Monday, April23, 2018 L-36.com


Marine Weather and Tides
Summerville, SC

Version 3.4
What's New / NOTES
3/3/2018 - There is a new GOES Satellite for the east coast that required rewriting that part of the code. Please report any issues.
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.

Sunrise 6:39AMSunset 7:58PM Monday April 23, 2018 5:40 AM EDT (09:40 UTC) Moonrise 12:37PMMoonset 1:45AM Illumination 56% Phase: First Quarter Moon; Moon at 8 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- 318 Am Edt Mon Apr 23 2018
.small craft advisory in effect through late tonight...
Today..E winds 15 kt with gusts to 20 kt, increasing to 20 to 25 kt with gusts to 30 kt late this morning. Waves building to 2 to 3 ft. Showers this morning, then showers with a slight chance of tstms this afternoon. Locally heavy rainfall possible this afternoon.
Tonight..SE winds 15 to 20 kt with gusts to 30 kt. Waves 1 to 2 ft. A slight chance of tstms. Showers. Locally heavy rainfall possible in the evening.
Tue..S winds 10 to 15 kt. A chance of showers with a slight chance of tstms in the morning, then a slight chance of showers in the afternoon.
Tue night..SW winds 5 to 10 kt.
Wed..SW winds 5 to 10 kt.
Wed night..W winds 5 to 10 kt.
Thu..SW winds 5 kt. A slight chance of showers.
Thu night..SW winds 5 kt. A chance of showers.
Fri..W winds 5 to 10 kt.
Fri night..SW winds 5 to 10 kt. Mariners are reminded that winds and waves higher in and near tstms. Unless otherwise noted, waves 1 foot or less. Charleston harbor water temperature 65 degrees.
AMZ300 318 Am Edt Mon Apr 23 2018
Synopsis for the coastal waters of south coastal south carolina and north coastal georgia.. Low pressure will approach from the west today, then slowly move up the east coast through mid week. An upper disturbance will move over the area Thursday, followed by a cold front late week. High pressure will return over the weekend.

7 Day Forecast for Marine Location Near Summerville, SC
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location: 32.96, -80.2     debug


Area Discussion for - Charleston, SC
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Fxus62 kchs 230821
afdchs
area forecast discussion
national weather service charleston sc
421 am edt Mon apr 23 2018

Synopsis
Low pressure will approach from the west today, then slowly
move up the east coast through mid week. An upper disturbance
will move over the area Thursday, followed by a cold front late
week. High pressure will return over the weekend.

Near term through tonight
Today: a vertically stacked cyclone both surface and aloft will
spiral through the tennessee valley today into tonight. The
occluded front extended from the surface low to the SE will link
up with a secondary but weaker low that forms near the
georgia alabama line this afternoon. Strong high pressure near
long island and southern new england will be reluctant to move
much to the east, blocked by a slow moving trough in the nw
atlantic. This in turn prevents the warm front over southern
georgia from making too much progress n-ne until this afternoon
and tonight, as it moves into the forecast zones.

Rainfall: although for the past 5-7 days the models have been
locked into the synoptic situation for today and tonight, it has
taken until yesterday or even now until it has a grasp on where
the heaviest rainfall will occur. While we are still forecasting
around 1.5 to 2.5 inches of rain, with the potential for
locally higher amounts, the highest amounts are in the
charleston tri-county district.

There are various mid level perturbations that pass through
today into tonight, and with strong low level convergence off
the atlantic and plenty of upper difluence and divergence with
the lfq of the upper jet. Combined with strong QG forcing and a
40-50 kt low level jet there is considerable upward vertical
velocities that will transpire. The air mass is about as moist
as it can be for late april, with pwat approaching 150-175% of
normal. This would be a major concern if we weren't in a
rainfall deficit for the year, which is around 4-7 inches below
normal and a d2 or severe drought going into this rain event.

So the overall flooding risk is low since the progression of the
surface and upper low is slow. But, if there is any back-
building that is able to develop, or there are persistent
convergent bands that set up.

Although tides are forecast to be around 3 4 to 1 foot mllw
below levels where typical coastal flooding occurs, with the
potential for heavy rains around the time of the mid afternoon
high tide, there could be concerns along the coast and in
downtown charleston, beaufort and savannah.

Severe thunderstorms: there is a little elevated instability
this morning, but with extensive cloud cover and the widespread
rains (100% pop), there ins't much chance for any surface based
convection to develop. That could change this afternoon into
this evening, especially over georgia where the best heating
will occur. It is in these locations where the steeper lapse
rates will occur in tandem with MUCAPE of near 1000 j kg, based
of course on our MAX temp forecast. This along with shear of
40-45 kt in the veering wind profiles with generate decent srh
values. The lifting condensation levels (lcl's) come down, and
with the northward advancing warm front we will need to maintain
a close watch for isolated supercells near this boundary. Spc
has the area in a "marginal risk" of severe weather, mainly for
potential damaging winds and maybe an isolated tornado.

