Marine Weather Net

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


TONIGHT

NW
WINDS
5 - 10
KNOTS

TUESDAY

NE
WINDS
20 - 25
KNOTS

TUESDAY NIGHT

S
WINDS
10 - 15
KNOTS

WEDNESDAY

W
WINDS
15 - 20
KNOTS

The Marine Weather Forecast In Detail:
AMZ454 Forecast Issued: 834 PM EST Mon Mar 01 2021

SMALL CRAFT ADVISORY IN EFFECT FROM 4 AM EST TUESDAY THROUGH WEDNESDAY MORNING
Tonight...Northwest Winds 5 To 10 Knots Becoming North 10 To 15 Knots Late In The Evening, Then Increasing To 15 To 20 Knots After Midnight Becoming Northeast 20 To 25 Knots Late In The Night. Seas 3 To 4 Feet With A Dominant Period 9 Seconds. Rough On The Intracoastal Waters. Slight Chance Of Showers In The Evening. Chance Of Showers After Midnight.
Tuesday...Northeast Winds 20 To 25 Knots Diminishing To 15 To 20 Knots In The Afternoon. Seas 5 To 7 Feet With A Dominant Period 7 Seconds. Rough On The Intracoastal Waters. Showers Likely.
Tuesday Night...East Winds 15 To 20 Knots Becoming South 10 To 15 Knots After Midnight. Seas 5 To 7 Feet With A Dominant Period 8 Seconds. Choppy On The Intracoastal Waters. Patchy Fog. Showers And Slight Chance Of Thunderstorms.
Wednesday...West Winds 15 To 20 Knots Becoming Northwest In The Afternoon. Seas 4 To 6 Feet. Choppy On The Intracoastal Waters. Showers Likely And Slight Chance Of Thunderstorms In The Morning, Then Slight Chance Of Showers In The Afternoon.
Wednesday Night...North Winds 10 To 15 Knots. Seas 4 To 6 Feet. A Light Chop On The Intracoastal Waters.
Thursday...North Winds 10 To 15 Knots Becoming Northeast 5 To 10 Knots In The Afternoon. Seas 3 To 5 Feet. A Moderate Chop On The Intracoastal Waters.
Thursday Night...North Winds 5 To 10 Knots. Seas 3 To 4 Feet.
Friday...Northeast Winds 10 To 15 Knots. Seas 3 To 4 Feet.
Friday Night...Northeast Winds 10 To 15 Knots. Seas 3 To 4 Feet. Chance Of Showers.
Saturday...Northeast Winds 10 To 15 Knots Increasing To 15 To 20 Knots In The Afternoon. Seas 3 To 4 Feet. Showers Likely And Slight Chance Of Thunderstorms.
SHARE THIS PAGE:           
AMZ400: Synopsis for Altamaha Sound GA to Flagler Beach FL out to 60 nm
834 PM EST Mon Mar 1 2021

A cold front will shift southward over area waters tonight as high pressure wedges southward behind it along the Atlantic coast. A surge of northeasterly wind is expected as this occurs tonight, leading to hazardous Small Craft conditions. Winds will weaken as they veer southerly ahead of another cold front Tuesday night, then northerly behind the front Wednesday afternoon. With multiple frontal passages forecast over the next couple of days, periods of showers are expected over area waters through Wednesday morning. High pressure will build over the waters late this week ahead of another weather disturbance this weekend.

Gulf Stream
The approximate location of the west wall of the Gulf Stream as of Mar 02, 2021 at 1200 UTC...
- 66 nautical miles east of Flagler Beach.
- 75 nautical miles east of Saint Augustine Beach.
- 88 nautical miles east of Jacksonville Beach.
- 99 nautical miles east southeast of St Simons Island.
Area Forecast Discussion
National Weather Service Jacksonville FL
1255am EST Tuesday Mar 2 2021

Near Term - Through Tonight
A cold front has accelerated into SE GA early this afternoon and will continue to push south across NE FL through the evening hours. Ahead of the front, a weak prefrontal trough agitated a few showers late this morning, but this activity is not expected to continue and will subside through the afternoon as the cold front sinks southward. The bulk of shower activity, and an outside chance of a thunderstorm, will be focused along the front through the evening. The cold front will slow and stall across central FL tonight. Isentropic ascent downstream from an opening mid-level wave will increase shower coverage across SE GA through the overnight hours, while shower chances decrease across NE FL.

