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

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FXUS64 KLIX 020200
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
800 PM CST SUN MAR 1 2015

.UPDATE...
RADAR COVERAGE REMAINS NUMEROUS TO WIDESPREAD ACROSS NORTHWEST
ZONES OVER BTR AND MCB THIS EVENING. HAVE INCREASED POPS THROUGH
MIDNIGHT TO REFLECT THIS ONGOING TREND. WHILE SOUNDING SHOWED NO
CAPE VALUES...THUNDER WAS PRESENT AT BTR AND OVER SOUTHWEST
MISSISSIPPI THIS EVENING...WILL INSERT TS FOR THROUGH MIDNIGHT.
LOOKING FOR AREA OF RAIN TO SWEEP EAST ACROSS THE FLORIDA
PARISHES. WILL MAINTAIN FOG ADVISORY.

&&

.PREV DISCUSSION... /ISSUED 649 PM CST SUN MAR 1 2015/

SOUNDING DISCUSSION...

ROUTINE FLIGHT TERMINATED OVER MISSISSIPPI SOUND ABOUT 3 MILES
SOUTHWEST OF PASCAGOULA. FLIGHT TERMINATED AT ABOUT 108K FEET OR
ABOUT 20.5 MILES IN ALTITUDE.

SOUNDING CONTINUES TO WARM AND MOISTEN THIS EVENING. PRECIPITABLE
WATER IS NOW UP TO 1.56 INCHES...WHICH IS ABOUT 175 PERCENT OF
NORMAL. MUCH OF THE SOUNDING BETWEEN 950 AND 730 MB IS ABOUT 5C
WARMER THAN 24 HOURS AGO. MARINE LAYER IS ABOUT 2000 FEET DEEP
THIS EVENING WHERE WINDS ARE OUT OF THE EAST. WINDS BECOME
SOUTHERLY ABOVE THE MARINE LAYER...AND GRADUALLY BECOME WESTERLY
BY ABOUT FL130. WIND MAX OF 104 KNOTS AT ABOUT 43K FEET. FREEZING
LEVEL AROUND 12.5K FEET AND -20C LEVEL AT ABOUT 24.5K FEET. 35

PREV DISCUSSION... /ISSUED 300 PM CST SUN MAR 1 2015/

SHORT TERM...
FROM A TEMPERATURE STANDPOINT...TODAY IS QUITE SIMILAR TO YESTERDAY.
BUT THATS WHERE THE SIMILARITIES END. 30 TO 40 DEGREE DEWPOINTS HAVE
BEEN REPLACED BY 60 DEGREE TD/S AS GULF MOISTURE HAS SURGED INTO THE
AREA. CLEAR SKIES HAVE GIVEN WAY TO OVERCAST SKIES WITH
ACCOMPANYING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. THIS IS
ALL IN RESPONSE TO THE AREA BEING IN A SHEAR ZONE BETWEEN AN UPPER
LEVEL RIDGE CENTERED OVER THE NORTHWESTERN CARIBBEAN AND A TROUGH
OVER THE GREAT LAKES REGION. A BROAD SURFACE TROUGH IN THIS REGION
OF THE GULF SOUTH HAS BEEN THE FOCUS OF INCREASE SHOWER DEVELOPMENT.
MOST OF THE HEAVIER RAIN EXISTS FROM NEAR BATON ROUGE TO LAKE
CHARLES TO SHREVEPORT AND THEN OVER TO JACKSON. PORTIONS OF THE CWA
SW OF THERE STILL HAVE A FEW SHOWERS BUT MUCH MORE ISOLATED IN
NATURE. THIS WILL CONTINUE TO BE THE CASE THROUGH THE AFTERNOON AND
EVENING HOURS. ACTIVITY WILL CONTINUE THROUGH THE NIGHT BUT THINKING
THAT COVERAGE WILL DWINDLE SOME. THE BIGGER IMPACT FROM WEATHER
TONIGHT AND TOMORROW MORNING WILL BE IN THE FORM OF FOG...ESPECIALLY
ALONG THE COASTAL AREAS OF THE CWA. DEWPOINTS ARE NOW AT OR SLIGHTLY
ABOVE WATER TEMPS. THIS IS A PRIME SITUATION FOR SEA FOG TO DEVELOP.
SO WILL BE GOING OUT WITH A MARINE FOG ADVISORY WITH THIS FORECAST
PACKAGE. DEFINITELY WILL BE MONITORED FOR THIS TO BE CARRIED
FURTHER INLAND. MONDAY WILL BE QUITE SIMILAR TO TODAY BUT POSSIBLY
SLIGHTLY WARMER IN SOME LOCATIONS IN THE SWRN HALF OF THE CWA.
EXPECTING HIGHER POPS IN NW AND LOWER ALONG THE COASTAL AREAS.

