textproduct: New Orleans/Baton Rouge

KEY MESSAGES

Updated at 642 PM CDT Mon Sep 21 2026

- Scattered thunderstorms are expected mainly this afternoon and evening, with the greatest coverage across the northern half of the area. A few stronger storms could produce localized strong to damaging wind gusts.

- Rain chances decrease Tuesday before a mostly dry cold front moves through Wednesday, bringing a shift to northerly winds and noticeably lower humidity.

- Drier air behind the front will allow for cooler Thursday morning temperatures, especially along and north of I-12, with quiet and dry weather continuing late in the week.

SHORT TERM

(Now through Wednesday night) Issued at 1208 PM CDT Mon Sep 21 2026

Today will be the most convectively active period of the short term as the approaching upper trough continues to weaken the mid- level cap that has been in place the last few days. Convective temperatures are generally around 91-92 degrees this afternoon, which most locations should begin reaching around 21z. That timing lines up well with the latest CAM guidance, which has trended towards greater coverage compared to previous runs, particularly across the northern half of the area. Given the improved agreement and higher confidence, PoPs were increased around 21z in those areas. Convection should initially be tied to differential heating and any lingering boundaries before storm-scale outflows increasingly take over. Deep-layer shear remains very weak, so storms should largely remain pulse-type or loosely organized multicells. Even so, strong instability and favorable thermodynamic profiles should support efficient downdraft acceleration with the stronger cores, and an isolated strong to severe downburst cannot be ruled out near peak heating. Damaging wind would be the main concern, though the overall severe threat remains limited by the weak shear and the relatively short-lived nature of individual cells. The CAMs are also fairly consistent in convection winding down quickly this evening, with coverage decreasing after sunset this evening and most activity largely finished around 03z.

Tuesday looks noticeably less active as the upper trough pulls farther east and northwesterly flow develops aloft. Enough low- level moisture and instability should remain for isolated afternoon convection, but forcing will be weaker and overall coverage should be lower than today. The better opportunity appears to favor the eastern and northeastern portions of the area where deeper moisture should linger a little longer. Farther west, increasing subsidence and slightly drier air aloft should make convective initiation more difficult. With less rain and cloud coverage, temperatures should respond accordingly and remain quite warm through the afternoon.

By Wednesday, attention turns to a cold front dropping south through the Lower Mississippi Valley. This does not look like a particularly active frontal passage locally, as surface high pressure builds quickly behind the boundary and deeper moisture is steadily displaced southward. Any meaningful precipitation signal remains weak, so the frontal passage will likely be easier to identify through a wind shift and falling dewpoints than through shower activity. The front should work through much of the area during the day and evening, with noticeably drier air beginning to filter into the northern half of the CWA by Wednesday night.

LONG TERM

(Thursday through Sunday) Issued at 1208 PM CDT Mon Sep 21 2026

The biggest change Thursday will be the arrival of a noticeably drier air mass behind Wednesday's front rather than any substantial cooldown. Northerly to northeasterly flow will continue advecting lower dewpoints into the area, and guidance has become more convincing that the drier air will reach further south by Thursday morning. With that in mind, overnight lows were nudged downward along and north of I-12 where lower dewpoints and better radiational cooling should allow temperatures to fall more efficiently. The New Orleans metro and immediate coastal areas should remain somewhat warmer given the usual urban and marine influences. Upper ridging building overhead will otherwise keep conditions dry, with warm afternoon temperatures but noticeably lower humidity.

The ridge should remain the dominant feature through the remainder of the long-term period, keeping convection largely suppressed and resulting in a fairly quiet late-week forecast. Surface high pressure will gradually shift east Friday and into the weekend, allowing easterly to southeasterly flow and a slow return of low- level moisture. Humidity should therefore begin creeping back upward by Saturday and Sunday, but moisture recovery appears gradual enough that any convection should remain isolated at best through the weekend.

AVIATION

(00Z TAFS) Issued at 642 PM CDT Mon Sep 21 2026

Prevailing VFR at all terminals right now, though some thunderstorms remain in the area and may impact HDC, MSY, and NEW. Brief low ceilings and visibility issues is possible as convection moves through. Tuesday can expect VFR conditions as convection chances are very limited. Not going to rule out a stray storm or two impacting a terminal, but not enough confidence to include PROB30s.

MARINE

Issued at 1208 PM CDT Mon Sep 21 2026

Generally benign marine conditions are expected through the first half of the week, with light winds and relatively low seas outside of scattered thunderstorms. Convection will be most numerous this afternoon and evening, and any stronger storms could produce brief periods of gusty and erratic along with locally higher waves. Winds should remain fairly light Tuesday before a cold front moves through the waters Wednesday into Wednesday night. Behind the front, northerly to northeasterly flow will strengthen as high pressure builds across the land, with the highest seas likely occurring late Wednesday night into Thursday, particularly the over the open Gulf waters. Conditions should gradually improve late in the week as the pressure gradient relaxes and the surface high shifts east.

LIX WATCHES/WARNINGS/ADVISORIES

LA...None. GM...None. MS...None. GM...None.