Sunday, April22, 2018

Marine Weather and Tides
Isle of Palms, 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 7:56PM Sunday April 22, 2018 2:13 PM EDT (18:13 UTC) Moonrise 11:27AMMoonset 12:38AM Illumination 49% Phase: First Quarter Moon; Moon at 7 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 221758
area forecast discussion
national weather service charleston sc
158 pm edt Sun apr 22 2018

High pressure will begin to lose its influence today as a low
pressure system approaches from the west. The low will bring
much needed rain to the area tonight into Monday before slowly
lifting up the coast through the middle of the week. Weak high
pressure will prevail before a cold front crosses the area late

Near term through tonight
Updated the pops and QPF to reflect the latest model guidance.

Also, adjusted the temperatures, dew points, and winds.

Rest of today: surface high pressure centered over the ne
portion of the country will gradually relax its grip on the
local area today, as a deep cyclone across oklahoma and arkansas
drifts east ans begins to absorb surface low initially near the
lower mississippi valley into its circulation. Dry air is
retreating and moisture is advancing.

Tonight: the surface and low aloft become vertically stacked as
it heads into the lower-middle mississippi valley. The surface
high is reluctant to move from its position over the NE states,
while a warm front slowly advances across northern florida and
into georgia in association with the upstream low. The results
in a deep and strong onshore low-middle level flow and
strengthening theta-e advection. Pwat climbs to near the 90th
percentile of around 1.5 inches between 06z and 12z Monday.

This occurs in sync with deep forcing for ascent created by
plentiful upper difluence with the left front quad of the upper
level jet, considerable low level convergence and strong
isentropic lift. This will allow for the development of numerous
to widespread showers, especially during the late evening and
overnight. We have categorical pop just about everywhere, except
maybe near the santee river where likely pop is in place.

The ingredients for a widespread heavy rainfall are certainly
in place with a deep s-se flow between a blocking high to the n
and the low to the w. But even at this late time there is just
enough model inconsistency to create some forecast uncertainty.

We did add mention of heavy rainfall into the forecast after
midnight, and our QPF tonight is generally a blend of the
previous forecast and the latest wpc guidance. This supports
amounts of 1 10 to 1 4 inch in the charleston tri-county
district, trending upward to 3 4 to 1 inch over SE georgia.

However, if training is able to develop up and or there are
some convergent bands that set up, higher amounts would occur.

Even so, since we're in a severe drought (d2), the area should
be able to handle the rainfall. The exceptions would be along
coastal areas from edisto beach south to sapelo and darien, and
in downtown savannah and beaufort during the 230-400 am high
tide which could well be occurring in tandem with heavy rains.

This would result in flooding of low lying and urban areas.

A little thunder and lightning could occur in a few spots late
south of i-16 in georgia where there is limited elevated cape,
but not enough to add mention to the forecast.

It'll be a warm night with elevated dewpoints, wet conditions
and a 35-45 kt low level jet moving in late to keep winds
elevated through the night. Highest winds from off the ocean will
be along the coastal zones, where 15-25 mph and higher gusts
will occur. This leads to lows about 5-8f above normal for this
time of year.

Short term Monday through Wednesday
Unsettled weather will continue through Monday as a closed upper low
and associated surface low spin over the tennessee valley. Strong
isentropic ascent and lift from upper diffluence will combine with
precipitable water values of 1.6 inches (near climatological
maximums for mid-late april) to drive widespread coverage of
showers. This system should bring decent rainfall with it, but
extremely dry antecedent conditions will keep the probabilities for
exceeding flash flood guidance numbers fairly low. Rainfall totals
Monday into Monday night are forecast to be 1-3 inches on average,
highest across the charleston tri-county area. Some instability is
present so mention of thunder will remain in the forecast, however
no severe weather is expected at this time.

Another concern for Monday is the winds. East southeast winds will
become gusty as the area becomes positioned between the approaching
low and stubborn high pressure to the north. The gradient will be
tightest across the northern zones where some gusts 30-35 mph will
be possible. Although mixing profiles are not the most favorable
over lake moultrie, the gradient wind could still be enough to
support lake wind advisory criteria. Will highlight this potential
within the hwo.

