textproduct: New Orleans/Baton Rouge

KEY MESSAGES

Updated at 542 AM CDT Sat Sep 12 2026

- An elevated risk for localized heavy rainfall leading to street flooding and overflowing of poor drainage will continue today.

- Lower rain chances and warmer temps return next week.

SHORT TERM

(Now through Tuesday) Issued at 1238 AM CDT Sat Sep 12 2026

A shortwave trough axis moving trough the region will continue to bring increased rain chances to the area today. This trough will interact with a very moist environment as noted by PWATS of 2 to 2.2 inches which are in excess of the 75th percentile for this time of year. As temperatures warm into the 80s, updraft development will begin in the mid- morning hours and scattered to numerous showers and storms will start to fire up by the late morning hours. These showers and storms will continue to fire up through the mid to late afternoon hours before beginning dissipate in the evening hours with the loss of daytime heating. Storm motion will remain around 10 mph and rainfall rates of 2 to 3 inches per hour can be expected with the strongest storms. As a result, another day of localized flooding concerns, especially for low lying and poorly drained urban areas, will be in play. The region remains in a level 1 out of 5, marginal, risk of flooding for today.

The trough axis will begin to pull east of the area tomorrow and a broad upper level ridge over Texas will start to expand eastward. As the influence of the ridge increases, the mid and upper levels of the atmosphere will begin to both warm and dry in response to increasing subsidence on Sunday and Monday. This will allow PWATS to fall to between 1.8 and 2 inches. These values are still elevated for this of year at between the median and 75th percentile, but the increasing ridging aloft will help to somewhat limit updraft development. Convective activity will struggle to maintain itself until temperatures warm into the lower 90s and the weak mid- level capping inversion is overcome. Overall, shower and storm coverage will be lower and will be more confined to the sea breeze and lake breeze boundaries where low level forcing is maximized. PoP will be closer to average in the 30 to 50 percent range. Another concern will the threat of stronger wind gusts with the most intense storms that form. Drier air will easily entrain in the tallest updrafts and this could lead to winds of 40 to 50 mph with these more intense storms. An isolated severe wind gust of 60 mph cannot be ruled out for Sunday and Monday. This is supported by DCAPE values of around 1100 J/KG and favorable model sounding profiles exhibiting very steep lapse rates below 3km in excess of 8.0C/km.

By Tuesday, continued drying and warming aloft as the ridge becomes centered over the Tennessee Valley will push PWATS down to around the median values for this time of year. Convection will fire up later in the day, more toward the mid to late afternoon, when the convective temperatures in the low to mid 90s are reached. The end result will be more isolated to widely scattered showers and storms and PoP of 20 to 40 percent. Once again, storms will fire up first along the sea breeze and lake breeze boundaries and then fire up along outflow from the previous convection as those first storms collapse shortly after forming. Although the severe threat will be lower on Tuesday, one or two storms could turn strong enough to pull in some drier air aloft and produce damaging wind gusts.

LONG TERM

(Tuesday night through Friday) Issued at 1238 AM CDT Sat Sep 12 2026

By Tuesday night, upper level ridging is expected to be centered (598dm) near Chattanooga, Tennessee. Meanwhile, an upper trough that moves off the Mid-Atlantic coast Monday night and Tuesday is expected to close off a low off the coast of the Carolinas Wednesday and head southwestward around the upper ridge, crossing Florida and entering the eastern Gulf Thursday night into Friday. There's actually pretty decent agreement on the mid level feature between the GFS and ECMWF operational runs from the daytime hours Friday, at least through the end of the workweek next week.

At this time, neither of the medium range models develops a surface low over the Gulf with this mid level feature. The drying of the airmass that is anticipated from the ridging on Sunday and Monday actually continues through most of the workweek, with precipitable water values even on Friday forecast to remain between the 50th and 75th percentiles in most of the area (1.5 to 1.8 inches).

If the moisture depicted in the forecast soundings is in the ballpark, we may not see a lot of thunderstorms during the workweek. That would also mean the hot weather continues for most of next week with temperatures in the mid 90s looking reasonable. May not be enough humidity to justify heat advisories though.

Beyond next Friday, the global operational models fall out of agreement with each other. The ECMWF continues to take the mid level system westward to the Texas coast without a lot of impact. The 18z GFS brings it to about 90W before starting to drift it east next weekend. We'll worry about those differences when next weekend falls within the range of the forecast.

AVIATION

(12Z TAFS) Issued at 542 AM CDT Sat Sep 12 2026

A weak inversion has formed over southwest Mississippi this morning in relation to light boundary layer winds and continued high relative humidity. This has resulted in LIFR low stratus and fog development at MCB. These conditions will persist through around 13z before quickly mixing out as temperatures begin to warm and inversion lifts. Prevailing VFR conditions will then be found at all of the terminals from 13-14z onward. After 16-17z, scattered showers and storms will begin to develop and could impact any of the terminals. PROB30 wording is in place from 17z to 23z at the majority of the terminals for thunderstorm impacts with gusty winds of 20 to 25 knots, lightning, and brief reductions in visibility. Toward the end of the forecast period, another round of fog and stratus has a decent probability of impacting MCB once again, and IFR stratus and fog is in the forecast from 10z to 12z.

MARINE

Issued at 1238 AM CDT Sat Sep 12 2026

Winds will turn more south-southwesterly but with the Bermuda ridge centered well east of the area, wind speeds should be light at 10 knots or less today. The high will become more centered over the north-central Gulf Sunday into next week. This will cause winds to turn more south-southeasterly and even light/variable at times. Seas will generally remain in the 2 feet or less range. Additionally, thunderstorm activity will develop each day, peaking in the early to mid-morning hours, and these storms will produce higher wind gusts, waterspouts, and lightning concerns.

LIX WATCHES/WARNINGS/ADVISORIES

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