textproduct: New Orleans/Baton Rouge

KEY MESSAGES

Updated at 136 PM CDT Sun Jun 21 2026

- Much lower rain chance through the start of the week.

- Extreme heat is expected for Monday and Tuesday. Heat index values 105 to 110 degrees. A Heat Advisory is in effect for areas around Lake Pontchartrain.

- Scattered afternoon storms return mid week. These storms will be capable of producing severe wind gusts.

SHORT TERM

(Now through Wednesday night) Issued at 136 PM CDT Sun Jun 21 2026

This morning's KLIX sounding showed a very unstable atmosphere with ample CAPE, abundant moisture, but modest to weak shear. Residual frontal boundary that played a role in recent heavy rain events no longer exists. Convection has initiated across portions of the CWA but not really seeing any upscale growth of any cells. BURF and RRFS model soundings show a dry slot developing in the 850mb-500mb level late morning through this afternoon as mid level air works its way in from the southwest. When you zoom out to a more regional perspective, that becomes quite evident. So thinking is that the rest of the day will be similar to less convection with widespread dissipation as the sun sets. Tomorrow will be quite similar as zonal flow spreads across the northern Gulf coast. CAMs suggest that subsidence from the ridge not quite strong enough to completely shut down all convection and that isolated to scattered storms will develop. Tended to agree with this, so went about NBM but not but about 10% above it...just enough to get some zones to include thunder in it.

Of concern tomorrow, slight increase in 500mb heights along with much less cloud cover tomorrow should lead to highs a few degrees warmer than today. Highest dewpoints look to be on all sides of Lake Pontchartrain. Thats the areas where warm temps combined with those higher dewpoints look to reach/exceed heat advisory criteria. Therefore, have issued a targeted Heat Advisory for Monday to account for those conditions.

MEFFER

LONG TERM

(Wednesday night through Saturday) Issued at 1051 PM CDT Sat Jun 20 2026

With upper level high pressure sitting over the desert southwest and northern Mexico, a northern stream trough will begin to deepen over the eastern half of CONUS on Wednesday. As this troughing develops, the flow aloft will turn more northwesterly. There are indications that a large MCS could form over the southern Plains Tuesday night into Wednesday morning and then sweep southeastward, following the theta-e moisture axis, into the forecast area by the afternoon hours. The system will be weakening as it moves into the area, but gusty winds and some locally heavy downpours will be possible across the northern half of the CWA during this time period. The increase in cloud cover and rain chances will also help to temper the extreme heat with highs falling closer to average in the upper 80s and lower 90s and heat index readings dropping back to between 100 and 105 degrees.

Thursday will see the upper level trough begin to pull to the east and the influence of the upper level ridging begin to increase. Overall, the day should be a fairly typical Summer day with highs climbing into the low 90s and scattered diurnally induced convection firing up in the late morning and afternoon hours. Rain chances will be highest north of I-10 where the influence of the ridge will be lowest and near average PoP for late June of 30 to 50 percent is forecast. South of I-10, only isolated activity is expected due to the slightly stronger capping inversion aloft.

Friday will continue to see the influence of the ridge grow as the trough pulls out of the area. A return to a warmer and drier pattern is expected as temperatures climb back into the low to mid 90s and rain chances fall to around 20 percent for the afternoon hours. These lower rain chances are direct result of the drier air dropping PWATS below average or around 1.5 inches and the increasing mid- level capping inversion that reduces mid-level lapse rates to below 6.0 C/km and drops MLCAPE to around 500 J/KG. The one thing to keep an eye on is the threat of strong wind gusts from any storms that do form as dry air entrainment into the updraft could occur.

By Saturday a zonal flow has developed with an upper level band of high pressure extending from Pacific to Atlantic. This brings classic summertime weather with afternoon thunderstorms predominating the pattern. [PG/Schlotz]

AVIATION

(18Z TAFS) Issued at 136 PM CDT Sun Jun 21 2026

MVFR to VFR cigs will gradually transition to VFR as cloud decks lift. Latest radar imagery shows scattered showers an storms developing. These will be capable of drastically lowering flight levels to LIFR or even VLIFR and causing strong ground and severe in- flight turbulence for at least the duration of the storm. It is possible that one or two of our terminals actually go through the day without seeing a storm but not likely. Tonight will be much of the same with lower cigs north causing IFR to MVFR conditions and VFR toward the coast. At this time, convection appears to be unlikely tomorrow.

MEFFER

MARINE

Issued at 136 PM CDT Sun Jun 21 2026

A surface ridge is currently centered in the eastern Gulf which is leading to southwesterly flow over the local marine zones. As an upper level trough digs into the southeastern US, the center of that high pressure will be driven west and into the north/central Gulf. That will put it right near the local area which will substantially decrease the wind field. So expect lighter and more variable winds Tues and Wed. As the trough lifts and tracks east, the surface ridge center than tracks back east which brings our winds back to southwest and closer to 10 to 15 knots and seas of 2 to 4 feet.

MEFFER

LIX WATCHES/WARNINGS/ADVISORIES

LA...Heat Advisory from 10 AM to 8 PM CDT Monday for LAZ058-064- 076>078-080-082-084-087-098-099.

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