Wednesday, August16, 2017 L-36.com


Marine Weather and Tides
Nantucket, MA

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 5:50AMSunset 7:39PM Wednesday August 16, 2017 11:22 AM EDT (15:22 UTC) Moonrise 12:31AMMoonset 3:11PM Illumination 31% Phase: Waning Crescent; Moon at 24 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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ANZ255 Coastal Waters Extending Out To 25 Nm South Of Marthas Vineyard And Nantucket- 716 Am Edt Wed Aug 16 2017
.small craft advisory for hazardous seas in effect through Thursday morning...
Today..NW winds 5 to 10 kt. Seas 4 to 7 ft. Patchy fog this morning with vsby 1 nm or less.
Tonight..SW winds around 5 kt, becoming nw after midnight. Seas 4 to 7 ft. Patchy fog. Vsby 1 to 3 nm.
Thu..NE winds 5 to 10 kt, becoming se in the afternoon. Seas 2 to 4 ft.
Thu night..S winds 5 to 10 kt. Seas 2 to 3 ft. Patchy fog. Vsby 1 to 3 nm.
Fri..S winds 5 to 10 kt. Seas around 2 ft.
Fri night..S winds 10 to 15 kt. Gusts up to 20 kt after midnight. Seas 2 to 4 ft. Showers likely with a chance of tstms.
Sat..S winds 10 to 15 kt with gusts up to 20 kt. Seas 4 to 6 ft. Showers likely with a chance of tstms.
Sat night..SW winds 5 to 10 kt. Seas 3 to 5 ft. A chance of showers.
Sun..W winds 5 to 10 kt. Seas 2 to 4 ft.
Sun night..W winds 5 to 10 kt. Seas 2 to 4 ft. Winds and seas higher in and near tstms. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height.
ANZ200 716 Am Edt Wed Aug 16 2017
Synopsis for massachusetts and rhode island coastal waters.. Hurricane gert will pass well south of the waters on today and will elevated southerly swells into today. High pressure returns for Thursday. A warm front will bring a chance of rain for Fri into Sat. High pressure will return on Sunday. For information on possible hazardous weather beyond the 24-36 hour forecast period, please visit www.weather.gov/boston and follow the current hazards link above the map on the left.

7 Day Forecast for Marine Location Near Nantucket, MA
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location: 41.27, -70.06     debug


Area Discussion for - Boston, MA
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Fxus61 kbox 161402
afdbox
area forecast discussion
national weather service taunton ma
1002 am edt Wed aug 16 2017

Synopsis
Dry weather will previal today and Thursday along with plenty
of sunshine. A weather system from the plains will bring showers
and scattered thunder Friday and Saturday along with clouds and
humid air. High pressure returns with fair seasonable weather
Sunday through Tuesday. A drying trend likely follows for Sunday
into early next week along with seasonable temperatures.

Near term until 6 pm this evening
10 am update...

little change needed this morning, noting the development of
some diurnal CU but wedge of drier air will also begin to filter
n-s across the region, so will see a gradual drop in dwpts
through the late morning and afternoon. Tricky call on sea-
breezes. If they begin it would be late, and not penetrate as
deeply inland as usual, but this may mitigate downsloping at
some E coastal locations.

Previous discussion follows...

cold front will move offshore today as longwave trough axis moves
overhead. Some mid to upper level moisture will help filter in
clouds late this remaining into the afternoon, but otherwise a dry day
is in store. Breezy conditions behind the front as winds turn to
the nw. Gusts could reach between 15 to 20 mph. Low confidence if a
sea breeze will develop today. Guidance suggests that the winds
slack off just enough to allow for the sea breeze to push onshore,
however, if winds are stronger than models projected, then sea breeze
will remain offshore.

Despite cold front moving through, and weak caa, 850 mb temps will
still be near 12-14c. This combined with westerly downsloping will
help warm temps into the low to mid 80s.

Beach forecast: we still expect areas of high surf along with a
high risk for rip currents along primarily south facing beaches
which are open to the ocean. This extends from watch hill all the
way across to the outer arm of CAPE cod and includes all islands. A
building swell this morning, from gert, will reach a 14 second
period and nearly 8 ft offshore. This will create a potentially life-
threatening situation due to high seas and rip currents. Will
maintain the current high surf advisory as it stands.

