Marine Weather Net

Southwest Pass of the Mississippi River to Port Fourchon, LA 20 - 60 NM Marine Forecast


REST OF TODAY

SE
WINDS
5 - 10
KNOTS

TONIGHT

SE
WINDS
5 - 10
KNOTS

THURSDAY

S
WINDS
5 - 10
KNOTS

THURSDAY NIGHT

SE
WINDS
5 - 10
KNOTS

The Marine Weather Forecast In Detail:
GMZ572 Forecast Issued: 920 AM CDT Wed Jul 06 2022

Rest Of Today...Southeast Winds 5 To 10 Knots. Seas Around 2 Feet. A Chance Of Thunderstorms. A Chance Of Showers Late This Morning And Early Afternoon, Then A Slight Chance Of Showers Late.
Tonight...Southeast Winds 5 To 10 Knots. Seas Around 2 Feet. A Slight Chance Of Showers And Thunderstorms In The Evening.
Thursday...South Winds 5 To 10 Knots. Seas Around 2 Feet In The Morning, Then 1 Foot Or Less. A Slight Chance Of Showers And Thunderstorms In The Morning.
Thursday Night...Southeast Winds 5 To 10 Knots. Seas Around 2 Feet. A Slight Chance Of Showers And Thunderstorms After Midnight.
Friday...Southeast Winds 5 To 10 Knots. Seas Around 2 Feet In The Morning, Then 1 Foot Or Less. A Chance Of Showers And Thunderstorms In The Morning.
Friday Night...South Winds 5 To 10 Knots. Seas Around 2 Feet.
Saturday...Southwest Winds Around 5 Knots. Seas Around 2 Feet In The Morning, Then 1 Foot Or Less. A Slight Chance Of Showers And Thunderstorms.
Saturday Night...Southwest Winds 5 To 10 Knots. Seas 1 Foot Or Less, Then Around 2 Feet After Midnight. A Slight Chance Of Showers And Thunderstorms After Midnight.
Sunday...West Winds 10 To 15 Knots. Seas Around 2 Feet. A Chance Of Showers And Thunderstorms.
Sunday Night...Southwest Winds 10 To 15 Knots. Seas Around 2 Feet. A Slight Chance Of Showers And Thunderstorms In The Evening, Then A Chance Of Showers And Thunderstorms After Midnight. Winds And Seas Higher In And Near Thunderstorms.
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Area Forecast Discussion
National Weather Service New Orleans LA
408am CDT Wednesday July 6 2022

Synopsis
At the surface, high pressure is centered pretty much over our CWA early this morning. Aloft, ridging extended from Alabama north- northwestward into the Dakotas. The upper disturbance that brought the heavy rainfall to portions of the area yesterday continues to drift westward toward the Sabine River. Convection has initiated over marine areas, but areal coverage as of this writing isn't quite as extensive as 24 hours ago. Temperatures at 3am CDT were running a couple of degrees cooler than yesterday, mainly in the 70s. Ground moisture from yesterdays rainfall is getting trapped under the inversion and has aided the development of patchy low clouds/fog.

.SHORT TERM (through Friday night)... High pressure at the surface and aloft isn't really going much of anywhere over the next 3 days. Unfortunately, the very moist airmass isn't going anywhere, either. Last night's LIX upper air sounding showed a precipitable water value of 2.24 inches. That's somewhat lower than yesterday morning's 2.39 inches, but still well above the 90th percentile of our early July soundings.

What do we have in store? Forecast soundings continue to show precipitable water values near 2.2 inches across much of the area today, and only dropping to right around 2 inches by Friday. While we don't have yesterday's disturbance to enhance lift across the area, differential heating should be more than enough to trigger convection by late morning/early afternoon each day. Convective temperatures may be a couple degrees warmer than yesterday, which may delay initiation somewhat as compared to yesterday. Initiation probably closer to noon in most areas today, then early afternoon tomorrow and Friday. With the slight drying of the airmass over the next couple of days, anticipate a gradual decrease in areal coverage tomorrow and Friday. Would note that forecast soundings show very weak low level winds fields. This means we'll get cell propagation more than actual movement. Isolated spots of very heavy rainfall can be expected with these storms. If they occur over urban areas, can't rule out reports of street flooding, but that threat will gradually diminish tomorrow and Friday.

Delayed initiation of convection should allow for somewhat warmer/hotter high temperatures each day. By the time we get to Friday, we'll likely see portions of the area approaching 95 for highs, as long as convection doesn't get going too early. The convection should allow our heat index values to remain below our 108 criteria for Heat Advisories through Friday, although the threat of reaching the criteria briefly in a few areas is not zero. 35

.LONG TERM (Saturday and beyond)... Northern stream troughing will eventually force the upper ridge west of the area by early next week, and it should remain there for much of next week. The GFS solution isn't quite as far west as the ECMWF (European Centre for Medium-Range Weather Forecasts) early in the week, but by next Wednesday or Thursday, both show it near the Four Corners. The eastern trough will try to force a frontal boundary into the area Sunday or Monday. That's somewhat unusual for July around here. It now appears that most of the area won't really get into a drier airmass, so there will be a continuing threat of daily, diurnally enhanced convection. That will keep convection primarily over the coastal waters at night, with most convection over land between noon and mid-evening each day. Not really enough difference in guidance temperatures to necessitate significant departures from the NBM values. 35

Marine
Outside of the normal Summer convective threats of waterspouts, gusty winds, and heavy downpours, no significant impacts are expected over the coastal waters through the upcoming weekend. Winds will generally be 10 knots or less and seas will remain 3 feet or less except where thunderstorms develop.

NOAA New Orleans LA Office: Watches - Warnings - Advisories
LA...None. GM...None. MS...None. GM...None.