Tuesday, January22, 2019 L-36.com

Marine Weather and Tides
Isle of Palms, SC

Version 3.4
What's New / NOTES
10/6/2018 Colors of tide XTide graphs changed to emphasize that they were upgraded. See next note. Comments welcome.
10/4/2018 I have fixed XTide and updated the harmonic files. There were some name changes so you might have to click EDIT to find the new station name.

Sunrise 7:18AMSunset 5:43PM Tuesday January 22, 2019 1:53 AM EST (06:53 UTC) Moonrise 7:33PMMoonset 8:22AM 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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7 Day Forecast for Marine Location Near Isle of Palms, SC
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location: 30.97, -77.7     debug

Area Discussion for - Charleston, SC
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Fxus62 kchs 220547
area forecast discussion
national weather service charleston sc
1247 am est Tue jan 22 2019

High pressure will extend across the region through Wednesday.

A cold front will push offshore early Thursday with high
pressure prevailing Friday and Saturday. A storm system could
affect the area Sunday.

Near term until 6 am this morning
As of 1245 am: IR satellite indicated that thin cirrus
was streaming across the forecast area. The cirrus extended
several states upstream of the cwa. I will update the forecast
to adjust sky coverage and timing.

Previous discussion:
temps have already fallen below freezing in parts of the
charleston quad-county area, with even a few spots in the upper
20s. This is in line with the latest forecast thinking, so
essentially no changes to the min temp forecast, with a hard
freeze to occur in locations along much of our north and
northwest tier. Coastal areas will experience northeast winds as
high as 15-20 mph with some pinching between the inland high and
a subtle trough trying to develop over the nearby coastal
waters. This will hold temps above freezing in most places east
of the intra-coastal.

We did raise sky cover a bit as thin cirrus moves through in
advance of a strong storm system in the plains, as well as from
some stratocumulus that will be near or brushing onshore of our
georgia coastline around daybreak. But even with this
adjustment, skies will still be mostly clear or clear through
the night.

Previous discussion...

with large dew point depressions and winds away from the coast
becoming light under clear or mainly clear skies, we expect the
coldest night since last winter in many locales. For the
evening update we have dropped hourly temps a bit from the
previous forecast, and also opened a little larger range of min
temps from the coldest north-northwest to the "warmest" south-
southeast. Temps will be below freezing for as much as 10-14
hours over jenkins and screven county in georgia, and across the
bulk of south carolina outside beaufort and jasper county. Most
other places inland from the intra-coastal of both states will
be down below freezing for as much as 5-9 hours. The lowest wind
chills (but not everywhere) will be in the mid and upper teens,
but not quite cold enough for an advisory.

Discussion from 411 pm...

this evening and tonight: a mid upper lvl trough of low pressure
will shift further away from the northeast coast while a wedge
of high pressure persists over the southeast united states. The
setup will lead to dry and cold conditions under clear skies and
a light northerly wind as the high becomes centered over the
mid-atlantic states late. Overnight lows should be a few degrees
cooler than the previous night, dipping into the mid upper 20s
inland to low mid 30s near the coast. The combination of light
northerly winds and these sfc temps will result in wind chill
values around 20 degrees well inland overnight. A weak coastal
trough could develop off the southeast georgia coast approaching
daybreak, but should only result in a few clouds drifting
onshore late.

Short term 6 am this morning through Thursday
Tuesday and Wednesday: modified arctic high pressure will gradually
shift offshore of the mid-atlantic coast as the large h5 ridge
aligned along the east coast propagates to the east. A weak coastal
trough will develop off the georgia and far southern south carolina
coast Tuesday afternoon, then lift to the north as a warm front
Wednesday as a strong storm system approaches from the west.

Weak isentropic ascent on several levels in the vicinity of the
coastal trough could produce isolated showers along and just
offshore of the georgia coast as early as late Tuesday
afternoon, then spread inland and to the north Tuesday night
into Wednesday as pre-frontal low-level jetting ahead of the
storm intensifies. The best lift through the period looks to
occur across southeast georgia coincident with the far eastern
flanks of the strongest h9-h8 winds. 20% pops will be
highlighted for late Tuesday afternoon along the georgia coast
with 30-40% pops Tuesday night into Wednesday, highest across
southeast georgia. Temperatures will steadily moderate through
the period with highs lower 50s north upper 50s south Tuesday
afternoon warming to upper 60s north lower 70s south Wednesday
afternoon. Lows Wednesday morning will range from the upper
30s lower 40s well inland to the mid 50s along the georgia

