Thursday, December12, 2019
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Marine Weather and Tides
St. Simons, GA

Version 3.4
NOTICE
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.
6/2/2019. Many thanks to a user for reporting an error on one of the Edit pages. The switch to PHP 7.2 caused many pages that previously worked to quit working. I fixed many but I still depend on users to report ones I missed. Please report errors HERE or send an email to me at L-36.com. Allen

Sunrise 7:13AMSunset 5:25PM Thursday December 12, 2019 11:45 PM EST (04:45 UTC) Moonrise 6:01PMMoonset 7:32AM Illumination 98% Phase: Waning Gibbous; Moon at 16 days in cycle
NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.
Marine Forecasts
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AMZ450 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- 909 Pm Est Thu Dec 12 2019
.small craft advisory in effect until 8 am est Friday...
Rest of tonight..East winds 15 to 20 knots. Seas 6 to 8 feet with occasional seas up to 10 feet. Dominant period 9 seconds. Inland waters a moderate chop. Showers and a slight chance of Thunderstorms.
Friday..South winds 5 to 10 knots. Seas 4 to 6 feet with occasional seas up to 8 feet. Dominant period 9 seconds. Inland waters a light chop. Showers and a chance of Thunderstorms.
Friday night..Southwest winds 10 to 15 knots. Seas 3 to 5 feet with occasional seas up to 6 feet. Dominant period 8 seconds. Inland waters a light chop. Showers likely and a chance of Thunderstorms.
Saturday..West winds 15 to 20 knots. Seas 3 to 5 feet with occasional seas up to 6 feet. Dominant period 9 seconds. Inland waters a moderate chop. A chance of showers.
Saturday night..Northwest winds 10 to 15 knots. Seas 2 to 4 feet. Dominant period 9 seconds. Inland waters a moderate chop.
Sunday..North northwest winds 5 to 10 knots becoming east northeast in the afternoon. Seas 2 to 4 feet. Dominant period 9 seconds. Inland waters smooth.
Sunday night..Southeast winds around 5 knots. Seas 2 to 3 feet.
Monday..South southeast winds 5 to 10 knots. Seas 2 to 4 feet.
Monday night..South winds 10 to 15 knots. Seas 2 to 4 feet. A slight chance of showers.
Tuesday..Southwest winds 5 to 10 knots. Seas 2 to 4 feet. Showers likely.
AMZ400 Synopsis For Altamaha Sound Ga To Flagler Beach Fl Out To 60 Nm- 909 Pm Est Thu Dec 12 2019
Synopsis.. The tight pressure gradient in place is still enough to produce winds of 15 to 20 knots near shore and 20 to 25 knots offshore through the night. Though these winds will subside by Friday afternoon, showers and Thunderstorms are expected to be on and off through Saturday morning, some of which could bring gusty winds. The cold front behind these storms will move through Saturday morning, which will cause winds and waves to surge again. Another small craft advisory may be needed this weekend, at least for the offshore waters. After that, high pressure will build in over the coastal waters early next week.
Gulf stream.. The approximate location of the west wall of the gulf stream as of dec 12, 2019 at 1200 utc... 64 nautical miles east northeast of flagler beach. 64 nautical miles east northeast of saint augustine beach. 71 nautical miles east of jacksonville beach. 99 nautical miles east of st simons island. This data courtesy of the naval oceanographic office.


7 Day Forecast for Marine Location Near St. Simons, GA
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location: 31.13, -81.39     debug


Area Discussion for - Jacksonville, FL
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FXUS62 KJAX 130210 AFDJAX

Area Forecast Discussion National Weather Service Jacksonville FL 910 PM EST Thu Dec 12 2019

UPDATE.

Inverted surface trough remains parked over the offshore marine coastal zones this evening. Said feature has relaxed the pressure gradient but winds still 15 to 25 mph near the coast. Offshore buoys reporting 25 knots. Small craft advisories remain in effect for coastal and offshore marine zones. High rip current risk for GA/FL beaches and High Surf Advisory for FL beaches extended through Friday morning. Precipitation coverage has been rather mute for much of the day, but radar composite showing uptick in coverage along the Florida coastal zones this evening where strong moisture flux convergence occurring. Additional light showers associated with a weak mid level shortwave were located across SE GA near Hazlehurst. Large north-south temperature gradient with upper 40s at Alma to the mid 60s at Ocala currently.

Offshore inverted trough will merge with developing warm front across central Florida tonight. Warm front expected to lift into northeast FL by 12z Friday. Isentropic lift (295-300K) very impressive areawide, shifting northward into SE GA Friday morning. 1-2 inches of rain possible for SE GA/NE FL coastal counties with lessor amounts inland. Another shortwave embedded in southwest flow aloft overrides this activity mainly after 06z, enhancing rainfall potential. Thunderstorm potential mainly confined to FL coastal zones and adjacent Atlantic waters where GFS CAPE values are forecast near 1500 J/Kg. Temperatures tonight will hold steady or climb a few degrees.

