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

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559
FXUS64 KLIX 142117
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
417 PM CDT SUN SEP 14 2014

.SYNOPSIS...

A MOSTLY ZONAL FLOW PATTERN IS NOTED OVER THE CONUS THIS AFTERNOON.
OVER THE GULF COAST REGION...A NARROW MID/UPPER LEVEL RIDGE DIVIDES
THE WESTERLIES TO THE NORTH AND THE EASTERLIES OVER THE GULF OF
MEXICO WITH A WELL DEFINED UPPER LOW NOTED IN WATER VAPOR IMAGERY
OVER THE SOUTH CENTRAL GULF OF MEXICO JUST NORTH OF THE YUCATAN
PENINSULA. AT THE SURFACE...A WEAK FRONTAL BOUNDARY HAS BECOME
SOMEWHAT DIFFUSE OVER THE FORECAST AREA TODAY WITH THE DAYTIME
SEABREEZE KICKING IN OVER THE MISSISSIPPI GULF COAST. MOST OF THE
SHOWERS AND THUNDERSTORMS HAD BEEN CONFINED TO THE COASTAL WATERS
AND SOUTHEAST LOUISIANA COASTAL SECTIONS...HOWEVER RECENT ISOLATED
DEVELOPMENT HAS OCCURRED ALONG THE SEABREEZE IN COASTAL
MISSISSIPPI.

.SHORT TERM...

THE MID/UPPER LEVEL RIDGE OVER THE GULF COAST REGION IS EXPECTED TO
BE SUPPRESSED AND PUSHED SOUTH INTO THE GULF OF MEXICO AS A RIDGE
BUILDS OVER THE WESTERN STATES AND A BROAD TROUGH DEVELOPS ACROSS
EASTERN CANADA INTO THE FAR EASTERN STATES. WEAK SHORTWAVE
DISTURBANCES IN NORTHWEST FLOW ALOFT WILL MOVE INTO THE LOWER
MISSISSIPPI VALLEY ON TUESDAY. WHILE THE OLD FRONTAL BOUNDARY WILL
BE DIFFUSE...A SURFACE TROUGH IS EXPECTED TO LINGER WITH AFTERNOON
SEA AND LAKE BREEZES ALSO COMING INTO PLAY. PRECIPITABLE WATER IS
EXPECTED TO LOWER BELOW 2 INCHES EARLY TONIGHT THEN RISE BACK INTO
THE 2 TO 2.2 INCH RANGE LATE TONIGHT THROUGH MONDAY AND REMAIN IN
PLACE INTO TUESDAY. HAVE CONTINUED THE TRENDS OF THE PREVIOUS
FORECAST PACKAGES KEEPING HIGHER CHANCES OF SHOWERS AND
THUNDERSTORMS IN THE FORECAST. HAVE GENERALLY GONE NEAR THE GFS MAV
MOS FOR LOWS AND LOWER THAN GUIDANCE FOR HIGHS.

.LONG TERM...
MEDIUM RANGE MODELS ARE IN DECENT AGREEMENT WEDNESDAY INTO FRIDAY
WITH THE LONGWAVE TROUGH AXIS SLIDING EAST OF THE ATLANTIC
COAST...AND A MID/UPPER LEVEL RIDGE MOVING EAST FROM THE SOUTHERN
ROCKIES INTO THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY. THE
THE BIG CHANGES WITH THE 12Z MODEL RUNS TODAY IS THE ECMWF IS MUCH
WEAKER WITH THE NEXT TROUGH TRYING TO RE-ESTABLISH THE ERN CONUS.
BECAUSE OF THIS...THE DIFFERENCES IN WEATHER IMPACTS REMAIN LOW OVER
THE FORECAST AREA SINCE IT IS NOW UNLIKELY ANYTHING MORE THAN A WEAK
COLD FRONT WILL MOVE INTO THE REGION...AND THE FRONT NOW LOOKS LIKE
IT MAY NOT GET AS FAR SOUTH AS PREVIOUSLY THOUGHT.
REGARDLESS...THERE WILL STILL BE SOME DRIER AIR MOVING INTO THE
NORTHERN PORTIONS OF THE FORECAST AREA ON WEDNESDAY AND SOUTHERN
PORTIONS WEDNESDAY NIGHT INTO THURSDAY. THAT TREND SHOULD HOLD INTO
FRIDAY BEFORE A SLIGHT RECOVERY IN MOISTURE NEXT WEEKEND.
THE POP IS EXPECTED TO LOWER TO AROUND 20 PERCENT THURSDAY AND
FRIDAY BEFORE PUSHING UP SLIGHTLY TO 20 TO 30 PERCENT RANGE FOR
DAYTIME PERIODS OVER NEXT WEEKEND. TEMPERATURES ARE EXPECTED TO BE
FAIRLY CLOSE TO THE SEASONAL NORMALS...AND SOMEWHAT BELOW THE MEX
GUIDANCE FOR HIGHS. 22/TD

&&

.AVIATION...
CUMULUS FIELD DEVELOPING WITH BASES SCT030-035 ASSOCIATED WITH GULF
BREEZE THIS AFTERNOON WILL THIN TO FEW OR SKC BY 01Z. VFR CONDITIONS
ARE THEN EXPECTED ALL TERMINALS THROUGH AT LEAST 15Z MONDAY BEFORE
MARITIME MOISTURE ADVANCES INLAND FOR BRIEF MVFR CIGS THAT LIFT TO
VFR LEVELS TOWARDS 17Z. AFTERNOON CONVECTION MONDAY SHOULD BE WORTHY
OF VCTS OR TEMPO GROUPS AT KGPT...KMSY...KNEW...KHUM AND KHDC.
PROB30 GROUPS FOR LESSER COVERAGE AT KBTR AND KMCB. 24/RR

&&

.MARINE...
FRONT WILL LINGER NEAR THE COAST OR JUST INLAND THROUGH MONDAY
BEFORE LOSING ITS IDENTITY MON NIGHT. HIGH PRESSURE CENTERED WELL
OFF TO THE NORTHEAST AND LOWER PRESSURE OVER THE WESTERN GULF WILL
MAINTAIN MOSTLY EASTERLY WINDS AT 10 TO 15 KNOTS TONIGHT. STARTING
MON...A LIGHTER WIND REGIME IS EXPECTED THROUGH MOST OF THE UPCOMING
WEEK AS WEAKER HIGH PRESSURE DEVELOPS CLOSER TO THE MARINE AREA.
22/TD

&&

.DECISION SUPPORT...
DSS CODE...GREEN.
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  69  89  71  87 /  10  30  20  40
BTR  72  91  73  89 /  20  40  30  50
ASD  72  89  73  89 /  30  40  30  60
MSY  77  90  76  89 /  30  50  40  60
GPT  74  89  74  88 /  30  50  40  60
PQL  73  89  72  88 /  30  50  40  60

&&

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

$$





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