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

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747
FXUS64 KLIX 171708 AAA
AFDLIX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1208 PM CDT THU APR 17 2014

.UPDATE...

RADAR LOOPS INDICATED RAIN APPEARED TO BE COMING INTO SOUTHWEST
AREAS A BIT MORE WIDESPREAD AND FASTER THAN FORECAST DURING
DAYTIME PERIOD TODAY...SO HAVE RAISED THE POP SUBSTANTIALLY TO
ACCOUNT FOR THE TRENDS OVER THE WESTERN COASTAL WATERS AND SOUTH
CENTRAL LOUISIANA COASTAL AREAS. NORTHEAST OF THE CURRENT RAINFALL
IS A BIT MORE PROBLEMATIC. DRIER AIR APPEARS TO BE PUTTING THE
BRAKES ON THE LEADING EDGE OF THE RAIN...SO MADE ONLY MINOR
CHANGES TO BUMP UP THE POP 10 PERCENT OR SO THROUGH 7 PM. LATEST
12Z GFS IS CONSISTENT WITH OTHER MODELS WITH SURFACE LOW MOVING
NORTHEAST ACROSS THE NORTH CENTRAL AND NORTHEAST GULF OF MEXICO
TONIGHT AND FRIDAY...EXCEPT IT IS A LITTLE STRONGER WITH THE LOW
AT 7 AM FRIDAY. WILL EVALUATE ALL THE NEW DATA BEFORE MAKING ANY
OTHER SUBSTANTIAL CHANGES TO THE LATER PERIODS OF THE FORECAST.
22/TD

&&

.AVIATION...

MODEST IMPROVEMENT FROM MVFR TO VFR IS POSSIBLE EARLY THIS
AFTERNOON...OTHERWISE...CONDITIONS WILL DETERIORATE LATER THIS
AFTERNOON THROUGH TONIGHT AND EARLY FRIDAY MORNING WITH WIDESPREAD
IFR EXPECTED /MAINLY DUE TO LOW CIGS/...WITH PERIODS OF LIFR
POSSIBLE. VSBY RESTRICTIONS 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. 22/TD

&&

.MARINE...

CMAN OBSERVATIONS INDICATED WINDS NEAR OR ABOVE SMALL CRAFT
ADVISORY CRITERIA ACROSS MUCH OF THE MISSISSIPPI SOUND...SO ADDED
THAT MARINE ZONE TO THE SMALL CRAFT ADVISORY. REMAINDER OF
COASTAL FORECAST WAS ON TRACK. 22/TD

&&

.PREV DISCUSSION... /ISSUED 403 AM CDT THU APR 17 2014/

SYNOPSIS...
SURFACE LOW PRESSURE IS CENTERED OVER EXTREME SE MINNESOTA WITH
COLD FRONT EXTENDING SOUTHWEST INTO NORTHERN TEXAS AND CENTRAL NEW
MEXICO. RIDGE AXIS EXTENDS ALONG THE EAST COAST AND THROUGH THE
FLORIDA PANHANDLE.

LOCALLY...TEMPS DEFINITELY WARMER THAN SAME TIME YESTERDAY...BUT
MORNING LOWS WILL STILL BE A SOLID 5 TO 10 DEGREES BELOW NORMAL.
GENERALLY SITTING IN THE MID TO UPPER 40S NORTH AND IN THE 50S
SOUTH. CLOUDS HAVE ROLLED IN OVER THE PAST FEW HOURS...AND THIS
HAS ACTUALLY ALLOWED TEMPS TO RISE A DEGREE OR TWO SINCE MIDNIGHT
IN MANY PLACES.

SHORT TERM...
EXPECT ONE MORE DAY OF BELOW NORMAL TEMPERATURES TODAY. MOST
PLACES SHOULD START THE MORNING 5 TO 10 DEGREES BELOW NORMAL.
THOUGH THE CURRENT AIR MASS HAS ALREADY MODIFIED A BIT...WINDS
HAVE NOT YET SHIFTED FULLY ON SHORE TO BRING BACK THE WARMER AND
MORE HUMID AIR FROM THE GULF. COMBINE THIS WITH MOSTLY CLOUDY
SKIES...AND AM FORECASTING AFTERNOON TEMPS TO TOP OUT NEAR OR JUST
ABOVE 70 DEGREES. THIS IS ROUGHLY 10 DEGREES WARMER THAN
YESTERDAY...BUT STILL ALMOST 10 DEGREES BELOW NORMAL FOR THIS TIME
OF YEAR.

RAIN CHANCES WILL BEGIN TO INCREASE THIS AFTERNOON AS A SURFACE
LOW DEVELOPS IN THE GULF IN RESPONSE TO A FAST MOVING UPPER SHORT
WAVE. THERE ARE STILL SOME FAIRLY SIGNIFICANT DIFFERENCES IN THE
MODELS CONCERNING THIS SYSTEM DESPITE BEING IN THE NEAR TERM. THE
ECMWF AND GFS ARE SIMILAR IN THEIR TRACKS... BUT THE GFS IS A BIT
STRONGER. COMPARED TO PREVIOUS RUNS...THE GFS AND EURO HAVE BOTH
SHIFTED A BIT TO THE NORTH AND WEST WITH THE TRACK OF THE LOW.
THIS HAS RESULTED IN A SIGNIFICANT INCREASE IN MODEL FORECAST POPS
WITHIN THESE TWO MODELS. THE NAM IS CONSIDERABLY DRIER AS IT KEEPS
THE LOW WEAKER AND MUCH FARTHER SOUTH AND EAST...THUS KEEPING MOST
OF THE PRECIP OFF SHORE.

