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373 FXUS64 KLIX 070517AFDLIXArea Forecast DiscussionNational Weather Service New Orleans LA1217 AM CDT Sun Sep 7 2025...New SHORT TERM, LONG TERM, AVIATION, MARINE....SHORT TERM...(Tonight through Monday night)Issued at 1153 PM CDT Sat Sep 6 2025The weak surface frontal boundary continues to gradually sink south across the northern Gulf Coast. Dew point temperatures are gradually dropping as drier air gets ushered in by light northerly flow behind the front. Dew points have fallen about 4-8 degrees north of the I-10/12 corridor compared to 24 hours ago thus far. Dews fall into the mid 60s to upper 50s through the day on Sunday as the continental drier air mass sinks to the south. PWATs will be near the 25th percentile for the area (0.8 to 1.0 inches) which will allow daytime humidities to crater to near 50% on Sunday and into the 30-45% range on Monday as diurnally-driven vertical mixing occurs. This will suppress cu development and any cu development will predominantly be limited in growth by dry air despite modest surface-based CAPE (1000-2000 j/kg). Only area with PoPs exceeding 15% are near the mouth of the Atchafalaya Basin, enhanced by the sea breeze in Terrebonne and Lafourche Parishes on Sunday. PoPs near 0% areawide on Monday as those PWATs bottom out.Limited cloud coverage will promote highly diurnal temperature fluctuations with highs in the upper 80s to near 90F along the coast. Given stronger mixing with elevated northerly winds Sunday night into Monday morning, radiational cooling will be less efficient so NBM deterministic is being maintained which is already closer to the 25th percentile within NBM suite for MinT.&&.LONG TERM...(Tuesday night through Saturday night)Issued at 1153 PM CDT Sat Sep 6 2025By Monday and into Tuesday, the main story is another reinforcingshot of the drier/cooler air builds into the region. Took a very close look at two items here:Min temperatures Monday and Tuesday morning and dewpoints Mondayand Tuesday afternoon. For lows, deterministic 13Z NBM is comingin already on the low side of the ensemble spread, generally inthe 25th-10th percentile so did not adjust suggested lows much inthis case, other than massaging traditionally cooler locationsacross the Pascagoula and Pearl River drainage basins. Next, didapply a noticeable target of opportunity to dewpoints both Mondayand Tuesday afternoons during peak diurnal mixing, as modelsoundings illustrate a well-mixed PBL/adiabatic thermal profile to1) support occasionally breezy winds and 2) likely mix down wellbelow suggested deterministic NBM guidance. Introduced a steadytransition to 25th to eventual 10th percentile dewpoints bothafternoons, bringing MinRH's into the 30's for most areas. Thiswill without a doubt make it feel much, much more comfortable bothdays. As mentioned yesterday, something to remember is the sunangle is still pretty high, and in the direct sunlight it'll stillfeel hot (and a much drier atmosphere will likely spike UV index making for a risk for sunburn). Something to consider, otherwise it'll be a nice change in the hot summer we've been through so farand a nice reminder that Fall is almost here! Beyond Tuesday intothe middle to later parts of the week, moisture steadily returns back to the region underneath a building upper-level weakness (broad SE US troughing pattern) that'll bring back a few scatteredshower/storm chances. For now, best chances are looking across the coastal areas of SE LA and MS, within greatest total column moisture, but will monitor how far north moisture return builds tosupport shower activity within this upper-level weakness with time. Temperatures remain seasonal, with no excessive heat concerns over the next 5-7 days. KLG&&.AVIATION...(06Z TAFS)Issued at 1153 PM CDT Sat Sep 6 2025Drier air is being ushered in by light northerly flow behind a weak frontal system, and VFR conditions will prevail through the period. Only a slight chance for pop-up weak convection near HUM on Sunday which does not warrant a PROB30 at this time.&&.MARINE...Issued at 1153 PM CDT Sat Sep 6 2025A cold front is expected to progress south across marine waters through the morning on Sunday, introducing a steady wind shift from the NNE to NE and drier air to progressively filter into the region into the day on Sunday. Winds will be delayed to respond increasing primarily 12-18kts for Gulf waters during the morning thru afternoon hours on Sunday, with another reinforcing push of NE winds expected overnight into early Monday. During this time period (primarily 10PM thru 1PM Monday), winds may reach sustained upwards of 15-20 knots, especially for outer Gulf zones south of the MS sound including Chandeleur and Brenton sounds. A Small Craft Advisory has been issued for these areas during this time frame. Waves/seas will respond into the 3-5ft range generally before abating Monday evening. Mid/late week, winds shift more easterly but remain slightly elevated in the 10-15kt range, especially for eastern zones which will keep waves/seas also slightly elevated in the 2-4ft range for outer waters, 1-2ft for protected waters.&&.PRELIMINARY POINT TEMPS/POPS...MCB 87 66 84 60 / 30 10 10 0 BTR 91 69 88 64 / 20 0 10 0 ASD 90 69 88 62 / 20 0 10 0 MSY 92 76 90 71 / 20 10 10 10 GPT 90 70 90 65 / 20 10 10 0 PQL 92 69 90 63 / 20 10 10 0 &&.LIX WATCHES/WARNINGS/ADVISORIES...LA...None.GM...Small Craft Advisory from 10 PM Sunday to 1 PM CDT Monday for GMZ536-538-555-557-575-577.MS...None.GM...Small Craft Advisory from 10 PM Sunday to 1 PM CDT Monday for GMZ538-555-557-575-577.&&$$SHORT TERM...TJSLONG TERM....KLGAVIATION...TJSMARINE...TJS
