FXUS64 KLIX 201843 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 143 PM CDT Sun Jul 20 2025 ...New SHORT TERM, LONG TERM, AVIATION, MARINE... .SHORT TERM... (This evening through Monday night) Issued at 135 PM CDT Sun Jul 20 2025 The weak upper low that was over the local area at the end of last week is now over Texas with mid level ridging off the coast of Plaquemines Parish. At the surface, high pressure is centered over the Gulf somewhere south of Pensacola. Scattered cumulus were noted on satellite, and there may be one or two showers out there, but the overwhelming majority of the area is, and will, be dry this afternoon. Temperatures at early afternoon range from the upper 80s to mid 90s with heat index values around 105. The upper ridge will continue to drift west and northwest over the next 36 hours, and cover most of the lower Mississippi River Valley by tomorrow night. Cannot entirely rule out isolated storms this afternoon and tomorrow afternoon, but most areas will remain dry, and any storms that do develop should dissipate by sunset. Main concern is going to be the heat. While conditions are borderline for an advisory today, high temperatures tomorrow look to be in the mid 90s areawide, and a few spots could reach 97F or so. Dew points look to be in the same general range as today, mid and upper 70s, so heat index values could actually be a touch higher tomorrow. Have already pre-emptively issued a Heat Advisory for tomorrow for all of the area except the lower portions of the southeast Louisiana coastal parishes. The same areas as today's advisory. && .LONG TERM... (Tuesday through Saturday night) Issued at 135 PM CDT Sun Jul 20 2025 The upper ridge will drift northward Tuesday and be centered near Memphis Tuesday, before moving eastward later in the week. This will allow an easterly wave to move across the northern Gulf Wednesday and Thursday. A northern stream shortwave could push a frontal boundary about as far south as Interstate 20 next weekend. Similar to Monday, any thunderstorm threat will remain very isolated, with most areas remaining dry. If there is a focus for convection on Tuesday, it would be lake/sea breeze boundaries. High temperatures Tuesday could actually be a degree or two higher than tomorrow, with some guidance indicating upper 90s for highs. With a northerly component to surface winds on Tuesday, it is one of those situations where the "hot spot" could actually the Pearl and Pascagoula River Basins (Bogalusa, Slidell, Mississippi coastal cities) if the sea breeze kicks in late or not at all and no storms develop. In fact the MAVPQL (GFS based MOS for Pascagoula) gives 101 for Tuesday. Heat Advisories almost certain to be issued for Tuesday, and later shifts may need to consider an Extreme Heat Warning for portions of the area. As the easterly wave moves across the northern Gulf Wednesday and Thursday, moisture levels will again be on the increase with precipitable water values jumping from the 1.5 to 1.7 inch range Tuesday to well in excess of 2 inches by late Wednesday afternoon into Thursday. Still some question as to how quickly the moisture spreads in on Wednesday, and how far north. Convective initiation may hold off until late afternoon, which may necessitate a Heat Advisory for portions or most of the area. Thursday into next weekend will likely see daily development of showers and thunderstorms across much of the area. The additional cloud cover and precipitation should hold high temperatures much closer to "normal" for late July, while overnight lows will be in the mid and upper 70s. && .AVIATION... (18Z TAFS) Issued at 135 PM CDT Sun Jul 20 2025 Only very isolated TSRA so far this afternoon, and threat was too low to mention in most terminals, other than VCTS at KHUM. Won't rule out 1 or 2 amendments this afternoon. Overnight should see VFR conditions, and don't expect a repeat from this morning of very low conditions at KMCB. Cumulus development tomorrow should be even less than today. && .MARINE... Issued at 135 PM CDT Sun Jul 20 2025 Main concerns for marine operations this week will be the threat of thunderstorms, as the general pressure gradient is expected to remain rather weak. Thunderstorm development is expected to remain fairly limited over the local waters until about Wednesday, when areal coverage increases significantly. The second half of the week will see multiple rounds of storms that will be capable of producing locally higher winds and seas. && .PRELIMINARY POINT TEMPS/POPS... MCB 73 95 73 96 / 0 0 0 10 BTR 76 94 75 95 / 0 10 0 10 ASD 75 94 75 96 / 10 10 0 20 MSY 78 94 78 96 / 10 20 0 20 GPT 77 94 78 96 / 0 10 0 20 PQL 76 95 75 97 / 0 10 10 30 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...Heat Advisory until 7 PM CDT this evening for LAZ034>037-039- 046>048-056>060-064-065-071-076>090. Heat Advisory from 10 AM to 7 PM CDT Monday for LAZ034>037-039- 046>048-056>060-064-065-071-076>090. GM...None. MS...Heat Advisory until 7 PM CDT this evening for MSZ068>071-077- 083>088. Heat Advisory from 10 AM to 7 PM CDT Monday for MSZ068>071-077- 083>088. GM...None. && $$ SHORT TERM...RW LONG TERM....RW AVIATION...RW MARINE...RW