Marine Weather Net

St. Augustine to Flagler Beach, FL 20 - 60 NM Marine Forecast


TONIGHT

SW
WINDS
15 - 20
KNOTS

WEDNESDAY

W
WINDS
10 - 15
KNOTS

WEDNESDAY NIGHT

S
WINDS
5 - 10
KNOTS

THURSDAY

E
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
AMZ474 Forecast Issued: 232 PM EDT Tue Jun 22 2021

SMALL CRAFT EXERCISE CAUTION
Tonight...Southwest Winds 15 To 20 Knots Diminishing To 10 To 15 Knots Towards Daybreak. Seas 3 To 5 Feet With A Dominant Period 5 Seconds. Widespread Showers And Thunderstorms In The Evening. Slight Chance Of Showers After Midnight.
Wednesday...West Winds 10 To 15 Knots Becoming Southeast 5 To 10 Knots In The Afternoon. Seas 3 To 4 Feet With A Dominant Period 9 Seconds. Chance Of Showers And Slight Chance Of Thunderstorms In The Afternoon.
Wednesday Night...South Winds 5 To 10 Knots Becoming East After Midnight. Seas 2 To 3 Feet With A Dominant Period 8 Seconds. Chance Of Showers And Slight Chance Of Thunderstorms.
Thursday...East Winds 10 To 15 Knots. Seas 3 To 4 Feet. Showers And Thunderstorms Likely In The Morning, Then Chance Of Showers And Thunderstorms In The Afternoon.
Thursday Night...Southeast Winds 10 To 15 Knots. Seas 3 To 5 Feet. Chance Of Showers And Thunderstorms.
Friday...East Winds 10 To 15 Knots. Seas 3 To 4 Feet. Showers And Thunderstorms Likely In The Morning, Then Chance Of Showers And Thunderstorms In The Afternoon.
Friday Night...East Winds 15 Knots. Seas 3 To 5 Feet. Chance Of Showers And Thunderstorms.
Saturday...East Winds 10 To 15 Knots. Seas 4 To 5 Feet. Chance Of Showers And Thunderstorms.
Saturday Night...East Winds 10 To 15 Knots. Seas 4 To 5 Feet. Slight Chance Of Showers And Thunderstorms.
Sunday...East Winds 10 To 15 Knots. Seas 4 To 5 Feet. Slight Chance Of Showers And Thunderstorms.
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AMZ400: Synopsis for Altamaha Sound GA to Flagler Beach FL out to 60 nm
232 PM EDT Tue Jun 22 2021

A cold front over the southeastern states will move southeastward, entering the Georgia waters on Wednesday before stalling and then gradually dissipating late this week. Widespread showers and thunderstorms will impact our local waters through the early evening hours tonight, with stronger activity producing briefly strong wind gusts. Outside of thunderstorm activity, west- southwesterly winds will increase to Caution levels both near shore and offshore and will remain breezy overnight. Meanwhile, high pressure will build over the Mid-Atlantic states on Wednesday and will only slowly move offshore through the upcoming weekend. Prevailing onshore winds will develop by Friday as this high pressure center wedges down the southeastern seaboard. Otherwise, scattered to numerous showers and thunderstorms will continue each day through Saturday.

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
344pm EDT Tuesday Jun 22 2021

...WET PATTERN CONTINUES THROUGH THE END OF THE WEEK WITH LOCALLY HEAVY RAINFALL THREAT EACH DAY... Near Term - Through Tonight
Convection ahead of approaching cold front over NE FL will weaken quickly late this afternoon, with generally just a few lingering isolated showers through tonight. Locally heavy rainfall will be the main threat through about 6pm south of a line from Ocala to Palm Coast. Lows generally near 70 degrees inland and lower to middle 70s along the Atlantic Coast.

Short Term - Wednesday Through Thursday Night
Weakening cold front sliding southward into the NE FL/SE GA region along with tropical moisture will continue above normal rainfall chances with probability of precipitation in the 60-80% range both days. Main difference between the days will be the steering flow which will remain westerly on Wednesday and push the storms back toward the US 301 and I-95 corridors where sea breeze mergers meet, while on Thursday the steering flow will become East to Southeast, although at light wind speeds, will begin to shift convection more towards inland areas on Thursday afternoon as the East Coast sea breeze front pushes further inland and the focus becomes the US 301 to I-75 corridors later in the day. Highs should reach back into the mid to upper 80s for both days and main threats from storms will be locally heavy rainfall due to the slow storm motion with greatest threats to NE FL urban areas. Enough diurnal heating should occur for a few stronger "pulse" storms with downburst wind potential to 50 mph each afternoon as well.

Long Term - Friday Through Tuesday
High Pressure ridge builds north of the region which will help to deepen the Easterly steering flow through the weekend. Normally this would be a drier pattern, but it will take a while for the moisture from the old frontal boundary to get pushed west of the region, so the tropical moisture with Precipitable Water Amounts close to 2 inches will continue at least numerous showers and storms on a daily basis Friday/Saturday, although the East Coast Sea breeze front will push these slowly inland each afternoon for better evening conditions along the I-95 corridor each day. The continued higher than normal rainfall chances will keep Max Temps below normal and generally in the mid/upper 80s. Finally by the Sunday/Monday/Tuesday time frame expect slightly drier airmass aloft to push into the region from the Western Atlantic with PWATS falling to around 1.75 inches or less, which will lead to a more "climo/normal" scattered diurnal convection each afternoon, starting along the I-95 corridor by early afternoon and pressing well inland by the late afternoon hours along the I-75 corridor. This will allow for a return to near normal highs into the lower 90s over inland areas and upper 80s along the Atlantic Coast.

Marine
Weakening cold front will slide south into the waters on Wednesday and wash out on Thursday. The offshore flow at 15 to 20 knots tonight will weaken on Wednesday and become light and variable by Wednesday Night with seas subsiding to 2 to 3 feet. High pressure ridge builds in north of the waters Friday through the weekend with easterly flow developing generally in the 10 to 15 knot range with seas rebuilding back towards 3 to 5 feet.

Rip Currents
Low end Moderate risk of rip currents will continue at Atlantic Beaches of NE FL/SE GA with surf/breakers of 2-3 ft. A more solid Moderate risk of rip current will develop Friday into the weekend as onshore/easterly flow develops.

Fire Weather
Wetter than normal conditions will continue through the end of the week with patchy low daytime dispersions Wednesday and Thursday.

Hydrology


River rises are expected on the Santa Fe and Black Creek basins over the next couple of days as the wet pattern continues with Action level stages likely. Too early to determine if minor river flooding will occur. Will depend on coverage and intensity of convection over the next couple of days.

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