Marine Weather Net

Altamaha Sound to Fernandina Beach FL Marine Forecast


THIS AFTERNOON

SE
WINDS
5 - 10
KNOTS

TONIGHT

SE
WINDS
5 - 10
KNOTS

THURSDAY

SE
WINDS
5 - 10
KNOTS

THURSDAY NIGHT

SE
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
AMZ450 Forecast Issued: 924 AM EDT Wed Sep 23 2020

This Afternoon...Southeast Winds 5 To 10 Knots. Seas 3 To 4 Feet With A Dominant Period Of 15 Seconds. Mostly Smooth On The Intracoastal Waters.
Tonight...Southeast Winds 5 To 10 Knots. Seas 3 To 4 Feet With A Dominant Period Of 15 Seconds. Mostly Smooth On The Intracoastal Waters.
Thursday...Southeast Winds 5 To 10 Knots, Increasing To 10 To 15 Knots In The Afternoon. Seas 3 To 4 Feet With A Dominant Period Of 13 Seconds. A Light Chop On The Intracoastal Waters.
Thursday Night...Southeast Winds 10 To 15 Knots. Seas 3 To 4 Feet. A Light Chop On The Intracoastal Waters. Chance Of Showers After Midnight.
Friday...Southeast Winds 10 To 15 Knots. Seas 2 To 4 Feet. A Light Chop On The Intracoastal Waters. Chance Of Showers And Slight Chance Of Thunderstorms.
Saturday...Southeast Winds 10 To 15 Knots. Seas 2 To 4 Feet. A Light Chop On The Intracoastal Waters. Chance Of Showers And Slight Chance Of Thunderstorms.
Saturday Night And Sunday...Southeast Winds 5 To 10 Knots. Seas 2 To 3 Feet. Chance Of Showers And Slight Chance Of Thunderstorms.
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AMZ400: Synopsis for Altamaha Sound GA to Flagler Beach FL out to 60 nm
924 AM EDT Wed Sep 23 2020

High pressure centered along the Carolina coast will move eastward and will strengthen near Bermuda on Friday. Seas will continue to slowly subside, but will remain at Small Craft Advisory levels through Thursday. Meanwhile, the remnants of Tropical Storm Beta will move northeastward through the lower Mississippi Valley tonight and will then weaken over the Tennessee and southern Appalachians on Thursday night and Friday. This weather pattern will result in gradually increasing southeasterly winds beginning tonight, followed by winds subsiding on Saturday night and Sunday ahead of an approaching cold front. Showers and thunderstorms will increase in coverage over our local waters from Friday through the weekend. A series of dry cold frontal passages are then expected early next week.

Gulf Stream
The approximate location of the west wall of the Gulf Stream as of Sep 22, 2020 at 1200 UTC...
- 56 nautical miles east of Flagler Beach.
- 65 nautical miles east of Saint Augustine Beach.
- 80 nautical miles east of Jacksonville Beach.
- 90 nautical miles east of St Simons Island.
Area Forecast Discussion
National Weather Service Jacksonville FL
351am EDT Wednesday September 23 2020

...MINOR TO MODERATE COASTAL FLOODING CONTINUES ALONG THE NE FL ATLANTIC COASTAL AREAS AND ST JOHNS RIVER BASIN... Near Term - Through Tonight
Upper ridge will shift south allowing clouds to funnel into the region from the remnants of Beta to our west near the southern Mississippi valley. At the surface, high pressure and a dry airmass (PWATs (Precipitable Waters) less than an inch) will lead to a rain free day. Temperatures today will be slightly warmer with a weaker onshore flow, however, cloudy conditions will keep highs in the upper 70s to mid 80s. Lows tonight will range from the low 60s to low 70s.

.SHORT TERM [Thursday Through Friday]... Thursday...High pressure pushes further east into the Atlantic and southerly steering flow will pump up Max Temps to above normal levels in the mid/upper 80s, while drier air aloft will limit any shower activity during the afternoon hours to only isolated across inland SE GA and along the weak SE Atlantic sea breeze front along the NE FL coast.

