Tuesday, July23, 2019 L-36.com

Marine Weather and Tides
Isle of Palms, SC

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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 6:25AMSunset 8:26PM Tuesday July 23, 2019 9:51 AM EDT (13:51 UTC) Moonrise 11:23PMMoonset 11:12AM Illumination 61% Phase: Waning Gibbous; Moon at 21 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 231126
area forecast discussion
national weather service charleston sc
726 am edt Tue jul 23 2019

A cold front will approach the area today and then move through
tonight. The front will stall offshore through late week, while
high pressure builds inland. High pressure will prevail into
early next week.

Near term through tonight
An amplified and unusual summertime large scale mid and upper
trough will continue to dig across the ohio and tennessee
valley today and tonight, forcing an uncommon summertime cold
front to approach from the northwest today, pushing into the
area late day and early tonight, then off the coast and near the
altamaha river overnight.

For this morning we will see isolated to scattered convection
impacting our mainly charleston and eastern berkeley county,
resulting from theta-e advection and moisture convergence off
the atlantic where decent instability exists. A couple of hard
downpours are certainly possible, especially over charleston
county. But fortunately we're in the low tide cycle. This
convective activity will pull back into the ocean by mid to late
morning, while everywhere else remains rainfree the first half
of the day.

Elsewhere, and once the aforementioned morning activity comes
to an end, it'll be our last typically hot and humid summer day
for awhile. The upstream cold front will overtake the previous
lee side trough as it approaches, and shunts the offshore high
further to the east-southeast. At the same time, the tropical
depression off the east and southeast florida peninsula will
have no chance of developing into anything further as it is
impacted on by the strong southwest flow in advance of the
front. At best some of the moisture associated with the system
could become entrained into the local area tonight.

It looks like a good portion of the day will be free of showers
and t-storms (aside from the morning convection over parts of
coastal south carolina). This will allow for MAX temps to peak
in the lower 90s inland, but "only" in the mid and upper 80s
along the coast with a fairly stiff afternoon resultant sea
breeze to develop with gusts reaching 20 or 25 mph.

As the front draws closer, moisture featuring pwat of 2.0 to 2.5
inches (at or above the 90th percentile) and instability with
mucape around 2500-3000 j kg) will pool over the region. With
falling heights aloft, further enhancement from the right
entrance region of the upper jet over the appalachians, clusters
and lines of showers and t-storms will arrive late in the day
over the west-northwest tier, and continues through at least
the first part of tonight. Consensus from the cams and global
models supports the most likely timing of the arrival of the
convective rains around 5-8 pm. Pop's will be as high as 80-90%
all areas the first half of tonight, so suffice to say it will
be wet as the incoming convection collides with isolated to
scattered activity along the sea breeze.

Since there is some shear for storms to work with, combined with
the instability there does appear to be at least some potential
for isolated severe weather, with damaging winds the main
weather hazard. This would appear to be between about 6 and 10
pm, when the combination of the best shear, upper difluence and
strongest updrafts per the href model will occur. A few special
weather statements and or severe thunderstorm warnings could
become necessary.

Additionally, due to the excessive pwat and integrated water
vapor transport, there is a concern for heavy rainfall, which
has been included in the local forecast products. Most likely
timing of such will between 6 pm and 1 am. Although cells will
be moving at a fairly steady pace, given that training might
occur, there is a concern for at least minor flooding. But with
rainfall rates of 1.5 to 2 inches possible per hour, we do
anticipate that a few flood advisories will become necessary. We
stayed close to the wpc QPF values which supports up to 2 inches
of rain in many areas. Of course, locally higher amounts will be
common. The only climate site that might have a chance of a
record rainfall is kchs, whose highest recorded rain for july 23
is 2.54 inches in 1941.

The bulk of the convection looks to fade after midnight, with
the passage of the cold front. Skies will remain mostly cloudy
or overcast, but there is enough cool advection to get temps
down to their lowest levels since last month. In fact, there
should even be upper 60s over the northwest zones.

Short term Wednesday through Friday
A cold front will have recently exited off the coast Wednesday
morning. The front is expected to stall offshore through much of the
period while high pressure builds inland. In the mid levels, an
amplified trough digging across the eastern seaboard on Wednesday
will weaken considerably Thursday.

