Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
Issued by NWS New Orleans/Baton Rouge, LA
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
623 FXUS64 KLIX 201125 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 625 AM CDT Mon May 20 2024 ...New AVIATION... .SHORT TERM... (Today through Wednesday Night) Issued at 303 AM CDT Mon May 20 2024 Strong and deep ridging will dominate the Gulf South through the entire short term period. The deep layer subsidence associated with this strong ridge axis will result in a very strong mid-level capping inversion remaining in place through Wednesday night. This will effectively suppress cloud development to below the inversion, and result in a dry forecast through the period. Beneath the inversion, Summer like heat and humidity will be on tap with highs easily warming into the upper 80s and lower 90s and lows only dipping into the upper 60s and lower 70s as dewpoints remain elevated on the back of sustained onshore flow. Overall, have opted to stick with NBM deterministic values for daytime highs as they were on the upper end of the probabilistic spectrum. However, deterministic lows were in line with the 25th percentile, and have opted to raise lows up to the 75th percentile to better reflect the high dewpoints in place. Additionally, high humidity at night will combine with clear skies and light winds to produce some patchy fog development during the overnight hours, especially for more inland areas. Overall, a very benign stretch of weather is expected through the short term with high pressure in place over the area. && .LONG TERM... (Tuesday night through Sunday) Issued at 303 AM CDT Mon May 20 2024 Going into Thursday, main focus will be on the ongoing warming trend as ridging remains parked over the southern US. Highs were not modified much from deterministic NBM forecast values, climbing into the mid 90`s possible late week into the Memorial Day Weekend which lies on the 75th percentile of the NBM ensemble envelope. Be aware, this does yield heat indicies crossing into the upper 90`s to low 100`s for many locations. While not excessive, could be strenuous to those spending time outdoors during the holiday weekend. With this being the first time in the year seeing highs and attendant heat indicies heat up this much, messaging will be focused for those to exercise caution spending time outdoors for extended periods. Also, kept the warmer bias in overnight lows going from the short-term into the long-term with warmer than average temperatures persisting. Additionally, not seeing much in the way of rain chances. Will make one small note about the quasi-zonal flow aloft. Seeing some deterministic runs hint at a few subtle shortwave impulses/PVA riding along the west to east mid-level flow. The response is a few MCS/thunderstorm complexes over Texas perhaps nosing into western Louisiana or into the NW Gulf. This will need to be watched, as any stronger cold-pool propagated complex (in conjunction with attendant weak PVA/forcing) could press more east than global guidance suggests (as global guidance typically struggles at convective allowing processes). Will monitor trends but for now, holding onto NBM values keeping it hot and mainly dry this upcoming weekend. Something to check back on. KLG && .AVIATION... (12Z TAFS) Issued at 621 AM CDT Mon May 20 2024 A very shallow ground level inversion has allowed for patchy dense fog and low ceilings to form at ASD, HUM, and GPT over the past couple of hours. Given the shallow nature of the inversion, the fog and low stratus will quickly burn off between 13z and 14z, and return to prevailing VFR conditions at all of the terminals is expected after 14z. Another round of fog and low stratus may develop later tonight, but overall probabilities are too low to mention fog in the forecast except at MCB where a period of IFR conditions are forecast to develop after 11z tomorrow. PG && .AVIATION... (06Z TAFS) Issued at 303 AM CDT Mon May 20 2024 VFR conditions across all terminals at late evening. There are some scattered clouds being reported around FL060 with moisture trapped under the inversion noted on the 00z LIX sounding near 800 mb. Don`t see any real indications that they are going anywhere any time soon, and will carry them in the terminals overnight. These clouds may be part of the reason that NBM probabilities of fog around sunrise have been diminishing this evening. Probabilities of visibilities below 3 SM are generally less than 15 percent across all terminals. Will mention a period around sunrise of 4-5SM at KMCB and KHUM, but will not carry any IFR conditions. Even these visibility restrictions should improve around 14z, with VFR the remainder of the day. Winds aren`t expected to provide any significant restrictions either. && .MARINE... Issued at 303 AM CDT Mon May 20 2024 A fairly benign period of weather is expected over the coastal waters through the end of the week as a broad ridge of high pressure dominates the region. A persistent southeasterly wind of around 10 knots and relatively calm seas of 1 to 3 feet are expected through the end of the week. The high pressure system over the area will also keep thunderstorm development at bay, so no waterspout, lightning, or localized gusty winds are anticipated through Friday. Overall, a great week for boating activities is on tap. && .PRELIMINARY POINT TEMPS/POPS... MCB 88 68 88 68 / 0 0 0 0 BTR 92 70 92 72 / 0 0 0 0 ASD 90 72 89 72 / 0 0 0 0 MSY 88 74 89 75 / 0 0 0 0 GPT 87 73 86 74 / 0 0 0 0 PQL 89 71 89 71 / 0 0 0 0 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$ SHORT TERM...PG LONG TERM....KLG AVIATION...PG MARINE...PG