Marine Weather Net

Volusia-Brevard County Line to Sebastian Inlet 20 - 60 NM Marine Forecast


TODAY

W
WINDS
5 - 10
KNOTS

TONIGHT

N
WINDS
10 - 15
KNOTS

FRIDAY

N
WINDS
10
KNOTS

FRIDAY NIGHT

NE
WINDS
5 - 10
KNOTS

The Marine Weather Forecast In Detail:
AMZ572 Forecast Issued: 322 AM EDT Thu Sep 23 2021

SMALL CRAFT SHOULD EXERCISE CAUTION
Today...West Winds 5 To 10 Knots Becoming North 15 Knots In The Late Morning, Then Increasing 15 To 20 Knots In The Afternoon. Seas 3 To 5 Feet With A Dominant Period 10 Seconds. Slight Chance Of Thunderstorms In The Morning. Chance Of Showers. Chance Of Thunderstorms In The Afternoon.
Tonight...North Winds 10 To 15 Knots Diminishing To 5 To 10 Knots After Midnight. Seas 4 To 6 Feet With A Dominant Period 9 Seconds. Chance Of Showers And Thunderstorms.
Friday...North Winds 10 Knots. Seas 4 To 5 Feet With A Dominant Period 9 Seconds. Chance Of Showers And Slight Chance Of Thunderstorms.
Friday Night...Northeast Winds 5 To 10 Knots. Seas 3 To 4 Feet. Slight Chance Of Showers And Thunderstorms.
Saturday...North Winds 5 To 10 Knots. Seas 3 To 4 Feet. Slight Chance Of Showers And Thunderstorms.
Saturday Night...Northeast Winds 5 To 10 Knots. Seas 4 Feet.
Sunday...North Winds 10 Knots. Seas 3 To 4 Feet.
Sunday Night...Northeast Winds 5 To 10 Knots. Seas 4 Feet.
Monday...Northeast Winds 10 Knots. Seas 3 Feet.
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Synopsis for Atlantic coastal waters from Flagler Beach to Jupiter Inlet out 60 nm - AMZ500
322 AM EDT Thu Sep 23 2021

Boating conditions will deteriorate today across the northern and central waters as a surge of north winds develops behind a cold front. Winds and seas gradually diminish Friday into the weekend as winds veer northeast. Numerous showers and storms likely over the local waters south of the Cape through Saturday, then drier conditions Sunday into early next week.

Gulf Stream Hazards: North winds increasing 15 to 20 knots north of Sebastian Inlet today. Seas building to 6 feet well offshore late today into tonight.
The approximate location of the west wall of the Gulf Stream based on the Real Time Ocean Forecast System as of Wednesday, September 22nd.
42 nautical miles east of Ponce Inlet.
28 nautical miles east of Port Canaveral.
23 nautical miles east of Sebastian Inlet.
16 nautical miles east of Fort Pierce Inlet. 9 nautical miles east of Saint Lucie Inlet.
Area Forecast Discussion
National Weather Service Melbourne FL
450am EDT Thu September 23 2021

Today...An early autumn cold front is pushing into central FL this morning but it will slow down and temporarily stall across our southern counties by tonight. A wind shift out of the north will occur before sunrise from Orlando/Titusville northward along with some stratus, then reach Melbourne/Palm Bay by mid morning. A light shower or sprinkle is possible but most areas will remain dry. Ahead of the front, patchy dense fog will affect portions of Okeechobee to the Treasure coast through early morning.

Drier air will filter into northern sections but high PWATs (Precipitable Waters) will remain across the south. This will produce a tight gradient of rain/thunder chances ranging from 10 percent across the far north to 70 percent across the Treasure coast counties. Once the stratus and fog lift to the south, there will be opportunity for heating along with sea/lake breeze boundaries interacting with the cool front this afternoon and early evening. A few strong storms may result, containing frequent lightning strikes and gusty winds. Numerous boundary collisions may be able to locally maximize low level shear and produce storm rotation. Another concern will be heavy rain that accumulates 1-3 inches in a short period of time. Standing water will develop quickly where recent heavy rains have occurred.

Tonight...The storms should linger into the early evening across the south then dissipate. With the front expected to stall across the treasure coast, there is a chance that one or two bands of rain may set up from the Atlantic and across portions of the Saint Lucie or Martin coasts overnight. The onshore flow does not look strong and the NE trajectory is not the most favorable but moisture will remain plentiful. So will keep a small Probability of Precipitation along the Treasure coast overnight. Min temps should drop into the upper 60s across Lake and Volusia counties with some mid 60s in rural locations. Elsewhere, mins will be around 70/lower 70s.

