National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS64 KLIX 180345
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1045 PM CDT THU APR 17 2014

.UPDATE...
THE LATEST TRENDS HAVE BEEN FOR A FASTER EVOLUTION OF THE RAINFALL
DEVELOPMENT BUT ALSO A FASTER EXIT AS THE MAIN INITIATION REGION
IN THE CENTRAL GULF APPEARS TO BE GETTING WELL OUT AHEAD OF THE
UPPER DYNAMIC SUPPORT. HAVE ADJUSTED POPS CONSIDERABLY FOR TONIGHT
TO REFLECT CATEGORICAL RAINFALL COVERAGE CLOSE TO THE ALABAMA LINE
AND TRENDING TO LOWER POPS WESTWARD. ALSO LATEST RAPID UPDATE
MODELS ARE SUGGESTING LESSER WINDS IN THE NEAR COASTAL WATERS AND
COASTAL C-MAN AND SHALLOW WATER BUOYS SUPPORT THIS NOTION. THE
HIGHER WINDS AND SEAS ARE OCCURRING...PARTICULARLY AT RIG LEVELS
IN THE OUTER WATERS. SMALL CRAFT ADVISORIES WILL BE LOWERED FOR
THE NEAR SHORE WATERS AT THIS TIME BUT MAINTAIN IN THE OUTER
WATERS NEXT TO THE GALE WARNING THAT OPC HAS NEAR THE GALE/LOW
CENTER. THE LAKE WINDS HAVE ALSO LESSENED BASED ON LATEST OBS.
ADDITIONALLY...WILL BE CANCELLING THE COASTAL FLOOD ADVISORY AT
THIS TIME AS TIDES ARE IN THE LOW PART OF THE CYCLE AND SHOULD
LOSE ANY SUPPORT FOR AUGMENTATION HEADING INTO THE NEXT HIGH TIDE
BY EARLY FRIDAY AFTERNOON.

&&

.SOUNDING DISCUSSION...
NO ISSUES WITH FLIGHT THIS EVENING. A HIGH BASED INVERSION AT 800
MB IS REDUCING RAINFALL TO SHALLOW WARM RAIN WITH LIMITED LIFT IN
THE MID-LEVELS. A NEARLY SATURATED COLUMN FROM SUFACE TO 800
MB...A DRY LAYER TO 600 MB THEN SATURATED THROUGH A VERY HIGH
TROPOPAUSE AT 165 MB. WINDS WERE SOLID EASTERLIES 5-25 KT SURFACE
TO 1900 FT...SE 10-25 KT TO 13.7KFT THEN SW 20-110 KT AVOVE. PEAK
WINDS 220/108KT AT 43.3KFT AT THE TROPOPAUSE. PRECIPITABLE WATER
1.20 INCHES IS RELATIVELY LOW FOR SIGNIFICANT RAINFALL. LIFTED
INDEX IS A STABLE 4.2.

&&

.AVIATION...
THOUGH SOME SPOTTY LIGHT SHOWERS MAY MOVE ACROSS THE AREA
OVERNIGHT...IMPACTS SHOULD BE MINIMAL FOR AVIATION PURPOSES.
CEILINGS ARE STILL EXPECTED TO LOWER TO IFR LEVELS LATER TONIGHT
BUT IMPROVE TO VFR SHORTLY AFTER SUNRISE AS UPPER TROUGH AXIS
MOVES THROUGH.

&&

.MARINE...
SEE UPDATE SECTION ABOVE.

&&

.DECISION SUPPORT...
DSS CODE...BLUE.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT
             MONITORING RIVER FLOODING
             SMALL CRAFT ADVISORY

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


&&

.PREV DISCUSSION... /ISSUED 503 PM CDT THU APR 17 2014/

SHORT TERM...

