textproduct: New Orleans/Baton Rouge

KEY MESSAGES

Updated at 1019 PM CDT Tue Aug 18 2026

- Dangerous heat continues with afternoon heat indices in the 105-113 degree range through the week. Warm overnight temperatures will offer limited to no relief.

- Only isolated to scattered afternoon storms are expected the next couple days. Coverage should be somewhat greater toward the Mississippi coast and eastern portions of the forecast area.

SHORT TERM

(Now through Saturday) Issued at 1019 PM CDT Tue Aug 18 2026

No big changes in the ongoing fcast. The old quasistationary 850mb trough that has been plagueing the SE CONUS will remain. At this writing, it is located from near Vicksburg to Pensacola where it bends and runs along the gulf coast to the Atlantic. Storms will once again fire along and south of this boundary but will not get too far south as they will run into stacked stability and suppression. Any one storm or two of those that develop will continue to have the potential to become severe. There may be even less in number of storms today than there have been. For most of the area, that will still be zero, but the most eastern portion of the area that has seen activity, could see less today. The heat headlines will remain as well, and cumulative effects can begin to have impacts as this continues. This same story should play out over the next few days. Some changes will occur by late Fri as a front moves toward the area causing a bit more storm activity that should help give the area some rain and cloud cover, not for most of Fri since the trough will be moving in late in the day, but Sat could have cloud cover long enough to retard heating. Residual cloud cover, if it can hold, may actually take the heat headlines down for a day or two by the end of the week.

LONG TERM

(Saturday night through Tuesday) Issued at 1019 PM CDT Tue Aug 18 2026

As we move into the long term portion of the forecast on Saturday night, the global models agree on the large scale pattern with upper ridging centered near the Texas/Oklahoma Panhandles with an extension southeastward into about the western half of the Gulf. The upper trough will extend from the western Great Lakes to the Florida Peninsula. By Tuesday evening, the ridge won't have moved very much, being centered near the Texas-New Mexico border and still controlling the western Gulf, while strengthening slightly, with the upper trough off the Atlantic Coast.

The frontal boundary between Interstates 20 and 40 Saturday night won't make much southward progress by Tuesday, either, perhaps approaching Interstate 10. Precipitable water values that will generally be between the 25th and 50th percentile on Sunday (1.6 inches) will increase to about the 75th percentile (2 inches) on Monday before dropping off again on Tuesday.

Shortwaves moving southeastward into the base of the upper trough appear to be displaced far enough away from the local area that they may keep any organized MCS activity away from the area during the Sunday-Tuesday period. Any isolated thunderstorm development is likely to continue recent trends of developing on lake and sea breeze boundaries early in the afternoon and propagating away from those boundaries. They also tend to dissipate prior to sunset. If there's going to be a day that favors a little greater threat of damaging winds, it would be Sunday, when forecast soundings show DCAPE values of 1100-1500. But that's also the day that looks to have the least (and possibly no) convective development.

The hot weather isn't going anywhere either. NBM numbers continue to show highs between 95-100 Sunday through Tuesday. Even if we assume that these values are a couple degrees on the high side of reality, it still keeps a significant portion of the area 5-7 degrees above normal. The GFS solutions do appear to be a little aggressive in bringing drier dew points into the area during this period, although the 18/18z wasn't quite as aggressive as earlier operational runs. ECMWF solutions tended to keep dew points in the 70s. This would primarily impact overnight lows Monday and Tuesday mornings. The NBM solution favors a forecast along the lines of the ECMWF solutions. We'll see how this works out over the next day or two.

AVIATION

(06Z TAFS) Issued at 1019 PM CDT Tue Aug 18 2026

VFR for most terminals today. TSRA will develop late in the day again with the highest chances within the same areas that we have seen for the last few days. Outside TSRA, VFR will be the rule for all terminals.

MARINE

Issued at 1019 PM CDT Tue Aug 18 2026

Surface high pressure centered over the central Gulf will maintain a generally weak pressure gradient through much of the period. A predominantly westerly flow will continue, with higher winds during the early morning and late night hours. Isolated thunderstorms will remain possible with winds and waves higher in and near this activity, particularly during the overnight and early morning hours.

LIX WATCHES/WARNINGS/ADVISORIES

LA...Heat Advisory from 11 AM to 8 PM CDT Wednesday for LAZ034>037- 039-046>048-056>058-064-070-071-076>087-089>100.

GM...None. MS...Heat Advisory from 11 AM to 8 PM CDT Wednesday for MSZ068>071- 077-083>088.

GM...None.