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

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476
FXUS64 KLIX 211003
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
403 AM CST FRI NOV 21 2014

.SHORT TERM...
WEAK UPPER LEVEL RIDGE IS STARTING TO BUILD OVER THE SOUTHEASTERN
UNITED STATES AS BROAD LONGWAVE TROUGH THAT HAS BEEN ENCOMPASSING A
MAJORITY OF THE EASTERN CONUS IS EJECTING EAST INTO THE NORTHERN
ATLANTIC OCEAN. SURFACE HIGH PRESSURE CENTERED JUST SOUTH OF THE
GREAT LAKES HAS BEGUN TO EXPAND AND WILL DOMINATE THE SERN CONUS AS
WELL. TIGHTENING PRESSURE GRADIENT FROM STRONG HIGH PRESSURE TO THE
NORTHEAST AND APPROACHING SURFACE TROUGH WILL STRENGTHEN  EAST TO
SOUTHEAST WINDS. IN RETURN...MOISTURE LEVELS THROUGH THE COLUMN WILL
BEGIN TO INCREASE...MORESO ON SATURDAY. THE COMBINATION OF
INCREASING 500MB HEIGHTS AND MOISTURE WILL KEEP TEMPERATURES ON THE
UPWARD TREND TODAY. WENT WITH A MOSTLY MAV GUIDANCE MAX TEMP
FORECAST AS IT PERFORMED QUITE WELL YSTRDY.

.LONG TERM...
THE MAIN FOCUS OF THE EXTENDED FORECAST REMAINS THE SAME...THE
POTENTIAL FOR SEVERE WEATHER SATURDAY NIGHT. COLUMN MOISTURE WILL BE
ON THE INCREASE SATURDAY AS WITH STRONG ONSHORE FLOW WELL
ESTABLISHED. MODEL SOUNDINGS SHOWING PRECIP WATER COMING UP TO OVER
1.5 INCHES LATE IN THE DAY. THE UPPER TROUGH WILL BE SWINGING ACROSS
TEXAS AND BECOMING NEGATIVELY TILTED DURING THE OVERNIGHT PERIOD.
MODEL SOUNDINGS ALSO SHOW MID LEVEL COOLING FROM LOWERING HEIGHTS
AND LOW LEVEL WARMING FROM THE WARM SECTOR SURGING NORTHWARD. THIS
WILL STEEPEN MID LEVEL LAPSE RATES AND INCREASE INSTABILITY. MODELS
INDICATE SLIGHTLY MORE INSTABILITY THIS RUN WITH -LI/S -4 TO -8 AND
CAPE OVER 1000 J/KG. THIS IS NOT OVER THE ENTIRE CWA. THE STRONGER
INSTABILITY WILL BE NEAR THE COAST WHERE LOW LEVEL MOISTURE IS
HIGHER. FURTHER NORTH IN SOUTHWEST MISSISSIPPI THE LOWER MOISTURE
MAY KEEP CAPE DOWN TO 500 J/KG OR LESS AND THAT INSTABILITY WILL BE
ELEVATED. THE OPPOSITE AFFECT WILL THE CASE FOR SRH. THE STRONGEST
HELICITY WILL BE IN NORTHERN PORTIONS OF THE CWA WHERE MID LEVEL
WINDS ARE STRONGER...POSSIBLY OVER 500 M2/S2...AND HALF THAT ALONG
THE COAST. OVERALL SHEAR SHOULD STILL BE SUFFICIENT WITH BULK SHEAR
OF 70+KTS. OF OTHER NOTE IS THE POSSIBLE A LIMITING FACTOR FOR
PORTIONS OF THE AREA WHICH IS THE MARINE LAYER ALONG THE COAST.
RECENT STRONG COLD FRONTS HAVE DROPPED NEARSHORE WATERS TO BELOW 60
DEGREES FOR PORTIONS OF THE LA COAST WEST OF LAFOURCHE PARISH...LAKE
PONTCHARTRAIN...AND THE SOUNDS. OTHER AREAS...ESP SOUTH OF THE NEW
ORLEANS METRO...STILL HAS WATER TEMPS NEAR 70 DEGREES. SO COULD HAVE
INTERMITTENT SHADOWING OR WEAKENING OF STORMS AS THE PASS FROM WEST
TO EAST ACROSS THE CWA. SOUNDINGS DO SHOW SOME FORM OF THIS MARINE
LAYER AT MOST LOCATIONS. ALL IN ALL...FEELING IS THAT AT LEAST SOME
SEVERE STORMS WILL DEVELOP SATURDAY NIGHT. TORNADOES AND DAMAGING
WINDS APPEAR THE BE THE GREATEST THREAT. HAIL TO A LESSER DEGREE
MAINLY DUE TO WETBULB ZERO HEIGHTS ARE SOMEWHAT HIGH AT 12KFT.

