Marine Weather Net

Biscayne Bay Marine Forecast


15 - 20


15 - 20


10 - 15


10 - 15

The Marine Weather Forecast In Detail:
AMZ630 Forecast Issued: 337 PM EDT Mon Sep 21 2020

Tonight...East Northeast Winds 15 To 20 Knots With Gusts To Around 30 Knots. Bay Waters Choppy. Chance Of Showers And Slight Chance Of Thunderstorms In The Evening, Then Slight Chance Of Showers After Midnight.
Tuesday...East Northeast Winds 15 To 20 Knots With Gusts To Around 25 Knots. Bay Waters Choppy. Slight Chance Of Showers.
Tuesday Night...East Northeast Winds 10 To 15 Knots With Gusts To Around 20 Knots. Bay Waters A Moderate Chop. Slight Chance Of Showers In The Evening.
Wednesday...East Winds 10 To 15 Knots. Bay Waters A Moderate Chop. Slight Chance Of Showers In The Afternoon.
Wednesday Night...East Winds 10 To 15 Knots. Bay Waters A Moderate Chop. Chance Of Showers In The Evening, Then Slight Chance Of Showers After Midnight.
Thursday...East Southeast Winds 10 To 15 Knots With Gusts To Around 20 Knots. Bay Waters A Moderate Chop. Chance Of Showers
Thursday Night...Southeast Winds Around 10 Knots. Bay Waters A Light Chop. Chance Of Showers And Thunderstorms.
Friday...South Southeast Winds 5 To 10 Knots. Bay Waters A Light Chop. Chance Of Thunderstorms In The Morning. Showers Likely. Thunderstorms Likely In The Afternoon.
Friday Night...Southeast Winds 5 To 10 Knots. Bay Waters A Light Chop. Chance Of Showers And Thunderstorms.
Saturday...Southeast Winds 5 To 10 Knots. Bay Waters A Light Chop. Chance Of Showers And Thunderstorms.
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AMZ600: Synopsis for Jupiter Inlet to Ocean Reef FL out to 60 nm and for East Cape Sable to Bonita Beach FL out to 60 nm
337 PM EDT Mon Sep 21 2020

A frontal boundary will continue to move through the local waters for the rest of this afternoon. The northeasterly winds will continue to increase tonight behind the frontal boundary. A gale warning remains in effect through the evening hours for the Atlantic waters while a small craft advisory remains in effect for all waters through Tuesday. In addition, northeasterly swells from Hurricane Teddy will add to the hazardous marine conditions in the Atlantic waters through the middle of the week before beginning to subside by the end of the week.

Gulf Stream Hazards: Hazardous marine conditions expected with increasing swells and northeasterly winds.
The approximate location of the west wall of the Gulf Stream as of Sep 19, 2020 at 1200 UTC...
- 3 nautical miles northeast of Fowey Rocks.
- 12 nautical miles east northeast of Port Everglades.
- 7 nautical miles east northeast of Lake Worth.
- 9 nautical miles east southeast of Jupiter Inlet.
Area Forecast Discussion
National Weather Service Miami FL
730pm EDT Monday September 21 2020

.Aviation... VFR conditions will prevail throughout the forecast period. Winds will remain gusty overnight into Tuesday out of the northeast. A drier air mass will work into the region during the overnight hours into Tuesday. An isolated fast moving shower is possible across the east coast terminals on Tuesday, however, confidence is too low to put in TAFS (Terminal Aerodrome Forecasts) at this time.

A drier air mass is beginning to filter into South Florida as an area of high pressure moves into the region from the north. There will be a few leftover showers this evening mainly across the eastern and southern areas as the frontal boundary continues to move southward into the Florida Straits. Many areas will remain dry overnight, however, winds will continue to be gusty out of the northeast across the region. The gusty conditions will continue across South Florida on Tuesday and there will be a slight chance of fast moving showers mainly across the eastern half of South Florida throughout the day. High temperatures will generally remain in the mid to upper 80s across the east coast metro areas to around 90 across the interior sections.

.Prev /issued 338pm EDT Monday September 21 2020/

..Heavy Rainfall/Localized Flooding Possible Over East Coast Areas... ..Hazardous Marine Conditions Due to High Winds/Waves... Short Term (Now through Tuesday)... Convection continues to develop over the Atlantic waters/metros in association with a vigorous shortwave trough/frontal boundary. This shortwave impulse is inducing a convergent, cyclonic low-level response in the wind field, which is allowing showers/t-storms to develop where localized moisture convergence is maximized. Areas where banding becomes quasi-stationary will have to be monitored for localized flooding potential, as this morning's environment is indicative of efficient, tropical rainfall processes, with PWI (precipitable water indices) roughly 2.4 ins and a tall, narrow CAPE profile. Furthermore, modest 0-3km bulk shear is present (on the order of roughly 15 kts), particularly along the coast, and effective SRH (storm relative helicity) on the order of 50-100 m2/s2 extending further inland. So the environment may be conducive for waterspout development along the offshore/nearshore waters where favorable parameters overlap a robust storm environment. This is an additional concern to monitor near the Atlantic coastline this morning and into early parts of the afternoon.