Models indicate another wave of low pressure will develop over
georgia later Monday night into Tuesday, which will slowly begin to
lift north and kick the best moisture out of the area. Rain chances
will decrease from south to north. May even see some breaks in the
clouds during the day. Temperatures will return closer to normal.

The closed upper low will open to a wave by Wednesday while the
surface low continues its slow track up the east coast. There
continues to be discrepancies between models, but it appears that a
trailing cold front could approach the area late in the day. Lack of
moisture will preclude mentionable pops.

Long term Wednesday night through Sunday
Forecast confidence is fairly low in the extended period due to
large differences in model solutions. A weak cold front is progged
to move across the area early in the period, then a rather ill-
defined pressure pattern will be in place through early Friday.

Models seem to diverge thereafter, but in general it looks like
another front could cross through early in the weekend. Main rain
chances will be on Thursday as shortwave energy traverses overhead.

Temperatures will be near normal.

Aviation 18z Sunday through Friday
18z tafs:
kchs: gusty winds this evening, easing for a few hours
overnight.VFR for roughly the first half of the TAF period.

Showers will begin impacting the terminal for the second half of
the TAF period, initially bringing MVFR. As the showers become
heavy after daybreak Monday, ifr seem favorable. But due to some
uncertainty with timing, we're opting to leave prevailing ifr
out of the TAF for now. Additionally, gusty winds will develop
late in the taf, with gusts ~30 kt.

Ksav: gusty winds for the entire TAF period, strongest during
the daylight hours.VFR for roughly the first half of the taf
period. Showers will begin impacting the terminal for the
second half of the TAF period, initially bringing MVFR. As the
showers become heavy around daybreak Monday, ifr seem favorable.

But due to some uncertainty with timing, we're opting to leave
prevailing ifr out of the TAF for now.

Extended aviation outlook: flight restrictions in reduced ceilings
and visibilities are expected Monday into at least Monday night.

Gusty winds expected on Monday.

Today and tonight: the waters will be positioned between strong
high pressure near the mid-atlantic region and long island,
while a deep low is located in the lower and middle mississippi
valley. The e-se gradient tightens to around 3-4 mb today, then
to around 4-5 mb tonight. This results in increasing winds and
building seas with the favorable onshore fetch. Small craft
advisories are in effect for all the waters and the charleston

Monday through Friday: hazardous marine conditions expected on
Monday as a tight pressure gradient remains in place due to an
approaching low pressure system. Small craft advisories will be
ongoing for all waters, including the charleston harbor. Models have
been consistent in showing some gusts to gale force across the
charleston county waters where the gradient is tightest during the
afternoon and evening. A gale watch has been raised which currently
runs 15z Monday through 06z Tuesday. Winds will drastically improve
early Tuesday, however seas will take a bit longer to subside. All
waters should be advisory-free by Wednesday morning. No additional
marine concerns are expected thereafter.

Rip currents: a continued moderate onshore wind, maybe a little
swell energy and small astronomical influences from the recent
perigee will lead to a moderate risk of rip currents at all
beaches today.

A prolonged stretch of moderate to perhaps strong onshore winds
and larger surf will lead to an enhanced risk of rip currents
at the beaches early this week.

Chs watches warnings advisories
Ga... None.

Sc... None.

Marine... Small craft advisory until 11 pm edt Monday for amz330.

Small craft advisory from 8 pm this evening to 2 pm edt
Tuesday for amz352-354.

Gale watch from Monday morning through late Monday night for

Small craft advisory from 8 pm this evening to 11 am edt
Monday for amz350.

Small craft advisory until 8 am edt Wednesday for amz374.

Near term...

short term...

long term... Ect


Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Charleston Executive Airport, SC171 mi18 minE 1510.00 miMostly Cloudy72°F55°F57%1025.1 hPa

Wind History from JZI (wind in knots)
Last 24hrNE15
1 day agoE13E12E10E8NE10E6E4CalmCalmCalmCalmCalmNE3NE6E8E8
2 days agoS9

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 (14,3,4,5)
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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 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 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.