Wednesday night and Thursday: a strong southern stream shortwave
will move across the southeast u.S. Through the period. The
associated cold front will move quickly east across the deep south
Wednesday, the southeast u.S. Wednesday night, and offshore the
carolina coast Thursday morning. 21 00z guidance is similar in
showing strong advection of gulf moisture along ahead of the front
with pwats surging 1.50-1.75 inches. Model t-sections at
kchs ksav krbw kmhp all show deep layered moisture juxtaposed with a
region of strong, deep-layered dpva forcing for assent in place
ahead the surface wind shift suggesting a large area of moderate to
locally heavy rainfall will accompany the front as it moves across
the forecast area. Increased pops to 100% given the consistent
signals noted in the models for the past several days with qpf
amounts ranging from 0.75 to 1.25 inches with higher amounts
possible. There is still evidence of a pool of elevated instability
developing ahead of the h5 trough with the latest GFS showing a
narrow corridor surface instability forming just ahead of the front
itself. Expanded a mention of a slight chance of tstms to all areas
given this. Rain will quickly end Thursday morning as the front
shifts offshore. Strong low-level jetting ahead of the front will
keep conditions rather mixed and warm Wednesday night with breezy
conditions along the coastal counties. Lows will only drop into the
mid-upper 50s in the evening hours with temperature holding steady
or slowly rising overnight. Highs Thursday will warm into the mid-
upper 60s with a few lower 60s well inland.

Lake winds: a lake wind advisory may be needed Thursday afternoon
with the onset of strong post-frontal cold air advection. Poor
mixing profiles with warm air advecting over the cold lake waters of
lake moultrie should keep winds below 20 kt Wednesday night Thursday

Long term Thursday night through Monday
Cool high pressure will build over the area Friday, then a
reinforcing dry cold front will sweep through Friday night.

Temps on Saturday will thus be a few degrees cooler than Friday.

Southerly flow will redevelop by Sunday as an upper trough
approaches. A potent storm system could affect the area Sunday
but considerable model disagreement exists.

Aviation 06z Tuesday through Saturday
Prior to the 6z tafs, IR satellite indicated that thin cirrus
was streaming across terminals. The cirrus extended several
states upstream of the forecast area. Under ridging sfc high
pressure, I will forecastVFR conditions with steady NE winds
through this afternoon. Llvl lift will increase this evening,
starting over SE ga and spreading northward. The combination of
increasing moisture and increasing llvl forcing should support
MVFR ceilings with periods of light rain.

Extended aviation outlook: flight restrictions possible Tuesday
night. MVFR ifr CIGS vsbys likely Wednesday night into Thursday as
rain associated with a cold pushes through. Gusty winds possible
Wednesday night and Thursday.

Tonight: high pressure will prevail over all coastal waters for
much of the overnight period with conditions expected to remain
below small craft advisory levels. However, a fairly tight
pressure gradient will support northeast winds upwards to 15-20
kt and gusty over most coastal waters, and 15 kt or less in
charleston harbor. Late tonight, winds will slightly veer beyond
the shelf waters as a subtle coastal trough attempts to develop
near the southeast georgia coast. But winds will hold northeast
in closer to shore. Seas will gradually build to 3-4 ft in
nearshore waters and 4-5 ft in offshore waters overnight.

Tuesday: the pressure gradient will tighten Tuesday with the
formation of a weak coastal trough. There are signals that winds
could reach as high as northeast 20-25 kt Monday, mainly in the
georgia and far southern south carolina marine zones. Confidence in
winds getting this high are not high enough at this point, so winds
will be capped at 20 kt for now. If this trend continues a small
craft advisory may be needed for some nearshore zones beginning as
early as the morning hours. Northeast winds will gradually turn to
the southeast the coastal through begins to transition into a warm
front and lifts north. Both wind speeds and seas could breach
advisory thresholds, especially over the georgia offshore leg. A
small craft advisory may be needed for this zone overnight.

Wednesday: south winds will begin to ramp up a cold front approaches
from the west and low-level jetting intensifies. The highest winds
will occur Wednesday night, but similar to the last marine event,
mixing profiles over the cool, shelf waters will severely curtail
potential wind speeds across the nearshore waters. Winds will be
capped at 20-25 kt with gusts 30 kt for now. Over the georgia
offshore waters, especially behind 40 nm, water temperatures are
considerably warmer and will support better mixing. Could see gusts
to gale force in this area. Small craft advisories are likely and a
gale watch may be needed for the georgia offshore leg. Seas will
build 5-9 ft nearshore and 9-12 ft offshore.

Thursday through Saturday: winds will turn westerly on Thursday,
continuing to be rather strong into the night before weakening
Friday. A period of small craft advisories is likely Wednesday night
through Thursday night.

Tides coastal flooding
There is still a possibility that tide levels could reach the low-end
of coastal flood advisory thresholds with high tide Tuesday morning.

Much will depend on how quickly northeast winds intensify prior to
high tide.

Chs watches warnings advisories
Ga... None.

Sc... None.

Marine... None.

Near term... Ned
short term... St
long term... Jrl
aviation... Ned

tides coastal flooding...

Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Charleston Executive Airport, SC171 mi58 minNNE 78.00 miFair34°F10°F38%1034.5 hPa

Wind History from JZI (wind in knots)
Last 24hrNW8NW5NW7NW6NW6N5N9NE8N8N10NW8N11N9
1 day agoS19
2 days agoCalmCalmCalmCalmCalmE6E4E3SE4SE5S7S10SW14SW10

Tide / Current Tables for
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Tide / Current Tables for
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Weather Map and Satellite Images
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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.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Charleston, SC (1,6,7,8)
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Ground Weather Radar Station Wilmington, NC
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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.