A couple waves of low pressure are progged to ride along the stalled
front in concert with a persistent stream of shortwave energy. This
pattern will keep rain chances in the forecast. Pops will be highest
along the coast and across our southeast georgia zones in proximity
to deepest moisture and best forcing. There will likely be a decent
gradient set up, so areas further north and inland could potentially
be dry for much of the period. It is worth noting that a couple
models show the front further south and thus a drier solution with
the rain staying mostly offshore. Trended pops down a touch, but
will likely need to be further refined. Mostly kept thunder to
slight chance given the lack of instability present.

Being on the cool side of the front, we will see a rare stretch of
below normal temperatures. Highs will mainly stay in the mid to
upper 80s, with the coolest day being on Wednesday. Lows are
forecast to range from upper 60s inland to low 70s at the coast.

Long term Friday night through Monday
Models are in fairly good agreement on the synoptic pattern through
the period. A stalled front offshore will become more diffuse with
time, with high pressure to remain the dominant feature over the
weekend into early next week. It is shaping up to be a pretty nice
set of days. There are no stand-out triggers for convection, so kept
rain chances fairly low. Best chances (no higher than 30%) are on
Saturday. Temperatures will generally be at or slightly below

Aviation 11z Tuesday through Saturday
An unusual pattern for summertime is forthcoming late today and
tonight, as a cold front moves into and through the area. It
will bring with it MVFR or possible ifr conditions in showers
and t-storms, some of which will produce heavy rainfall.

First is the potential the nearby showers and t-storms from off
the atlantic that should stay east of the kchs terminal through
about 14z. Thus no mention of flight restrictions, but we will
amend if necessary.

Otherwise we are expectingVFR conditions at kchs and ksav
through late in the day, with gusty s-sw winds this afternoon.

Isolated to scattered showers and t-storms will form along the
sea breeze during the mid and late afternoon. Then as the cold
front approaches, widespread showers and numerous t-storms will
arrive by sunset and continue the first part of tonight as the
cold front pushes through. While we'll probably need to alter
our timing somewhat as the event draws closer, there is enough
confidence to indicate at least vcts and shra, with MVFR
ceilings and visibilities.

Extended aviation outlook: flight restrictions, mainly in ceilings,
possible Wednesday morning early afternoon. MainlyVFR expected

Since there is a line of convection off the coast this morning
there is a concern for possible waterspouts. Since the SPC non-
supercell tornado parameter is as high as 3 units over these
areas, we have issued a marine weather statement through late

Today and tonight: the oceanic high will move further to the
east-southeast in advance of a cold front that moves into the
southeast states. Meanwhile, the tropical depression off the
florida peninsula will lift north, then northeast as it turns
away from the shore in advance of the front in a weakening
state. At present it looks like this feature will not have any
direct bearing on our local conditions. Instead it'll be the sea
breeze and packing of the gradient between the upstream front
and offshore high that occurs. The cold front will impinge on
the waters early tonight, then should clear the entire area

Regarding the winds and seas: SW winds will be as high as 15 or
15-20 kt early this morning, dropping off about 5 kt or so
during the late morning and early afternoon, before climbing
again later in the day. Winds will then clock around to the nw
and N behind the cold front, but with only minimal cool
advection and little pressure rises, winds won't be any more
than 10-15 kt.

There looks to be a window of possible small craft advisory
conditions, especially on the charleston county atlantic waters
and in charleston harbor. Should this occur, the most likely
timing is from about 4 pm through 11 pm. It looks to be
marginal, so we have opted not to raise any advisory flags.

Mariners are also advised that some stronger t-storms will move
in the first part of tonight, and special marine warnings will
likely be required.

Wednesday through Sunday: the marine zones will be positioned
between a stalled front to the east and high pressure building
inland. This pattern will keep winds generally onshore late week
into the weekend. Speeds will be elevated at times, however
conditions are expected to remain below small craft advisory
criteria. Seas will be 2-3 feet on average.

Chs watches warnings advisories
Ga... None.

Sc... None.

Marine... None.

Near term...

short term... Etm
long term... Etm


Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Charleston Executive Airport, SC171 mi56 minSW 67.00 miA Few Clouds82°F77°F84%1014.2 hPa

Wind History from JZI (wind in knots)
Last 24hrSW76W74S10S11S9
1 day agoW5SW7S9SW8
2 days agoS8SW8S9SW10S8S7

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.
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Wind Forecast for Charleston, SC (9,2,3,4)
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Ground Weather Radar Station Wilmington, NC
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