Thu Night...Moisture levels will continue to slowly increase with a more moist mid level SW flow aloft and a few showers and storms will be possible across inland SE GA and the Suwannee Valley as well as over the Atlantic Coastal Waters, but still many locations remain dry across NE FL through the night with abundant clouds keeping the overnight lows much milder in the lower 70s inland and mid to upper 70s along the Atlantic Coast.

Friday and Friday Night...Deeper Tropical Moisture remnants from Beta finally push over top of the ridge and into the region and a combination of daytime heating and Precipitable Water Amounts (PWATs) around 2 inches or so should be enough to trigger scattered to numerous showers with a few embedded storms by the afternoon and evening hours, with leftover isolated showers Friday Night. Mild Southeast Flow will push Max Temps into the mid/upper 80s once again and while severe storms are not expected, some brief heavy downpours will be the main threat from convection.

.LONG TERM [Saturday Through Tuesday]... Sat/Sun...Continued warm/humid with above normal temps for late Sept with highs in the upper 80s/near 90 degrees and muggy overnight lows in the 70s. Still enough lingering moisture with PWATs (Precipitable Waters) around 2 inches to continue the threat of scattered showers and isolated storms during the afternoon and early evening hours, but certainly not a weekend washout. Weak flow aloft will limit any strong convection with just brief heavy downpours the main impact from the weekend convection.

Mon/Tue...A weakening cold frontal boundary will push through the SE US and settle into the NE FL/SE GA region early next week. Not much dynamics assocd with this feature so basically just a new injection of moisture into the region which will continue the warm/humid conds with scattered showers and isolated storms, mainly during the afternoon/early evening hours. Above normal temps continue with highs in the upper 80s/near 90 and lows in the 70s. Still some uncertainty if the frontal boundary gets enough push to allow for some drier airmass to reach inland SE GA by the Tuesday time frame, so still only low to moderate confidence in forecast for this time period.

Marine
High pressure over the area will begin to shift east today. While winds have diminished from the recent strong onshore flow pattern, waves will be slower to subside. Small Craft conditions will linger over the northeast Florida nearshore waters and southeast Georgia offshore waters into tonight and across the northeast Florida offshore waters into tomorrow. As we head into the weekend, our next front will approach the area, bringing an increase in chances for showers and thunderstorms.

Rip Currents
High risk of rip currents in effect for NE FL and SE GA beaches through Thursday. High surf advisory in effect along NE FL beaches through tonight.

Coastal Flood
Points south of Jacksonville along the St. Johns River continue to peak in moderate flood stage due to trapped tides. Moderate flooding (1.5-2 ft MHHW) is still expected during today's high tide cycle along the St. Johns River south of Jacksonville and its tributaries. Otherwise, with the weakening of onshore flow and lower astronomical tides, peak tides have lowered into minor to action flood stages (about 0.5-2 ft MHHW) along the Atlantic coast and in the lower St. Johns River (Duval county). Tides will continue to lower, however, elevated tides could linger in the St. Johns River south of Jacksonville through the end of the week.

NOAA Jacksonville FL Office: Watches - Warnings - Advisories
FL...High Rip Current Risk through Thursday evening for Coastal Duval- Coastal Flagler-Coastal Nassau-Coastal St. Johns.

High Surf Advisory until 11pm EDT this evening for Coastal Duval-Coastal Flagler-Coastal Nassau-Coastal St. Johns.

Coastal Flood Advisory until 11pm EDT this evening for Coastal Duval-Coastal Flagler-Coastal Nassau-Coastal St. Johns- Inland Duval.

Coastal Flood Warning until 11pm EDT this evening for Clay- Inland Flagler-Inland St. Johns-Putnam.

GA...High Rip Current Risk through Thursday evening for Coastal Camden-Coastal Glynn.

AM...Small Craft Advisory until 8pm EDT Thursday for Waters from Fernandina Beach to St. Augustine FL from 20 to 60 NM- Waters from St. Augustine to Flagler Beach FL from 20 to 60 NM.

Small Craft Advisory until 2am EDT Thursday for Coastal waters from Fernandina Beach to St. Augustine FL out 20 NM-Coastal waters from St. Augustine to Flagler Beach FL out 20 NM- Waters from Altamaha Sound GA to Fernandina Beach FL from 20 to 60 NM.