Winds: we raised a lake wind advisory where our confidence is
high on winds reaching 20-25 kt late this morning through
sunset. Regarding any potential wind advisory our confidence is
much lower, since we're not certain on how high we're able to
tap into the robust 40-50 kt winds in the lower levels. For now
we have winds capped at no more than 30 or 35 mph in gusts,
highest along the coast and in charleston county. We will issue
a special weather statement to address travel concerns due to
the winds on the bridges of charleston county and tidal
berkeley. Even with winds not technically at the advisory
thresholds of at least 30 mph sustained and or 40 mph in gusts,
given the saturated grounds, these winds could still bring down
some weaker trees and tree limbs, with maybe a risk of isolated
power outages.

Temperatures: cloud cover and the widespread rains will limit
max temps in sc to no warmer than upper 60s and lower 70s, but
there could be a few breaks over georgia this afternoon to get
temps into the mid or upper 70s.

Deep moisture will begin to strip out during tonight and rain
chances steadily diminish from s-sw to n-ne through the night.

The heaviest and steadiest of the rains will be mainly over the
charleston tri-county district early tonight where we still have
categorical pop. Isolated thunderstorms are still in the
forecast all locations early, then mainly east of i-95
overnight. Lows tonight mainly 60-65f.

Short term Tuesday through Thursday
At the start of the period, an area of low pressure will be
stretched from tennessee into central sc and ga. Through the day,
the low will slowly start to lift northeastward. As this occurs, the
flow will turn more westerly and drier air will begin to work into
the forecast area. Southern zones should have a precip-free day, but
couldn't rule out some isolated showers and maybe a rumble of
thunder or two in the north with the upper low nearby. Models are
showing little to no QPF so rain chances will be capped at 20-30%.

Temperatures will return closer to normal.

The surface low will continue to lift away from the area on
Wednesday. Meanwhile aloft, the main shortwave will also exit the
area allowing the flow to become more zonal. Mostly sunny skies
expected although could see some cumulus pop up in the afternoon.

High temperatures will peak near 80 across most locations inland of
the beaches. Temperatures Wednesday night will be mild, with lows in
the ranging from mid 50s inland to around 60 at the coast.

On Thursday, a strong shortwave will drop into the gulf coast states
and head towards the local area. This will bring our next chance of
rain. There are still discrepancies between models on the timing of
this feature, which in turn has implications on rain chances. GFS is
the slower of the global models, with rain mostly holding off until
the next period, and ECMWF canadian is a bit faster. Took a blend of
models and the current forecast features 30% chances. Highs will be
in the mid 70s.

Long term Thursday night through Sunday
Forecast confidence in the extended period continues to be low given
large spread in model guidance. General consensus is that a cold
front will cross the area late week early weekend. Given the
uncertainty on details, have kept pops pretty low until trends
become clearer. Models come into better agreement on Sunday with a
return to high pressure. Temperatures through the period will
generally be near normal, perhaps slightly cooler on Saturday.

Aviation 08z Monday through Friday
Kchs:VFR conditions will remain in place before morning with
-shra and breezy E winds of around 10-20 kt to occur. Conditions
will then deteriorate later this morning into tonight as
moderate convective rains develop as low pressure approaches
from the west. Currently expecting conditions down into the
MVFR category from 14-20z, then down to the ifr range
thereafter. SE winds will become even stronger, averaging a
solid 20-30 kt through the bulk of the day, dropping off to
15-20 kt tonight. There is a risk for tsra, mainly near
the approaching warm front during the late afternoon and
evening. Probabilities are too low to include mention at this
time.

Ksav: we begin the TAF set withVFR conditions in -shra, but that will
change this morning and today as low pressure approaches from
the west and a warm front lifts into the area from the sw. Expecting
flight restrictions mainly in the MVFR range, but possibly down into
the ifr range after 09z as shra impacts the terminal, before tapering
off this evening. There is a chance for tsra during the afternoon
near the warm front, and we will address this concern in later tafs.

A tight e-se gradient will boost winds into the 15-25 kt range, maybe
even occasionally higher.

Extended aviation outlook:VFR is expected to return by Tuesday
afternoon. Flight restrictions possible in showers late
Thursday early Friday.

Marine
Today and tonight: poor to hazardous marine conditions will
impact all waters, with a tight pinching of the gradient between
strong high pressure off new england and low pressure spinning
in the tennessee valley. With as much as a 4-5 mb spread across
the waters, solid small craft advisories are in place for all
marine zones for e-se winds reaching 20-30 kt today, dropping
around 5 kt tonight as the gradient slackens a little. Where the
best pressure packing occurs we have raised a gale warning on
the charleston county atlantic waters beginning at 11 am and
continuing through late tonight. Winds will peak at 35 kt or
higher during this time. There has been several days of onshore
winds and with it continuing today, seas will easily reach 5-10
ft, highest on the outer georgia waters and the 0-20 nm off
charleston county. Mariners should also be prepared for reduced
visibility in heavy rains at times, plus the risk for afternoon
and night time t-storms. A few of these could be strong or
severe with damaging winds and maybe an isolated waterspout.

