Mississippi Sound GMZ532 Marine Forecast
| Today...West Winds 5 To 10 Knots, Becoming Southwest 10 To 15 Knots Late. Waves 1 Foot Or Less, Then 2 To 3 Feet This Afternoon. A Chance Of Showers And Thunderstorms Until Late Afternoon, Then Showers And Thunderstorms Likely Late. |
| Tonight...West Winds 10 To 15 Knots. Waves 2 To 3 Feet. A Chance Of Showers And Thunderstorms. |
| Monday...West Winds 10 To 15 Knots. Waves 2 To 3 Feet. Showers. A Chance Of Thunderstorms In The Morning, Then Thunderstorms Likely In The Afternoon. |
| Monday Night...West Winds 15 To 20 Knots, Diminishing To Around 10 Knots After Midnight. Waves 2 To 3 Feet. Showers With Thunderstorms Likely In The Evening, Then Showers Likely With A Chance Of Thunderstorms After Midnight. |
| Tuesday...West Winds 10 To 15 Knots. Waves 2 To 3 Feet. Showers Likely. A Chance Of Thunderstorms In The Morning, Then Thunderstorms Likely In The Afternoon. |
| Tuesday Night...West Winds 10 To 15 Knots. Waves 2 To 3 Feet. A Chance Of Showers. A Chance Of Thunderstorms, Mainly In The Evening. |
| Wednesday...West Winds 5 To 10 Knots. Waves Around 2 Feet. A Slight Chance Of Showers And Thunderstorms. |
| Wednesday Night...West Winds Around 10 Knots. Waves Around 2 Feet. A Slight Chance Of Showers And Thunderstorms. |
| Thursday...Northwest Winds 5 To 10 Knots, Becoming Southwest In The Afternoon. Waves 1 To 2 Feet. A Slight Chance Of Showers And Thunderstorms. |
| Thursday Night...West Winds Around 10 Knots. Waves Around 2 Feet. A Slight Chance Of Showers And Thunderstorms. Winds And Waves Higher In And Near Thunderstorms. |
| Area Forecast Discussion National Weather Service New Orleans LA 1253pm CDT Sunday July 12 2026 .SHORT TERM... (Now through Wednesday night) Issued at 1252pm CDT Sunday July 12 2026 The broad upper ridge that covered much of the southern CONUS has shifted west/northwest. This is allowing heigheights to fall across the north-central Gulf Coast as a weakness develops on the eastern side of the ridge. A trough settling into the Southeast US through Monday will provide greater large-scale support for convection. Early offshore convection has not followed the typical summertime cycle, with little in the way of storms inland but very active south of Louisiana in the open Gulf waters. A closer inspection of PW field across the region suggest deeper moisture profile offshore is surging north. Convergence along that gradient has been and will continue to support this activity. The 12Z KLIX sounding sampled a very moist and increasingly unstable environment. Precipitable water was 2.2" inches (likely well above that offshore), up slightly from 2.15 inches at 00Z and considerably higher than the 1.83 inches observed Saturday morning. CAPE was a fairly typical 1500-2500J/kg. The sounding with that much instability along with a moisture rich column supports efficient warm-rain processes, with a wet-bulb-zero height near 14.8 kft and a very moist boundary layer. Weak 0-6 km shear near 5 kt, mean flow under 10 kt, and Corfidi vectors generally under 10 kt favor poorly organized, slow-moving convection. The primary concern today will consequently be locally heavy rainfall and boundary interactions rather than organized severe weather. The modest DCAPE near 475 J/kg and relatively weak lapse rates further limit the overall wind threat, although precipitation loading and collapsing storms could still produce localized gusty winds. Forecast POPs for the rest of the day generally range from 60 to 80 percent, but those values do not fully convey the uncertainty associated with the ongoing convective suppression. CAMs continue to indicate potential for the subsidence to weaken sufficiently for late-afternoon development along the interstate corridors. If that occurs, storms will have access to a very moist and unstable environment, and slow movement could quickly produce ponding or localized flash flooding. Conversely, coverage could underperform the forecast if the subsident influence of the Gulf complex persists longer than expected. The greatest flash flooding concern of this forecast period continues to be Monday as the upper weakness and surface boundary settle closer to or on top of the CWA. A deeply moist airmass, with precipitable water values expected to be near daily climatological max of ~2.4 inches, will combine with weak steering flow and multiple low-level convergence boundaries. This setup will favor slow-moving storms, backbuilding and localized training. Widespread rainfall totals of 1 to 3 inches are forecast through the Tuesday, but localized amounts over 5 inches are possible where repeated convection occurs. Confidence is high that numerous thunderstorms will produce pockets of heavy rain Monday, but remains considerably lower regarding the precise location of the heaviest axis. Current indications favor portions of the coastal parishes/counties along/south of I-10, but meaningful shifts remain possible. Numerous showers and thunderstorms may continue into at least part of Tuesday while the upper weakness remains nearby. The heavy-rain threat will increasingly depend on Monday's rainfall footprint and the location of any lingering boundaries. Areas receiving substantial rain Monday would be more susceptible to additional flooding Tuesday even if rainfall rates or overall coverage begin to decrease. Greater cloud cover and more frequent convection should hold daytime temperatures below recent levels Monday and Tuesday with highs unlikely to reach 90. Long Term (Thursday through Saturday night) Issued at 1252pm CDT Sunday July 12 2026 The mid-level weakness should begin moving away from the central Gulf Coast Tuesday night into Wednesday as ridging gradually rebuilds from the northwest. Surface high pressure is also expected to become more established across the region. This evolution should bring decreasing deep-layer moisture and a transition from numerous thunderstorms to more isolated or scattered, primarily diurnal convection Wednesday and Thursday. The heavy-rain threat should then diminish considerably, although any slow-moving storm could still produce a localized downpour. The upper ridge is forecast to become more influential over the region Friday into next weekend as it builds across the Central Plains to the northern Gulf Coast. Increasing heigheights from that and greater insolation should allow temperatures to climb back into the lower and middle 90s. With higher surface moisture remaining in place that keeps dewpoints in the mid/upper 70s, heat index values will also rise. At this range, confidence is greater in a warming trend than in temperatures or heat indices reaching any specific headline threshold. The strength and placement of the ridge will determine how much convection is suppressed and how quickly heat stress increases. A stronger ridge centered closer to the Lower Mississippi Valley would support hotter conditions, while a ridge remaining farther west would permit somewhat greater afternoon storm coverage and temper the heat. Regardless, may be looking at heat advisories for at least local urban areas Friday thru weekend Marine Issued at 1252pm CDT Sunday July 12 2026 West to southwest winds will prevail through Tuesday as a weak frontal boundary approaches and then stalls near the coastal waters. Winds today will generally remain 5 to 10 knots across the western waters, and tidal lakes with 10 to 15 knots developing across the Mississippi Sound, Chandeleur Sound, and adjacent eastern coastal waters as the local pressure gradient tightens there. Seas will generally be 2 to 3 feet over the open Gulf waters and 2 feet or less across the protected waters. The pressure gradient further tightens across the eastern waters Monday as the upper trough and surface boundary approach. West winds respond by increasing to 15 to 20 knots during the afternoon and evening hours. That appears to be the peak winds supported by this pressure regime as they then begin falling off thereafter. Waves may build to 3 to 4 feet but then fall back to around 2 feet thereafter as weaker and more variable flow pattern returns. Thunderstorms remain the primary short-duration hazard. Timing is a bit out of the norm as that frontal boundary mentioned above moves closer into the region. Storms may produce frequent lightning, waterspouts, and sudden wind gusts with locally higher waves. Thunderstorm coverage should be greatest through Tuesday before decreasing later in the week. NOAA New Orleans LA Office: Watches - Warnings - Advisories LA...None. GM...None. MS...None. GM...None. |
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