Marine Weather Net

Straits of Florida from west end of Seven Mile Bridge to south of Halfmoon Shoal out 20 NM Marine Forecast


TONIGHT

NW
WINDS
10
KNOTS

TUESDAY AND TUESDAY NIGHT

NNW
WINDS
10 - 15
KNOTS

WEDNESDAY AND WEDNESDAY NIGHT

NNE
WINDS
10 - 15
KNOTS

THURSDAY

ENE
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
GMZ054 Forecast Issued: 431 PM EST Mon Nov 18 2019

Tonight...Northwest Winds Near 10 Knots. Seas 2 To 3 Feet. Isolated Showers.
Tuesday And Tuesday Night...Northwest To North Winds 10 To 15 Knots. Seas 2 To 4 Feet.
Wednesday And Wednesday Night...North To Northeast Winds 10 To 15 Knots. Seas 2 To 4 Feet.
Thursday...Northeast To East Winds 10 To 15 Knots. Seas 2 To 4 Feet.
Thursday Night...East Winds 10 To 15 Knots. Seas 2 To 4 Feet.
Friday And Friday Night...East Winds 10 To 15 Knots. Seas 2 To 4 Feet.
Saturday And Saturday Night...Southeast To South Winds 5 To 10 Knots. Seas 1 To 3 Feet. Isolated Showers.
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Synopsis for Keys coastal waters from Ocean Reef to Dry Tortugas: GMZ005
431 PM EST Mon Nov 18 2019

High pressure over Texas will move slowly eastward tonight, reaching the Carolinas by Thursday, then the western Atlantic on Thursday night. The high will stretch out into an east west ridge axis over the Florida Peninsula Thursday Night through Friday Night, then weaken this weekend.

Gulf Stream
The Approximate Shoreward Edge of the Gulf Stream as of November 16...
- 56 NM South of Dry Tortugas Light...on Loggerhead Key.
- 38 NM South of Cosgrove Shoal Light...off the Marquesas Keys.
- 33 NM South of Sand Key Light...off Key West.
- 25 NM South of Looe Key...off Big Pine Key.
- 15 NM South of Sombrero Key Light...off Marathon. Less than
- 1 NM Southeast of Alligator Reef Light...off Islamorada.
- 1 NM Southeast of Molasses Reef Light...off Key Largo.
- 1 NM East of Carysfort Reef Light...off Ocean Reef.
Area Forecast Discussion
National Weather Service Key West FL
330pm EST Monday Nov 18 2019

In the middle and upper levels(700-200 mb), latest available satellite imagery overlaid with model streamline analysis as of 200 pm, depicts middle and upper ridging across the Western third of the CONUS, while downstream exists a large middle and upper gyre, with a well defined negatively tilted axis in place from Northern Michigan south southeast to the upland of South Carolina. Hence, at our Keys latitude, 50 to 75 knot west northwesterlies at 250 mb, within the southern end of the deep cyclonic flow were streaming southeast from Texas to across the breadth of the Gulf to over South Florida and the Keys.

At the surface and in the lower to middle levels, latest available marine and land surface observations and analysis detail a 1020 mb surface ridge centered over the Rio Grande Valley. East of that, a weaker cold front than as of late extends from low pressure near Lake Superior south to Louisiana. Well to the east of that, the 996-998 mb centers of an ocean storm are associated with a gale on the NE side, and located several hundred miles east of the Delmarva. The Keys are in a light to gentle northwest flow.

As of 200 pm, locally a few sprinkles are leftover to the west and northwest of the Keys, with partly cloudy to mostly sunny skies across the Keys and immediate surrounding waters. Temperatures across the islands have reached the lower to middle 70s across the islands with dewpoints in the lower 60s. C-man stations along the Florida Reef are light to gentle between west northwest and north northwest.

Short Term
Tonight thru Friday, the upcoming week will feature slightly lower normal temperatures and dewpoints than normal which will make it fee very comfortable. Surface ridging over SE TX this afternoon will take its time to move east near the Northern Gulf coast for tonight, reaching the Carolinas by Thursday evening then offshore Thursday night and Friday. As such, light to gentle winds will stay backed between northwest and north until Tuesday night, then only between north and northeast thru Wednesday night, before more Northeasterly Thursday thru Friday. This means that high and low temperatures will continue to only reach the mid to high 70s with lows in the mid to high 60s which is a few degrees below the normal highs of 80 and 71 respectively, which will occur by Friday as mentioned above, when the low level flow returns more to Northeasterly.

The only slight chance for showers would occur tonight as a weak lingering impulse to our west may deliver a few more sprinkles or light showers. As such, just a dime Probability of Precipitation is in the grids tonight with no chances for measurable rain Tuesday thru Friday.

Long Term
The high center mentioned above will move offshore Friday night and elongate into an east to west ridge across Florida, before weakening a bit for Saturday and Saturday Night. Another weak cold front will approach the Keys Saturday Night and Sunday before moving across the islands late Sunday/Sunday night. It looks to be moisture starved at this point. For now will just maintain 10 percent probability of precipitation thru this entire periods for now. High around 80 with lows near 70.

Marine
A SCEC for seas will continue across the Easternmost Straits for tonight. No headlines or advisories are anticipated thereafter.

NOAA Key West FL Office: Watches - Warnings - Advisories
FL...None. GM...None.