Marine Weather Net

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


TODAY

NE
WINDS
10 - 15
KNOTS

TONIGHT

E
WINDS
10 - 15
KNOTS

SUNDAY

SE
WINDS
5 - 10
KNOTS

SUNDAY NIGHT

S
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
GMZ572 Forecast Issued: 413 AM CST Sat Feb 22 2020

Today...Northeast Winds 10 To 15 Knots. Seas 3 To 5 Feet With Occasional Seas To 6 Feet. Dominant Period 7 Seconds.
Tonight...East Winds 10 To 15 Knots. Seas 3 To 5 Feet. Dominant Period 7 Seconds.
Sunday...Southeast Winds 5 To 10 Knots. Seas 2 To 4 Feet. Dominant Period 6 Seconds.
Sunday Night...South Winds 10 To 15 Knots. Seas 2 To 4 Feet. Dominant Period 4 Seconds.
Monday...Southwest Winds 10 To 15 Knots. Seas 3 To 5 Feet. Dominant Period 7 Seconds. Slight Chance Of Showers In The Late Morning And Afternoon.
Monday Night...West Winds 5 To 10 Knots. Seas 3 To 5 Feet. Dominant Period 7 Seconds. Chance Of Showers And Slight Chance Of Thunderstorms.
Tuesday...Northwest Winds 5 To 10 Knots. Seas 1 To 3 Feet. Dominant Period 7 Seconds. Slight Chance Of Showers Through The Day.
Tuesday Night...Northwest Winds 10 To 15 Knots Rising To 20 To 25 Knots After Midnight. Seas 3 To 5 Feet. Dominant Period 7 Seconds. Slight Chance Of Showers.
Wednesday...Northwest Winds 20 To 25 Knots. Seas 3 To 5 Feet With Occasional Seas To 6 Feet. Dominant Period 7 Seconds. Waves Or Seas Building To 5 To 8 Feet With Occasional Seas To 10 Feet. Dominant Period 7 Seconds In The Afternoon.
Wednesday Night...North Winds 20 To 25 Knots. Seas 4 To 7 Feet With Occasional Seas To 9 Feet.
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Synopsis for Pascagoula to SW Pass Mississippi - GMZ501
Synopsis for SW Pass Mississippi River to Atchafalaya River- GMZ500
413 AM CST Sat Feb 22 2020

High pressure will settles into the area through much of the weekend. A strong cold front will push the coastal waters Wednesday morning.
Area Forecast Discussion
National Weather Service New Orleans LA
355am CST Sat Feb 22 2020

Short Term
A deep layer ridge axis and associated negative vorticity advection will continue to feed into the area through tonight. This ridging and the associated subsidence will keep mostly clear skies and dry weather in place. Temperatures will also remain cooler than average as a thermal trough gradually pulls away from the Gulf South. Highs should only rise into the upper 50s today, and lows will cool into the upper 30s and 40s tonight.

Cloud cover will be on the increase tomorrow as the ridge axis begins to pull to the east and an upper level trough moves into the southern Plains. Moisture return will remain somewhat limited in the low levels, and expect to see only some mid and high level cloud cover form through the day. By tomorrow night, increased onshore flow will result in higher low level moisture content, and this will promote the development of lower clouds and some rain showers by the late evening hours across the northern third of the CWA. After midnight, Probability of Precipitation values will increase to 30 to 50 percent across the northern half of the CWA. This shower development will also be supported by a difluent flow pattern aloft and the resultant increase in upper level forcing associated with that type of pattern. A strengthening surface low will also serve as a focus for increased shower development as a cold front forms over Texas and begins to push into Louisiana by late Sunday night. Temperatures will be closer to average tomorrow into tomorrow night with highs in the 60s and lows in the 50s.

The region will be beneath the right entrance region of a strong 140 knot jet streak Monday into Monday night, and this will allow for continued unsettled weather. A surface front will also be pushing into the area on Monday, but this front will stall and dissipate by Monday night as the mid and upper level flow pattern turns parallel to the front. This will keep the risk of rainfall in the 30 to 50 percent chance range across the southeastern two thirds of the CWA throughout Monday night. Fortunately, most of the rain will be in the form of showers due to a lack of instability. At most, an isolated thunderstorm may develop Monday afternoon across the northern half of the CWA where weak CAPE values of 500 J/KG or less will be possible. A lack of supportive dynamics will keep any thunderstorm activity on the weaker side. Temperatures will be mild on Monday with highs in the upper 60s and lower 70s and lows in the upper 40s and 50s Monday night.

Long Term
Tuesday will see a dissipating frontal boundary linger across the forecast area in the morning hours, and a risk of isolated to scattered rain showers will persist during the first half of the day across metro New Orleans and the Mississippi coast. A much stronger upper level trough and surface front will begin to dive into the southern Plains through the day on Tuesday, and this will force the weak dissipating initial frontal boundary offshore by Tuesday afternoon. As a result, rain chances should come to an end by Tuesday afternoon for all areas expect the offshore waters mainly east of the river. Temperatures will be near average in the middle to upper 60s.

The much stronger northern stream trough axis and associated front will sweep through the area Tuesday night. This system will be largely moisture starved, but some lingering cloud cover can be expected. There could be some light rain showers that form across our southwest Mississippi zones, but the odds are too low to include at this point. These showers would be associated with the passing upper level trough axis simply due to a very impressive cold pool(a region of relatively cold air) aloft creating favorable lapse rates. Strong winds will develop behind the front as a much colder airmass advects into the region, and expect to see winds of 20 to 30 mph with higher gusts in place by midnight Tuesday night. Temperatures will also begin to cool rapidly with lows in the 40s expected by Wednesday morning.

A 925mb thermal trough axis will be parked directly over the region Wednesday into Thursday. Some lingering low level moisture across the northern half of the CWA Wednesday into Wednesday night could keep skies mostly cloudy, but increasing subsidence aloft should clear things out by Thursday. Temperatures will be significantly cooler than average with highs in the 50s both Wednesday and Thursday. Lows will cool into the 30s both Wednesday and Thursday nights, and a light freeze will once again be possible north of the I-10/12 corridor. Winds will remain elevated in the 15 to 25 mph range through Thursday morning, but will begin to decrease by Thursday afternoon as a surface becomes more centered over the Gulf South.

Deep layer troughing will continue to dominate the eastern third of the nation through Saturday, and this will keep a northwest flow pattern in place across the Gulf South. As a result, clear skies and low relative humidities can be expected both days. Temperatures should gradually modify as the thermal trough over the region on Wednesday and Thursday begins to pull to the east, but readings will still remain around 5 degrees below normal with highs near 60 and lows upper 30s and lower 40s.

Marine
High pressure will remain in place through the weekend. Surface high will move off the Carolina coast by Sunday evening producing a light southeast flow over the coastal waters. A weak cold front will into the coastal waters Tuesday morning. A second stronger surge will push through Wednesday morning. Wednesday through Wednesday night brisk north winds will yield Small Craft Advisory conditions to all waters. 18

NOAA New Orleans LA Office: Watches - Warnings - Advisories
LA...Freeze Warning until 7am CST this morning for LAZ034>037-039- 040-046>050-071-072.

GM...None. MS...Freeze Warning until 7am CST this morning for MSZ068>071-077- 080>082.

GM...None.