Marine Weather Net

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


REST OF TODAY

SW
WINDS
10 - 15
KNOTS

TONIGHT

SW
WINDS
10 - 15
KNOTS

THURSDAY

SW
WINDS
10 - 15
KNOTS

THURSDAY NIGHT

NW
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
AMZ452 Forecast Issued: 938 AM EDT Wed Apr 08 2020

Rest Of Today...Southwest Winds 10 To 15 Knots. Seas 2 To 4 Feet. Dominant Period 11 Seconds. Inland Waters A Light Chop. A Chance Of Showers And Thunderstorms.
Tonight...West Southwest Winds 10 To 15 Knots. Seas 2 To 4 Feet. Dominant Period 11 Seconds Becoming 4 Seconds After Midnight. Inland Waters A Moderate Chop. Showers Likely And A Slight Chance Of Thunderstorms.
Thursday...West Southwest Winds 10 To 15 Knots. Seas 2 To 3 Feet. Dominant Period 11 Seconds. Inland Waters A Moderate Chop. A Slight Chance Of Showers And Thunderstorms.
Thursday Night...West Northwest Winds 10 To 15 Knots. Seas 2 To 3 Feet. Dominant Period 10 Seconds Becoming 3 Seconds After Midnight. Inland Waters A Light Chop. A Slight Chance Of Showers And Thunderstorms.
Friday...North Northwest Winds 10 To 15 Knots. Seas 2 To 3 Feet. Dominant Period 4 Seconds. Inland Waters A Moderate Chop. A Chance Of Showers.
Friday Night...North Winds 5 To 10 Knots. Seas 2 To 3 Feet.
Saturday...East Northeast Winds 5 To 10 Knots Becoming East Southeast In The Afternoon. Seas 1 To 2 Feet.
Saturday Night...South Southeast Winds 15 To 20 Knots. Seas 2 To 3 Feet. A Chance Of Showers And A Slight Chance Of Thunderstorms.
Sunday...South Winds 15 To 20 Knots. Seas 3 To 5 Feet With Occasional Seas Up To 6 Feet. A Chance Of Showers And A Slight Chance Of Thunderstorms.
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AMZ400: Synopsis for Altamaha Sound GA to Flagler Beach FL out to 60 nm
938 AM EDT Wed Apr 8 2020

Long period northeast swells will subside tonight. Surface high pressure will remain south of the area through Thursday which will continue west-southwest winds for the area waters. An isolated thunderstorm will be possible this afternoon and evening. A cold front is forecast to move into the forecast area Thursday night and Friday with stronger northerly winds expected Friday. The cold front will lift back north as a warm front over the local area Saturday night.

Gulf Stream
The approximate location of the west wall of the Gulf Stream as of Apr 07, 2020 at 1200 UTC...
- 59 nautical miles east northeast of Flagler Beach.
- 63 nautical miles east of Saint Augustine Beach.
- 81 nautical miles east southeast of Jacksonville Beach.
- 103 nautical miles east southeast of St Simons Island.
Area Forecast Discussion
National Weather Service Jacksonville FL
108pm EDT Wednesday April 8 2020

Near Term - Through Tonight
The upper ridge centered over the Yucatan flattens as zonal flow develops aloft. Surface high pressure will remain south of the area resulting in west-southwesterly flow over the area. Deep layer west-southwesterly flow will advect warm, moist air into the region increasing PWATs (Precipitable Waters) to 1.9" and highs into the mid to upper 80s. A weak disturbance aloft moves through the Gulf states today into tonight. Scattered showers and thunderstorms will increase in coverage across southeast Georgia beginning this afternoon and spread southward toward the I-10 corridor of northeast Florida into the evening hours. With 0-6 km bulk shear of 45-55 kt and MUCAPE of 2000-25000 J/kg, an isolated strong to severe thunderstorm cannot be ruled out. The highest potential will be over southeast Georgia with locally damaging winds as the main threat.

