Marine Weather Net

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


TONIGHT

S
WINDS
10 - 15
KNOTS

FRIDAY

S
WINDS
5 - 10
KNOTS

FRIDAY NIGHT

S
WINDS
10
KNOTS

SATURDAY

SE
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
AMZ472 Forecast Issued: 223 PM EDT Thu Aug 06 2020

Tonight...South Winds 10 To 15 Knots Diminishing To 5 To 10 Knots Towards Daybreak. Seas 3 Feet With A Dominant Period 8 Seconds. Slight Chance Of Showers And Thunderstorms.
Friday...South Winds 5 To 10 Knots. Seas 2 To 3 Feet With A Dominant Period 8 Seconds.
Friday Night...South Winds 10 Knots. Seas 3 Feet With A Dominant Period 9 Seconds. Slight Chance Of Showers And Thunderstorms.
Saturday...Southwest Winds 5 To 10 Knots Becoming Southeast 10 To 15 Knots In The Afternoon. Seas 2 To 3 Feet. Slight Chance Of Showers And Thunderstorms.
Saturday Night...South Winds 10 To 15 Knots. Seas 3 Feet. Slight Chance Of Showers And Thunderstorms In The Evening, Then Chance Of Showers And Thunderstorms After Midnight.
Sunday...Southwest Winds 5 To 10 Knots Becoming Southeast In The Afternoon. Seas 2 To 3 Feet. Slight Chance Of Showers And Thunderstorms.
Sunday Night...South Winds 10 To 15 Knots Becoming Southwest 5 To 10 Knots After Midnight. Seas 2 To 3 Feet. Slight Chance Of Showers And Thunderstorms.
Monday...Southwest Winds 5 To 10 Knots Becoming South In The Afternoon. Seas 2 Feet. Slight Chance Of Showers And Thunderstorms.
Monday Night...Southwest Winds 5 To 10 Knots. Seas 2 To 3 Feet. Slight Chance Of Showers And Thunderstorms.
Tuesday...Southwest Winds 5 To 10 Knots Becoming South In The Afternoon. Seas 2 To 3 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
223 PM EDT Thu Aug 6 2020

High pressure will extend across the Florida peninsula with surface troughs remaining north of the local waters. The Atlantic sea breeze will develop near the coast towards noon, resulting in onshore winds over the near shore waters each afternoon, followed by southerly evening wind surges each evening.

Gulf Stream
The approximate location of the west wall of the Gulf Stream as of Aug 06, 2020 at 1200 UTC...
- 65 nautical miles east of Flagler Beach.
- 72 nautical miles east of Saint Augustine Beach.
- 82 nautical miles east of Jacksonville Beach.
- 98 nautical miles east southeast of St Simons Island.
Area Forecast Discussion
National Weather Service Jacksonville FL
308pm EDT Thu August 6 2020

Near Term - Through Tonight
Afternoon convection continue over inland areas near both inland advancing sea breezes and along a SW-NE oriented boundary across SE GA. This activity will continue to expand in coverage northward across SE GA and between both sea breezes across NE Fl through early evening. High moisture content, slow SW storm motion near 10 kts, steeper mid level lapse rates and cooler mid level temps (500 mb -6.7 degC) all continued to support strong to pulse severe storm potential into the evening, especially across NE FL where boundary collisions will focus between Highway 301 and the St. Johns River basin. Storms will tend to drift back toward the Atlantic coast through 9-11 pm under light SW steering flow while fading in coverage and intensity as diurnal instability fades. Convection will continue over the Atlantic waters tonight and resurrect near the Gulf Coast region after 06z through sunrise possibly impacting parts of our Suwannee River Valley zones. Partly to mostly clear skies will develop after midnight with lingering debris clouds across the area.

Muggy, mild lows will trend above normal in the mid 70s inland to upper 70s coast with possibly some shallow ground fog where heavy rainfall recently fell.

.SHORT TERM [Friday Through Sunday]... Synopsis...Dog days of summer are here - hot, sticky with mainly afternoon & early evening t'storms.