Short term 6 pm this evening through 6 pm Thursday
Tonight into tomorrow... High confidence.

Upper level trough will push offshore tonight as mid-level ridge
builds into the region. At the surface, high pressure will begin to
slide eastward resulting in dry weather and light winds tonight.

High level cirrus could filter into the region, but still feel
clouds will be thin enough to allow for radiational cooling. This
will allow for temps to drop into the mid to low 50s. Metro regions
of pvd and bos will stay a few degrees warmer into the low 60s.

A secondary front will push into the region early Thursday morning.

This is noticed as 850 mb dewpoint drops from 8c to -2c. This stout
dry air will keep Thursday quite dry and clouds at bay. Weak caa
will keep temps a few degrees cooler than today but overall a
pleasant day will be in store for southern new england.

Beach forecast: while waves will begin to subside from gert, may
need to watch for lingering swell which could result in moderate
risk of rip current. Nantucket and outer CAPE would have the highest
potential if this did occur.

Long term Thursday night through Tuesday
Big picture...

subtropical high remains in control across the southern usa while a
general zonal flow continues across canada and the northern usa.

Multiple shortwaves move through new england in two periods: Friday
through Sunday and Tuesday night.

Model mass and thermal fields from the 00z suite are in general
agreement through Monday. Differences in details emerge Monday and
Tuesday.

Details...

Thursday night to Saturday... Moderate confidence.

A group of shortwaves from the great lakes moves through during this
time, supporting a surface cold front that moves through early
Saturday. Zone of upper difluence moves over new england during
Friday afternoon through Saturday morning. Deep layer of moisture
arrives in western ct during Friday morning, then reaches eastern
mass toward midday. Increasing pw values, reaching 2 inches for
Friday afternoon. Stability parameters are mixed, especially in
Friday. No CAPE on Friday, but values of 500-1000 j kg on Saturday.

Low level airmass will be equiv to an 850 mb temp of 8-10c,
supporting MAX sfc temps in the 70s Friday. Airmass warms several
degrees Saturday with support for MAX temps in the upper 70s to mid
80s.

Looks like showers with some potential for thunder especially on
Saturday. High dew points will contribute to areas of fog each
overnight morning.

Sunday through Tuesday...

moisture fields dry out Saturday evening night, becoming dry through
the deep layer while hanging onto a layer of moisture based at 850
mb. High pressure builds later Sunday into Monday, moving offshore
Monday night and Tuesday. This looks like a dry forecast most of
the period, but with increasing moisture at all levels late Tuesday
as another shortwave approaches. This would support showers Tuesday
night.

Aviation 14z Wednesday through Sunday
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Thursday ...

today... High confidence. Fog will burn off within a few hours
after sunrise. MainlyVFR with NW winds. Gusts to around 15 kts
at times through the daylight hours.

Tonight and tomorrow... High confidence.VFR with light winds through
the period. Sea breezes along the coast.

Kbos terminal... High confidence in taf. Low confidence on sea
breeze development this afternoon.

Kbdl terminal... High confidence in taf.

Outlook Thursday night through Sunday ...

Thursday night through Saturday... Moderate confidence.

Vfr trending to MVFR ifr in showers and scattered thunderstorms
Friday and Saturday. Areas of fog also possible early morning Friday
and early morning Saturday. Lowest conditions are expected Friday
night.

Sunday... Ifr in morning fog low clouds, then improving toVFR.

Marine
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Thursday ... High confidence.

Building southerly swell today. Reaching as high as 7-9 ft in
the open ocean waters well south of nantucket, meanwhile seas
could reach 5-7 ft in nearer to the shore as this long period
swell peaks toward the morning hours. Small craft advisories
will continue for all southern waters. These seas will gradually
subside tonight. Lingering swell on Thursday may keep seas from
falling as fast as guidance is suggesting so SCA may need to be
expanded.

Outlook Thursday night through Sunday ...

Thursday night-Friday...

southerly winds less than 20 knots and seas 3 feet or less.

Increasing chance of showers west to east during Friday. Showers and
scattered thunderstorms Friday night.

