Wednesday, May24, 2017 L-36.com


Marine Weather and Tides
Nantucket, MA

Version 3.4
What's New / NOTES
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 5:11AMSunset 8:04PM Wednesday May 24, 2017 12:04 AM EDT (04:04 UTC) Moonrise 4:39AMMoonset 6:37PM Illumination 2% Phase: Waning Crescent; Moon at 28 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- 717 Pm Edt Tue May 23 2017
.small craft advisory in effect from Wednesday morning through late Wednesday night...
Tonight..E winds 5 to 10 kt. Seas 2 to 3 ft. Patchy fog. A slight chance of rain this evening...then a chance of rain after midnight. Vsby 1 nm or less.
Wed..NE winds 15 to 20 kt with gusts up to 25 kt. Seas 2 to 4 ft. Patchy fog. A chance of rain. Vsby 1 nm or less.
Wed night..NE winds 15 to 20 kt...diminishing to 5 to 10 kt after midnight. Gusts up to 25 kt. Seas 4 to 6 ft.
Thu..E winds 10 to 15 kt with gusts up to 25 kt. Seas 4 to 6 ft. Showers likely. Vsby 1 to 3 nm.
Thu night..SE winds 10 to 15 kt with gusts up to 25 kt... Diminishing to 5 to 10 kt after midnight. Seas 4 to 7 ft. Showers. Vsby 1 to 3 nm.
Fri..SW winds 5 to 10 kt...becoming W 10 to 15 kt in the afternoon. Gusts up to 20 kt. Seas 5 to 7 ft. Showers likely.
Fri night..NW winds 10 to 15 kt. Gusts up to 20 kt in the evening. Seas 4 to 7 ft.
Sat..NW winds 5 to 10 kt. Seas 3 to 5 ft.
Sat night..S winds 5 to 10 kt. Seas 2 to 4 ft.
Sun..SE winds 5 to 10 kt. Seas 2 to 4 ft.
Sun night..SE winds 5 to 10 kt. Seas 3 to 5 ft. A chance of showers. 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 717 Pm Edt Tue May 23 2017
Synopsis for massachusetts and rhode island coastal waters.. Another coastal low will move across the benchmark tonight followed by another high pressure system on Wednesday. A potent low pressure system will move over the area late Thursday into Friday. Followed by quiet weather for the weekend. 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 240212
afdbox
area forecast discussion
national weather service taunton ma
1012 pm edt Tue may 23 2017

Synopsis
Dry conditions prevail early tonight. Another wave of low
pressure tracks south of new england late tonight into early
wed, bringing a chance for rainfall to the south coast. This
will be followed by dry and seasonable conditions Wed afternoon
and night. Low pressure brings showers and cooler temperatures
Thursday and Friday. Weak high pressure will bring a dry start
to the holiday weekend Saturday. Another coastal low brings late
Sunday into early Monday. Leftover showers are possible Monday
and Tuesday.

Near term until 6 am Wednesday morning
1030 pm update...

18z rgem and 00z NAM has come in quite dry for tonight which
cause a bit of a pause for the near term forecast. Comparing the
latest hi-res guidance, will begin a trend in that direction.

Coastal low is staying a bit further offshore with a lot of dry
air in the mid to upper levels. Right now, confidence is that
the immediate south coast, CAPE and islands have the best
potential for rainfall very late tonight into tomorrow morning.

Otherwise high level clouds aloft will keep temperatures from
falling tonight. Anticipate overnight lows remaining in the
50s.

Cannot rule out some patchy fog across the islands and the south
coastal plain as better low level moisture advects into the
area. Still a good temp dewpoint spread so am not expecting
dense fog tonight.

Aside from the adjustments mentioned above, the overall trend in
the forecast generally is on track.

Short term 6 am Wednesday morning through Wednesday night
Wednesday...

low pressure tracks further northeastward during Wednesday, with the
low center likely passing near 40n 70w in the morning. Precip
chances are at their highest early in the morning, with chance pops
ijd-sfz-near owd and southeast, then high chance to likely pops cape
and islands. Where it does rain, QPF should be limited to around
0.25 inch or less.

Otherwise, chances for rain diminish for late morning, with a dry
afternoon, as the low moves further offshore and away from our
region. Northeast winds will gust during the morning hours across
the CAPE and islands due to tight pressure gradient from building
high pressure to our west, and passing coastal low to the east.

Gusts will be near 15 to 25 mph.

As a surface high pressure builds into the area, should see
increasing sunshine, partly sunny skies. The east northeast onshore
winds will limit high temps to some extent across the coastal plain.

In addition there is a chance of sea breeze development across south
coastal ma ri. Forecasting high temps in the mid 60s to mid 70s,
except lower highs in the upper 50s to mid 60s along east and south
coastal ma coastal ri.