Deep tropical moisture with precipitable water (PWAT) above climo (1.8"+) will linger across NE FL and eastern parts of SE GA (generally east of Waycross) into the weekend as a mean layer 1000-500 mb ridge strengthens westward from the central Atlantic with a ridge axis across south FL Friday pivoting northward across central FL through Sunday. This will keep frontal systems well north and west of the region and favors active diurnally enhanced sea breezes over the FL peninsula and parts of SE GA, with lower rain chances across our inland GA zones from roughly Jesup toward Pearson Sat/Sunday due to drier air (PWAT (Precipitable Water) < 1.6"). SW steering flow will be light (< 10 kts) with the ridge axis building northward toward the local area. This regime favors morning convection near the Gulf Coast drifting slowly inland through mid-morning but generally remaining west of the I-75 corridor. By midday as convective temps are achieved, more 'pop-corn' airmass showers will begin to Probability of Precipitation inland with tstorm potential increasing along the slight strong west coast sea breeze as it begins to press inland and along near the slowly inland progressing east coast sea breeze. Sea breeze and outflow boundary mergers will focus across the interior of the forecast area each afternoon and early evening generally between I-75 and St. Johns River basin/Highway 301 for SE GA, with a slightly drift back toward the east coast under mean layer SW flow. Convection will fade through 9-11p each evening with just a rogue shower overnight mainly near the Gulf Coast region due to such a saturated airmass.

Main tstorm hazard this period will be locally heavy, potentially briefly flooding rainfall due to such high atmospheric moisture content and slow, erratic storm motion along boundary mergers. Does not appear to be as much hail potential into the weekend compared to the past few days due to weaker mid/upper level winds as the ridge builds northward over the FL peninsula and the moisture profile deepens. However, cool near to just below normal 500 mb temps of -6 to -7 and hot low levels will create steeper low level lapse rates so a few strong to pulse severe storms will still be possible in the afternoon into the early evening where boundary mergers occur, with wet downburst winds capable of outflow gusts of 40-60 mph.

Above normal temperatures expected as mean layer ridging strengthens over the FL peninsula. Highs will range in the low/mid 90s inland to near 90 coast before the east coast sea breeze advances inland. Sticky dew pts in the mid/upper 70s combined with the dry bulb temps will create heat index values of 105-110 degF. Nighttime lows will trend above normal as well in the mid/upper 70s for most areas.

.LONG TERM [Monday Through Thursday]... Light SSW steering flow continues as the the mean layer 1000-500 mb ridge axis lifts from central FL Monday to across north FL Wednesday with high atmospheric moisture (PWATs (Precipitable Waters) over 2") edging northward, blanketing SE GA and NE FL. This will bring elevated rain chances across the entire CWA with convection mainly driven by sea breeze and outflow boundary intersections. Thu through the end of the week a pattern shift is advertised with a more dominant east coast sea breeze regime as the mean layer ridge lifts across SE GA where the higher PWAT (Precipitable Water) plume will linger and favor elevated rain chances, while lower rain chances are expected south of the ridge axis across much of NE FL where PWATs (Precipitable Waters) are expected to fall below normal and a dominant east coast sea breeze regime will be favored. This set-up will bring morning coastal showers and possibly a tstorm toward the Atlantic coast, then clearing from the east into the afternoon with the focus for afternoon/evening storms inland across the Suwannee River Valley and SE GA.

Temperatures expected to trend near to slightly above normal.

Marine
High pressure will extend across the Florida peninsula with surface troughs remaining north of the local waters. This weather pattern will produce prevailing south-southwesterly winds through much of the forecast period until the east coast sea breeze develops along the coast around midday each day which will back winds onshore and increase speeds to near 10-15 kts. Combined seas will will continue near 2-4 ft. Scattered showers and thunderstorms possible each period.

Rip Currents
Low to moderate risk expected into the weekend.

Fire Weather
Low daytime dispersion today (< 20 units) and most of NE FL Fri due to light transport winds.

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