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

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926
FXUS64 KLIX 301018
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
518 AM CDT MON MAR 30 2015

.DISCUSSION...

NOT A LOT OF CHANGES HAVE BEEN MADE TO THE PREVIOUS FORECAST.
SATELLITE AND RADAR IMAGERY INDICATED A SHORTWAVE TROUGH MOVING
SOUTHEAST THROUGH THE OHIO/TENNESSEE/LOWER MISSISSIPPI VALLEY
REGION. THE ASSOCIATED WELL DEFINED COLD FRONT IS PRECEDED BY A BAND
OF WIDESPREAD SHOWERS AND NUMEROUS THUNDERSTORMS MOVING THROUGH THE
SOUTHEAST STATES WITH THE SOUTHWEST PORTION PUSHING INTO CENTRAL
MISSISSIPPI. THIS FRONT IS EXPECTED TO WEAKEN AND SLOW ITS SOUTHWARD
PROGRESS AS IT PUSHES INTO SOUTH CENTRAL MISSISSIPPI AND NORTHERN
LOUISIANA TODAY...THEN THE FRONT IS EXPECTED TO DISSIPATE TONIGHT AS
HIGH PRESSURE BUILDS IN FROM THE SOUTHEAST AND LOW PRESSURE DEVELOPS
OVER THE SOUTHERN PLAINS. SOME PATCHY FOG HAS DEVELOPED OVER
PORTIONS OF THE FORECAST AREA...AND THIS WILL CONTINUE UNTIL ABOUT
8 OR 9 AM.

TO THE SOUTH OF THE FRONTAL BOUNDARY...SHALLOW LOW LEVEL MOISTURE
WILL YIELD PRECIPITABLE WATER VALUES JUST ABOVE ONE INCH WITH ONLY A
WEAK CAPPING INVERSION AND MODERATE INSTABILITY AS TEMPERATURES
WARM INTO THE LOWER 80S IN MOST AREAS. ISOLATED SHOWERS ARE
EXPECTED TO DEVELOP DURING THE MID TO LATE MORNING...AND ISOLATED
THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON...BUT THAT WILL LIKELY
DEPEND ON SLIGHTLY DEEPER LOW LEVEL MOISTURE COINCIDENT WITH
SUBTLE CONVERGENCE AND FORCING FEATURES IN ADDITION TO THE
BUOYANCY FROM DAYTIME HEATING. ANY THUNDERSTORMS THAT CAN DEVELOP
WILL HAVE THE POTENTIAL TO BECOME STRONG AND PRODUCE GUSTY WINDS
AND SOME HAIL DUE TO STEEP MID LEVEL LAPSE RATES AND RELATIVELY
LOW WET-BULB ZERO HEIGHTS DOWN NEAR 8000 FEET. THE BEST BOUNDARY
INTERACTIONS AND HIGHEST POTENTIAL FOR STRONGER THUNDERSTORMS WILL
LIKELY OCCUR NEAR THE MISSISSIPPI COAST AND POSSIBLY THE NORTH
SHORE OF LAKE PONTCHARTRAIN WHERE ANY SOUTHWARD MOVING WEAK
BOUNDARY COULD INTERACT WITH THE SEABREEZE AND LAKE BREEZE.

A FEW SHOWERS OR THUNDERSTORMS COULD LINGER INTO THE EARLY EVENING
HOURS OVER EXTREME SOUTHEAST MISSISSIPPI...OTHERWISE TONIGHT IS
EXPECTED TO BE DRY AS THE ATMOSPHERE STABILIZES AND THE SHORTWAVE
MOVES EAST OF THE REGION. ANOTHER SETUP FOR PATCHY FOG IS EXPECTED
WITH LIGHT SOUTHWEST WINDS. TUESDAY AND TUESDAY NIGHT ARE STILL
EXPECTED TO BE DRY WITH WARM TEMPERATURES ABOVE THE SEASONAL
NORMALS. SOME PATCHY RADIATION FOG IS EXPECTED AGAIN LATE
TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING.

