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

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793
FXUS64 KLIX 142126
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
426 PM CDT MON APR 14 2014

.SHORT TERM...

TONIGHT THROUGH WEDNESDAY...

A STRONG COLD FRONT AND ASSOCIATED UPPER LEVEL TROUGH WILL
CONTINUE TO IMPACT THE FORECAST AREA THROUGH THE SHORT TERM
PERIOD. INITIALLY...THE COMBINATION OF INCREASED OVERALL
INSTABILITY AND STRONG FORCING WILL CONTINUE TO PRODUCE BANDS OF
SHOWER AND THUNDERSTORM ACTIVITY THROUGH THE OVERNIGHT HOURS. HAVE
KEPT IN CATEGORICAL POPS FOR THE EVENING HOURS...WITH A TREND
TOWARD DECREASING COVERAGE FROM WEST TO EAST LATE TONIGHT. LOCALLY
HEAVY RAINFALL WILL BE POSSIBLE THROUGH THE EVENING HOURS...DUE TO
COMBINATION OF HIGH PRECIPITATION EFFICIENCY AND PW VALUES RUNNING
150-200 PERCENT OF NORMAL. GIVEN THESE CONDITIONS...HAVE KEPT THE
FLASH FLOOD WATCH IN PLACE FOR THE EVENING HOURS. THERE WILL ALSO
CONTINUE TO BE A MARGINAL THREAT FOR SEVERE WEATHER THROUGH THE
EVENING HOURS. THE WIND FIELD WILL TURN MORE UNIDIRECTIONAL DURING
THE EVENING HOURS...SO THE PRIMARY SEVERE THREAT WILL BE LOCALLY
STRONG WIND GUSTS AND HAIL. IN FACT...MUCH OF THE THUNDERSTORM
ACTIVITY WILL BE POST-FRONTAL AND AS A RESULT ELEVATED. OVERALL
LAPSE RATES WILL BE MORE FAVORABLE FOR HAIL DEVELOPMENT WITH THIS
ELEVATED POST-FRONTAL CONVECTION.

THE OTHER SIGNIFICANT IMPACT WILL BE A PERIOD OF ENHANCED WINDS IN
THE IMMEDIATE WAKE OF THE FRONT ON THE SOUTHSHORE OF LAKE
PONTCHARTRAIN. STRONG BOUNDARY LAYER WINDS OF 25 TO 30 KNOTS WILL
EASILY MIX DOWN TO THE SURFACE AS IT MOVES OVER THE WARMER WATERS
OF LAKE PONTCHARTRAIN. THESE WINDS WILL THEN SPREAD OVER METRO NEW
ORLEANS TONIGHT. AS THE OVERALL PRESSURE GRADIENT WEAKENS DURING
THE DAY TOMORROW...WINDS WILL FALL BACK BELOW 20 KNOTS. GIVEN THE
EXPECTED WINDS...A WIND ADVISORY IS IN EFFECT FOR THE SOUTHSHORE.
ANOTHER IMPACT FROM THESE STRONG WINDS WILL BE LARGE BATTERING
WAVES IMPACTING THE ORLEANS PARISH SHORELINE ALONG LAKESHORE
DRIVE. GIVEN THESE EXPECTED CONDITIONS...HAVE ISSUED A COASTAL
FLOOD ADVISORY FOR TONIGHT AND EARLY TOMORROW FOR AREAS OUTSIDE OF
THE LEVEE PROTECTION ALONG THE LAKEFRONT IN NEW ORLEANS.

TEMPERATURES WILL COOL DRAMATICALLY AS A DEEP COLD POOL
OVERSPREADS THE FORECAST AREA TONIGHT. LOWS WILL COOL INTO THE 40S
AND 50S TONIGHT...AND WILL STRUGGLE TO RISE INTO THE LOWER 60S
TOMORROW AFTERNOON. WITH CLEAR SKIES...LOW HUMIDITY...AND LIGHTER
WINDS EXPECTED TOMORROW...CONDITIONS WILL BE PRIME TO SEE
OVERNIGHT LOWS COOL INTO THE LOWER TO MIDDLE 30S ACROSS THE
NORTHERN HALF OF THE FORECAST AREA. CONDITIONS WILL BE VERY CLOSE
TO FREEZING...BUT AT THIS TIME A FREEZE IS NOT ANTICIPATED.
HOWEVER...FROST COULD BE A CONCERN. THE HEART OF THE COLD POOL
WILL BEGIN TO PULL TO THE EAST BY WEDNESDAY...ALLOWING FOR SOME
MODERATION IN TEMPERATURES. HOWEVER...READINGS WILL REMAIN A GOOD
10 TO 15 DEGREES BELOW AVERAGE.

