textproduct: New Orleans/Baton Rouge

KEY MESSAGES

Updated at 1236 PM CDT Tue Jul 21 2026

- Hot and mostly dry today, and across northern sections on Wednesday. Highs in the mid 90s to near 100 with heat indices 105-112. An Extreme Heat Warning has been issued for Wednesday as heat indices look to increase to 110-115 degrees.

- Tropical Storm Bertha is forecast to move westward toward our general area through midweek. Impacts are still low confidence, but an increase in rainfall (mainly south of I-10) with breezy conditions along with potential coastal flooding are more and more possible with time. Tropical Storm Watches and Warnings are in place for coastal areas along and south of I-10.

SHORT TERM

(Now through Friday night) Issued at 1236 PM CDT Tue Jul 21 2026

The primary forecast challenges through Thursday will be the track and structure of Tropical Storm Bertha, the extent of its rainfall footprint, coastal flooding, and dangerous heat across areas that remain outside of cloud cover.

As of early Tuesday afternoon, Bertha was located over the northeastern Gulf and beginning its turn towards the west. A continued west-northwest to west motion is expected tonight through Thursday as a mid-level ridge builds southeastward towards the Gulf Coast. The current track of Bertha brings the center near the Mississippi and southeast Louisiana coastal waters on Wednesday, near or just south of lower Plaquemines Parish Wednesday evening, and west of the coastal waters during the day on Thursday. However, small track or structural changes will significantly affect the placement of the strongest winds and heavier rain bands, especially since there's a chance that the low-level center and mid-level center becomes detached due to increasing wind shear and dry air tomorrow. If that were to occur, the low-level center would track more north until a new low-level center forms under the heaviest convection pushed to the south of the low-level center.

For the remainder of today, much of the area should remain hot and relatively dry beneath subsidence northwest of Bertha. However, most of the CAMs and some of the latest radar trends point to a convective band developing across the river and bayou parishes this afternoon. With the mid-level dry air in the vicinity and ample instability (4000+ j/kg SBCAPE), damaging winds will be the primary concern with these storms. Although, with the localized forcing and vorticity of Bertha, very isolated and brief tornadoes can't be ruled out with this activity through sunset across mainly East Baton Rouge Parish southward through Terrebonne Parish. Outside of the convective development, highs are expected to peak out in the mid to upper 90s, which when combined with dewpoints in the mid to upper 70s, will support heat indices from 108-112 degrees this afternoon.

Conditions will begin deteriorating from the east to west over the coastal waters and immediate coast tonight into Wednesday as Bertha approaches. Persistent northerly vertical wind shear is keeping the storm asymmetric, with most of the organized convection, strongest winds, and heaviest rainfall displaced south and east of the center. Consequently, the greatest rainfall totals should remain offshore or close to the immediate coast. Much of the inland CWA may receive less than one inch of rain, although locally higher amounts will remain possible where individual bands move repeatedly across coastal areas. Any heavier band could produce rapid ponding or localized urban flooding, but the overall flash flood threat appears to be limited compared to previous forecasts.

Tropical storm conditions will be most likely over the open Gulf waters and portions of the immediate Louisiana and Mississippi coast Wednesday and into Wednesday night. Farther inland, including the New Orleans metro area and tidal lakes, sustained winds should generally remain below tropical storm force, but gusts 30-40 mph will be possible, with locally higher gusts near exposed coastal locations and within heavier rain bands. The tornado threat on Wednesday currently appears low given the displaced convection and limited overlap of stronger low-level shear with surface-based instability over land.

Coastal flooding will likely be the most significant local impact. Inundation of 2-4 feet above normally dry ground is possible along the Mississippi Coast and the more vulnerable portions of lower Plaquemines, lower St. Bernard, eastern Orleans, and southeast St. Tammany Parishes. Water levels of 1-3 feet above ground will be possible elsewhere along the southeast Louisiana coast and around portions of Lake Pontchartrain. Numerous low-lying coastal roads could become flooded or impassable Wednesday through early Thursday.

Because much of Bertha's rainfall shield is expected to remain offshore Wednesday, dangerous heat will continue across a large portion of the CWA due to the compression of the ridge and Bertha overhead. Inland locations are expected to see highs in the upper 90s with heat indices from 110-115, thus an Extreme Heat Warning has been issued for all of SE LA and SW MS. A more southerly wind component across the MS Coast is expected to keep high temps in the low 90s with subsequent heat indices in the 108-110 range. So, please do not let the extreme heat sneak up on you even though a tropical system is passing by.

