Monday, August21, 2017 L-36.com


Marine Weather and Tides
Sullivan's Island, SC

Version 3.4
What's New / NOTES
6/25/2017 - NOAA is having a major issue that impact the 7 day forecast load times. Many users are reporting problems. The issue has been reported.
5/23/2017 - Worked with NOAA again to speed up the 7 day forecast load times. Thanks to them for being responsive.
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.

Sunrise 6:46AMSunset 7:58PM Monday August 21, 2017 2:00 PM EDT (18:00 UTC) Moonrise 5:31AMMoonset 7:04PM Illumination 0% Phase: New Moon; Moon at 29 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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AMZ330 Charleston Harbor- 138 Pm Edt Mon Aug 21 2017
This afternoon..SE winds 10 kt. A chance of showers and tstms.
Tonight..SE winds 5 to 10 kt, becoming S after midnight. A slight chance of showers and tstms.
Tue..SW winds around 5 kt, becoming S in the afternoon. A slight chance of showers and tstms in the morning, then a chance of showers and tstms in the afternoon.
Tue night..SW winds 5 to 10 kt. A slight chance of showers and tstms.
Wed..SW winds 5 kt, becoming S in the afternoon. A chance of showers and tstms.
Wed night..SW winds 5 to 10 kt. A chance of showers and tstms.
Thu..SW winds 5 kt. A chance of showers and tstms.
Thu night..E winds 5 kt. A chance of showers and tstms.
Fri..NE winds 5 to 10 kt. A chance of showers and tstms.
Fri night..NE winds 5 to 10 kt. A slight chance of showers and tstms. Mariners are reminded that winds and waves higher in and near tstms. Unless otherwise noted, waves 1 foot or less. Charleston harbor water temperature 87 degrees.
AMZ300 138 Pm Edt Mon Aug 21 2017
Synopsis for the coastal waters of south coastal south carolina and north coastal georgia.. A weak stationary front will gradually dissipate across the region today. High pressure will extend across the area Tuesday and Wednesday with a piedmont trough developing inland. A stronger cold front is expected to pass over the region on Thursday. A wave of low pressure could form on the front well offshore Friday. Slightly cooler and drier conditions are then expected into early next week.

7 Day Forecast for Marine Location Near Sullivan's Island, SC
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location: 32.77, -79.91     debug


Area Discussion for - Charleston, SC
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Fxus62 kchs 211744
afdchs
area forecast discussion
national weather service charleston sc
144 pm edt Mon aug 21 2017

Synopsis
A weak stationary front will gradually dissipate across the
region today. High pressure will extend across the area Tuesday
and Wednesday with a piedmont trough developing inland. A
stronger cold front is expected to pass over the region on
Thursday. A wave of low pressure could form on the front well
offshore Friday. Slightly cooler and drier conditions are then
expected into early next week.

Near term through tonight
Early this afternoon: no changes to the overall forecast
thinking with which is detailed below. Updated pop's based on
current radar trends and made some tweaks to cloud cover based
on satellite.

Late this morning: well eclipse day has arrived but we are sorry
to say that there has been no improvement to the viewing
forecast. We actually started off the morning with mostly clear
skies for locations away from the coast, with isolated
convection along the coast and over the coastal waters. However,
as can be seen in the morning sounding, plentiful low level
moisture combined with rapid heating has led to a rapid
expansion of low level convective clouds and resulted in mostly
cloudy skies. The surface pattern is pretty complex with low
level northeast flow prevailing due to the presence of high
pressure just to the north in almost a subtle cold air damming
setup. Aloft, an expansive ridge extends from the tropical
atlantic across the southern plains and into northern mexico,
but there is a subtle shortwave across north florida that is an
extension of an upper low over the gulf of mexico. Therefore,
the impact of some larger scale lift combined with low level
convergence along the coast is helping to kick off showers and
thunderstorms along the coast and the adjacent coastal waters.

Thus far the most vigorous convection has been closer to the
altamaha and forecast models seem to be handling this reasonably
well. We are easily above convective temperatures (85 degrees)
as observations show current values already into the upper 80s
in many areas. Showers and storms will be capable of developing
at any time just about anywhere through the morning. As we
transition to the afternoon the focus will likely become further
inland as the sea breeze pushes inland and the flow turns more
southeasterly. Mostly cloudy skies will prevail through eclipse
time, but there will be some periodic breaks. High temperatures
are tough as we are already in the upper 80s, but cloud cover
will likely prevent most areas from rising too much higher. Some
low 90s expected inland, but most areas will be around 90.

Tonight: convection far inland will fade this evening, as the
short wave lifts further inland. There will be some reformation
of convection over the atlantic, some of which will make a run
for the coast late at night. There certainly could be some late
night fog in locations where it rained, but since various layers
of clouds will persist we are not showing any in the forecast at
this time. Lows generally in the mid and upper 70s, or still
well above normal.