.LONG TERM...

THURSDAY THROUGH MONDAY...

AFTER REVIEWING THE MEDIUM RANGE GUIDANCE...HAVE DECIDED TO TOSS
OUT THE GFS MODEL RUN AND WENT EXCLUSIVELY WITH THE EURO. WITH
THAT IN MIND...EXPECT A FAST MOVING UPPER LEVEL TROUGH TO SLIDE
THROUGH THE MIDWEST AND TENNESSEE VALLEYS THURSDAY INTO FRIDAY.
THE STRONGEST DYNAMICS WITH THIS SYSTEM WILL REMAIN WELL NORTH OF
THE AREA...BUT THERE SHOULD BE ENOUGH OVERALL OMEGA AND MOISTURE
IN PLACE TO SPARK OFF SOME SCATTERED SHOWERS AND THUNDERSTORMS
BEGINNING THURSDAY AFTERNOON AND PERSISTING INTO FRIDAY MORNING.
IN THE WAKE OF THIS UPPER LEVEL TROUGH A VERY STRONG DEEP LAYER
RIDGE AXIS WILL SETTLE OVER THE AREA FOR THE WEEKEND. THIS RIDGE
WILL EFFECTIVELY CAP OFF ANY CONVECTIVE RISK FOR THE WEEKEND AND
ALSO ALLOW TEMPERATURES TO SURGE BACK INTO THE UPPER 70S AND LOWER
80S FOR SATURDAY AND SUNDAY. ANOTHER WEAK SHORTWAVE TROUGH WILL
APPROACH THE REGION ON MONDAY BRINGING ANOTHER CHANCE OF SHOWERS
TO THE AREA.

&&

.AVIATION...

IN GENERAL...MVFR RESTRICTIONS CAN BE EXPECTED FOR ALL OF THE
TERMINALS THROUGH TOMORROW MORNING. CEILINGS WILL GENERALLY RANGE
FROM 1500-2500 FEET AND VISIBILITIES WILL FLUCTUATE FROM 3 TO 5
MILES. HOWEVER...PERIODS OF CONVECTION WILL IMPACT ALL OF THE
TERMINALS THROUGH AROUND 06Z TONIGHT. THIS CONVECTION WILL BRING
REDUCED VISIBILITIES OF 1 TO 3 MILES TO THE TERMINALS...RESULTING
IN IFR RESTRICTIONS FOR BRIEF PERIODS OF TIME. ADDITIONALLY...THERE
MAY BE A WINDOW OF IFR CEILINGS DEVELOPING FROM 06Z TO 14Z TONIGHT
AS COLDER AIR ADVECTING IN AT THE SURFACE FORMS AN ELEVATED
INVERSION. CONDITIONS WILL BEGIN TO IMPROVE AFTER 15Z
TOMORROW...AS DRIER AIR MIXES DOWN. THIS WILL BRING VFR CONDITIONS
TO THE TERMINALS. THERE WILL ALSO BE STRONG WINDS IMPACTING KNEW
AND KMSY THROUGH THE PERIOD. NORTH WINDS OF 30 TO 35 KNOTS WILL BE
POSSIBLE AT KNEW.

&&

.MARINE...