Tuesday through Saturday: marine conditions will continue to
improve on Tuesday as low pressure lifts northeast away from the
area. Small craft advisories will gradually drop as seas fall
below 6 feet, first in the southern two coastal zones early
Tuesday afternoon then charleston county waters and outer ga
waters Wednesday morning. Low confidence in forecast late week
given model discrepancies, but it appears conditions will remain
below any headline criteria. A cold front could drop through
the waters early in the weekend, then high pressure will return
for the remainder of the weekend.

High surf: with strong e-se winds, our local wave breaking
matrices show around 5 foot breakers will impact the beaches of
charleston county this afternoon into tonight. That along with
seas building to 8-10 ft on the waters within 20 nm of the coast
suggests that a high surf advisory is necessary. In addition
areas of beach erosion can occur, especially near the time of
the 330-400 pm high tide.

Rip currents: the large surf and strong e-se winds will produce
a high risk of rip currents on the charleston county beaches
today. A moderate risk is forecast on the lower south carolina
and georgia beaches, but if swells are greater than we now
indicate, a high risk would be required on the other beaches as
well.

Chs watches warnings advisories
Ga... None.

Sc... Lake wind advisory from 11 am this morning to 8 pm edt this
evening for scz045.

High rip current risk from 8 am edt this morning through this
evening for scz050.

High surf advisory from 11 am this morning to 5 am edt Tuesday
for scz050.

Marine... Small craft advisory until 2 pm edt Tuesday for amz352-354.

Small craft advisory until 11 am edt this morning for amz350.

Gale warning from 11 am this morning to 2 am edt Tuesday for
amz350.

Small craft advisory until 8 am edt Wednesday for amz374.

Small craft advisory until 2 am edt Tuesday for amz330.

Near term...

short term... Ect
long term... Ect
aviation...

marine...



Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
CHTS1 19 mi41 min E 14 G 17 65°F 65°F1020.2 hPa (-1.4)
ACXS1 - ACE Basin Reserve, SC 31 mi56 min N 5.1 65°F 60°F
41029 - Capers Nearshore (CAP 2) 32 mi33 min E 16 G 21 65°F 64°F1020.7 hPa
41033 48 mi33 min E 16 G 25 65°F 64°F1018.3 hPa

Wind History for Charleston, SC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Summerville Airport, SC8 mi46 minE 310.00 miMostly Cloudy61°F57°F88%1020.7 hPa
Charleston, Charleston Air Force Base, SC10 mi45 minESE 118.00 miLight Rain65°F59°F81%1020.4 hPa
Moncks Corner Berkeley County, SC18 mi46 minESE 47.00 miMostly Cloudy59°F55°F88%1021.3 hPa
Charleston Executive Airport, SC21 mi46 minE 135.00 miFog/Mist64°F60°F88%1020 hPa
Mount Pleasant Regional-Faison Field, SC23 mi66 minE 67.00 miMostly Cloudy64°F60°F88%1021.3 hPa
Walterboro Lowcountry Regional Airport, SC24 mi46 minE 610.00 miOvercast61°F59°F94%1020.3 hPa

Wind History from DYB (wind in knots)
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Last 24hrCalmCalmCalmE5E7E5SE6E9SE6
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G15
E5E9E3E5E6
1 day agoCalmCalmCalmN4E8NE8NE3E5E4E5S8S3E8SE4CalmE3E4E4E4E3NE3CalmCalmCalm
2 days agoN6N7NE11
G16
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NE6N10NE4NE4N4N7NE3NE3CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalm

Tide / Current Tables for Bacon Bridge, Ashley River, South Carolina
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Bacon Bridge
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Mon -- 12:01 AM EDT     0.02 feet Low Tide
Mon -- 02:44 AM EDT     Moonset
Mon -- 05:24 AM EDT     2.24 feet High Tide
Mon -- 06:41 AM EDT     Sunrise
Mon -- 12:53 PM EDT     0.03 feet Low Tide
Mon -- 01:36 PM EDT     Moonrise
Mon -- 06:09 PM EDT     1.96 feet High Tide
Mon -- 07:56 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
00.20.81.422.22.221.71.30.80.40.100.30.81.41.821.91.71.30.90.5

Tide / Current Tables for Charleston Harbor Entrance, South Carolina Current
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Charleston Harbor Entrance
Click for Map
Mon -- 02:42 AM EDT     Moonset
Mon -- 03:21 AM EDT     -0.00 knots Slack
Mon -- 06:39 AM EDT     -2.38 knots Max Ebb
Mon -- 06:40 AM EDT     Sunrise
Mon -- 09:52 AM EDT     0.00 knots Slack
Mon -- 12:01 PM EDT     1.39 knots Max Flood
Mon -- 01:35 PM EDT     Moonrise
Mon -- 03:51 PM EDT     -0.00 knots Slack
Mon -- 07:07 PM EDT     -2.13 knots Max Ebb
Mon -- 07:55 PM EDT     Sunset
Mon -- 10:09 PM EDT     0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.61.30.90.3-0.7-1.6-2.2-2.3-1.8-0.90.111.41.210.6-0.1-1-1.8-2.1-1.9-1.1-0.20.8

Weather Map and Satellite Images
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wmap_A
GOES Local Image of Southeast    EDIT
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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Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Charleston, SC (5,6,7,8)
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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.