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

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301
FXUS64 KLIX 162051
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
351 PM CDT TUE SEP 16 2014

.SHORT TERM...
THE COMBINATION OF CONVERGENCE ALONG A STALLED FRONTAL BOUNDARY IN
PLACE AND TRANSITION TO NORTHWESTERLY UPPER LEVEL FLOW OVER THE AREA
HAS BEEN CONDUCIVE FOR NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP
TODAY. LATEST RADAR IMAGERY SHOWS THE MAJORITY OF THE STORMS TO BE
ALONG THE FRONT WHICH IS ROUGHLY ALONG THE INTERSTATE CORRIDORS OF
I-10 AND I-12.  MOVEMENT IS GENERALLY NW TO SE BUT OUTFLOW
BOUNDARIES FROM DECAYING CELLS HAVE COMPLICATED MOVEMENT AND
REDEVELOPMENT OF STORMS.

MODELS STRONGLY SUGGEST PERSISTENT AND DEEPENING TROUGHING TO TAKE
PLACE OVER THE EASTERN SEABOARD COUPLED WITH AMPLIFICATION OF A
PROGRESSIVE RIDGE OVER THE ROCKIES BY THURSDAY. THIS PLACES THE
FORECAST AREA IN A NORTHWEST FLOW REGIME WHICH OPENS A VULNERABILITY
FOR SUBTLE MESOSCALE VORTEX STRUCTURES TO TRIGGER CONVECTION EACH
LATE AFTERNOON AND EVENING. FRONTOGENETIC FORCING STILL IN PLACE
WEDNESDAY AFTERNOON AND EVENING WOULD ALSO FAVOR ORGANIZED
CONVECTION MOVING FROM THE NORTH. HAVE SLIGHTLY BUMPED UP POPS ON
WEDNESDAY WITH A GRADIENT FROM ISOLATED IN NORTHEAST ZONES TO 50 PCT
ALONG THE LA COAST. TEMPERATURES WEDNESDAY WILL ONCE AGAIN BE
VARIABLE BY PRECIPITATION COVERAGE IN THE AFTERNOON HOURS BUT MOST
AREAS SHOULD REACH CLOSE TO 90F BEFORE CLOUD COVER THICKENS.

.LONG TERM...
A RELATIVELY EARLY ESTABLISHMENT OF PERSISTENT NORTHWESTERLY FLOW
ALOFT WILL MAINTAIN A VULNERABILITY OF MCV FEATURES DROPPING FROM
NORTHERN BRANCH FLOW THROUGH THE REST OF THIS WEEK. THERE WILL
HOWEVER BE A GRADUAL DECREASE IN COVERAGE GOING INTO THE WEEKEND AS
THE UPPER TROUGH EXITS EAST AND SLIGHT UPPER RIDGING TRANSLATES
ACROSS THE SOUTHERN CONUS. GFS AND ECMWF SHOWING THE NEXT SOMEWHAT
DECENT COLD FRONT MOVING INTO THE AREA LATE NEXT MONDAY ALTHOUGH THE
BOUNDARY WILL BE IN A DECAY STAGE.

MEFFER
&&

.MARINE...
REMNANTS OF OLD FRONTAL SYSTEM HAS BEEN A FOCUS FOR CONVECTION
THIS AFTERNOON. SEVERAL REPORTS OF TROPICAL FUNNEL CLOUDS AND
WATERSPOUTS AROUND MIDDAY. CONVECTIVE COVERAGE WILL BE DIMINISHED
FOR THE NEXT FEW DAYS WITH USUAL DIURNAL ONSHORE/OFFSHORE TRENDS.
WINDS GENERALLY 10 KNOTS OR LESS THROUGH THURSDAY. HIGH PRESSURE
BUILDS IN FROM THE NORTHEAST ON FRIDAY...BUT GFS SOLUTION OF 20
KNOT SUSTAINED EAST WINDS APPEARS WELL OVERDONE. WILL GO WITH A
NON GFS SOLUTION FOR FRIDAY...WHICH IS CLOSER TO 10-15 KNOTS...AND
NEAR 15 KNOTS OVER THE WEEKEND. HAVE TEMPERED WAVE HEIGHTS
SLIGHTLY DURING THAT PERIOD AS WELL FROM PREVIOUS FORECAST. SWELL
MAY ENHANCE WAVE HEIGHTS AND TIDAL LEVELS A BIT OVER THE WEEKEND. 35

&&

.AVIATION...
NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE AREA THIS
AFTERNOON HAVE RESULTED IN TEMPORARY IFR VISIBILITIES AT SEVERAL
TERMINALS. ANTICIPATE THAT CONVECTION SHOULD START WINDING DOWN
CLOSE TO SUNSET...WITH MOST OR ALL TERMINALS SHED OF THEIR
CONVECTION BY 01Z OR 02Z. AREAL COVERAGE OF CONVECTION ON WEDNESDAY
SHOULD BE SIGNIFICANTLY LESS...ESPECIALLY NORTH OF LAKE
PONTCHARTRAIN. HAVE ONLY CARRIED VCTS AT KHUM...KNEW AND KMSY FOR
THE LATE MORNING HOURS. 35

&&

.DECISION SUPPORT...
DSS CODE...GREEN.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT AND SUPPORTING USCG SSW OF PASCAGOULA.

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  90  69  89 /  30  20  10  20
BTR  71  91  70  89 /  30  30  10  40
ASD  71  90  72  89 /  30  30  10  30
MSY  75  89  76  88 /  30  30  10  30
GPT  72  90  73  89 /  30  30  10  20
PQL  69  89  70  90 /  30  20  10  10

&&

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

$$







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