Tuesday, May23, 2017 L-36.com


Marine Weather and Tides
Garden City, GA

Version 3.4
What's New / NOTES
5/19/2016 - There were issues with the 3 day airport observation history. I switched to another data source. Let me know if you see any issues with the data feeds.
3/12/2015 - Added section for Gulf current for users in the GMZ marine zones.
This was requested by a user. If you have requests, please let me know.

Sunrise 6:20AMSunset 8:22PM Tuesday May 23, 2017 4:53 AM EDT (08:53 UTC) Moonrise 3:53AMMoonset 5:01PM Illumination 6% Phase: Waning Crescent; Moon at 27 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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AMZ354 Waters From Savannah Ga To Altamaha Sound Ga Out 20 Nm...including Grays Reef National Marine Sanctuary- 344 Am Edt Tue May 23 2017
.small craft advisory in effect from this evening through late tonight...
Today..SW winds 15 to 20 kt. Seas 3 to 4 ft. Showers and tstms likely. Rain heavy at times with vsbys less than 1 nm.
Tonight..SW winds 15 to 20 kt with gusts to 25 kt. Seas 3 to 4 ft. Showers and Thunderstorms. Rain heavy at times with vsbys less than 1 nm.
Wed..SW winds 15 to 20 kt. Seas 3 to 4 ft... Building to 4 to 5 ft in the afternoon. Showers and Thunderstorms likely.
Wed night..SW winds 20 to 25 kt with gusts to 30 kt. Seas 4 to 6 ft...subsiding to 4 to 5 ft after midnight. Showers and Thunderstorms...mainly in the evening. Locally heavy rainfall possible in the evening.
Thu..W winds 15 to 20 kt with gusts to 25 kt. Seas 3 to 4 ft. A chance of showers and Thunderstorms...mainly in the morning.
Thu night..W winds 15 to 20 kt...diminishing to 10 to 15 kt after midnight. Seas 3 to 4 ft...subsiding to 2 ft after midnight. A slight chance of showers and Thunderstorms in the evening.
Fri..W winds 10 to 15 kt. Seas 1 foot.
Fri night..SW winds 5 to 10 kt. Seas 2 ft.
Sat..SW winds 10 kt. Seas 2 ft.
Sat night..SW winds 10 to 15 kt. Seas 3 to 4 ft. Mariners are reminded that winds and seas can be higher in and near tstms.
AMZ300 344 Am Edt Tue May 23 2017
Synopsis for the coastal waters of south coastal south carolina and north coastal georgia.. Unsettled weather will persist across the southeast through Wednesday. A cold front will push offshore Wednesday night into Thursday followed by high pressure prevailing into the weekend.

7 Day Forecast for Marine Location Near Garden City, GA
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location: 32.07, -81.11     debug


Area Discussion for - Charleston, SC
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Fxus62 kchs 230812
afdchs
area forecast discussion
national weather service charleston sc
412 am edt Tue may 23 2017

Risk for flash flooding and severe weather through this
evening...

Synopsis
Unsettled weather will persist across the southeast through
Wednesday. A cold front will push offshore Wednesday night into
Thursday followed by high pressure prevailing into the weekend.

Near term /through today/
An impressive moisture plume originating out of the gulf of
mexico will remain anchored across the southeast u.S. Today as
the region remains heavily influenced by the increasing
cyclonic flow ahead of a powerful upper low meandering over the
northern mississippi valley. Early morning sounder data and
23/00z raobs indicate pwats remain near 2 inches within the
plume which is ~135% of normal for late may. A number of
impulses embedded within the subtropical jet will traverse
southeast south carolina and southeast georgia today bringing a
risk for numerous to widespread showers/tstms. Pops 90-100% look
reasonable as most areas will likely see some degree of
measurable rainfall, although it will not rain consistently
through the day.