Saturday...

lingering showers and scattered thunderstorms Saturday. Seas build
to 6 feet on the outer waters, and possibly the exposed portions of
the southern waters. Southerly winds Saturday turn from the west
Saturday night. A small craft advisory may be needed.

Sunday...

high pressure builds over the waters. Winds remain 20 knots or less,
and seas 4 feet or less. Leftover showers early, but these move off
to the east during the morning.

Box watches warnings advisories
Ct... None.

Ma... High surf advisory until 8 pm edt this evening for maz020-
022>024.

Ri... High surf advisory until 8 pm edt this evening for riz006>008.

Marine... Small craft advisory for hazardous seas until 8 pm edt this
evening for anz232>234.

Small craft advisory for hazardous seas until 3 am edt
Thursday for anz235-237.

Small craft advisory for hazardous seas until 8 am edt
Thursday for anz254>256.

Synopsis... Wtb dunten
near term... Doody dunten
short term... Dunten
long term... Wtb
aviation... Wtb dunten
marine... Wtb dunten


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
NTKM3 - 8449130 - Nantucket Island, MA 2 mi53 min N 5.1 G 8 1012.6 hPa
44020 - NANTUCKET SOUND 13 mi93 min NNW 5.8 G 5.8 72°F 70°F1 ft1012.3 hPa (+0.3)72°F
WAXM3 - Waquoit Bay Reserve, MA 33 mi98 min 4.1 78°F 1013 hPa68°F
BZBM3 - 8447930 - Woods Hole, MA 37 mi53 min 78°F 71°F1012.7 hPa
44090 42 mi49 min 69°F1 ft

Wind History for Nantucket Island, MA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Nantucket, Nantucket Memorial Airport, MA1 mi30 minN 1110.00 miFair77°F66°F71%1012.7 hPa

Wind History from ACK (wind in knots)
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Last 24hrS7S7SE7S9S6S6S6CalmSE4S3CalmCalmSW3W4W3SW4W4W4W6W5NW4NW6N10N11
1 day agoSE7SE7SE8SE7SE4S6SE6SE5SE6SE3SE6SE4CalmSE4S5S5S3SW3CalmCalmNW3Calm--Calm
2 days agoW10W9W8W9SW10W11SW9SW5W4NW3S3CalmCalmNE4CalmCalmN5N5N5N5CalmE4E7SE6

Tide / Current Tables for Nantucket, Nantucket Island, Nantucket Island, Massachusetts
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Nantucket
Click for Map
Wed -- 12:31 AM EDT     Moonrise
Wed -- 01:10 AM EDT     0.07 feet Low Tide
Wed -- 05:50 AM EDT     Sunrise
Wed -- 07:40 AM EDT     3.04 feet High Tide
Wed -- 01:17 PM EDT     0.25 feet Low Tide
Wed -- 03:11 PM EDT     Moonset
Wed -- 07:37 PM EDT     Sunset
Wed -- 08:01 PM EDT     3.94 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.50.10.20.81.422.6332.72.11.40.70.30.411.82.53.23.73.93.73.12.2

Tide / Current Tables for Nantucket Harbor Entrance Channel, Massachusetts Current
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Nantucket Harbor Entrance Channel
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Wed -- 12:31 AM EDT     Moonrise
Wed -- 01:27 AM EDT     0.00 knots Slack
Wed -- 03:28 AM EDT     1.31 knots Max Flood
Wed -- 05:50 AM EDT     Sunrise
Wed -- 06:02 AM EDT     -0.00 knots Slack
Wed -- 11:53 AM EDT     -1.18 knots Max Ebb
Wed -- 01:58 PM EDT     0.00 knots Slack
Wed -- 03:11 PM EDT     Moonset
Wed -- 03:54 PM EDT     1.21 knots Max Flood
Wed -- 06:20 PM EDT     -0.00 knots Slack
Wed -- 07:37 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
-1.1-0.40.51.21.20.60-0.3-0.4-0.5-0.7-1-1.2-0.800.91.20.80.2-0.3-0.4-0.5-0.6-0.9

Weather Map and Satellite Images
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Weather Map
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IR Satellite Image from GEOS
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GOES Local Image of Northeast    EDIT
Geos

Wind Forecast for Boston, MA (11,2,3,4)
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Ground Weather Radar Station Boston, MA
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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.