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

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496
FXUS64 KLIX 200116
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
816 PM CDT FRI SEP 19 2014

...SOUNDING DISCUSSION...

DRY AIR HAS ARRIVED OVER MUCH OF THE CENTRAL GULF COAST AS NOTED
ON WV IMAGERY THIS EVENING. THIS MEANS CONDITIONS ARE QUITE
COMFORTABLE FOR THE MIDDLE OF SEPTEMBER. WITH THE COLUMN DRYING
OUT...PRECIPITABLE WATER VALUES ARE ALSO DROPPING AND ARE AT 1.45
INCHES. THIS IS ABOUT A HALF INCH LOWER THAN THIS MORNING/S
SOUNDING AND ABOUT A QUARTER INCH BELOW THE CLIMATOLOGICAL VALUE.
INSTABILITY HAS ALSO DECREASED WITH MLCAPES CALCULATED NEAR 150
J/KG AND THE LIFTED INDEX AROUND -2. TEMPERATURES GENERALLY FOLLOWED
THE PSEUDO ADIABATS ABOVE 700MB WITH THE EXCEPTION OF TEMPERATURE
INVERSIONS AROUND 575MB AND 430MB. LOW LEVEL WINDS AVERAGING 15 TO
25 KNOTS FROM THE EAST CARRIED THE BALLOON TO LACOMBE BEFORE MID
AND UPPER LEVEL WINDS FROM THE NORTHWEST CARRIED THE BALLOON OVER
LAKE PONTCHARTRAIN AND EAST OF NEW ORLEANS. A MAXIMUM WIND SPEED
OF 43 KNOTS WAS LOCATED AT 32500 FEET ABOVE THE GROUND.

00Z BALLOON INFO: A SUCCESSFUL FLIGHT THIS EVENING THAT REACHED A
HEIGHT OF 21 MILES ABOVE THE GROUND BURSTING 26.7 MILES DOWNRANGE
JUST EAST OF CHALMETTE.

ANSORGE

&&

.PREV DISCUSSION... /ISSUED 343 PM CDT FRI SEP 19 2014/

SYNOPSIS...
LATEST SURFACE ANALYSIS SHOWED A STATIONARY BOUNDARY FROM NORTH
FLORIDA TO COASTAL LOUISIANA AND WEAK HIGH PRESSURE FROM
MISSISSIPPI TO NORTHEAST CONUS. SURFACE DEWPOINTS RANGE FROM THE
MID 60S ACROSS SOUTH MISSISSIPPI TO LOWER 70S ALONG THE
LOUISIANA..DRY TO THE NORTHEAST. UPPER AIR CHARTS SHOWED A
POSITIVELY TILTED TROUGH AXIS FROM THE MID ATLANTIC COAST TO THE
NORTH CENTRAL GULF. WATER VAPOR SHOWED THE DEMARCATION LINE FROM
PENSACOLA TO THE MISSISSIPPI DELTA TO LAKE CHARLES WITH MID LAYER
DRYING NORTH. WRF3KM SHOWED ISOLATED TO SCATTERED SHOWERS DEVELOPING
OVER THE NORTH HALF ZONES THIS AFTERNOON BUT DRY AIR ALOFT SHOULD
HAMPER DEEP GROWTH AND CONVECTION.

SHORT TERM...
NORTHEAST WINDS NORTH OF THE BOUNDARY WILL CONTINUE TO ADVECT IN LOWER
60S ACROSS THE NORTH HALF ZONES TONIGHT. CONVECTION SHOULD DISSIPATE BY
SUNSET AND CLEARING SHOULD ALLOW NORTHERN POINTS TO RADIATE. AS A
RESULT...OVERNIGHT WILL DIP INTO THE UPPER 60S ACROSS THE NORTH
ZONES BUT REMAINING THE 70S FOR SOUTH ZONES AND REPEAT POSSIBLY A
DEGREE OR TWO COOLER FOR SUNDAY MORNING. UPPER LEVEL TROUGH JUST TO
THE EAST WILL SLOWLY THROUGH THE WEEKEND MAINTAIN A LIGHT NORTH
FLOW OVER THE LOWER MISSISSIPPI VALLEY. PRECIPITABLE WATER VALUES
SHOULD BELOW 1 INCHES BY SATURDAY AND REMAIN AT OR BELOW 1 INCH
THROUGH THE WEEKEND. THEREFORE...WILL ONLY KEEP SLIGHT RAIN
CHANCES ALONG THE LOUISIANA COASTAL AND COASTAL WATERS.

