Marine Weather Net

Fernandina Beach to St. Augustine, FL Out 20 NM Marine Forecast


TONIGHT

S
WINDS
5 - 10
KNOTS

FRIDAY

SE
WINDS
5 - 10
KNOTS

FRIDAY NIGHT

S
WINDS
5 - 10
KNOTS

SATURDAY

S
WINDS
5 - 10
KNOTS

The Marine Weather Forecast In Detail:
AMZ452 Forecast Issued: 324 PM EDT Thu Jun 17 2021

Tonight...South Winds 5 To 10 Knots Becoming Southwest After Midnight. Seas 2 To 3 Feet With A Dominant Period 10 Seconds. Mostly Smooth On The Intracoastal Waters. Slight Chance Of Showers And Thunderstorms In The Evening.
Friday...Southeast Winds 5 To 10 Knots. Seas 1 To 2 Feet With A Dominant Period 7 Seconds. A Light Chop On The Intracoastal Waters.
Friday Night...South Winds 5 To 10 Knots. Seas 2 Feet With A Dominant Period 9 Seconds. Mostly Smooth On The Intracoastal Waters.
Saturday...South Winds 5 To 10 Knots. Seas 2 Feet. A Light Chop On The Intracoastal Waters. Slight Chance Of Showers And Thunderstorms In The Afternoon.
Saturday Night...South Winds 10 To 15 Knots. Seas 2 To 3 Feet. A Light Chop On The Intracoastal Waters. Slight Chance Of Showers After Midnight.
Sunday...South Winds 10 To 15 Knots. Seas 3 To 4 Feet. A Moderate Chop On The Intracoastal Waters. Chance Of Showers And Slight Chance Of Thunderstorms.
Sunday Night...Southwest Winds 10 To 15 Knots. Seas 3 To 4 Feet. Slight Chance Of Showers And Thunderstorms.
Monday...Southwest Winds 10 To 15 Knots. Seas 3 To 4 Feet. Chance Of Showers And Thunderstorms.
Monday Night...Southwest Winds 10 To 15 Knots. Seas 3 To 4 Feet. Slight Chance Of Showers And Thunderstorms.
Tuesday...Southwest Winds 10 To 15 Knots. Seas 3 To 4 Feet. Chance Of Showers And Thunderstorms.
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AMZ400: Synopsis for Altamaha Sound GA to Flagler Beach FL out to 60 nm
324 PM EDT Thu Jun 17 2021

Remnants of a stalled front will lay across area waters through Friday, with isolated to scattered showers and storms possible along it. High pressure will build to the east as a tropical cyclone lifts northeastward from the Gulf of Mexico and into the Southeast US this weekend. Southerly winds are expected to increase, to near small craft advisory levels, as the cyclone passes to the northwest on Sunday. High pressure will be located to the southeast through the early part of next week and allow offshore flow to return over the waters until a frontal boundary approaches from the northwest by Wednesday or Thursday.

Gulf Stream
The approximate location of the west wall of the Gulf Stream as of Jun 17, 2021 at 1200 UTC...
- 60 nautical miles east northeast of Flagler Beach.
- 68 nautical miles east of Saint Augustine Beach.
- 81 nautical miles east of Jacksonville Beach.
- 98 nautical miles east southeast of St Simons Island.
Area Forecast Discussion
National Weather Service Jacksonville FL
331pm EDT Thu Jun 17 2021

Near Term - Through Tonight
A weakening, broad frontal zone is draped across northeast Florida this afternoon. Meanwhile along the coast, the Atlantic sea breeze has been unlocked and has made its way inland after being pinned to the immediate coast for several days. The Gulf coast has begun to push inland as well, initiating scattered storms along it as it heads northeast toward I-75. There will be a low chance (20-30%)for scattered showers and storms through the late afternoon and early evening as the aforementioned features interact. The best chances will along the Highway-301 corridor and into the southern portions of inland southeast Georgia. The caveat will be the anomalously dry air aloft and updraft entrainment of that air, which will act to suppress total storm coverage. Any convection that manages to beat the dry air will dissipate this evening with the loss of daytime heating. Strong pulse storm cannot be totally ruled out this afternoon, but would hedge my bet toward storms of the garden- variety type with convection today.