As this impulse treks southward, the foci for convective development will also drift southerly. Activity should wane across much of the region, and any isolated/scattered convection that does develop will generally be over the Atlantic waters. This is reflected in the latest forecast for Tuesday, with Probability of Precipitation no greater than 30 across the entire region. As the backdoor front continues its southerly progression, broad differential anticyclonic vorticity advection will induce synoptic scale subsidence, and the environment appears to dry out quite a bit, with most model guidance hinting at PWI < 1.2 ins. This should suppress widespread storm activity Tuesday, and any showers/storms that do develop will be relatively benign in nature, owing to a hostile synoptic scale environment.

Temperatures will be seasonably cooler today and Tuesday, in association with the passing modified cold front. High temperatures will be in the mid to upper 80s across the region, with a higher trend in temperatures towards the Gulf coast region. Dewpoints will modestly decrease Tuesday as well in association with the passing front, making for a more pleasant day overall; heat indices should generally be in the upper 80s/lower 90s across the region tomorrow.

Long Term - Tuesday Night through Sunday
With the frontal boundary remaining south at the start of the long term period, dry air aloft (and modestly dry air at the surface) will remain over the region. This will limit the overall rain chances Tuesday night perhaps into Wednesday. That said, some isolated showers may still be possible from time to time, especially across the waters where the better boundary layer moisture interacts with a lingering density frontal boundary across the region.

Going into midweek the surface front/trough begins to lift northward again as the upper level flow patterns begins to transition to a southwesterly flow (albeit weak) in time. Models show an open surface trough or perhaps a weak low pressure developing within the decayed surface frontal boundary. This feature will bump rain chances back up Thursday and into Friday...continuing into the upcoming weekend. Some heavy rain and additional hydro concerns may arise given increase in tropical moisture. In fact, medium range guidance show PWATs (Precipitable Waters) well above 2" across much of the area late this week. The aforementioned trough/low and supportive synoptic flow late this week will help enhance daily sea breeze activity, again leading to higher POPs. Eventually the synoptic flow begins to transition as a weak H5 ridge sets up over the area going into Saturday and Sunday, however, diurnally driven convection will still be likely during the afternoon hours, especially across the interior and Atlantic coast to round out the long term.

Marine... Increasing gradient flow behind the frontal boundary and Atlantic swell from Hurricane Teddy will create hazardous marine conditions through the next few days. Frequent gusts to gale force are anticipated over the Atlantic waters through tonight, and isolated gale force gusts are possible over the Gulf waters tonight. A Gale Warning/Watch is in place for the Atlantic/Gulf waters respectively, with both hazards active until 06Z. An upgrade from watch to warning may be necessary for the Gulf waters, but will update and monitor based on latest trends/conditions in the evening. Hazardous marine conditions may linger a bit longer in the Atlantic waters due to incoming swell.

Aviation (18z TAFs)... Mixed periods of VFR/MVFR (Marginal Visual Flight Rules) through this afternoon, as a backdoor frontal boundary approaches area. Intermittent periods of IFR/LIFR possible, as intense tropical rain-rates reduce VIS and lower CIGs within ongoing convection. Activity should trend downward towards ISLD/SCT convection this evening, waning by roughly 20-22Z as front moves south. Winds generally NE/ENE with gusts near 30kts, though ISLD higher gusts possible over waters. Localized LLWS possible, however does not merit including in latest TAF pkg.

Beach Forecast... The risk of rip currents along the Atlantic beaches will remain elevated through the week and potentially into the weekend, owing to strong gradient flow oriented somewhat perpendicular to the coastline. Therefore, the High Risk of Rip Currents will remain along east coast beaches of South Florida.

High surf along the Palm Beaches is expected to persist into at least Wednesday with beach erosion also a concern, due to Northeast Swells coming from Hurricane Teddy.

Astronomically high tides are beginning to decrease as we pull away from the new moon phase, but the persistent northeasterly wind flow and swell are still producing elevated high tide cycles along the Atlantic coast in the 1.5 to 1.7 feet MHHW neighborhood. With that being near the point where moderate flooding impacts are possible, a Coastal Flood Advisory remains in effect through Tuesday.

NOAA Miami FL Office: Watches - Warnings - Advisories
FL...High Rip Current Risk through Friday evening for FLZ168.

High Surf Advisory until 8pm EDT Wednesday for FLZ168.

Coastal Flood Advisory until 8pm EDT Tuesday for FLZ168-172-173.

Wind Advisory until 2am EDT Tuesday for FLZ168-172-173.

High Rip Current Risk through Thursday evening for FLZ172-173.

AM...Small Craft Advisory until 8pm EDT Tuesday for AMZ610-630.

Small Craft Advisory from 2am Tuesday to 8pm EDT Wednesday for AMZ651-671.

Gale Warning until 2am EDT Tuesday for AMZ650-651-670-671.

Small Craft Advisory from 2am Tuesday to 8pm EDT Thursday for AMZ650-670.

GM...Small Craft Advisory until 8pm EDT Tuesday for GMZ656-657-676.

Update...55/CWC Aviation...55/CWC