO 6 AM WEDNESDAY FOR THE
FOLLOWING ZONES: LOWER JEFFERSON...LOWER LAFOURCHE...LOWER
PLAQUEMINES...LOWER ST. BERNARD...LOWER
TERREBONNE...ORLEANS...ST. CHARLES...ST. JOHN THE
BAPTIST...ST. TAMMANY...TANGIPAHOA...UPPER JEFFERSON...AND
UPPER ST. BERNARD.
GM...GALE WATCH FROM NOON TUESDAY TO 9 AM WEDNESDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST
PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60 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...AND COASTAL WATERS
FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO LOWER
ATCHAFALAYA RIVER LA OUT 20 NM.
SMALL CRAFT ADVISORY FROM 6 PM MONDAY TO NOON TUESDAY FOR THE
FOLLOWING ZONES: COASTAL WATERS FROM PASCAGOULA MS TO THE
SOUTHWEST PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60
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...AND COASTAL WATERS
FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO LOWER
ATCHAFALAYA RIVER LA OUT 20 NM.
MS...COASTAL FLOOD WATCH FROM NOON TUESDAY TO 6 AM WEDNESDAY FOR THE
FOLLOWING ZONES: HANCOCK...HARRISON...AND JACKSON.
GM...GALE WATCH FROM NOON TUESDAY TO 9 AM WEDNESDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST
PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60 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...AND COASTAL WATERS
FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO LOWER
ATCHAFALAYA RIVER LA OUT 20 NM.
SMALL CRAFT ADVISORY FROM 6 PM MONDAY TO NOON TUESDAY FOR THE
FOLLOWING ZONES: COASTAL WATERS FROM PASCAGOULA MS TO THE
SOUTHWEST PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60
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...AND COASTAL WATERS
FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO LOWER
ATCHAFALAYA RIVER LA OUT 20 NM.
&&
$$
