982
FXUS64 KLIX 131818
AFDLIX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
118 PM CDT SUN SEP 13 2026
..NEW SHORT TERM, LONG TERM, AVIATION, MARINE
KEY MESSAGES
UPDATED AT 116 PM CDT SUN SEP 13 2026
- LOWER RAIN CHANCES AND WARMER TEMPS RETURN FIRST HALF OF THE
WEEK. HEAT INDICES COULD APPROACH HEAT ADVISORY CRITERIA.
- STRONGER EASTERLY WINDS MAY RESULT IN SMALL CRAFT ADVISORY
CONDITIONS FOR THE LATTER HALF OF THE WEEK IN THE COASTAL
WATERS.
SHORT TERM
(NOW THROUGH WEDNESDAY NIGHT)
ISSUED AT 116 PM CDT SUN SEP 13 2026
THE MID-LEVEL SHORTWAVE THAT MOVED ACROSS THE LOWER MISSISSIPPI
VALLEY YESTERDAY IS NOW WELL EAST OF THE LOCAL AREA (ALREADY
CROSSING THE APPALACHIAN MOUNTAINS). MEANWHILE, 500MB HEIGHTS ARE
RISING FROM THE WEST AS AN UPPER LEVEL RIDGE AXIS THAT EXTENDS FROM
SOUTH TEXAS TO CANADA BEGINS EXPANDING TOWARD THE REGION. TODAY IS
BEEN THE START OF A TRANSITION TOWARD A DRIER PATTERN THAN RECENT
DAYS AS SUBSIDENCE INCREASES FROM THAT RIDGE AND COLUMN MOISTURE
DROPS A BIT. STORMS THAT DO DEVELOP INCREASINGLY TIED TO THE SEA
BREEZE, DIFFERENTIAL HEATING, AND LEFTOVER OUTFLOW BOUNDARIES. WE'RE
SEEING THAT NOW WITH MINIMAL COVERAGE OUTSIDE OF CAPPED SHOWERS
SOUTH OF I-10 IN LOUISIANA. IN ADDITION, INCREASING HEIGHTS ALONG
WITH LESS SHOWER/STORM ACTIVITY WILL ALLOW TEMPS TO MODERATE SOLIDLY
INTO THE 90S.
THE UPPER RIDGE BECOMES CENTERED ACROSS THE TENNESSEE VALLEY REGION
MONDAY AND SHOULD REMAIN THE DOMINANT FEATURE ACROSS THE SOUTHERN US
THROUGH AT LEAST THE MIDDLE OF THE WEEK. INCREASING SUBSIDENCE
BENEATH THE RIDGE WILL RESULT IN A NOTICEABLE REDUCTION IN
CONVECTIVE COVERAGE COMPARED WITH LAST WEEK, ALTHOUGH ENOUGH
BOUNDARY-LAYER MOISTURE SHOULD REMAIN FOR ISOLATED TO SCATTERED
AFTERNOON STORMS ALONG THE SEA BREEZE AND OTHER MESOSCALE
BOUNDARIES. SO THINK ALONG THE LINES OF 20-40% COVERAGE MONDAY WITH
HIGHS GENERALLY IN THE LOWER TO MID 90S. WILL BE WATCHING HEAT INDEX
FORECAST CLOSELY AS A FEW LOCATIONS SHOULD BE APPROACHING ADVISORY
CRITERIA. BIGGEST QUESTION IS IF ENOUGH OF THE AREA WILL BE WARM
ENOUGH TO JUSTIFY EVEN A TARGETED ADVISORY.
TUESDAY CURRENTLY APPEARS THAT IT WILL BE THE HOTTEST AND RELATIVELY
DRIEST DAY THIS FORECAST PERIOD AS THE 596-598DM RIDGE REMAINS
STRONGEST OVERHEAD OR JUST TO THE NORTH. AFTERNOON HIGHS IN THE MID
90S COMBINED WITH DEWPOINTS GENERALLY IN THE LOWER TO MIDDLE 70S
SHOULD YIELD HEAT INDICES LARGELY IN THE 100 TO 107 DEGREE RANGE. SO
AGAIN, RIGHT AT THE CUSP OF HEAT ADVISORY CRITERIA. A FEW LOCALIZED
LOCATIONS COULD REACH JUST ABOVE 108 IF TEMPERATURES REACH THE
WARMER END OF GUIDANCE WHILE DEWPOINTS REMAIN ELEVATED. CONVERSELY,
GREATER MIXING OR AN ISOLATED AFTERNOON STORM WOULD KNOCK APPARENT
TEMPERATURES DOWN QUICKLY. STRONG SUBSIDENCE FROM THAT RIDGE WILL
REALLY STUNT POPS AS WELL DURING THIS TIMEFRAME. RAIN CHANCES MAY
START TO CREEP UP ALONG COASTAL AREAS OF THE CWA AS TROUGH THE NORTH
FLATTENS THE NORTHERN SIDE OF THE NEARBY UPPER RIDGE AND ALSO CAUSES
IT TO WEAKEN SOME.
