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739 FXUS64 KLIX 111826AFDLIXArea Forecast DiscussionNational Weather Service New Orleans LA126 PM CDT Fri Sep 11 2026...New SHORT TERM, LONG TERM, AVIATION, MARINE....KEY MESSAGES... Updated at 120 PM CDT Fri Sep 11 2026- An elevated risk for localized heavy rainfall leading to street flooding and overflowing of poor drainage will continue this afternoon and again on Saturday.- Lower rain chances and warmer temps return first half of next week.&&.SHORT TERM...(Now through Monday night)Issued at 120 PM CDT Fri Sep 11 2026A weak mid-level shortwave will continue to move slowly through the Lower Mississippi Valley today and Saturday, while a weak surface trough/low gradually shifts east across the central Gulf Coast. The environment across southeast Louisiana and southern Mississippi remains quite favorable for widespread convection. PW values generally ranging from around 1.7 inches inland to over 2 inches closer to the coast, locally approaching 2.4 inches, combined with weak forcing aloft and ample daytime instability will support scattered to numerous showers and thunderstorms into this afternoon. Coverage should remain lowest across southwest Mississippi and portions of the northwest CWA, with the greatest coverage generally from southeast Louisiana into coastal Mississippi as thats how the vertical moisture field is oriented. Heavy rain will remain the primary concern with any more persistent convection. Deep moisture and relatively weak steering flow will support efficient rainfall processes, and localized rates of 2 to 4 inches per hour will be possible in the strongest cells. Most locations will not see amounts anywhere near that high, but repeated development along remnant outflow boundaries or other mesoscale convergence zones could quickly produce several inches in a small area. This will maintain a risk for street flooding, especially across urban or poor-drainage locations. The very moist profiles argue against a classic inverted-V/high-DCAPE environment, so organized damaging-wind potential is low, though a stronger pulse storm may still produce a locally gusty wet microburst. Convection should gradually diminish inland this evening with the loss of heating, although showers and thunderstorms will remain possible closer to the coast and over the waters overnight. The shortwave remains in the vicinity Saturday while deep moisture is slow to depart, so another round of scattered to numerous convection is expected. Coverage may be somewhat less organized than today as the surface reflection weakens, but PW values near or above 2 inches will continue to support locally heavy rainfall. Areas that receive heavy rain today will be somewhat more susceptible to renewed street or poor-drainage flooding Saturday.By Sunday, the shortwave begins pulling farther east and heights rise from the west and the Southern Plains ridge begins expanding toward the region. This should mark the start of a transition toward a more typical late-summer convective pattern, with storms increasingly tied to the sea breeze, differential heating, and leftover outflow boundaries. Rain chances will decrease from Saturday but will not disappear with the area still on the eastern periphery of the ridge. Increasing sunshine should also allow temperatures to begin trending upward with highs in the lower 90s. MEFFER &&.LONG TERM...(Tuesday through Thursday night)Issued at 120 PM CDT Fri Sep 11 2026The upper ridge becomes established across the Tennessee Valley/northern Alabama region Monday and should remain the dominant feature through at least the middle of the week. Increasing subsidence beneath the ridge will result in a noticeable reduction in convective coverage compared with the weekend, although enough boundary-layer moisture should remain for isolated to scattered afternoon storms along the sea breeze and other mesoscale boundaries. Monday should begin the warmer portion of the forecast with highs generally in the lower to middle 90s.Tuesday and Wednesday currently appear to be the hottest and relatively driest days as the 597-598DM ridge remains strongest overhead or just to the north. Afternoon highs in the lower to middle 90s combined with dewpoints generally in the lower to middle 70s should yield heat indices largely in the 100 to 107 degree range. Thats mostly below the 108 degree Heat Advisory criteria, but there's not much room to spare. A few localized readings around or just above 108 cannot be ruled out, particularly Tuesday, 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. Warm overnight lows in the middle 70s inland and upper 70s around the urban/coastal corridor will also provide only modest overnight relief.Pattern change looks to then be coming Thursday. Global models continue to favor some weakening of the eastern side of the ridge as an inverted trough or an upper low approaches from the Florida / western Atlantic region. This would allow deeper moisture to begin returning, with an increase in afternoon shower and thunderstorm coverage and a corresponding easing of daytime temperatures. The timing and amplitude of that feature remain less certain, however, and a slower evolution would allow the hotter and relatively drier ridge-dominated pattern to persist another day.MEFFER&&.AVIATION...(18Z TAFS)Issued at 120 PM CDT Fri Sep 11 2026MVFR conditions currently in place from ~2500' cloud decks should be lifting in the coming hour or so. Radar imagery early this afternoon is showing widespread light to moderate showers with isolated storms mixed in. PROB30 groups were continued at all terminals since there's not really a specific region with more/less coverage. Should start to see this activity dwindle as daytime heating wanes late this afternoon into the early evening hours. Any direct thunderstorm impact could produce brief IFR visibility in heavy rain, lower ceilings, frequent lightning, and gusty outflow winds. Attention then turns back to ceilings and visibility late tonight into Saturday morning. Light winds, high low-level moisture, and locally wet ground from today's rainfall will favor at least patchy MVFR to IFR stratus and/or fog, particularly at KMCB and other inland terminals and in areas receiving appreciable rain today. Confidence in widespread dense fog is low, as lingering low clouds could limit radiational cooling, but localized IFR conditions appear possible roughly in the 08-13Z period before improvement after sunrise.MEFFER &&.MARINE...Issued at 120 PM CDT Fri Sep 11 2026A weak area of low pressure that was moving across the local area has dissipated. Observations show light and variable winds of 10 knots or less which lends to minimal waves/seas. Tomorrow, winds will turn more south-southwesterly but with the Bermuda ridge centered well east of the area, wind speeds should be light at 10 knots or less. These conditions will persist into Saturday. The high will become more centered over the north-central Gulf Sunday into next week. This will cause winds to turn more south-southeasterly and even light/variable at times. Seas will generally remain in the 2 feet or less range. Additionally, thunderstorm activity will develop each day, peaking in the early to mid-morning hours, and these storms will produce higher wind gusts, waterspouts, and lightning concerns.MEFFER &&.LIX WATCHES/WARNINGS/ADVISORIES...LA...None.GM...None.MS...None.GM...None.&&$$SHORT TERM...MELONG TERM....MEAVIATION...MEMARINE...ME
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Topic: [Alert]LIX issues Area Forecast Discussion (AFD) at Sep 11, 1:26 PM CDT ...New SHORT TERM, LONG TERM, AVIATION, MARINE... (Read 18 times)