PREV DISCUSSION [700 PM EST].

NEAR TERM [Through Tonight].

Into the afternoon, a coastal trough/pseudo warm front will continue to develop along the FL Atlantic coast. As this inverted trough amplifies, it will weaken the local pressure gradient along the NE FL coast so expect a gradual decrease of the winds. As the coastal trough forms along the NE FL coast this afternoon, plentiful low level moisture combined with onshore convergence under SW flow aloft will start a coastal rainfall event that is expected to increase in intensity overnight as a yet another strong short wave trough overrides this activity from the GOMEX with locally heavy rainfall potential. Stable conditions prevail today so thunderstorms are not expected, but a low chance of tstorms will develop tonight and and trailing the lift warm front, mainly over the Atlantic waters and possibly the immediate coast.

Cloudy skies and cool NE flow will trend temperatures below normal across SE GA where highs will only reach the mid/upper 50s. Temperatures moderate southward across NE FL to warm into the low/mid 60s near the I-10 corridor and along the Atlantic coast, to upper 60s possibly near 70 southward and inland toward Gainesville and Ocala where there will be the potential for some cloud breaks.

SHORT TERM [Friday Through Saturday Night].

Strong isentropic lift ahead of the approaching inverted trough will likely work to keep low level cloud cover in place through Friday morning, keeping us stable, but also soggy. The approaching inverted trough however, will continue to deepen Friday as it sweeps eastward thanks to an upper level shortwave punching into the northern Gulf waters by the afternoon hours. As this deepening system swings eastward towards us Friday afternoon, a coastal warm front will lift through the FL Peninsula into southern GA and advect in warm, moist air, destabilizing us enough to see thunderstorms in NE FL, possibly into SE GA as well. Model PW values over 1.5" and moderate mid-level lapse rates (around 6 C/km) suggest good rain production along/ahead of this warm front, so its forward speed will affect how much we accumulate (the slower it lifts, the more rain we'll get), but latest forecast estimates are around 1-2" along coastal NE FL and into SE GA, less than 1" further south/west.

As we move into the evening and overnight hours and the deepening low and its associated cold front begin to near our western border/the Suwannee River, deep layer (0-6km) shear will increase, posing a marginal threat for severe weather. In the afternoon hours, when we'd have more instability to tap into, deep layer shear will be around 30-35 kts. This wouldn't lead to a lot of organized storms, but could allow for some gusty afternoon thunderstorms. As the low pressure system moves eastward in the overnight hours, these shear values will increase to 40-50 kts. Enhanced lift from divergence aloft may be enough to develop a few more potent storms overnight.

The cold front will move across the area Saturday morning, then high pressure will begin to build over the area Saturday afternoon and night. Temperatures will be near to slightly above normal, with highs Saturday in the upper 60s to low 70s and lows Saturday night in the low-mid 40s.

LONG TERM [Sunday Through Thursday].

A ridge of high pressure will continue to build over the area early next week, giving us warmer temperatures (peaking in the upper 60s to mid 70s) and a short break from rain chances. On Monday night, another upper level shortwave trough will push into the Srn Plains, developing a cold front out in the MS Valley. This cold front will move into the Southeast and TN Valley on Tuesday, reaching our area Tues evening/night. Behind this cold front, much a colder, drier air will advect into the area. Highs Wed and Thurs behind the front will be in the mid 50s to low 60s and overnight lows will be in the 30s, with low 40s possible in north- central FL and along the coast.

AVIATION. [Through 00Z Saturday]

Ceilings have dropped into the IFR category early this evening and will remain there for the rest of tonight. Isentropic lift to generate scattered to numerous showers tonight. 4-6SM SHRA BR prevailing, dropping below 2SM SHRA BR at times for mainly coastal TAF sites where mesoscale models bullish with QPF. A warm front lifts into SE GA on Friday with ceilings lifting to MVFR and potentially VFR during the afternoon under warm SSW flow across NE FL TAF sites. KSSI may remain in the soup depending on how far north the warm front pushes. Have held off on mention of TSRA in the TAFs at this time given the relatively low chances. Winds likely to stay northeast at KSSI through Friday, but for rest of the TAFs, northeast winds will transition to south and southwest early Friday and rest of the day as the warm front lifts northward.

MARINE.

Wind gusts to 35 knots offshore have subsided, but waves will be slower to subside and the tight pressure gradient in place is still enough to bring winds of 15 to 20 knots near shore and 20 to 25 knots offshore through the night. Though these winds will subside by tomorrow afternoon, showers and thunderstorms are expected to be on and off through Saturday morning, some of which could bring gusty winds. The cold front behind these storms will move through Saturday morning, which will cause winds and waves to surge again. Another small craft advisory may be needed this weekend, at least for the offshore waters. After that, high pressure will build in over the coastal waters early next week.

