textproduct: New Orleans/Baton Rouge

KEY MESSAGES

Updated at 120 PM CDT Wed Sep 30 2026

- Scattered showers and a few storms will return to the area Thursday afternoon. One or two storms could become strong, producing gusty winds, frequent lightning and brief periods of heavy rainfall.

- Widespread rain and embedded thunderstorms will affect the area Friday through at least Sunday. While specific rainfall totals are still uncertain, heavy rain and at least localized flash flooding will be a threat. Residents should continue to monitor the forecast for updates regarding this threat.

SHORT TERM

(Now through Thursday) Issued at 120 PM CDT Wed Sep 30 2026

Low level return flow is becoming more established across the area with winds now solidly out of the southeast. Dewpoints across the southern half of the area have mostly recovered into the low to mid 70s but more interior areas are still in the upper 60s. Expect a continued gradual increase in low level moisture through tonight.

We should see slightly faster atmospheric moisture recovery tomorrow (Thursday) as the edge of a deeper tropical moisture plume begins to move into the area. Model profiles are indicating precipitable water (overall atmospheric moisture) values of 1.6-1.8 inches by tomorrow afternoon, which is around the 75th percentile for this time of year.

As a result of the increased moisture, rain chances will also increase tomorrow. The added moisture will allow for scattered showers to develop mainly during the afternoon hours as daytime heating will be necessary to break through any remaining cap. That being said, we can't rule out a couple thunderstorms, and any storms that do break through the cap will be capable of producing gusty winds, lightning and and brief periods of heavy rainfall.

LONG TERM

(Friday through Tuesday) Issued at 120 PM CDT Wed Sep 30 2026

Main weather concerns come during the Friday through Sunday time frame and there hasn't been much change in the overall forecast thinking. Still looks like a quite active weather pattern as a tropical wave moves into the northern Gulf and interacts with a slow-moving cold front. The result will be widespread rainfall with embedded thunderstorms across the local area mainly from late Friday through Sunday, with the most intense rain tapering off by Monday.

The moisture associated with this system still looks to be near- record-setting for this time of year based on our observed sounding climatology back to 1950 (1988 if only using data from the current launch site). Most guidance continues to indicate indicates precipitable water (PW) values will be approaching or exceeding 2.5 inches across much of the area by late Friday with similar values Saturday and Sunday. PW values like these are well above the 90th percentile and nearing the daily maximum observed values for the Oct 2-4 time frame. For the climate data enthusiasts out there, the current daily records are 2.54, 2.53 and 2.72 inches, respectively, with the records on Oct 3 and 4 both associated with 2002's Hurricane Lili. The record on Oct 2 may be associated with remnants of 1965's TS Debbie which made landfall in SE LA on Sep 30, but that one is less conclusive without more thorough digging.

The ample moisture will result in prime conditions for efficient rainfall processes and thus high rainfall rates are likely. Instantaneous rates of over 4 inches per hour will be possible in the heaviest storms, which can easily overwhelm drainage capacity in urban and other poor drainage areas, even over short durations. Currently we continue to highlight a marginal risk (level 1 of 4) of excessive rainfall/flash flooding Friday followed by slight risks (level 2 of 4) Saturday and Sunday. These threat levels could change as the specifics of the event become clearer and unfold.

Current storm totals for the Friday through Sunday period are still forecast in the 3-6" range, with higher confidence in the threat across roughly the southeastern half of the area. There will likely be pockets of higher totals and the higher end potential continues to be tough to nail down given the multi-day lead time.

The good news is that rivers across the region are currently low and thus water storage capacity is currently high - meaning that at least for now, this appears to be more of a flash flood concern than a significant river flood concern.

By Monday and Tuesday, the front should sink a little farther south in response to another upper trough moving through the lower Mississippi Valley. While the front doesn't currently look to push far enough south to completely dry out the local area, it should shift the axis of any remaining heavy rain into the northern Gulf.

AVIATION

(18Z TAFS) Issued at 120 PM CDT Wed Sep 30 2026

VFR conditions will prevail through the period with winds generally 10 knots or less. A few showers will be possible Thursday afternoon, but probabilities in any given spot are too low to mention in the TAFs at this time.

MARINE

Issued at 120 PM CDT Wed Sep 30 2026

A tightening pressure gradient will allow winds to strengthen to 15 to 20 knots by Thursday or Thursday night. Showers and some thunderstorms will begin to increase in coverage Thursday and especially Friday through the weekend as a tropical wave moves through the northern gulf and interacts with an approaching weak cold front.

LIX WATCHES/WARNINGS/ADVISORIES

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