Short term Tuesday through Thursday
Tuesday and Wednesday: short term guidance indicates that the center
of a broad h5 ridge will remain around the forecast area on Tuesday.

The ridge should shift southward over the gulf coast as a longwave
trough ripples towards the appalachians by Wednesday afternoon.

Forecast soundings show a fairly significant inversion around h85
across the cwa, with CIN of 10 j kg or more well into the afternoon.

However, the pressure pattern should support steady onshore flow,
setting the stage for sea breeze development during the mid day. I
will forecast chc pops over the coastal counties by the early
afternoon, spreading east during the rest of the afternoon into the
early evening. High temperatures are forecast to range from the
upper 80s across the beaches to the low to mid 90s across the inland
counties. On Wednesday, forecast soundings indicate that the
inversion will lift to around h75 and inhibition should decrease.

Flow should shift from the SE to S during the daylight hours
Wednesday. A slow moving sea breeze will likely serve as a focus for
moisture convergence, supporting at least sct storms over the
forecast area during the afternoon. High temperatures are forecast
to range 1 to 2 degrees above values reached on Tuesday.

Thursday: guidance has been consistent with the timing of a cold
front across the CWA during the daylight hours Thursday. The axis of
the h5 trough is expected to slide over the region during the
afternoon. The arrival of the trough over the slowing front will
likely support a frontal wave to develop, the GFS and ECMWF indicate
over the mouth of the savannah river by 0z fri. Given the passage of
the mid level trough and sfc front, pw above 2 inches, and
widespread weak to moderate instability, I will forecast likely
pops. H85 CAA is not expected until Thursday night, highs should
range around 90 degrees for most areas Thursday afternoon.

Long term Thursday night through Monday
Friday through Monday: high pressure sourced from canada will remain
centered well north of the region through the rest of the week.

Confidence in the day 5 through 7 forecast remains low. Medium range
guidance indicates that the sfc high center will shift over new
england, ridging SW across the carolinas into ga. In addition, both
the GFS and ECMWF show a coastal low developing off the ga sc coast
by late this week, with run to run trends shifting east. Guidance
supports prolonged NE winds across the cwa, yielding afternoon
dewpoints in the upper 60s inland by the weekend. I will favor the
marine and near shore zones for chc pops through much of the day 4
through 6 period. I will keep the forecast dry for day 7, indicating
the best chance for drier air to arrive on the west side of the
departing coastal low.

Aviation 18z Monday through Saturday
Main immediate concern is for showers and thunderstorms to
impact the terminals for the next couple of hours. After about
20z the overall potential for direct impacts should diminish as
the main focus for activity pushes inland. Included tempo's at
both sites for MVFR visibilities, but it is certainly likely
that ifr conditions will occur for a very short time. Could also
see some gusty winds as ksav reported a 26 knot gust with a
passing storm earlier. Then overnight there is some potential
for stratus and fog, mainly inland of the TAF sites. Will keep
the forecastVFR due to the low likelihood for now.

Extended aviation outlook: thunderstorms may result in short periods
of flight restrictions, greatest potential during the afternoon and
early evening.

Marine
Today and tonight: deep layered sub-tropical ridging with a
slackened surface pressure pattern will be the main feature
across the area, interrupted by a weak inverted trough that
moves into the local waters today, then dissipates tonight.

Outside of scattered convection ( which will cause some locally
heavy rains, frequent lightning, and maybe a few strong winds
gusts) there are no concerns regarding the synoptic winds (which
hold under 12kt) and the resulting seas of 2-3 ft.

Tuesday through Saturday: western atlantic high pressure will yield
a weak pressure gradient over the coastal waters into the mid week.

A cold front should sweep across the forecast area on Thursday. Sfc
winds are forecast to remain light from the SE on Tuesday, then
veering from the south-southwest Wednesday and Thursday. Wave
heights are expected to generally range between 2-3 feet Monday
through Thursday. Large high pressure centered over the great lakes
will build over the region Friday into Saturday. In addition, a
coastal low may develop off the ga and sc coast by Friday and may
slowly depart on Saturday. Winds should shift from the ne,
increasing to 10 to 15 kts by Friday afternoon. Four foot wave are
forecast across portions of amz350 and possibly beyond 20 nm
offshore. On Saturday, NE winds are forecast to strengthen to 15 to
20 kts, gusts between 20 to 25 kts. Wave heights are expected to
range from 4 to 6 feet with 20 nm, reaching 7 feet across amz374.

Rip currents... The combination of small swell, onshore flow,
and astronomical influences will lead to an enhanced environment
for rip currents today. Considering the fact that we had
numerous rip currents reported yesterday at isle of palms and
hilton head, the cuts in the sandbar could still be there. Thus
we have maintained a moderate risk through the evening.