HAVE TRENDED TOWARD THE LATEST GFS/EURO BLEND WHICH DID REQUIRE A
BIT OF AN INCREASE IN POPS...MAINLY FOR TONIGHT. WITH THE CURRENT
FORECAST TRACK OF THE LOW...THUNDERSTORMS SHOULD GENERALLY BE
LIMITED TO THE COASTAL WATERS...AND EVEN THEN ONLY A SLIGHT CHANCE
WILL BE MENTIONED AT BEST. THERE IS NO SURFACE BASED INSTABILITY
TO SPEAK OF...AND EVEN ELEVATED INSTABILITY APPEARS LIMITED. MODEL
SOUNDINGS INDICATE AN INCREASE IN PW WITH NEARLY SATURATED
SOUNDINGS BY 06Z. THIS COULD RESULT IN AT LEAST A FEW EFFICIENT
RAIN MAKERS OVERNIGHT. GENERALLY SPEAKING...QPF SHOULD BE A HALF
INCH OR LESS...BUT SOME HIGHER AMOUNTS WILL BE POSSIBLE UNDER THE
HEAVIER SHOWERS.

THE UPPER SHORT WAVE AND LOW SHOULD BE PULLING AWAY FROM THE AREA
FRIDAY...THOUGH A FEW SHOWERS MAY LINGER THROUGH THE MORNING
HOURS. EXPECT TEMPERATURES TO RETURN TO NEAR NORMAL WITH LOWS IN
THE MID TO UPPER 50S NORTH AND NEAR 60 SOUTH AND HIGHS IN THE MID
70S.

LONG TERM...
GENERALLY QUIET WEATHER WILL BE THE RULE SATURDAY THROUGH MONDAY
AS DEEP RIDGING TAKES HOLD OF THE AREA. GRADUAL WARMING CAN BE
EXPECTED THROUGH THE PERIOD WITH NO SIGNIFICANT RAIN CHANCES.
AFTERNOON HIGHS SHOULD RISE FROM MID TO UPPER 70S ON SATURDAY TO
NEAR OR JUST ABOVE 80 SUNDAY AND MONDAY. ANOTHER SHORT WAVE WILL
TRAVERSE THE AREA ON TUESDAY. THIS WILL BRING THE NEXT CHANCE OF
RAIN TO THE AREA. HOWEVER...WITH WEAK FORCING AND NOT A LOT OF
MOISTURE IN PLACE...NOT EXPECTING MUCH MORE THAN ISOLATED TO
WIDELY SCATTERED COVERAGE. HIGH PRESSURE WILL BUILD BACK INTO THE
AREA WEDNESDAY WITH A RETURN TO QUIET AND WARM WEATHER.

AVIATION...
LOWER CEILINGS WILL BE SHIFTING NORTHWARD ACROSS THE FORECAST AREA
EARLY THIS MORNING WITH MVFR OR NEAR MVFR CONDITIONS GENERALLY
EXPECTED DURING THE COURSE OF THE DAY. IFR CEILINGS WILL DEVELOP
LATER TONIGHT. RAIN CHANCES WILL BE ON THE INCREASE LATE TODAY FOR
THE TAF SITES ACROSS THE SOUTHERN SECTIONS OF THE AREA...AND
ESPECIALLY TONIGHT INTO EARLY FRIDAY MORNING FOR THE ALL OF THE
TERMINALS AS AN AREA OF LOW PRESSURE DEVELOPS OVER THE NORTH CENTRAL
GULF OVERNIGHT AND MOVES NORTHEAST FRIDAY.

MARINE...
MODERATE TO STRONG EASTERLY FLOW WILL PREVAIL ACROSS THE GULF
COASTAL WATERS INTO EARLY FRIDAY...ESPECIALLY FOR THOSE AREAS TO THE
EAST OF THE MISSISSIPPI RIVER WHERE SMALL CRAFT ADVISORIES AND
EXERCISE CAUTION HEADLINES WILL BE POSTED FOR TODAY AND TONIGHT. AN
AREA OF LOW PRESSURE IS EXPECTED TO DEVELOP OVER THE NORTH CENTRAL
GULF OF MEXICO TONIGHT AND TRACK NORTHEAST ON FRIDAY BRINGING
WIDESPREAD RAIN TO THE COASTAL WATERS. WINDS WILL BECOME NORTHEAST
FRIDAY AND GRADUALLY DIMINISH IN MAGNITUDE FRIDAY INTO SATURDAY.
GENERALLY LIGHT NORTHEAST TO EAST FLOW OVER THE WEEKEND WILL BECOME
SOUTHERLY EARLY NEXT WORK WEEK.

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  68  56  75  54 /  10  30  20  10
BTR  71  58  77  58 /  30  40  20  10
ASD  68  58  75  56 /  20  40  20   0
MSY  70  60  74  60 /  30  50  20   0
GPT  68  59  73  57 /  20  50  30  10
PQL  68  57  73  52 /  20  50  50  10

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 6 AM FRIDAY FOR THE FOLLOWING ZONES:
     CHANDELEUR SOUND...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
     MISSISSIPPI SOUND.

MS...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 6 AM FRIDAY FOR THE FOLLOWING ZONES:
     CHANDELEUR SOUND...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
     MISSISSIPPI SOUND.

&&

$$







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