Bertha should continue westward along the Louisiana coast Thursday, with lingering bands most likely across coastal Louisiana and west of I-55. Winds, rain coverage, and coastal water levels should gradually improve from east to west Thursday afternoon and evening. By Friday, the circulation should remain well west of the area, although residual tropical moisture will support isolated to scattered mainly afternoon thunderstorms with temperatures back in the lower 90s.

LONG TERM

(Saturday through Monday night) Issued at 1236 PM CDT Tue Jul 21 2026

Surface and upper-level ridging should expand across the central Gulf Coast during the weekend as Bertha and its remnants move farther west and dissipate. Increasing subsidence and somewhat lower deep-layer moisture should reduce the shower/storm coverage compares with the middle of the week. However, sufficient moisture will remain for isolated to scattered afternoon convection along the sea breeze, lake breeze, and any remnant outflow boundaries. Rain chances should generally remain in the 20-40 percent range Saturday and Sunday, the with greatest coverage during peak afternoon heating. With weak steering flow, any storm that develops could produce locally heavy rainfall, frequent lightning, and brief gusty winds, but there is no current signal for organized severe weather or a widespread heavy rainfall event.

Heat will again become the primary concern during the weekend and early next week. High temps should generally reach the low to mid 90s, with locally upper 90s possible across northern and western portions of the area, Persistent dewpoints in the upper 70s could produce afternoon heat indices between 105 and 110, potentially requiring additional heat headlines.

The ridging may strengthen even further on Monday and Tuesday, which would favor slightly lower rain chances and continued above-normal temperatures. Confidence is moderate in the overall hot and mainly diurnal-driven convective pattern, but lower regarding daily thunderstorm coverage and whether the center of the ridge is strong enough to largely suppress convection.

AVIATION

(18Z TAFS) Issued at 1236 PM CDT Tue Jul 21 2026

VFR conditions are expected to prevail at most terminals through the period, with northerly winds generally around 5-10 knots this afternoon and tonight. Isolated to scattered convection may briefly affect MCB, HDC, NEW, MSY, and especially HUM through the early evening, producing short-lived visibility reductions, gusty winds, and MVFR ceilings beneath heavier showers and thunderstorms. Conditions should remain largely quiet overnight, but winds generally veer north-northeasterly and increase Wednesday morning as Tropical Storm Bertha approaches from the east. The greatest aviation impacts are expected at GPT beginning around 12-14z Wednesday, where gusts of 20-25 knots and periods of MVFR to IFR ceilings and visibility will become possible in rain bands and thunderstorms. Lower-confidence restrictions may spread toward ASD and NEW later Wednesday morning.

MARINE

Issued at 1236 PM CDT Tue Jul 21 2026

Tropical Storm Bertha will meander over the northeast gulf for the next day or so. It is forecast to move westward along or off the north central gulf coast. As the system moves over our local waters, expect winds and seas to increase with tropical storm conditions possible for most if not all the local waters. The system will move west of the region later Thursday and conditions should improve going into the upcoming weekend.

LIX WATCHES/WARNINGS/ADVISORIES

LA...Tropical Storm Watch for LAZ058-064-077-087-089-090-092-094- 096>100.

Tropical Storm Warning for LAZ070-076-078-091-093-095.

Heat Advisory until 7 PM CDT this evening for LAZ034>037-039- 046>048-056>058-064-070-071-076>087-089>100.

Extreme Heat Warning from 10 AM to 8 PM CDT Wednesday for LAZ034>037-039-046>048-056>058-064-070-071-076>087-089>100.

Coastal Flood Advisory until 4 AM CDT Thursday for LAZ058-080- 082-093-095-097-098.

Coastal Flood Warning until 4 AM CDT Thursday for LAZ070-076-078- 091.

GM...Tropical Storm Watch for GMZ529-531-533-541-551-570.

Tropical Storm Warning for GMZ532-534>536-543-553-554-557-572- 575-577.

MS...Tropical Storm Watch for MSZ083>085.

Tropical Storm Warning for MSZ086>088.

Heat Advisory until 7 PM CDT this evening for MSZ068>071-077- 083>088.

Extreme Heat Warning from 10 AM to 8 PM CDT Wednesday for MSZ068>071-077.

Coastal Flood Warning until 4 AM CDT Thursday for MSZ086>088.

Heat Advisory from 10 AM to 8 PM CDT Wednesday for MSZ083>088.

GM...Tropical Storm Watch for GMZ531-533-541-551-570.

Tropical Storm Warning for GMZ534>536-543-553-554-557-572-575- 577.