Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA

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821
FXUS64 KLIX 211355
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
755 AM CST WED JAN 21 2015

.SOUNDING DISCUSSION...

THE SOUNDING THIS MORNING HAD LIGHT NORTHERLY WINDS UP TO 850 MB
THEN WESTERLY FLOW ABOVE WITH A JET MAX OF 120 KTS AT 185 MB.
THERE WAS A STRONG 16 F SFC INVERSION UP TO 500 FT. THE PROFILE
OVERALL IS RELATIVELY DRY WITH A PW OF 0.68 INCHES.

AK

&&


.PREV DISCUSSION... /ISSUED 258 AM CST WED JAN 21 2015/

SYNOPSIS...

COLD FRONT HAS APPARENTLY MOVED THROUGH MCCOMB AND BATON ROUGE
AREAS...WHERE WINDS HAVE ACQUIRED A NORTHERLY COMPONENT. ANY
WIDESPREAD FOG/LOW CLOUDS HAVE BEEN MAINLY CONFINED WEST OF THE
ATCHAFALAYA RIVER THROUGH 2 AM. THERE ARE A FEW PATCHES OF FOG
SOUTH OF LAKE PONTCHARTRAIN...BUT SATELLITE WOULD INDICATE THESE
ARE LOCALIZED. TEMPERATURES GENERALLY RANGE FROM THE MID 40S TO
MID 50S.

SHORT TERM...

NOT REALLY MUCH CHANGE IN THE FORECAST SCENARIO FROM WHAT WAS
ALREADY IN THE FORECAST. TODAY SHOULD BE A QUIET DAY WITH MOSTLY
SUNNY CONDITIONS AND WARMER THAN NORMAL TEMPERATURES.

AS A STRONGER SYSTEM KICKS OUT OF THE 4 CORNERS REGION
TONIGHT...MOISTURE WILL BEGIN TO SATURATE THE COLUMN FROM THE TOP
DOWN. PRECIPITABLE WATER VALUES SHOULD BE NEAR SEASONAL NORMS
AFTER MIDNIGHT TONIGHT. EXPECT TO SEE SOME ECHOES ON RADAR AFTER
MIDNIGHT...WITH THE MAIN QUESTION WHETHER WE CAN SATURATE THE
LOWER LEVELS ENOUGH FOR MEASURABLE PRECIPITATION PRIOR TO 12Z
THURSDAY. WILL CARRY LOW CHANCE POPS.

SURFACE LOW WILL DEVELOP OFF THE TEXAS COAST BY THURSDAY MORNING
AND MOVE ACROSS THE NORTHERN GULF THURSDAY NIGHT...TO THE FLORIDA
PANHANDLE BY FRIDAY AFTERNOON. THIS WILL KEEP THE FORECAST AREA ON
THE COLD SIDE OF THE LOW AND WILL NOT CARRY THUNDER IN THE
FORECAST. LIGHT TO MODERATE RAIN WILL OVERSPREAD THE AREA THURSDAY
AND CONTINUE THROUGH MUCH OF THE EVENING. WILL CONTINUE WITH
LIKELY TO CATEGORICAL POPS THURSDAY AFTERNOON...AND CATEGORICAL
THURSDAY NIGHT. TEMPERATURE PROFILE ON 00Z GFS SOLUTION OVER
SOUTHERN MISSISSIPPI REMAINS TOO WARM TO SUPPORT SNOW.

MODELS DEPICT A DRY SLOT DEVELOPING OVER THE AREA DURING THE DAY
ON FRIDAY...ENDING ANY SIGNIFICANT PRECIPITATION BY EARLY TO MID
AFTERNOON.

EXPECT THAT TEMPERATURES THURSDAY WILL LIKELY MAX OUT DURING THE
LATE MORNING HOURS. DIURNAL RANGE THURSDAY NIGHT INTO FRIDAY IS
GOING TO BE RATHER LIMITED DUE TO CLOUDS/PRECIPITATION...PROBABLY
LESS THAN A 10 DEGREE SPREAD. WILL BLEND TEMPERATURE GUIDANCE FOR
THOSE TWO PERIODS WITH A BIAS TOWARD THE ECMWF SOLUTION. 35

LONG TERM...

ONCE FRIDAYS SYSTEM CLEARS THE AREA...DO NOT EXPECT ANY
SIGNIFICANT PRECIPITATION FOR THE REMAINING PORTION OF THE
FORECAST. A STRONG NORTHERN STREAM SHORTWAVE MOVING ACROSS THE
OHIO RIVER VALLEY SUNDAY NIGHT AND MONDAY WILL ONLY REINFORCE THE
DRY AIR AND DROP TEMPERATURES 5-8 DEGREES FOR A DAY OR SO. WILL
TREND TOWARD THE COOLER SOLUTIONS FOR MUCH OF THE EXTENDED PERIOD.
35

AVIATION...

RIGHT NOW MOST OF THE AREA IS STILL IN VFR STATUS BUT MVFR AND
IFR CONDITIONS COULD STILL SPREAD OVER THE REGION WITH MARINE
LAYER LOW CLOUDS AND MODIFIED SEA FOG MIXING WITH RADIATIONAL FOG
THROUGH ABOUT 15Z. AFTERWARDS VFR CONDITIONS WILL REDEVELOP WITH
SCT CU AROUND 2500-3500 OVER MUCH OF THE AREA. /CAB/

MARINE...