There are signals in the various guidance that a squall line
type feature could develop across east-central georgia by early
afternoon, move slowly east and potentially become anchored
across parts of the forecast area as it becomes aligned with the
mean steering flow mid-late afternoon. Should this line
develop, it would bring not only heavy rainfall and a potential
for flash flooding where as much as 3-7 inches of rain has
already fallen in some areas, but a risk for damaging winds and
possible a few tornadoes per output from modified point
soundings. Surface based instability will be somewhat curtailed
by an extensive cloud canopy, but will likely be augmented to
some degree by a strengthening h2-h3 difluence channel and
increased dpva ahead of a more significant shortwave which is
progged to pass across the region during peak heating. There
will likely be pockets of higher instability lurking about due
to thinning of the cloud canopy later this morning per latest
rap/cmc total sky cover progs, but pinning down exactly where
these pockets will setup is proving extremely difficult. This
would only serve to locally enhance the severe risk. The risk
for severe weather looks to be the greatest from roughly 2-9 pm.

Short term /tonight through Friday/
Tonight: convection will gradually wind down and push offshore
as subsidence overspreads the area in the wake of a passing
shortwave. Likely to categorical pops will be held for the
evening hours with pops slowly decreasing with time, highest
along the coast. Lows will range from the upper 60s inland to
the lower 70s at the coast.

Wednesday: an amplifying longwave trough will be over the ms valley.

Naefs indicates the 500 mb heights over the lower ms valley become -
4 to -5 standard deviations for this time of year, which is very
impressive. A shortwave will round the base of the trough and head
in our direction towards the afternoon. At the surface, low pressure
is forecasted to strengthen across the oh river valley. A cold front
attached to this low will stretch into the deep south, pushed
eastward by the aforementioned shortwave. A jet streak strengthening
to ~130 kt will be on the eastern side of the trough and moving over
the southeast in the late afternoon. The 850 mb jet will increase to
30-45 kt in the afternoon while a deep layer of moisture will
persist with pwats approaching 1.8" near record values for the day.

This regime will support numerous/widespread showers. The convective
threat doesn't appear to start off too high due to morning
precipitation and cloud cover. However, some breaks in the clouds
ahead of pre-frontal convection to our west will destabilize the
atmosphere. Deep synoptic forcing will combine with instability in
the form of blcapes approaching 1,500 j/kg and steepening lapse
rates along with 0-6 km bulk shear increasing to 40-50 kt to support
severe weather, especially in the late afternoon/evening. SPC now
has our area under a slight risk. The main threat should be damaging
winds, but given the cool mid-levels, hail is also a concern. A
tornado is not out of the question given the low-level hodographs,
especially if the low-level winds back a little more than expected
in discrete cells. The main line of storms is expected to move cross
late in the afternoon through the evening hours. The cold front will
move through our area overnight, allowing precipitation to wind down
from west to east as the atmosphere stabilizes and drier air builds
into the area. Though, remnant showers could persist along the coast
for much of the night.

Thursday: the trough and surface low pressure will move across the
great lakes region stretching into the mid-atlantic states.

Meanwhile, high pressure will build over the gulf of mexico and the
central u.S. The surface pressure gradient is forecast to range from
2-3 mb across the forecast area, meaning wsw winds should
remain gusty across forecast area. Models hint at some remnant
showers across the charleston tri-county, so we have slight
chance pops in the forecast. However, minimal precipitation is
expected, especially when compared to previous days. Despite
mostly sunny skies across the area, thickness values only
support high temperatures in the lower 80s, which is a few
degrees below normal for this time of year.

Friday: the trough will be moving into new england while a ridge and
surface high pressure will be building towards the southeast. Good
subsidence will lead to sunny skies with highs rising well into the
80s.

Long term /Friday night through Monday/
A ridge over the east coast combined with surface high pressure will
provide dry weather in the long term along with a gradual warming
trend each day. Models hint at maybe some rain on Monday.

Aviation /06z Tuesday through Saturday/
Showers/tstms will persist at kchs through about 08z, although
convection will remain in the vicinity of the terminal until
just about sunrise. At ksav, risk for tstms has ended, but light
showers will linger there through 07z or so.