CONDITIONS SHOULD RAPIDLY IMPROVE FROM WEST TO EAST SUNDAY MORNING
AFTER SUNRISE. THE REMAINDER OF THE WEEK SHOULD BE DRY AND COOLER AS
A DEEP TROUGH SENDS ANOTHER STRONG COLD FRONT THROUGH THE AREA
MONDAY AND THEN AGAIN TUESDAY NIGHT WITH A REINFORCING BOUNDARY.

MEFFER
&&

.MARINE...MULTIPLE IMPACTS EXPECTED OVER THE COASTAL WATER LIKELY
THROUGH THE NEXT 4-5 DAYS. AS HAS BEEN MENTIONED THE LAST FEW DAYS A
VERY STRONG LATE FALL STORM SYSTEM WILL BRING A MULTITUDE OF ISSUES
TO THE REGION WITH SOME BEGINNING AS EARLY AS TODAY. DEVELOPING SFC
LOW IN TX AND STRONG HIGH CNTRD OVER THE TOBACCO ROAD REGION WILL
LEAD TO A TIGHTENING OF THE PRESSURE GRADIENT WITH ERLY FLOW PICKING
UP TO AROUND AROUND 15-20 KTS BY MIDDAY OVER THE OPEN WATERS WITH
FREQUENT GUSTS LIKELY ABV 20 KTS. WITH THAT WE WILL ISSUE A SCY
BEGINNING AT 18Z TODAY AND HAVE IT RUN THROUGH AT LEAST 12Z SUN.
THIS WILL LIKELY NEED TO BE EXTENDED OR AT LEAST REISSUED LATE
SUN/MON. THE SCY WILL EXPAND AT 12Z SAT TO INCLUDE THE TIDAL LAKES
AND SOUNDS. THE STRONG WIND AND PERSISTENT ERLY TO SERLY FLOW TODAY
THROUGH SUN MORNING WILL LEAD TO WATER PILING UP ON THE COAST. WITH
THAT A COASTAL FLOOD ADV HAS ALREADY BEEN ISSUED AND NO CHANGES WILL
BE MADE TO IT. LAST OF COURSE WILL BE CONVECTION THAT WILL LIKELY
BEGIN TO IMPACT THE REGION SAT AFTN WITH A SQUALL LINE ANTICIPATED
OVERNIGHT SAT AND EARLY SUN MORNING. /CAB/

&&

.AVIATION...SIMILAR TO LAST NIGHT VFR CONDITIONS WILL PERSIST
THROUGH THE FCST. ONLY ISSUE AT THIS TIME WOULD BE TEMPO MVFR VSBYS
DUE TO FOG AT THE NORMAL PROBLEM SITES...MCB/ASD/GPT/HDC. /CAB/

&&

.DECISION SUPPORT...
DSS CODE...GREEN.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT.

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  69  49  70  61 /  10  10  40  90
BTR  72  51  73  62 /  10  10  60  90
ASD  71  51  71  61 /  10  10  60  90
MSY  72  57  72  65 /  10  10  70  90
GPT  70  52  68  62 /  10  10  50  90
PQL  70  48  69  61 /   0  10  50  90

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...COASTAL FLOOD ADVISORY FROM NOON SATURDAY TO 6 AM SUNDAY FOR THE
     FOLLOWING ZONES: LOWER PLAQUEMINES...LOWER ST.
     BERNARD...ORLEANS...AND UPPER ST. BERNARD.

GM...SMALL CRAFT ADVISORY FROM 6 AM SATURDAY TO 6 AM SUNDAY FOR THE
     FOLLOWING ZONES: BRETON SOUND...CHANDELEUR SOUND...LAKE
     BORGNE...LAKE PONTCHARTRAIN AND LAKE MAUREPAS...AND
     MISSISSIPPI SOUND.

     SMALL CRAFT ADVISORY FROM NOON FRIDAY TO 6 AM SUNDAY 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...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...AND COASTAL WATERS FROM
     THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO PORT
     FOURCHON OUT 20 NM.

MS...COASTAL FLOOD ADVISORY FROM NOON SATURDAY TO 6 AM SUNDAY FOR THE
     FOLLOWING ZONES: AND HANCOCK.

GM...SMALL CRAFT ADVISORY FROM 6 AM SATURDAY TO 6 AM SUNDAY FOR THE
     FOLLOWING ZONES: BRETON SOUND...CHANDELEUR SOUND...LAKE
     BORGNE...LAKE PONTCHARTRAIN AND LAKE MAUREPAS...AND
     MISSISSIPPI SOUND.

     SMALL CRAFT ADVISORY FROM NOON FRIDAY TO 6 AM SUNDAY 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...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...AND COASTAL WATERS FROM
     THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO PORT
     FOURCHON OUT 20 NM.

&&

$$







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