Port Fourchon Louisiana to Lower Atchafalaya River Louisiana Marine Forecast
|Today...South Winds 10 To 15 Knots. Seas 2 To 4 Feet. Dominant Period 5 Seconds.|
|Tonight...South Winds 10 To 15 Knots. Seas 2 To 4 Feet. Dominant Period 5 Seconds. Chance Of Showers And Thunderstorms Through The Night.|
|Saturday...Southwest Winds 10 To 15 Knots Becoming Northwest In The Late Morning And Afternoon. Seas 2 To 4 Feet. Dominant Period 5 Seconds. Chance Of Showers And Slight Chance Of Thunderstorms Early In The Morning.|
|Saturday Night...North Winds 15 To 20 Knots. Seas 2 To 4 Feet. Dominant Period 5 Seconds.|
|Sunday...Northwest Winds 10 To 15 Knots. Seas 2 To 4 Feet. Dominant Period 5 Seconds.|
|Sunday Night...Northwest Winds 5 To 10 Knots. Seas 1 To 2 Feet. Dominant Period 5 Seconds.|
|Monday...North Winds Near 5 Knots Becoming Southeast In The Afternoon. Seas 1 Foot Or Less. Dominant Period 5 Seconds.|
|Monday Night...South Winds 10 To 15 Knots. Seas 1 To 2 Feet. Dominant Period 4 Seconds.|
|Tuesday...South Winds 10 To 15 Knots. Seas 2 To 4 Feet. Chance Of Showers And Slight Chance Of Thunderstorms Through The Day.|
|Tuesday Night...South Winds 10 To 15 Knots. Seas 2 To 4 Feet. Chance Of Showers Through The Night. Slight Chance Of Thunderstorms After Midnight.|
Synopsis for Pascagoula to SW Pass Mississippi - GMZ501|
Synopsis for SW Pass Mississippi River to Atchafalaya River- GMZ500
259 AM CST Fri Nov 22 2019
Onshore flow is expected to become better established today in advance of an approaching cold front. A cold front will push off the coast Saturday morning and early afternoon. Cool high pressure then builds into the Gulf Saturday evening through Sunday.
Area Forecast Discussion|
National Weather Service New Orleans LA
358am CST Fri Nov 22 2019
A plume of high level moisture advecting in from the southwest will continue to bring high level cloud cover to the area through the morning hours. At the same time, a broad region of increasing upper level positive vorticity advection and omega will overspread eastern Texas and western Louisiana. Expect to see scattered to numerous showers and a few thunderstorms develop just west of the forecast area by late this morning. Temperatures will remain unseasonably warm this morning with readings in the 60s and lower 70s expected.
By this afternoon, the forecast area will be beneath a broad region of upper level difluence. Deep layer forcing associated with this difluence will interact with the warm and moderately unstable airmass in place across the region to produce shower and thunderstorm activity this afternoon and evening. Currently, the northwest third of the forecast area generally extending from metro Baton Rouge toward Southwest Mississippi will see the strongest deep layer omega values and most favorable lapse rates to support more numerous to widespread convective activity. Closer to the coast, some moderation in heating will keep instability values on the lower end resulting in more scattered convective activity through the evening hours. Given the moist adiabatic nature of the lapse rates across the area and a lack of shear, severe thunderstorm development is not expected today. Locally heavy downpours will be the main concern from any thunderstorms that form. Daytime highs should warm into the upper 70s over inland areas and the lower to middle 70s along the coast.
During the overnight hours, temperatures should cool into the upper 50s and lower 60s, and this will lead to lower instability values. As a result, expect to see the risk of thunderstorms diminish later tonight across inland areas, but shower activity will persist as the cold front begins to push into the region. Any thunderstorm activity by late tonight and early tomorrow morning should be confined to the coastal waters where the warmer water temperatures will produce more favorable lapse rates and encourage some scattered thunderstorm development.
The cold front will quickly race across the entire forecast area tomorrow, and expect to see clearing skies and drier weather develop from west to east throughout the day. By tomorrow evening, only a few showers over the offshore waters are forecast as the front continues to race off to the east. Temperatures will climb back into the upper 60s and lower 70s before the front rolls through, but cold air advection through the afternoon hours should result in dropping temperatures after midday. With clear skies and lower humidity values in place tomorrow night, lows will easily fall into the 40s.
A 925mb thermal trough axis and strong surface ridging will dominate the forecast area on Sunday. Mostly clear skies and cooler than average temperatures in the lower to middle 60s can be expected. Sunday night will see the coldest temperatures through the forecast period as mostly clear skies, light boundary layer flow, and low humidity values allow for strong radiational cooling. Lows should upper 30s and lower 40s north and west of the tidal lakes and the middle 40s south of the tidal lakes.
The ridge and associated thermal trough will quickly shift to the east on Monday, and expect to see a more zonal flow pattern develop in the mid and upper levels. High level Pacific based moisture will feed back into the area, and a broken deck of cirrus should begin to develop. Weak low level warm air advection will also take hold, and this will allow temperatures to warm back into the upper 60s and possibly lower 70s by Monday afternoon.
As moisture continues to increase across the area Monday night, higher dewpoints will result in warmer overnight lows in the upper 40s north of the lake and the lower to middle 50s south of the lake. Cloud cover will also increase through the night and a few showers may begin to form over western zones late Monday night in advance of a vigorous vorticity maxima sliding into the area from Texas. This vort max will pass over the area on Tuesday, and will interact with an increasingly unstable atmosphere to produce scattered showers and a few thunderstorms across the region Tuesday afternoon and evening. Forecast soundings indicate that a high degree of directional shear will be in place across the area, and this could support the development of some strong to possibly severe thunderstorms Tuesday afternoon and evening. This potential severe weather event will continue to monitored over the coming days.
The vort max will quickly shift to the east of the area on Wednesday, a strengthening deep layer ridge axis will begin to build over the Gulf South. Another passing vort max is expected to ride over the ridge through portions of north Louisiana and central Mississippi on Wednesday, and a weak frontal boundary will continue to linger over the northern third of the forecast area on Wednesday before surging northward toward the I-20 corridor on Thanksgiving day. Expect to see a gradient of conditions across the area over Thanksgiving weekend with more cloud cover and a risk isolated to scattered showers across the northern third of the CWA. Closer to the coast, the ridge will exert more influence and stronger subsidence should produce clearer skies and keep rain chances at bay over the holiday period. Temperatures will be near to slightly warmer than average with highs in the middle 70s and lows in the 50s.
Surface high pressure moved well east of the area with steady state onshore flow having become established. This will continue through Saturday morning when a cold front pushes off the coast in the morning hours west of the MS River delta, early afternoon hours eastern waters. Convection may attempt to become a broken squall line along the front in the near coastal waters. Moderate NW winds expected to sustain 15-20 kt post-frontal into early Sunday before settling to lighter levels throughout the day. Frontal zone stalls south of the coastal waters by Monday and then moves north as warm front Tuesday. Some strong thunderstorms may develop in the warm sector in the near shore waters Tuesday morning and afternoon before flushing out Tuesday night. 24/RR
NOAA New Orleans LA Office: Watches - Warnings - Advisories
LA...None. GM...None. MS...None. GM...None.