DEVELOPING SURFACE LOW PRESSURE SYSTEM IN THE NORTH CENTRAL GULF
OF MEXICO WILL MOVE SLOWLY NORTHEAST TONIGHT AND FRIDAY MORNING
BEFORE MOVING ACROSS THE NORTHEAST GULF TOWARDS THE CENTRAL AND
EASTERN FLORIDA PANHANDLE LATE FRIDAY AFTERNOON. ALTHOUGH THE LOW
PRESSURE SYSTEM WILL BE FAIRLY WEAK...THE IMPACTS WILL BE HIGHER
DUE TO THE STRONG PRESSURE GRADIENT BETWEEN THE 1010-1015 MB LOW
AND A 1040-45 MB HIGH CENTER OVER THE NEW ENGLAND AREA WITH A
STRONG RIDGE EXTENDING SOUTHWEST WITH THE 1028 MB PRESSURE LINE
INTO NORTHEAST GEORGIA. THIS WILL CREATE WINDY CONDITIONS AT TIMES
ALONG THE COAST...SOUTH SHORE OF LAKE PONTCHARTRAIN...AND
ESPECIALLY OVER OPEN WATER AREAS OFFSHORE. IN ADDITION...THERE HAS
BEEN JUST ENOUGH PERSISTENCE AND FETCH FROM STRONGER EAST WINDS TO
PUSH TIDE LEVELS AS MUCH AS 1.5 FEET ABOVE NORMAL ALONG THE COAST
OF HANCOCK COUNTY AND SHELL BEACH ON LAKE BORGNE. HAVE ISSUED A
COASTAL FLOOD ADVISORY FOR THE GULF FACING COAST FROM HANCOCK
COUNTY TO PLAQUEMINES PARISH THROUGH FRIDAY MORNING. THE GREATEST
IMPACT SHOULD BE NOW THROUGH EARLY EVENING SINCE THE HIGH TIDE WAS
ALREADY OCCURRING OR WILL EARLY TONIGHT. THE GRADIENT WINDS WILL
CONTINUE TO PUSH WATER IN EVEN AS THE TIDE FALLS...SO THE NET
RESULT MAY BE ONLY A SLOW FALL UNTIL WINDS BECOME DUE NORTHEAST
LATER FRIDAY MORNING.

REGARDING RAINFALL...THE AREA OF HEAVIER RAIN HAS BEEN STAYING
JUST OFFSHORE THE SOUTH CENTRAL AND SOUTHEAST LOUISIANA
COAST AND MOVING MORE EAST THAN NORTHEAST...HOWEVER...THE MODELS
INSIST A NORTHEAST PUSH TOWARDS THE MISSISSIPPI COAST AND
ESPECIALLY THE ALABAMA AND WESTERN FLORIDA PANHANDLE WILL OCCUR AS
THE POTENT SHORTWAVE TROUGH WITH TWO VORTICITY LOBES MOVES THROUGH
THE LOWER MISSISSIPPI VALLEY AND CENTRAL GULF COAST REGION TONIGHT
AND FRIDAY. SOME HEAVIER AMOUNTS OF ONE TO TWO INCHES ARE POSSIBLE
FROM NEAR LOWER PLAQUEMINES PARISH TO THE EASTERN MISSISSIPPI GULF
COAST WITH MODERATE AMOUNT`S AROUND ONE HALF INCH POSSIBLE AS FAR
NORTHWEST AS LAKE PONTCHARTRAIN AND THE LOWER PEARL RIVER VALLEY.
RAINFALL SHOULD REMAIN ON THE LIGHT SIDE ACROSS SOUTHWEST
MISSISSIPPI AND ADJACENT EAST CENTRAL/SOUTHEAST LOUISIANA.

CONDITIONS WILL DRY OUT AND CLOUDS WILL DECREASE FRIDAY AFTERNOON
AS THE LOW PRESSURE AND SHORTWAVE MOVE EAST OF THE REGION. ONLY A
SLIGHT PUSH OF COOLER AIR IS THEN EXPECTED FRIDAY NIGHT WITH LOWS
IN THE UPPER 40S NORTH TO 50S ELSEWHERE WITH HIGHS IN LOW TO MID
70S FRIDAY AND MID TO UPPER 70S SATURDAY WITH LOW HUMIDITY.

LONG TERM...

