textproduct: New Orleans/Baton Rouge

KEY MESSAGES

Updated at 709 PM CDT Fri May 1 2026

- Heavy rainfall and increased risk of flash flooding will impact the area tonight. - The threat for strong to severe thunderstorms tonight will primarily be over lower portions of the southeast Louisiana coastal parishes.

- Strong winds will produce hazardous boating conditions over the waters this weekend. A Small Craft Advisory is in effect.

UPDATE

Issued at 709 PM CDT Fri May 1 2026

Frontal boundary appears to be just off the Louisiana coast, with the exception of possibly the portion of Plaquemines Parish near Southwest Pass. Strong convection is anchoring to that boundary for now. Further north, light to moderate rain continues across much of the area. There may be occasional breaks, but that doesn't signal the end of the rain yet. The final batch of convection associated with the shortwave is moving off the Texas coast at this time and probably won't reach western portions of our CWA until closer to midnight.

Temperatures are running roughly 5F below most guidance from the day shift, and we may need to bump overnight lows down a few degrees in the next couple hours.

SHORT TERM

(Now through Sunday night) Issued at 1241 PM CDT Fri May 1 2026

A potent shortwave trough and upper level jet couplet will continue to advance through the region tonight providing ample deep layer forcing. Further down into the low to mid-levels, a low pressure system will continue to strengthen in a region of enhanced baroclinicity along a stationary front stretching across the forecast area. The front is currently situated along the coast of Louisiana, but it will push inland toward the I-10 corridor by this evening in response to increased southerly mid-level flow. This stalled frontal boundary will serve as the primary focusing mechanism for multiple rounds of strong to occasionally severe thunderstorms capable of producing very high rainfall rates of 1 to 2 inches per hour this evening into the early overnight hours over portions of the Southshore and River Parishes. Storm motion will be nearly parallel to the frontal boundary, so the concern for localized flooding issues has increased for areas south of Lake Pontchartrain as back building storms are highly likely to develop. Probabilities of 4 to 6 inches of rain over the areas continues to increase and confidence is fairly high that some flooding issues will develop this evening into tonight for parts of the River Parishes and metro New Orleans. To the north of the front, a broad region of isentropic forcing over a cooler and more stable airmass at the surface will allow for a broad shield of moderate rain with embedded elevated thunderstorms to impact the area this afternoon into tonight. Although rainfall rates will not be as high in these areas, a general 1 to 3 inches of rain could still fall between now and tomorrow morning.

A longwave northern stream trough will quickly dig into the area late tonight into tomorrow. As this trough moves in, the southern stream vorticity and forcing will shift east toward Florida. A secondary front associated with the longwave trough will sweep through in the early morning hours, and will be well offshore by the afternoon. Significantly drier air will advect into the region behind this front, and this will allow for rapidly clearing skies by mid-day. There will be some lingering shower activity along the coast and in the offshore waters, but the threat of heavy rainfall and severe weather will end by daybreak tomorrow as the reinforcing front and longwave trough axis pass by. Clear and dry conditions will then persist through the remainder of the short term period. Temperatures will run below average as some cooler air advects into the region with highs in the low 70s and lows dipping into the upper 40s and lower 50s.

LONG TERM

(Monday through Thursday night) Issued at 1241 PM CDT Fri May 1 2026

The workweek will start off quiet as a broad and deep ridge of high pressure dominates the region. Temperatures will begin to modify as winds turn southerly and allow for increasing warm and moist air advection into the region. However, a strong mid-level capping inversion will remain in place, and this will prohibit any rain chances from developing on Monday and Tuesday. At most, some fair weather cumulus will form during peak heating hours each afternoon when temperatures climb into the upper 70s and lower 80s.

Conditions will turn more unsettled as we move into Wednesday as a trough axis passes to the north of the region. The trailing end of the trough and a weak front will slip through the region Wednesday into Wednesday night. The increased lift associated with these features will tap into an increasingly warm, moist, and unstable environment to produce showers and thunderstorms over the region. A review of model soundings for Wednesday afternoon indicates the potential for some strong to severe thunderstorm activity as 0-6km shear ranges from 50 to 60 knots and MLCAPE averages around 1500 J/KG. Directional shear is limited, so straight line winds and large hail appear to be the primary concern with any severe storms that fire up. We will continue to monitor the trends with this next system and will refine our forecast as we get closer to Wednesday.

The trough and associated front will sweep east of the area by Thursday, and this will allow for increasing negative vorticity, dry, and cold air advection to take hold. Highs will be closer to average in the upper 70s and lower 80s and skies will clear through the day as the drier air moves in. There may be some lingering coastal showers in the morning hours, but dry weather should be the rule across the region by the afternoon.

AVIATION

(00Z TAFS) Issued at 709 PM CDT Fri May 1 2026

Rain across the area is producing IFR conditions at most terminals, primarily for ceilings. That's likely to remain the case for most of the night, with potential for occasional LIFR or VLIFR with the heaviest cells. However, there may be a period of a couple hours where conditions could briefly improve as the current wave of convection departs. That will be short-lived, as there is at least one more and possibly two waves of convection to move across the area in the next 6 to 9 hours. Over the last couple hours, most of the lightning has remained offshore, but not confident that trend continues much longer, at least at KHUM and the New Orleans terminals.

Most guidance and current trends indicate that any significant precipitation should end prior to sunrise Saturday. Any significant flight restrictions should improve to at least MVFR by mid-morning, if not sooner, and VFR near or prior to 18z.

North to northeast winds will remain gusty overnight and only abate slightly for most of the day.

MARINE

Issued at 1241 PM CDT Fri May 1 2026

This afternoon, a developing low pressure system will move into the area along a stationary front draped over the region. Winds will increase in response to this low with northeast winds of 15 to 20 knots forming over the tidal lakes and sounds and southeast winds of 10 to 15 knots developing in the open Gulf waters. As the low tracks to the east, it will help drive the front offshore later tonight into Saturday. Strong northerly winds of 20 to 25 knots will develop late tonight and persist through Sunday morning over all of the waters, and a small craft advisory has been issued for these conditions. Winds and seas will quickly fall off to less than 10 knots and 3 feet into the start of the new workweek as a broad area of high pressure settles over the region. As the high shifts to the east on Tuesday, winds will turn southerly at 10 to 15 knots and remain so into Wednesday.

LIX WATCHES/WARNINGS/ADVISORIES

LA...None. GM...Small Craft Advisory until 7 AM CDT Sunday for GMZ529-531>536- 541-543-551-553-554-557-570-572-575-577.

MS...None. GM...Small Craft Advisory until 7 AM CDT Sunday for GMZ531>536-541- 543-551-553-554-557-570-572-575-577.