BIGGEST ISSUE WILL BE IN THE FIRST 60 HRS. HOWEVER TODAY WILL BE
OK ON THE WATER. WINDS OF 10-15 KTS VEERING AROUND FROM NRLY TO
ERLY WILL BE THE CASE TODAY BUT THAT WILL CHANGE OVERNIGHT. A SFC
LOW WILL BEGIN TO TAKE SHAPE OVER SRN TX WHILE A LARGE ARE OF HIGH
PRESSURE WILL CONTINUE TO WORK SOUTH ACROSS THE PLAINS AND
CONTINENTAL DIVIDE. THIS WILL START TO TIGHTEN THE PRESSURE
GRADIENT WITH ERLY WINDS OF 15-20 KTS AFTER 6Z. WINDS WILL
CONTINUE TO RAMP UP DURING THE DAY THU AS THE SFC LOW MOVES INTO
THE WRN GULF. SCY CONDITIONS WILL DEVELOP AND COULD DEVELOP PRIOR
TO 12Z BUT MORE LIKELY DURING THE DAY THU. THE LOW WILL MOVE
ACROSS THE COASTAL WATERS THU NIGHT AND ONSHORE WINDS WILL QUICKLY
VEER AROUND TO OFFSHORE. THERE WILL BE A TEMPORARY REPRIEVE FROM
THE STRONG WINDS AS THE SFC LOW MOVES RIGHT OVER THE REGION. WINDS
WILL QUICKLY PICK BACK UP FRI MORNING AND STRONG OFFSHORE WINDS
WILL LIKELY CONTINUE THROUGH SAT. SEAS WILL ALSO RESPOND WITH SEAS
OF UP TO 8 FT POSSIBLE IN THE OUTER WATERS. WITH THAT WILL GO
AHEAD AND ISSUE A SCY BEGINNING 12Z THU AND CONTINUE IT THROUGH
FRI WITH THE LIKELIHOOD OF IT NEEDING TO BE EXTENDED. /CAB/

DECISION SUPPORT...

DSS CODE...BLUE.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT
             SMALL CRAFT ADV

DECISION SUPPORT SERVICES (DSS) CODE LEGEND
GREEN  = NO WEATHER IMPACTS THAT REQUIRE ACTION
BLUE   = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH
         VISIBILITY EVENT
YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED
         WATCH/WARNING/ADVISORY ISSUANCES; RADAR SUPPORT
ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY
         TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES
RED    = FULL ENGAGEMENT FOR MODERATE TO HIGH RISK SVR
         AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL
         SIGNIFICANCE.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  65  45  53  42 /   0  20  80 100
BTR  68  46  55  43 /   0  20  90 100
ASD  67  46  56  45 /   0  20  70 100
MSY  66  49  57  45 /   0  20  80 100
GPT  67  48  57  47 /   0  20  60 100
PQL  68  47  57  50 /   0  10  60 100

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...SMALL CRAFT ADVISORY FROM 6 AM THURSDAY TO 6 PM FRIDAY FOR THE
     FOLLOWING ZONES: BRETON SOUND...CHANDELEUR SOUND...COASTAL
     WATERS FROM BOOTHVILLE LA TO THE SOUTHWEST PASS OF THE
     MISSISSIPPI RIVER OUT 20 NM...COASTAL WATERS FROM
     PASCAGOULA MS TO STAKE ISLAND LA FROM 20 TO 60 NM...COASTAL
     WATERS FROM PASCAGOULA MS TO STAKE ISLAND LA OUT 20
     NM...COASTAL WATERS FROM PORT FOURCHON TO LOWER ATCHAFALAYA
     RIVER FROM 20 TO 60 NM...COASTAL WATERS FROM PORT FOURCHON
     TO LOWER ATCHAFALAYA RIVER OUT 20 NM...COASTAL WATERS FROM
     STAKE ISLAND LA TO THE SOUTHWEST PASS OF THE MISSISSIPPI
     RIVER FROM 20 TO 60 NM...COASTAL WATERS FROM THE SOUTHWEST
     PASS OF THE MISSISSIPPI RIVER TO PORT FOURCHON FROM 20 TO
     60 NM...COASTAL WATERS FROM THE SOUTHWEST PASS OF THE
     MISSISSIPPI RIVER TO PORT FOURCHON OUT 20 NM...LAKE
     BORGNE...AND MISSISSIPPI SOUND.

MS...NONE.
GM...SMALL CRAFT ADVISORY FROM 6 AM THURSDAY TO 6 PM FRIDAY FOR THE
     FOLLOWING ZONES: BRETON SOUND...CHANDELEUR SOUND...COASTAL
     WATERS FROM BOOTHVILLE LA TO THE SOUTHWEST PASS OF THE
     MISSISSIPPI RIVER OUT 20 NM...COASTAL WATERS FROM
     PASCAGOULA MS TO STAKE ISLAND LA FROM 20 TO 60 NM...COASTAL
     WATERS FROM PASCAGOULA MS TO STAKE ISLAND LA OUT 20
     NM...COASTAL WATERS FROM PORT FOURCHON TO LOWER ATCHAFALAYA
     RIVER FROM 20 TO 60 NM...COASTAL WATERS FROM PORT FOURCHON
     TO LOWER ATCHAFALAYA RIVER OUT 20 NM...COASTAL WATERS FROM
     STAKE ISLAND LA TO THE SOUTHWEST PASS OF THE MISSISSIPPI
     RIVER FROM 20 TO 60 NM...COASTAL WATERS FROM THE SOUTHWEST
     PASS OF THE MISSISSIPPI RIVER TO PORT FOURCHON FROM 20 TO
     60 NM...COASTAL WATERS FROM THE SOUTHWEST PASS OF THE
     MISSISSIPPI RIVER TO PORT FOURCHON OUT 20 NM...LAKE
     BORGNE...AND MISSISSIPPI SOUND.

&&

$$







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