Behind the front, surface high pressure to our north will wedge southward along the First Coast tonight. As it does so, gradients will tighten and bring a surge of onshore/northeasterly flow. Short-lived and weak cold advection behind the front will lead to a cooler night compared to the last few, but readings will remain well-above normal. Lows will be the coolest across SE GA, in the lower 50s, and warm southward to the lower 60s north-central FL

Short Term - Tuesday Through Wednesday Night
The stalled front will remain to the south Tuesday morning, gradually becoming more diffuse, with onshore/easterly flow continuing under an extensive cloud cover. Meanwhile to the west, a cutoff low aloft will reemerge into the northern stream jet as it ejects northeastward into the Tennessee River valley, energizing a surface low over the northern Gulf. Low-level flow and surface winds will quickly veer southerly ahead of this feature, enhancing isentropic ascent over SE GA and lifting the stationary boundary to our south northward as a warm front. This will allow showers to persist over our GA zones throughout Tuesday, while coastal trough development will enhance shower chances over coastal areas. The aforementioned surface low will lift from the northeast Gulf across SE GA before consolidating/deepening along the Carolina coast Tuesday night. As this occurs, strong forcing for ascent will occur over the surface front, resulting in a heavy band of rainfall with embedded thunderstorms across the northern counties of SE GA, adjacent to the Altamaha River. Localized flooding will be possible with additional rainfall amounts of 1-2+ inches across portions of SE GA Tuesday night. Meanwhile, dry. A trailing cold front will shift across the entire forecast area from west to east on Wednesday, exiting into the Atlantic waters by the mid-afternoon. Scattered showers and potentially a few strong thunderstorms will accompany the front as it passes through the region. Winds will shift to the northwest behind the with skies gradually clearing from northwest to southeast behind the front Wednesday evening.

Highs will vary widely, with temps only reaching the mid 50s across SE GA where scattered showers and stratiform rain is expected. Most of NE FL will be on the cool-side of the stationary front, limiting highs to the low to mid 60s. Warmer temps, in the low 70s, are expected across north-central FL where more sunshine is expected to sneak through. Cloudy skies will continue ahead of the trailing cold front on Wednesday, with highs trending slightly warmer and occurring late morning prior to the frontal passage. Lows are expected to cool to near normal Wednesday night behind the front.

Long Term - Thursday Through Monday
Cool high pressure will expand across the eastern US on Thursday and Friday before another upper level cut-off swings into the early Saturday morning. This feature will bring a chance of rain back to the area Saturday as the associated surface low pivots across the FL peninsula. Slightly cooler than normal temperatures are expected late this week under clear skies, with a more robust cool down this weekend behind the aforementioned system.

Marine
A cold front will shift southward over area waters through this evening as high pressure wedges along the Atlantic coast. A surge of northeasterly wind is expected leading to hazardous Small Craft conditions, with winds 20-25 knots and gusts near 30 knots. Seas will eventually build 6-9 feet offshore and 5-7 feet near shore on Tuesday and remain elevated through early Wednesday day. Winds will weaken as they veer southerly ahead of another cold front Tuesday night, then northerly behind the front Wednesday afternoon. With multiple frontal passages forecast over the next couple of days, periods of showers are expected over area waters through Wednesday morning. High pressure will build over the waters late this week ahead of another weather disturbance this weekend.

Rip Currents
Moderate Risk through Today, increasing to High Risk on Tuesday with increasing onshore flow and rising seas.

Fire Weather
Scattered showers and slight chance of thunder will continue through the rest of the afternoon and into the early evening as a cold front continues to move south NE FL. Surface and transport winds will shift to the north then trend to the east-northeast through Tuesday while remaining 15-20 mph. Despite favorable transport, daytime dispersions will trend lower on Tuesday (30-50 units) as abundant cloud cover will limit heating and hamper mixing. Best rain chances will be across SE GA through Tuesday night before another cold front sweeps across the area Wednesday morning/early afternoon. While acceptable dispersion is expected ahead of the front, dispersion will trend toward critically low values behind the front on Wednesday, particularly across SE GA.

Hydrology


An inch or two of rainfall is forecast across SE GA through Wednesday evening, with totals below an inch anticipated in NE FL. Heavier rainfall in Georgia will prolong flooding along portions of the Altamaha, Satilla, and Alapaha Rivers. Rises continue along the Santa Fe River, with moderate flooding at the Three Rivers Estates gage continuing through early next week.

NOAA Jacksonville FL Office: Watches - Warnings - Advisories
FL...None. GA...None. AM...Small Craft Advisory from 4am early this morning to 10pm EST Wednesday for Waters from Altamaha Sound GA to Fernandina Beach FL from 20 to 60 NM-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 from 4am early this morning to 7am EST Wednesday for Coastal waters from Altamaha Sound to Fernandina Beach FL out 20 NM-Coastal waters from Fernandina Beach to St. Augustine FL out 20 NM-Coastal waters from St. Augustine to Flagler Beach FL out 20 NM.