HIGH PRESSURE WILL GENERALLY RULE SUNDAY...THEN A MINOR SHORTWAVE
TROUGH WILL MOVE INTO THE AREA MONDAY AND MONDAY NIGHT WITH ONLY
SOME CLOUDS AND NO RAIN. TRANQUIL CONDITIONS ARE THEN EXPECTED TO
CONTINUE THROUGHOUT MOST OF NEXT WEEK AS THE STORM TRACK SHIFT
WELL NORTH OF THE GULF COAST REGION. LITTLE OR NO RAIN IS EXPECTED
WITH TEMPERATURES MOSTLY NEAR TO SLIGHTLY ABOVE NORMAL. 22/TD

AVIATION...

CONDITIONS WILL DETERIORATE THROUGH TONIGHT AND EARLY FRIDAY MORNING
WITH WIDESPREAD IFR EXPECTED /MAINLY DUE TO LOW CIGS/...WITH PERIODS
OF LIFR POSSIBLE. VSBY RESTRICTIONS OF 3-6 MILES ARE ALSO LIKELY
DURING RAIN AND ALSO POSSIBLE WHERE THE LIFR CIGS DEVELOP. THE LOW
PRESSURE SYSTEM OVER THE GULF WILL ALSO CAUSE NORTHEAST WINDS TO
RISE AS HIGH AS 20 TO 25 KNOTS NEAR KNEW LATE TONIGHT AND FRIDAY
MORNING WITH 15 TO 20 KNOTS POSSIBLE FOR A FEW HOURS AT
KMSY...KHUM...AND KGPT. CONDITIONS WILL IMPROVE BACK TO VFR WITH
CLEARING SKIES AND DIMINISHING WINDS FRIDAY AFTERNOON. 22/TD

MARINE...
STRONG EAST TO NORTHEAST WINDS AND ELEVATED SEAS/WAVES WILL CONTINUE
TONIGHT INTO FRIDAY AS A LOW PRESSURE SYSTEM GRADUALLY GETS BETTER
ORGANIZED AND MOVES NORTHEAST ACROSS THE NORTH CENTRAL AND NORTHEAST
GULF OF MEXICO. THE SMALL CRAFT ADVISORY HAS BEEN EXTENDED IN SPACE
AND TIME THROUGH FRIDAY AFTERNOON FOR ALL MARINE ZONES EXCEPT THE
TIDAL LAKES AND FAR WESTERN COASTAL WATERS. WIDESPREAD RAIN IS
EXPECTED OFFSHORE AND SOME OF THE OUTER WATERS MAY HAVE SOME STRONG
THUNDERSTORMS WITH GUSTY WINDS TONIGHT AND EARLY FRIDAY. NORTHEAST
WINDS ARE EXPECTED TO PEAK IN THE 25 TO 30 KNOTS RANGE LATE TONIGHT
AND FRIDAY MORNING ACROSS SOME OF THE WATERS EAST OF THE
RIVER...THEN WIND SPEEDS WILL DIMINISH FROM WEST TO EAST FRIDAY
AFTERNOON AND EVENING WITH THE EASTERN ZONES FALLING BELOW SMALL
CRAFT ADVISORY CRITERIA FRIDAY EVENING. NORTHEAST TO EAST WINDS
SHOULD FALL TO MOSTLY LESS THAN 15 KNOTS OVER THE WEEKEND THEN
TRANSITION TO SOUTH AND SOUTHWEST AT GENERALLY AROUND 10 KNOTS OR
LESS EARLY NEXT WORK WEEK AS HIGH PRESSURE SETTLES OVER THE NORTH
GULF. 22/TD

DECISION SUPPORT...
DSS CODE...BLUE.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT
             MONITORING RIVER FLOODING
             SMALL CRAFT ADVISORY

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  54  71  53  78 /  30  20  10  10
BTR  57  74  57  79 /  10  20  10  10
ASD  58  72  55  76 /  30  20  10  10
MSY  60  73  58  75 /  30  20  10  10
GPT  60  72  57  76 / 100  30  10  10
PQL  57  71  51  75 /  90  40  10  10

&&

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

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

&&

$$

24/RR