Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
Issued by NWS New Orleans/Baton Rouge, LA
436 FXUS64 KLIX 011826 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 126 PM CDT Mon Sep 1 2025 ...New SHORT TERM, LONG TERM, AVIATION, MARINE... .SHORT TERM... (Tonight through Wednesday night) Issued at 1213 PM CDT Mon Sep 1 2025 A very deep trough axis will continue to dominate the eastern half of the CONUS through the short term period. This will keep deep layer northwest flow in place across the Gulf South resulting in a continuation of the overall cooler and drier conditions experienced the past few days. A series of weak upper level disturbances and associated reinforcing frontal boundaries embedded within the deep layer northwest flow in the mid and upper levels will pass through the region on Tuesday and Wednesday. Although these features will have very little moisture to tap into, as noted by PWATS of only 1.5 to 1.6 inches, both the GFS and ECMWF show that enough forcing aloft from these disturbances will support low end chance PoPs during peak heating hours for Tuesday and Wednesday afternoons. Any convective development will be weak and short-lived due to the limited moisture availability. The northwest flow regime will also keep temperatures a bit cooler than average by a degree or two. Highs will continue to climb to around 90 degrees each afternoon and lows will dip into the upper 60s and lower 70s. The lower humidity will also continue as drier air aloft mixes down to the surface each day. This will help to keep heat index values manageable in the mid to upper 90s each day. && .LONG TERM... (Thursday through Sunday night) Issued at 1213 PM CDT Mon Sep 1 2025 The deep layer troughing in the mid and upper levels will persist through the entire forecast period. Within this northwest flow, a stronger upper level impulse and associated surface front will push through the Gulf South on Thursday. This stronger front will sweep well offshore and into the central Gulf by Thursday night. In the wake of this system, a strong surface high and ample negative vorticity in the upper levels will advect into the region. These two features will induce ample subsidence throughout the atmospheric column, and this will lead to significant drying and warming for the entire long term period through Sunday. The end result will be limited cloud development, low PoP of less than 20 percent, and warmer daytime highs. Highs will easily climb into the low to mid 90s each afternoon as the drier airmass quickly heats up in response to strong solar insolation from the clear skies. The diurnal range will be on the order of 25 to 30 degrees, so overnight lows will still dip into the lower 70s over inland areas and the mid 70s along the coast. The dry air will also help to keep heat index values in check with heat indices maxing out between 100 and 105 each day. The biggest change on Sunday will be a shift in the low level winds as the surface high over the area begins to pull to the east. Winds will turn southerly, and this will allow for seabreeze induced convection to return to the coastal portions of Louisiana by Sunday afternoon. However, dry conditions are expected to persist across the remainder of the region. && .AVIATION... (18Z TAFS) Issued at 1213 PM CDT Mon Sep 1 2025 VFR conditions will be in place at all of the terminals through tomorrow afternoon as a drier and more stable airmass continues to reside over the area. Although a very isolated shower or thunderstorm may try to develop near MSY or HUM between 18z and 00z, the probabilities of development are too low to include in the forecast. If a storm does form near one of these terminals, short term amendments to the forecast will be made. && .MARINE... Issued at 1213 PM CDT Mon Sep 1 2025 A slightly stronger pressure gradient over the northern Gulf along a stalled frontal boundary will persist through the evening hours before gradually easing tonight into tomorrow. Easterly winds of 15 knots with gusts to 20 knots will continue to impact the open waters east of the Mississippi River over this period and small craft are urged to exercise caution due to the choppy conditions in place. Seas of 3 to 5 feet can be expected due to these winds and some swell. A strong reinforcing front will sweep through the waters on Thursday and will turn more northerly behind the front. Winds will also weaken to 10 knots or less and seas will fall to 2 feet or less by Thursday as a broad surface high becomes centered over the area. As drier air moves in from the north, it will bring an end to the scattered thunderstorm activity across the open Gulf waters that has been in place for the past several days as drier air moves in from the north. These drier conditions will be in place on Thursday and Friday. The surface high will then shift to the east over the weekend and winds will turn back to the southeast and south. These southerly winds will allow for deeper moisture to feed back into the coastal waters and scattered thunderstorm activity will become more common over the weekend. && .PRELIMINARY POINT TEMPS/POPS... MCB 68 89 67 90 / 10 20 10 30 BTR 72 91 70 91 / 10 20 10 20 ASD 70 89 69 90 / 10 20 10 20 MSY 77 89 75 90 / 10 30 10 20 GPT 72 87 70 88 / 0 20 10 10 PQL 70 87 68 89 / 0 10 10 10 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$ SHORT TERM...PG LONG TERM....PG AVIATION...PG MARINE...PG