Marine Weather Net

Port Fourchon, LA to Lower Atchafalaya River, LA out 20 - 60 NM Marine Forecast


5 - 10




10 - 15


15 - 20

The Marine Weather Forecast In Detail:
GMZ570 Forecast Issued: 359 AM CDT Fri Oct 22 2021

Today...Northeast Winds 5 To 10 Knots. Seas 2 To 4 Feet. Dominant Period 6 Seconds.
Tonight...East Winds Near 10 Knots. Seas 2 To 4 Feet. Dominant Period 6 Seconds.
Saturday...East Winds 10 To 15 Knots. Seas 3 To 5 Feet. Dominant Period 7 Seconds.
Saturday Night...Southeast Winds 15 To 20 Knots. Seas 3 To 5 Feet With Occasional Seas To 6 Feet. Dominant Period 6 Seconds.
Sunday...Southeast Winds 15 To 20 Knots. Seas 3 To 6 Feet. Dominant Period 6 Seconds. Chance Of Showers Through The Day. Slight Chance Of Thunderstorms In The Afternoon.
Sunday Night...Southeast Winds 10 To 15 Knots. Seas 3 To 5 Feet. Dominant Period 6 Seconds. Chance Of Showers And Slight Chance Of Thunderstorms Through The Night.
Monday...Southwest Winds 5 To 10 Knots. Seas 2 To 4 Feet. Dominant Period 6 Seconds. Slight Chance Of Showers.
Monday Night...South Winds 5 To 10 Knots. Seas 2 To 4 Feet. Dominant Period 6 Seconds.
Tuesday...South Winds 5 To 10 Knots. Seas 1 To 3 Feet. Dominant Period 6 Seconds. Slight Chance Of Showers And Thunderstorms In The Afternoon.
Tuesday Night...South Winds 10 To 15 Knots. Seas 2 To 4 Feet. Dominant Period 5 Seconds. Chance Of Showers Through The Night. Slight Chance Of Thunderstorms After Midnight.
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Synopsis for Pascagoula to SW Pass Mississippi - GMZ501
Synopsis for SW Pass Mississippi River to Atchafalaya River- GMZ500
359 AM CDT Fri Oct 22 2021

A weak front will move through the waters tonight, and high pressure will then build in during the day tomorrow. This high will shift toward the eastern seaboard over the weekend.
Area Forecast Discussion
National Weather Service New Orleans LA
335am CDT Fri Oct 22 2021

Synopsis upper low was near the Ontario-Quebec border with shortwaves over New York, Illinois and North Dakota. Upper ridging extended from Mexico northward to Montana, with another deep upper trough approaching the West Coast.

The Illinois shortwave was pushing a weak surface frontal boundary toward our area. At this writing, it appears that the boundary is somewhere near the northern edge of the CWA if one connects the convection over Alabama to the patch of clouds over east Texas. There is not much in the way of sensible weather associated with the front over our area, as there isn't much in the way of clouds or precipitation noted with the boundary, and only a gradual decrease in temperatures and dew points as one moves northward.

That being said, there has been some patchy fog noted over the area, but to this point of the morning, it hasn't been very persistent or widespread. Will continue to monitor, and certainly can't rule out the need for a Dense Fog Advisory at some point this morning. Temperatures at 3am CDT generally ranged from the upper 60s to mid 70s.

.SHORT TERM (through Sunday night)... Can't eliminate the need for a short notice Dense Fog Advisory early this morning, but conditions at this writing don't really support one. Beyond that, the weather over the next few days should be relatively quiet. With the boundary drifting southward through the area today, cannot rule out isolated showers or perhaps a thunderstorm during the max heating portion of the day. If there's a preferred area, it'd be south of Interstate 10. Considering the highs yesterday, somewhat concerned that forecast high temperature guidance from the models is a bit too low. Forecast soundings from the GFS don't show much of a temperature change at 925 mb today compared to yesterday, and that produced highs between 85 and 90 across much of the area. Will agree with the NBM and edge toward the warmer end of the guidance envelope today.

Otherwise, it should be a fairly quiet weekend. Onshore flow becomes a little more significant by Saturday night/Sunday, allowing low level moisture to return. Can't rule out a few isolated showers by Sunday afternoon or Sunday night.

Temperatures will remain well above normal (on the order of 10 degrees F) through the weekend. Highs in the mid and upper 80s aren't all that far away from records for the dates. As noted above, NBM values are somewhat toward the higher end of the envelope in most cases. 35

.LONG TERM (Monday and beyond)... For the start of the long term portion of the forecast period Monday and Tuesday, with the remnants of the ridge impacting the region. With the ridge axis mainly over and to the east of the CWA the main impact is diurnal showers and thunderstorms. Beyond this point things get a little more complicated.

Still seeing significant strength and timing issues between the ECMWF (European Centre for Medium-Range Weather Forecasts) and GFS as we get into mid-week next week, with the GFS being quicker and further north with low pressure. As a comparison, at 12z Thursday, the GFS has a low over western Ontario with a secondary low over the Carolinas, while the ECMWF has a stronger (986 mb) low over Illinois with a secondary over the Carolinas. In either case, that would push a front through our area Wednesday afternoon or Wednesday night, but the ECMWF solution would be much more of a potential significant weather impact locally.

Considering the significant differences in model solutions at Day 6 and beyond, a blended solution is the best choice at this point. As timing and strength differences better resolve over the next couple of days, expect changes to details for midweek next week, but there's certainly some potential for high impact weather at midweek next week. KO/35

First 36 hours or so should be pretty quiet for marine concerns. As surface high shifts east of the area Saturday afternoon, southeast winds will begin to increase, and may necessitate Small Craft Exercise Caution headlines by sometime Saturday night over the western waters. Those conditions likely to continue for much of the waters through Sunday before relaxing a bit. Wouldn't be surprised if we end up beefing up the wind forecast at midweek next week, but timing/magnitude on that is still somewhat uncertain. 35

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