Main concern for today is tstms and heavy rain impacts at the
terminals. High atmospheric moisture and passing impulses aloft
suggest showers/tstms could impact either terminal at just about
any time this morning before the risk for more concentrated
activity increases this afternoon. Window for greatest impacts
at both terminals looks to be about 22-03z at kchs and 20-02z at
ksav, give or take an hour or so. Potential for ifr conditions
at times as periods of heavier convective elements push through,
but overall suspect MVFR vsbys will be the dominate mode this
afternoon. Will carry prevailing MVFR conditions at both
terminal, but hold off on ifr tempo groups until event draws a
bit closer. Will reevaluate with the 12z TAF cycle.

Extended aviation outlook: flight restrictions are expected
Wednesday due to a cold front bringing showers and thunderstorms
to the region. Conditions will improve Wednesday night withVFR
prevailing into the weekend.

Marine
Today: winds and seas will increase today as low-level jetting
intensifies ahead of a slowly moving cold front. Winds look to
increase to 20-25 kt with seas 4-6 ft by this afternoon across
the georgia offshore and charleston county waters so a small
craft advisory will be issued for those legs beginning at noon.

The remaining nearshore legs, including charleston harbor, look
to remain just below advisory thresholds during the day. Strong
to potentially severe convection could approach or impact the
marine area late in the afternoon brining a risk for winds >35
kt.

Tonight: strong to locally severe convection should push east
with time, but strong low-level jetting will continue through
the night brining 20-25 kt winds and seas 4-7 ft. Small craft
advisories will be expanded to including the remaining nearshore
legs beginning at 6 pm. Will not include the charleston harbor
just yet as winds look to remain just sky of advisory
thresholds.

Wednesday through Saturday: SW winds will increase Wednesday as a
cold front approaches from the west and then crosses through the
region Wednesday night. A strong surface pressure gradient behind
the departing front will lead to elevated winds on Thursday. As a
result small craft advisories are will remain in effect through this
time period for gusty winds and steep seas, especially beyond 20 nm.

Conditions will improve Friday into Saturday as high pressure builds
into the area.

Hydrology
Kclx sta and surface observations show some areas across
southeast georgia and extending into portions of the lower
south carolina coast have seen as much as 3-7 inches of rain
over the past 2 days. Ksav observed 6.61 inches of rain just
yesterday and is an indication of the heavy rainfall potential
that could be realized through tonight as stronger upper forcing
and numerous showers/tstms impact the region. Updated gridded
1-hr flash flood guidance values are generally around 3 inches,
which could easily be overcome based on the degree of available
atmosphere moisture and possible convective anchoring due to
mesoscale boundary interactions. A flash flood watch has been
posted for all but mcintosh and coastal portions of liberty
county through midnight tonight. Although flash flooding will
likely not be realized across the entire watch area, the
potential is there for several pockets of flash flooding per
latest high resolution guidance. Expect general rainfall
amounts of 2-3 inches with localized amount potentially
exceeding 6 inches. Depending on how the convective pattern
evolves today, the watch may be extended into the day on
Wednesday.

Tides/coastal flooding
Evening high tide levels will trend higher each day as we approach
the new moon perigee this Friday. The mean lower low water (mllw)
levels are forecast to remain below flood stage. However, it is
possible that thunderstorms could pass over urban coastal areas
during the evening high tide cycle. Rainfall rates could exceed
0.75/hr during any thunderstorm. The combination of elevated mllw
water levels and heavy downpours could result in shallow freshwater
flooding during this evenings and Wednesday evenings high tide
cycles.

Climate
Rainfall records for 23 may:
kchs: 4.86 inches set in 1976.

Kcxm: 5.40 inches set in 1976.

Ksav: 2.41 inches set in 1976.

Rainfall records for 24 may:
kchs: 1.78 inches set in 1979.

Kcxm: 2.23 inches set in 1895.

Ksav: 2.29 inches set in 1938.