.SHORT TERM [Thursday Through Friday]... Hot Thu with near record heat under breezy westerly flow as the pressure gradient strengthens ahead of a cold front. As the front slides across SE GA in the morning and approaches the I-10 corridor, expect a low chance of showers and potentially an isolated t'storm given limited deep layer moisture and weakening upper level forcing aloft but continued low level instability with surface based CAPEs near 1500-2000 J/kg. Focused the best rain chances near the I-10 corridor in the afternoon & evening, with resultant rainfall tracking eastward as the surface front settles south across NE FL Thu night. Cooler and stable northerly flow Thu night trailing the surface front, but rain chances increase toward sunrise Fri as PVA within the based of a long wave mid/upper level trough deepening across the eastern CONUS streams eastward across the Gulf Coast states. This mid/upper level lift combined with unseasonably high moisture (PWAT (Precipitable Water) 1-1.6" Fri) over stable surface conditions will bring a cool, rainy day through the day Fri with rainfall tapering off from north to south Fri afternoon into Fri evening as yet another surface cold front shifts across the local area as the upper level trough advances downstream. Much cooler and dry Fri night as surface high pressure builds north of the region, but conditions will become favorable for shallow ground fog through sunrise Sat morning as skies clear due to recent rainfall.

A temperature roller-coaster ride over this 48 hr period ranging from record warmth on Thu with highs in the 90s, then trailing the frontal passage Thu night highs will near 20 deg cooler Fri in the low 70s under cloudy skies and cool rain. Minimum temperatures will also plunge from the upper 60s to near 70 Thu morning, cooling into the mid 50s to low 60s Fri morning, then falling further into the mid 40s to low 50s inland by sunrise Sat.

Long Term - Saturday Through Wednesday
A progressive pattern as a brief cooler and dry pattern Sat yields to rain chances once again increasing Sat night into Sunday morning as a warm front lifts northward over the local area. There will be a chance of isolated embedded, elevated thunderstorms within lifting stratiform rainfall with warming temperatures Sunday as the entire forecast area within the warm sector. Strong warm air advection pattern returns Sunday under breezy SW winds as highs once again rise near 90 deg. Still some model timing differences with the timing of a pre-frontal squall line crosses the local area late Sunday into Monday which could produce a few strong to severe storms, then models do agree on the front stalling across the FL peninsula late Monday into Tuesday as yet a stronger upper level trough begins to deepen across the central CONUS. Temperatures will moderate over the weekend to near daily highs potentially again on Sunday across NE FL. Generally cooling trend back toward near to just below climo early next week with more cloudiness/convection.

Marine
Long period northeast swells subside tonight. Surface high pressure will remain south of the area through Thursday which will continue west-southwest winds for the area waters. An isolated thunderstorm will be possible this afternoon into evening for the coastal waters. A cold front is forecast to move into the forecast area by Thursday night and Friday with stronger northerly winds expected Friday. The cold front will lift back north as a warm front over the local area Saturday night.

Rip Currents
Moderate risk for NE FL and SE GA beaches today.

Fire Weather
Warmer, unstable, and more moist southwest flow develops today between high pressure south of the area and a front approaching from the north. Breezy WSW winds will gust near 20 mph by early afternoon with a weak east coast sea breeze pinned near the Atlantic coast due to stronger SW flow. Scattered showers and thunderstorms will increase in coverage across SE Georgia through midday with less coverage of showers and storms southward toward the I-10 corridor of NE Florida into the evening. Isolated shower and thunderstorm potential again on Thursday as yet another front slides south across the local area. Gusty WSW winds are expected expected Thu as highs warm into the 90s with high dispersion. Despite a low chance of rain, RHs will trend drier especially north of the I-10 corridor where minimum values will range near 40%.

Hydrology
A couple of gauges along the Atlantic coast have risen into Action Stage during high tide over the past 12-24 hours. Water levels continue to rise through the next couple of days with the peak of astronomical tidal rise tonight (April 8-9) coinciding with offshore flow with negligible 'surge' impact. Total astronomical tide inundation of 1-1.5 ft is possible per PETSS guidance. A Coastal Flood Statement continues today to account for nuisance flooding along the coast as water levels more uniformly rise into Action Stage.

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