LONG TERM...
SOUTHEASTERLY FLOW TO PICK UP AGAIN GOING INTO TUESDAY AS SFC TROUGH
TO THE NORTH DISSIPATES AND RIDGE BUILDS IN FROM THE NE/EAST. AT THE
SAME TIME...A DEEP UPPER TROUGH AND ASSOCIATED COLD AIR MASS WILL BE
DIVING SOUTH OUT OF CANADA. LATEST MODELS SHOW THIS FRONT TO REACH
INTO OKLAHOMA BY LATE IN THE DAY. LOCALLY...HAVE KEPT POPS TO A
MINIMUM AS A FEW SHOWERS COULD DEVELOP BUT DONT FORESEE WIDESPREAD
DEVELOPMENT W/O A DEFINED FOCUS. THIS IS NOT THE CASE PROGRESSING
WELL INTO WEDNESDAY. THE FRONT MARCHING THROUGH THE CENTRAL PLAINS
WILL RACE TOWARDS THE GULF COAST. WIDESPREAD SHOWERS AND POSSIBLY A
FEW THUNDERSTORMS WILL ACCOMPANY THIS FRONT WITH MOST PRECIP ALONG
AND BEHIND THE BOUNDARY. STILL HAVE SOME TIMING DIFFERENCES WITH THE
GFS BRINGING IN THE PRECIP ABOUT 6 HRS BEFORE THE ECMWF. FOR NOW THE
FCST IS SIMILAR TO THE PREVIOUS WHICH DOES HAVE RAIN COMING IN BY
LATE AFTERNOON. IF THE ECMWF IS RIGHT...THE FCST POPS FOR WED WILL
BE WAY TOO HIGH. THIS TIMING ALSO PLAYS INTO THE BACKSIDE FREEZING
PRECIP POTENTIAL. THE GFS STILL SHOWS COLD AIR MOVING IN PLENTY FAST
ENOUGH WITH PRECIP STILL OVERHEAD FOR FREEZING RAIN TO DEVELOP AS
FAR SOUTH AS MCB AND BTR. THE ECMWF OBVIOUSLY DOES NOT WITH IS
SLOWER PROGRESSION OF THE LOW LEVEL COLD AIR. STILL HOLDING OFF ON
THE MENTION OF FRZL IN THE ZONES DUE TO THIS UNCERTAINTY.

MODEL DISAGREEMENT CONTINUES LATE IN THE WEEK AND INTO THE WEEKEND.
GFS KEEPS THE AREA DRY FOR TILL SUNDAY WHEN A SOUTHERN STREAM TROUGH
PULLS MOISTURE BACK INTO THE AREA. THE ECMWF SUGGESTS MOISTURE
DOESN/T QUITE GO AWAY AFTER THE LATEST FRONT AND BACKTRACKS OVER THE
CWA FRIDAY BEFORE THE SOUTHERN TROUGH MOVES IN FROM THE WEST. MADE
NO SIG CHANGES TO THE EXTENDED FORECAST B/C OF THE DISAGREEMENT.

MEFFER

AVIATION...
MAINLY IFR CONDITIONS AT THE TERMINALS THIS AFTERNOON DUE TO LOW
CEILINGS WILL DETERIORATE OVERNIGHT TO LIFR AND VLIFR CATEGORY
CONDITIONS DUE TO BOTH LOW CEILINGS AND FOG. THESE CONDITIONS WILL
PERSIST THROUGH MUCH OF THE DAY MONDAY WITH PERHAPS SOME SLIGHT
IMPROVEMENT DURING THE AFTERNOON HOURS. 11

MARINE...
LIGHT TO OCCASIONALLY MODERATE ONSHORE FLOW WILL PREVAIL ACROSS THE
COASTAL WATERS FOR MUCH OF THE FIRST HALF WORK WEEK. A STRONG COLD
FRONT WILL THEN PUSH SOUTH ACROSS THE COASTAL WATERS WEDNESDAY NIGHT
AND EARLY THURSDAY BRINGING MUCH COLDER AIR TO THE REGION AND
PRODUCING STRONG OFFSHORE FLOW THAT WILL REQUIRE SMALL CRAFT
ADVISORIES FOR THE END OF THE WORK WEEK. 11

DECISION SUPPORT...

DSS CODE...BLUE.
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  58  68  60  74 /  60  50  20  20
BTR  59  72  62  78 /  60  50  20  20
ASD  58  72  61  75 /  30  30  20  20
MSY  60  73  62  77 /  20  30  20  20
GPT  58  69  59  71 /  20  30  20  10
PQL  55  72  58  73 /  20  30  20  10

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...DENSE FOG ADVISORY UNTIL 9 AM MONDAY FOR THE FOLLOWING ZONES:
     ASSUMPTION...LOWER JEFFERSON...LOWER LAFOURCHE...LOWER
     PLAQUEMINES...LOWER ST. BERNARD...LOWER
     TERREBONNE...ORLEANS...SOUTHERN TANGIPAHOA...ST.
     CHARLES...ST. JAMES...ST. JOHN THE BAPTIST...ST.
     TAMMANY...UPPER JEFFERSON...UPPER LAFOURCHE...UPPER
     PLAQUEMINES...UPPER ST. BERNARD...AND UPPER TERREBONNE.

GM...DENSE FOG ADVISORY UNTIL 9 AM MONDAY 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 PORT FOURCHON TO
     LOWER ATCHAFALAYA RIVER OUT 20 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...DENSE FOG ADVISORY UNTIL 9 AM MONDAY FOR THE FOLLOWING ZONES:
     HANCOCK...HARRISON...AND JACKSON.

GM...DENSE FOG ADVISORY UNTIL 9 AM MONDAY 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 PORT FOURCHON TO
     LOWER ATCHAFALAYA RIVER OUT 20 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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