GALE WARNINGS REMAIN IN PLACE FOR ALL OF THE COASTAL WATERS
BEGINNING LATE IN THE EVENING AND PERSISTING THROUGH TOMORROW
MORNING. STRONG GRADIENT WINDS ALOFT OF 30 TO 35 KNOTS WILL
EASILY MIX DOWN TO THE SURFACE TONIGHT OVER THE WARMER MARINE ZONE
WATERS. THESE STRONG WINDS WILL PRODUCE VERY DANGEROUS SEAS OF 7
TO 10 FEET IN THE OFFSHORE WATERS AND ROUGH WAVES OF 4 TO 6 FEET
IN THE SOUNDS AND LAKES. CONDITIONS WILL IMPROVE A BIT DURING THE
DAY TOMORROW AS THE OVERALL PRESSURE GRADIENT WEAKENS.
HOWEVER...SMALL CRAFT CONDITIONS WILL PERSIST INTO TOMORROW NIGHT.
THE SURFACE HIGH WILL SETTLE OVER THE SOUTHEAST ON WEDNESDAY AND
LINGER OVER THE REGION THROUGH WEEKEND. THERE WILL BE SOME
TIGHTENING OF THE GRADIENT ON THURSDAY AND FRIDAY AS A LOW
PRESSURE SYSTEM MOVES THROUGH THE GULF OF MEXICO. THIS WILL PUSH
CONDITIONS BACK INTO SMALL CRAFT ADVISORY RANGE FROM THURSDAY
THROUGH FRIDAY EVENING. WINDS WILL BEGIN TO WANE FRIDAY NIGHT INTO
SATURDAY AS THE LOW PULLS TO THE EAST AND THE OVERALL PRESSURE
GRADIENT EASES.

&&

.DECISION SUPPORT...

DSS CODE...YELLOW.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT
MONITORING RIVER FLOODING AND SEVERE THUNDERSTORM/HEAVY RAIN
THREATS.

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  44  61  33  64 /  70  10   0   0
BTR  46  61  34  66 /  70  10   0   0
ASD  49  62  33  65 /  90  10   0   0
MSY  50  61  43  65 /  90  10   0   0
GPT  52  63  37  65 /  90  10   0   0
PQL  52  62  34  65 /  90  10   0   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...FLASH FLOOD WATCH UNTIL 11 PM MONDAY FOR THE FOLLOWING ZONES:
     ASSUMPTION...LOWER JEFFERSON...LOWER LAFOURCHE...LOWER
     PLAQUEMINES...LOWER ST. BERNARD...LOWER
     TERREBONNE...ORLEANS...ST. CHARLES...ST. JAMES...ST. JOHN
     THE BAPTIST...ST. TAMMANY...UPPER JEFFERSON...UPPER
     LAFOURCHE...UPPER PLAQUEMINES...UPPER ST. BERNARD...AND
     UPPER TERREBONNE.

     COASTAL FLOOD ADVISORY FROM 7 PM MONDAY TO 1 PM TUESDAY FOR THE
     FOLLOWING ZONES: AND ORLEANS.

     WIND ADVISORY FROM 10 PM MONDAY TO 10 AM TUESDAY FOR THE
     FOLLOWING ZONES: LOWER JEFFERSON...LOWER LAFOURCHE...LOWER
     PLAQUEMINES...LOWER ST. BERNARD...ORLEANS...ST.
     CHARLES...ST. JOHN THE BAPTIST...UPPER JEFFERSON...UPPER
     PLAQUEMINES...AND UPPER ST. BERNARD.

GM...GALE WARNING FROM 10 PM MONDAY TO 9 AM TUESDAY 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...LAKE PONTCHARTRAIN AND LAKE MAUREPAS...AND
     MISSISSIPPI SOUND.

     SMALL CRAFT ADVISORY FROM 9 AM TUESDAY TO 6 AM WEDNESDAY 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...LAKE PONTCHARTRAIN AND LAKE MAUREPAS...AND
     MISSISSIPPI SOUND.

MS...FLASH FLOOD WATCH UNTIL 11 PM MONDAY FOR THE FOLLOWING ZONES:
     HANCOCK...HARRISON...AND JACKSON.

GM...GALE WARNING FROM 10 PM MONDAY TO 9 AM TUESDAY 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...LAKE PONTCHARTRAIN AND LAKE MAUREPAS...AND
     MISSISSIPPI SOUND.

     SMALL CRAFT ADVISORY FROM 9 AM TUESDAY TO 6 AM WEDNESDAY 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...LAKE PONTCHARTRAIN AND LAKE MAUREPAS...AND
     MISSISSIPPI SOUND.

&&

$$

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