Friday...The cold front that moved into Central FL on Thursday will stall across our area on Friday, with the bulk of deep moisture located south of a line from Titusville to Tampa. The highest rain chances will focus along the Treasure Coast and Okeechobee County, where there is a 50-70 percent chance of showers/storms, with decreasing coverage to the north. Areas north of I-4 are forecast to remain dry. There could end up being a tight moisture gradient, meaning areas as far south as the Space Coast might not see much in the way of shower/storm activity. This will depend on how far south the drier air can make it before the front stalls, the GFS is more bullish with this, while the ECMWF/CMC/NAM keep drier air along and north of a line from Kissimmee to Titusville.

Afternoon temps reach around 90 degrees, though it should feel better for northern areas where low 60s dew points will be present, and sultry for southern areas with dew points in the low/mid 70s. Scattered showers and a few storms could linger along the Treasure Coast into the evening before dissipating. Friday night temps drop into the low/mid 70s, with upper 60s possible in rural areas of northern Lake and northwest Volusia Counties.

Saturday...The weekend starts of wet for the far southern areas as the stalled front remains, with high rain chances (50-60 percent) from Okeechobee to PSL southward. The good news is that the dry air is expected to shift south, eliminating rain chances from Kissimmee to Titusville northward, and only a low chance of rain (20 percent) for the rest of Brevard/Osceola counties. Again, this will all depend on how far south the initial surge of dry air makes it, with a tight moisture gradient likely to still be in place making the rainfall forecast difficult and uncertain.

Sunday-Wednesday...A large upper-level trough will move across the eastern CONUS on Sunday causing a reinforcing cold front to move through Central FL Sunday afternoon. While no temperature changes occur, this frontal passage will bring in much drier air and push out any lingering moisture/shower activity. High pressure builds across the Southeastern U.S. giving us a period of mostly dry conditions Monday and Tuesday, as only a marginal 15-20 percent chance of rain exists across the southern areas each afternoon. Moisture increases slightly Wednesday, as low 70s dew points with scattered showers and isolated storms return to the forecast.

Highs each afternoon will reach the upper 80s to around 90 degrees, but with dew points in the 60s it will be a manageable heat through mid week. Morning lows Monday/Tuesday in the upper 60s to around 70 degrees for inland areas, and low 70s along the coast.

Marine
Today/tonight...A cool front is pushing into central FL and the adjacent Atlantic waters this morning. Boating conditions will deteriorate behind the front as north winds increase 15-20 knots first across the Volusia waters this morning then the Brevard waters by afternoon. So have raised a Caution there for both nearshore and offshore. Seas will build 4 to 5 feet, and up to 6 feet well offshore in the Gulf Stream. The front is forecast to stall across the southern waters late today and tonight so winds there will be W/SW 5-10 knots this morning becoming north 10 knots late today and tonight. Seas 2-3 ft then building 4-5 ft in the gulf stream tonight. The bigger concern south of the Cape will be the high coverage of showers and storms this afternoon and early eve. Then a small band of showers may develop overnight from the Atlc and affect portions of the Treasure coast where the front will be stalled.

Friday-Monday...A cold front is expected to stall south of the Cape on Friday and Saturday, with numerous afternoon showers and lightning storms expected south of the front. Dry conditions will be present north of the frontal boundary. North to northeast winds around 10-15 knots through Saturday night, before diminishing to near 10 knots Sunday. A reinforcing front will cross the local area on Sunday afternoon, ushering in mostly dry conditions through he start of next week.

On Friday seas will be 3-4 feet nearshore and up to 5 feet offshore north of Sebastian Inlet. For this weekend seas around 3-4 feet, then becoming around 3 feet on Monday.

Hydrology
The St. Johns River at Astor/ASTF1 is forecast to hover at or near Minor Flood Stage (2.3ft) through the weekend as a period of north winds should keep the water level higher there. At Geneva above Lake Harney/GENF1, the river crossed into Action Stage earlier tonight and is forecast to crest at 6.5ft this weekend which is below Flood stage.

NOAA Melbourne FL Office: Watches - Warnings - Advisories
FL...None. AM...None.