MEFFER
LONG TERM
(THURSDAY THROUGH SATURDAY NIGHT)
ISSUED AT 116 PM CDT SUN SEP 13 2026
GLOBAL MODELS CONTINUE TO FAVOR CONTINUED WEAKENING OF THE PORTION
OF THE UPPER RIDGE ALOFT AS AN UPPER LOW APPROACHES FROM THE
FLORIDA/WESTERN ATLANTIC REGION. ONE INTERESTING FEATURE TO WATCH
WITH THIS SYNOPTIC EVOLUTION IS DRY SLOT ON THE NORTHWESTERN SIDE OF
THE UPPER LOW COMING ACROSS THE GULF. MODELS SUGGEST IT MAY BE
PULLING IN DRY AIR CAUGHT UNDERNEATH THE RIDGE INTO THE CWA,
EFFECTIVELY KEEPING RAIN CHANCES DOWN QUITE A BIT INLAND WITH MOST
OF THE CONVECTION ALONG THE COAST AND IN THE OPEN GULF WATERS. FROM
THE TEMPS SIDE, YOU'D THINK LOWER 500MB HEIGHTS MEANS COOLER TEMPS.
IN THIS PARTICULAR SITUATION, AS DRIER AIR MIXES TO THE SURFACE,
DEWPOINTS CRATER. THAT'LL RESULT IN A WIDER DIURNAL RANGE IN TEMPS
WITH LOWER LOWS AND HIGHER HIGHS. THE GREAT THING IS THAT EVEN
THOUGH AIR TEMP STILL REACHES MID 90S, THOSE MID AFTN SUB-70
DEWPOINTS WILL KEEP HEAT INDICIES DRASTICALLY LOWER THAN EARLIER IN
THE WEEK. SOMEWHERE ON THE ORDER OF 10-15 DEGREES COOLER FOR THOSE
MAX HEAT INDICES.
MEFFER
AVIATION
(18Z TAFS)
ISSUED AT 116 PM CDT SUN SEP 13 2026
VFR CONDITIONS WILL DOMINATE THE FORECAST PERIOD OUTSIDE OF
CONVECTION. SUBSIDENCE FROM UPPER LEVEL RIDGE MOVING INTO AND ACROSS
THE LOWER MISSISSIPPI VALLEY IS REALLY STUNTING SHOWER/STORM
DEVELOPMENT TODAY. RADAR SHOWS ONLY ISOLATED TO SCATTERED SHOWERS
SOUTH OF KMSY/KNEW AND THAT ACTIVITY IS SO CAPPED THAT SHOWERS HAVE
BEEN STRUGGLING TO MATURE INTO THUNDERSTORMS. THIS ACTIVITY SHOULD
DISSIPATE AS DAYTIME HEATING DROPS OFF THIS AFTERNOON INTO THE EARLY
EVENING HOURS. LIGHT AND VARIABLE WINDS WILL PERSIST THROUGH THE
PERIOD.
MEFFER
MARINE
ISSUED AT 116 PM CDT SUN SEP 13 2026
A BROAD SURFACE HIGH OVER THE AREA WILL KEEP BENIGN CONDITIONS IN
PLACE ACROSS THE WATERS THROUGH TUESDAY WITH LIGHT AND VARIABLE
WINDS OF LESS THAN 10 KNOTS AND SEAS OF LESS THAN 2 FEET
EXPECTED. A FEW SHOWERS OR STORMS WILL POP UP IN THE MORNING HOURS
WITH SOME LOCALLY HIGHER WINDS AND WAVES, BUT THESE IMPACTS WILL
BE SHORT- LIVED EACH DAY. THE PRESSURE GRADIENT WILL BEGIN
TIGHTENING WEDNESDAY AND REMAIN THAT WAY AS AN AMPLIFYING SURFACE
RIDGE DRAPED ALONG THE EASTERN SEABOARD EXPANDS SOUTHWESTWARD AND
TAKES OVER THE HIGH CURRENTLY OVER THE NORTHEASTERN GULF. THIS
WILL CREATE AN EASTERLY FLOW REGIME WITH STRENGTHENING WINDS.
LATEST FORECAST CALLS FOR WINDS TO INCREASE TO AT LEAST 20 TO 25
KNOTS WITH GUSTS APPROACHING GALE FORCE WEDNESDAY INTO THURSDAY.
SEAS WILL RESPOND TO THESE HIGHER WINDS AND INCREASE TO 8 TO 10
FEET. SOME MINOR COASTAL FLOODING MAY ALSO IMPACT EAST FACING
SHORELINES OVER THIS PERIOD.
MEFFER
LIX WATCHES/WARNINGS/ADVISORIES
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
SHORT TERM...ME
LONG TERM....ME
AVIATION...ME
MARINE...ME
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