Before the sea breezes make it inland, high temps will reach the lower 90s, with a cooler afternoon at the beaches with readings in the mid/upper 80s. Tonight, increasing moisture will lead to a warmer night across southeast Georgia as temps bottom out in the low 70s across the entire the area.

Short Term - Friday Through Saturday Night
Prevailing flow will strengthen out of the southwest as compact lower ridge strengthens over the Bahamas and the likely tropical cyclone moving north-northeastward across the western Gulf of Mexico. With this flow, blowoff from the tropical system will send a shield of dense mid/upper clouds over the region through Saturday and reintroduce richer moisture back into the area. Outside of breezy gradient-driven winds, the impacts (heavy rainfall) associated with the tropical disturbance will stay well to the west as it lifts northeastward and meanders across the Southeast through the weekend. Given the various tracks of the cyclone, it's tough to say which sea breeze (Gulf or Atlantic) will be more dominant on Saturday. Nonetheless, with the rebirth of moisture into the area, sea breeze initiated storms are possible both Friday and Saturday afternoons. In addition to the sea breeze convection, there may also be some rain/storm bands on the eastern side of the asymmetrical TC that skim the Suwannee Valley/Inland southeast GA areas Saturday.

Before the considerable cloudiness arrives on Saturday, highs will be near normal, with inland areas in the low 90s and beaches in the upper 80s. Thanks to an extensive shield of cloud cover overspreading the region, temperatures will be muted with highs in the low to mid 80s.

.LONG TERM [Sunday Through Thursday]... A tropical disturbance will quickly undergo extratropical transition as it lifts across the Southeast toward the Mid Atlantic coast through Monday. Meanwhile, a ridge axis will extend across southern FL from Atlantic high pressure allowing a tropical, southwesterly flow to continue across the area. Rich, tropical moisture stream over the area through much of next week amid the southwesterly flow. With this pattern, the Gulf sea breeze will be favored each day with the Atlantic sea breeze pinned to the beach. Diurnal instability is expected each day, with storms firing along the sea breezes and likely along the I-95 corridor as the Gulf sea breeze nears the Atlantic. That said, chance to likely Probability of Precipitation are forecast throughout the long term period. An upper trough axis is forecast to shift across the area by mid week but not to certain that the front and dry air behind it will make it far enough south to scour out the tropical airmass.

Dewpoints will surge back into the mid 70s next week, allowing the Heat Index values to reach triple digits in some locations. Barring the frontal intrusion, the hot and humid airmass will stick around throughout next week.

Marine
Remnants of a stalled front will lay across area waters through Friday, with isolated to scattered showers and storms possible along it. High pressure will build to the east as a tropical cyclone lifts northeastward from the Gulf of Mexico and into the Southeast US this weekend. Southerly winds are expected to increase, to near small craft advisory levels, as the cyclone passes to the northwest on Sunday. High pressure will be located to the southeast through the early part of next week and allow offshore flow to return over the waters until a frontal boundary approaches from the northwest by Wednesday or Thursday.

RIP CURRENTS: Low to Moderate Risk at area beaches through the weekend.

Fire Weather
Like today, an easterly sea breeze will move inland Friday, reaching the I-95 corridor between 2-3 PM. Outside of the sea breeze, weak transport winds will lead to poor or low daytime dispersion through Saturday. Breezy southerly winds are expected to develop by Sunday as a tropical system lifts inland from the Gulf into the Southeastern US. The stream of tropical moisture with and behind this system will elevate minimum RHs and enhance thunderstorm chances/coverage this weekend and through next week.

NOAA Jacksonville FL Office: Watches - Warnings - Advisories
FL...None. GA...None. AM...None.