FIRE WEATHER.

Light transport winds and low and mixing heights Friday will lead to low daytime dispersions across the area. A fair amount of rainfall is anticipated today and tomorrow with a very wet and unsettled pattern in place ahead of an approaching cold front. The cold front will pass through Saturday morning and then colder, drier air will filter into the area. Not dry enough, however, for red flag conditions.

HYDROLOGY.

Strong northeast flow coinciding with high tides caused a few of our gauges along the St. Johns River to peak at/near Action Stage this morning. The winds have continued to gradually lower this afternoon, so coastal flood statement that was in effect was allowed to expire. Tomorrow, as a coastal warm front lifts through NE Fl into Srn GA, heavier showers along and north of the front may bring around 1-2" of rainfall. This could lead to localized flooding in urban areas and area with poor drainage, but no widespread flooding is anticipated.

PRELIMINARY POINT TEMPS/POPS.

AMG 49 58 54 67 43 / 90 90 80 20 0 SSI 56 65 58 68 48 / 80 80 70 20 0 JAX 59 71 58 72 46 / 80 70 60 20 0 SGJ 61 74 60 72 49 / 80 60 50 30 0 GNV 61 73 60 72 46 / 60 60 60 30 0 OCF 61 75 60 74 46 / 60 40 60 30 0

JAX WATCHES/WARNINGS/ADVISORIES. FL . High Rip Current Risk through Friday morning for Coastal Duval- Coastal Flagler-Coastal Nassau-Coastal St. Johns.

High Surf Advisory until 9 AM EST Friday for Coastal Duval- Coastal Flagler-Coastal Nassau-Coastal St. Johns.

GA . High Rip Current Risk through Friday morning for Coastal Camden- Coastal Glynn.

AM . Small Craft Advisory until 3 PM EST Friday 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 until 8 AM EST Friday 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.


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
41112 - Offshore Fernandina Beach, FL (132) 30 mi45 min 62°F6 ft
FRDF1 - 8720030 - Fernandina Beach, FL 32 mi45 min NNE 4.1 G 13
41008 - GRAYS REEF - 40 NM Southeast of Savannah, GA 33 mi115 min NE 18 G 21 62°F 62°F7 ft1024.4 hPa (-0.7)61°F

Wind History for Fernandina Beach, FL
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Brunswick, Malcolm McKinnon Airport, GA1 mi52 minNE 95.00 miFog/Mist60°F57°F90%1024.2 hPa
Brunswick / Glynco, GA10 mi50 minNE 95.00 miFog/Mist57°F56°F96%1024.4 hPa

Link to 5 minute data for KSSI

Wind History from SSI (wind in knots)
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1 day agoSW3W6W4SW4NW10NW10NW8NW6NW4N7N9N9N7NE13
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2 days agoSW6S3SE5CalmS3SW5S4W4CalmSW4SW5S44S6S7S11
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Tide / Current Tables for St. Simons Light, Georgia
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St. Simons Light
Click for Map
Thu -- 12:14 AM EST     Full Moon
Thu -- 02:08 AM EST     -0.26 feet Low Tide
Thu -- 07:14 AM EST     Sunrise
Thu -- 07:31 AM EST     Moonset
Thu -- 08:07 AM EST     7.85 feet High Tide
Thu -- 02:46 PM EST     0.11 feet Low Tide
Thu -- 05:23 PM EST     Sunset
Thu -- 06:01 PM EST     Moonrise
Thu -- 08:30 PM EST     6.59 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.80.4-0.20.21.73.85.87.37.87.56.553.21.60.40.10.92.54.25.76.56.55.84.5

Tide / Current Tables for St. Johns River Entrance, Florida Current (3)
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St. Johns River Entrance
Click for Map
Thu -- 12:14 AM EST     Full Moon
Thu -- 12:39 AM EST     -2.14 knots Max Ebb
Thu -- 04:18 AM EST     0.00 knots Slack
Thu -- 07:14 AM EST     Sunrise
Thu -- 07:31 AM EST     Moonset
Thu -- 07:41 AM EST     2.88 knots Max Flood
Thu -- 10:51 AM EST     -0.01 knots Slack
Thu -- 01:23 PM EST     -2.19 knots Max Ebb
Thu -- 05:25 PM EST     Sunset
Thu -- 05:36 PM EST     0.00 knots Slack
Thu -- 06:02 PM EST     Moonrise
Thu -- 08:06 PM EST     2.02 knots Max Flood
Thu -- 10:48 PM EST     -0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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-2-2.1-1.7-1-0.20.51.62.62.82.21.2-0.2-1.5-2.1-2.1-1.7-1.1-0.50.41.421.70.9-0.2

Weather Map
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NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
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Wind Forecast for Jacksonville, FL (23,6,7,8)
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Ground Weather Radar Station Jacksonville, FL
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The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerious of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.