LONG TERM...
UPPER LEVEL TROUGH OVER THE UPPER PLAINS WILL DIVE SOUTHEAST OVER
THE GREAT LAKES AND PUSH A TROUGH AXIS ACROSS THE LOWER
MISSISSIPPI VALLEY MONDAY. MOISTURE WILL BE LIMITED HOWEVER...MID
LAYER INSTABILITY WILL BE IN PLACE BEFORE THE PASSAGE AXIS AND
ASSOCIATED FRONTAL BOUNDARY. WILL MAINTAIN ISOLATED TSRA MONDAY
THRU MONDAY EVENING AHEAD OF THE BOUNDARY. 1000 TO 700MB LAYERS
BEHIND THIS TROUGH DECREASE ONLY 10 TO 15 METERS. HOWEVER...SURFACE
DEWPOINTS ARE EXPECTED TO DROP INTO THE LOWER 50S ACROSS THE NORTH
ZONES BY TUESDAY MORNING ACCORDING TO EURO AND GFS. WILL NOT GO AS
LOW AS MEX NUMBERS ACROSS THE NORTH...BUT THESE TEMPS WILL PROVIDE
AC RELIEF MONDAY AND TUESDAY NIGHTS. WITH THE TROUGH MOVING
THROUGH THE NORTHEAST CONUS...A HIGH WILL DEVELOP AND AMPLIFY OVER
THE OHIO VALLEY...CREATING A MORE EAST FLOW OVER THE GULF COAST
THURSDAY INTO FRIDAY...THUS INCREASING RAIN CHANCES ACROSS THE
SOUTH ZONES.

MARINE...A WEAK AREA OF LOW PRESSURE IN THE CNTRL GULF HAS
TIGHTENED THE PRESSURE GRADIENT ACROSS THE COASTAL WATERS AND WILL
REMAIN IN PLACE FOR ANOTHER 24 HRS. THIS IS LEADING TO WINDS ABV 20
KTS WITH HIGHER GUSTS IN MUCH OF THE COASTAL WATERS AND THUS HAVE
ISSUED A SCY FOR ALL MARINE ZONES OUTSIDE OF THE TIDAL LAKES AND
SOUNDS. SEAS WILL RISE TO AS MUCH AS 7 FT IN THE OUTER WATERS EAST
OF THE MS RIVER. THIS LOW WILL PULL TO THE EAST BY SUNDAY...ALLOWING
THE PRESSURE GRADIENT TO DECREASE SOMEWHAT FOR SUNDAY AND MONDAY.
EXPECT TO SEE EASTERLY FLOW OF AROUND 10 KNOTS AND SEAS DROPPING TO
2 TO 3 FEET DURING THIS PERIOD.  A COLD FRONT WILL THEN PASS THROUGH
THE MARINE ZONES TUESDAY INTO TUESDAY NIGHT.  AS SOME DRIER AIR
ADVECTS OVER THE AREA...A BRIEF INCREASE IN WINDS BACK TOWARD
EXERCISE CAUTION RANGE WILL BE POSSIBLE.  /CAB/

AVIATION...OVERALL VFR CONDITIONS SHOULD RULE FOR THE MOST PART BUT
FOR THE REMAINDER OF THE AFTN AND INTO THE VERY EARLY EVNG HRS SOME
VERY SHALLOW SHRA WILL IMPACT PORTIONS OF THE REGION. ONCE WE LOSE
THE DAYTIME HEATING WHAT EVER CONVECTION IS OUT THERE WILL
DISSIPATE. ONCE THIS OCCURS LOOK FOR SOME CU AROUND 4-5 FT BUT
OVERALL SKIES SHOULD BECOME CLEAR. /CAB/

DECISION SUPPORT...
DSS CODE...GREEN.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT AND SUPPORTING USCG SSW OF PASCAGOULA.

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  68  88  66  90 /  10  10  10  10
BTR  68  90  68  90 /  10  10  10  10
ASD  69  89  67  91 /  10  10  10  10
MSY  74  88  75  91 /  10  10  10  10
GPT  73  89  71  91 /  10  10  10  10
PQL  69  88  67  90 /  10  10  10  10

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 7 PM SATURDAY FOR THE FOLLOWING
     ZONES: 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...AND COASTAL WATERS FROM STAKE ISLAND LA TO THE
     SOUTHWEST PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60 NM.

     SMALL CRAFT ADVISORY FROM 7 PM FRIDAY TO 7 PM SATURDAY FOR THE
     FOLLOWING ZONES: 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 THE SOUTHWEST PASS OF THE
     MISSISSIPPI RIVER TO PORT FOURCHON FROM 20 TO 60 NM...AND
     COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI
     RIVER TO PORT FOURCHON OUT 20 NM.

MS...NONE.
GM...SMALL CRAFT ADVISORY FROM 7 PM FRIDAY TO 7 PM SATURDAY FOR THE
     FOLLOWING ZONES: 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 THE SOUTHWEST PASS OF THE
     MISSISSIPPI RIVER TO PORT FOURCHON FROM 20 TO 60 NM...AND
     COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI
     RIVER TO PORT FOURCHON OUT 20 NM.

     SMALL CRAFT ADVISORY UNTIL 7 PM SATURDAY FOR THE FOLLOWING
     ZONES: 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...AND COASTAL WATERS FROM STAKE ISLAND LA TO THE
     SOUTHWEST PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60 NM.

&&

$$







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