Chs watches/warnings/advisories
Ga... Flash flood watch through this evening for gaz087-088-099>101-
114>119-137-138.

Sc... Flash flood watch through this evening for scz040-042>045-
047>052.

Marine... Small craft advisory from 6 pm this evening to 8 pm edt
Thursday for amz352.

Small craft advisory from noon today to midnight edt Thursday
night for amz350-374.

Small craft advisory from 6 pm this evening to 6 am edt
Wednesday for amz354.



Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
FPKG1 - 8670870 - Fort Pulaski, GA 11 mi53 min SW 7 G 8.9 73°F 80°F1011.6 hPa (-2.4)
41033 40 mi105 min SW 14 G 21 74°F 78°F1011 hPa
SAXG1 - Sapelo Island Reserve, GA 46 mi53 min SSW 11 74°F 1012 hPa (-2.0)72°F
ACXS1 - ACE Basin Reserve, SC 48 mi68 min Calm 72°F 1011 hPa72°F
41008 - GRAYS REEF - 40 NM Southeast of Savannah, GA 48 mi63 min SSW 18 G 21 77°F 78°F5 ft1011.1 hPa (-2.4)72°F

Wind History for Fort Pulaski, GA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hunter U. S. Army Airfield, GA3 mi1.9 hrsSSW 610.00 miFair72°F72°F100%1011.1 hPa
Savannah, Savannah International Airport, GA7 mi60 minS 910.00 miFair72°F70°F94%1011.2 hPa
Hilton Head Island, Hilton Head Airport, SC24 mi58 minS 610.00 miFair73°F73°F100%1011.5 hPa

Wind History from SVN (wind in knots)
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Last 24hrSW5CalmSW3S3S5SW4SW7S8S6SE10
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CalmCalmSE3S6SW3CalmCalmCalmCalmSW6SW4
1 day agoSE5S4S5SE10S8S9
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2 days agoCalmCalmCalm----SE8SE8SE8SE12SE8
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Tide / Current Tables for Savannah (Bull Street), Georgia
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Savannah (Bull Street)
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Tue -- 01:18 AM EDT     0.11 feet Low Tide
Tue -- 04:53 AM EDT     Moonrise
Tue -- 06:22 AM EDT     Sunrise
Tue -- 06:57 AM EDT     7.93 feet High Tide
Tue -- 01:38 PM EDT     -0.59 feet Low Tide
Tue -- 06:00 PM EDT     Moonset
Tue -- 07:25 PM EDT     9.09 feet High Tide
Tue -- 08:20 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
10.20.424.16.27.57.97.56.44.72.70.9-0.3-0.50.83.35.9898.98.16.54.5

Tide / Current Tables for Savannah River Entrance, Georgia Current
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Savannah River Entrance
Click for Map
Tue -- 01:34 AM EDT     0.00 knots Slack
Tue -- 04:06 AM EDT     2.10 knots Max Flood
Tue -- 04:52 AM EDT     Moonrise
Tue -- 06:21 AM EDT     Sunrise
Tue -- 07:46 AM EDT     -0.00 knots Slack
Tue -- 10:47 AM EDT     -2.12 knots Max Ebb
Tue -- 01:47 PM EDT     0.00 knots Slack
Tue -- 04:28 PM EDT     2.62 knots Max Flood
Tue -- 05:59 PM EDT     Moonset
Tue -- 08:07 PM EDT     -0.00 knots Slack
Tue -- 08:19 PM EDT     Sunset
Tue -- 11:15 PM EDT     -2.41 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
-1.7-0.80.61.72.11.91.40.7-0.2-1.3-2-2.1-1.9-1.10.31.72.52.51.91.20.2-1.1-2.1-2.4

Weather Map and Satellite Images
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Weather Map
wmap_A
IR Satellite Image from GEOS
east_satellite

GOES Local Image of Southeast    EDIT
Geos

Wind Forecast for Charleston, SC (4,6,7,8)
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Ground Weather Radar Station Charleston, SC
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Disclaimer:
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.