Waterspouts: we will keep watch on possible spouts today due to
favorable conditions with light winds, ample moisture and
instability. We have not issued any marine weather statements
just yet since the SPC non-supercell tornado parameter is still
not favorable, nor are there any well defined boundaries.

Tides coastal flooding
Astronomical influences and onshore winds (albeit light) will
continue to produce elevated tides through Tuesday. Only small
tidal departures are necessary and we should reach shallow
coastal flooding levels with the evening high tides along parts
of the sc coast. Coastal flood advisories will likely be needed.

For now it looks like conditions will stay just below any
advisory thresholds on the ga coast and in jasper county.

Equipment
The kclx radar continues to be down due to lighting strikes.

Parts are on order but the radar is not expected to return to
service until Tuesday afternoon at the earliest.

The nwr transmitter, wxm-93 at cross, sc will be off the air
until further notice. An off site tech will be at the site
later today.

The temperature and dew point sensors at the downtown charleston
observation site (kcxm) could periodically fail. Technicians
plan on fixing the problem.

Chs watches warnings advisories
Ga... None.

Sc... None.

Marine... None.

Near term... Bsh
short term... Ned
long term... Ned
aviation... Bsh ned
marine... Ned
tides coastal flooding...

equipment...



Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
CHTS1 1 mi42 min E 8.9 G 11 85°F 88°F1021.6 hPa
FBIS1 - Folly Island, SC 6 mi60 min E 8.9 G 9.9 85°F 1022.2 hPa (-0.4)78°F
41029 - Capers Nearshore (CAP 2) 15 mi52 min E 12 G 16 84°F 86°F1021.5 hPa
ACXS1 - ACE Basin Reserve, SC 32 mi75 min NE 1 85°F 1022 hPa78°F
41033 43 mi52 min ESE 7.8 G 12 84°F 1021.4 hPa
41004 - EDISTO - 41 NM Southeast of Charleston, SC 47 mi30 min ESE 5.8 G 7.8 82°F 85°F1021.3 hPa78°F

Wind History for Charleston, SC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Charleston Executive Airport, SC7 mi65 minE 810.00 miA Few Clouds86°F78°F79%1021.7 hPa
Mount Pleasant Regional-Faison Field, SC11 mi65 minESE 510.00 miA Few Clouds88°F78°F75%1021.3 hPa
Charleston, Charleston Air Force Base, SC12 mi64 minESE 810.00 miMostly Cloudy89°F75°F65%1021.1 hPa

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Last 24hr4SE10E7S7SE9S8S10SE5S3CalmCalmCalmCalmCalmCalmCalmNE4N3CalmN4NE7E7E8SE8
1 day agoSW7SW9SE10S9S7S8S10S7SW6SW4SW5S4S3SW3CalmCalmCalmCalmCalmW3SW5N3CalmS5
2 days agoSW84S8SW10S14S11S11S7S9SW8S8S6S6S6SW6SW5SW3SW4W5SW5W5S65W6

Tide / Current Tables for Fort Johnson, South Carolina
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Fort Johnson
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Mon -- 02:07 AM EDT     -0.25 feet Low Tide
Mon -- 06:31 AM EDT     Moonrise
Mon -- 06:47 AM EDT     Sunrise
Mon -- 08:08 AM EDT     5.66 feet High Tide
Mon -- 02:17 PM EDT     -0.63 feet Low Tide
Mon -- 02:31 PM EDT     New Moon
Mon -- 07:57 PM EDT     Sunset
Mon -- 08:04 PM EDT     Moonset
Mon -- 08:32 PM EDT     6.48 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.60.3-0.20.11.32.94.35.35.75.44.53.11.50.2-0.6-0.40.92.64.45.76.46.45.84.5

Tide / Current Tables for Charleston Harbor Entrance, South Carolina Current
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Charleston Harbor Entrance
Click for Map
Mon -- 02:46 AM EDT     0.00 knots Slack
Mon -- 04:58 AM EDT     1.67 knots Max Flood
Mon -- 06:31 AM EDT     Moonrise
Mon -- 06:47 AM EDT     Sunrise
Mon -- 08:49 AM EDT     -0.00 knots Slack
Mon -- 11:58 AM EDT     -2.93 knots Max Ebb
Mon -- 02:31 PM EDT     New Moon
Mon -- 02:56 PM EDT     0.00 knots Slack
Mon -- 05:20 PM EDT     2.00 knots Max Flood
Mon -- 07:57 PM EDT     Sunset
Mon -- 08:03 PM EDT     Moonset
Mon -- 09:18 PM EDT     -0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
-3.1-2.3-1.10.31.41.71.61.40.9-0.2-1.4-2.5-2.9-2.4-1.30.11.421.91.81.30.4-0.9-2.2

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 (14,3,4,5)
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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.