THE NEXT SYSTEM OF CONCERN WILL BE A SHORTWAVE TROUGH MOVING OUT
OF THE BAJA MEXICO REGION THAT WILL MOVE EAST ACROSS CENTRAL/SOUTH
TEXAS AND ADJACENT MEXICO TUESDAY NIGHT...AND THEN DAMPEN/WEAKEN
AS IT MOVES INTO THE CENTRAL GULF COAST REGION WEDNESDAY
NIGHT. THE MODELS HAVE TRENDED WEAKER WITH THIS SYSTEM AS IT
MOVES THROUGH THE FORECAST AREA...HOWEVER THE ECMWF STILL PAINTS
FAIRLY WIDESPREAD LIGHT TO MODERATE RAINFALL AMOUNTS WEDNESDAY
INTO THURSDAY WHILE THE GFS IS DRIER AND MORE SPORADIC WITH THE
AREAL COVERAGE. THE GFS MOS GUIDANCE NOW DOES NOT SHOW ANY POP
OVER 10 PERCENT DURING THESE PERIODS...HOWEVER HAVE HELD ONTO 20
TO 30 PERCENT CHANCES FOR SHOWERS AND SOME THUNDERSTORMS WEDNESDAY
INTO THURSDAY TO MAINTAIN FORECAST CONSISTENCY.

THE WESTERLIES AND UPPER JETSTREAM WILL BE SAGGING SOUTH INTO THE
SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY FRIDAY AND FRIDAY
NIGHT AS A SERIES OF SHORTWAVE TROUGH/DISTURBANCES MOVE THROUGH.
THIS IS EXPECTED TO DRIVE A PACIFIC COLD FRONT THROUGH THE
FORECAST AREA FRIDAY NIGHT AND EARLY SATURDAY. THE FORCING WILL
NOT BE THAT STRONG AND MOISTURE CONTENT NOT THAT HIGH...SO MOSTLY
LIGHT QPF AMOUNTS FROM ISOLATED TO SCATTERED SHOWERS AND A FEW
THUNDERSTORMS ARE ANTICIPATED FRIDAY THROUGH SATURDAY MORNING WITH
THE HIGHEST RAIN CHANCE LOOKING TO BE ON FRIDAY NIGHT INTO
SATURDAY MORNING ACROSS NORTHERN AREAS. TEMPERATURES ARE EXPECTED
TO LOWER TO NEAR TO SLIGHTLY BELOW NORMAL OVER THE WEEKEND.

22/TD
&&

.AVIATION...

SCATTERED CLOUDS BETWEEN FL030-040 ACROSS THE AREA...BUT HAVE SEEN A
FEW FOG OBSERVATIONS IN THE SURFACE OBS. WHERE WIND IS
CALM...PATCHY FOG WILL CONTINUE DEVELOPING.

ANY FOG STILL AROUND AT 12Z SHOULD BURN OFF BY 15Z WITH A CUMULUS
FIELD EXPECTED TO DEVELOP LATE THIS MORNING. BOUNDARY TO THE NORTH
OF THE AREA MAY DRAW CLOSE ENOUGH TODAY WITH PUSH OF SHORTWAVE
ACROSS MISSISSIPPI TO PRODUCE ISOLATED CONVECTION AT KMCB OR KGPT
AND WILL LIKELY CONTINUE THE VCTS MENTION FOR THE AFTERNOON HOURS AT
THOSE TERMINALS. CHANCES TOO LOW FOR A MENTION ELSEWHERE.

ISSUE TONIGHT WILL AGAIN BE FOG POTENTIAL. GUIDANCE HITTING FOG
HARDER TONIGHT THAN IT IS CURRENTLY. WHERE WIND DROPS OFF TO
CALM...FOG DEVELOPMENT WILL BE LIKELY...PROBABLY AS EARLY AS 08Z.
WILL DEAL WITH THIS IN 12Z TAF PACKAGE. 35

&&

.MARINE...

AT 08Z...A FEW ELEVATED RIG AWOS OBSERVATIONS EAST OF THE MOUTH OF
THE MISSISSIPPI RIVER IN THE 15-18 KNOT RANGE...WHICH WOULD INDICATE
EXERCISE CAUTION CONDITIONS...BUT WINDS SHOULD BE SHOWING A
WEAKENING TREND AS WEAK LOW PRESSURE OVER NORTHEAST MISSISSIPPI
PULLS AWAY. WILL NOT CARRY A HEADLINE WITH PACKAGE ISSUANCE...BUT
WILL CONTINUE TO MONITOR CLOSELY.

BEYOND THAT...NO REAL MARINE ISSUES TO SPEAK OF. SOUTHERLY FLOW ON
TAP FOR MUCH OF THE WORK WEEK WITH NO STRONG WEATHER SYSTEMS MOVING
THROUGH THE COASTAL WATERS. 35

&&

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


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 TONIGHT RISK SVR
         AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL
         SIGNIFICANCE

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  81  57  80  60 /  20  10  10  10
BTR  84  60  83  61 /  20  10  10  10
ASD  82  58  81  59 /  20  10  10   0
MSY  82  64  81  65 /  20  10  10   0
GPT  79  61  79  61 /  20  10  10   0
PQL  79  57  81  60 /  30  20  10   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&

$$



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