Wednesday night...

increasing clouds expected in anticipation of another low pressure
system to affect our region. The low emerges from the vicinity of
virginia and north carolina, starting to make its way to the mid
atlantic coastline during the overnight. 12z model runs look to
provide a slower approach of this low, so Wed night should be
predominantly dry. However as we advance towards daybreak thu, have
slight chance pops for northern ct southern ri. In addition, could
see some low clouds and patchy fog within the coastal plain as a
light east wind continues.

Long term Thursday through Tuesday
Big picture...

the longwave scale retains cyclonic flow over the eastern usa much
of the period while a ridge builds over the western usa.

Deep trough over the eastern usa evolves into a closed low that
sweeps across new england Friday. A weak ridge brings drier weather
Saturday, then a shortwave races through on Sunday. A northern
stream closed low over canada drops south over the great lakes, then
guides a southern stream shortwave across new england early in the
week.

Upper mass fields are similar through Saturday. The fields
thereafter show similar projections but with different timing
through the early week. We used a blend of model data for the
extended range grids with low-moderate confidence for the Sunday
night-Monday system.

Details...

Thursday-Friday...

shortwave coming around the upper low will generate a coastal low
near chesapeake bay Thursday. That low will then move up the coast
Thursday night and cross our area Friday. The 12z models show a 40-
50 knot south jet between 850 and 1000 mb moving up the coast
Thursday. This shifts well offshore over Thursday night as the upper
shortwave kicks east to the coast. Meanwhile a 20-30 knot east jet
at the surface will feed surface level moisture into our area. The
presence of these low level jets suggest a good inflow of moisture
into our area, while the shortwave and upper jet will provide
sufficient dynamics for lift.

Two questions in the data are the jet shifting well offshore as it
does and a mid-level dry zone overhead Thursday afternoon which
fills in Thursday night. Either of these could interfere with the
expected rainfall. For now, we will slow the onset of rain into
Thursday morning... Which may still be too soon if that dry layer has
anything to say about it... With the major portion of rain taking
place Thursday night and Friday morning.

The coastal low and upper low move past southern new england Friday
morning. This will bring winds around out of the north-northwest and
cut off the inflow of moisture. Expect the leading precip to taper
off, but with leftover showers through the day Friday.

Low level flow will be from the east Thursday, coming over water
temps in the 50s. Thursday MAX temps in eastern mass will be
buffered by this water with MAX values upper 50s and lower 60s.

Farther inland, low level temps suggest a MAX of 60-65. With dew
points in the upper 40s to mid 50s and rain, expect min temps to be
close to dew point. Temps aloft on Friday suggest MAX temps around
60 or low 60s in the east and mid to upper 60s in the ct valley.

Saturday...

high pressure brings a day of rest from the wet weather. Temps of 8c
to 9c at 850 mb suggests MAX temps in the low to mid 70s. If the
surface flow is light enough, a sea breeze may occur along the east
mass coast and hold MAX temps there in the 60s.

Sunday through Tuesday...

the models show a dance of sorts in the atmosphere. Closed low from
canada dips south into the great lakes area. In doing this, it pulls
a shortwave in the southern stream farther northeast. This will push
surface low pressure through the ohio valley and to the new jersey
coast on Sunday. The ECMWF is faster with the surface low, with less
resulting interaction between upper systems. The GFS is farther
north and shows more interaction. In any case, expect showers for
our area for Sunday afternoon and night. For Monday and Tuesday the
northern closed low shifts closer to us and should provide a
continued chance of clouds and showers.

Aviation 02z Wednesday through Sunday
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Wednesday night ...

tonight... Moderate confidence. MainlyVFR with possible MVFR ifr
developing after 2am across the south coast, CAPE and islands.

Expect low clouds and fog, as well as passing showers from
coastal low later tonight. Also areas of fog south coastal
ma CAPE islands. Gusty NE winds to near 20 kts possible near
daybreak. Chance for showers mainly CAPE islands later tonight.

Wednesday... High confidence. Improving trend toVFR, with the
exception of CAPE islands, where ifr vsbys CIGS may linger thru wed
am, and ifr CIGS may last into the afternoon. East wind
persists. Passing showers Wed am, mainly across CAPE islands.

Wed night... Across interior southern new england,VFR likely and
dry. Along east coastal and south coastal ma including CAPE islands,
ifr possible in low clouds and fog. Light NE E wind persists thru
the night.

Kbos taf... High confidence in taf.

Kbdl taf... High confidence in taf.

Outlook Thursday through Sunday ... Moderate to high forecast
confidence.

Thursday... Ifr CIGS and vsbys in rain and fog with east wind
gusting to 20 knots along the shoreline.

Friday... Conditions improve to mixedVFR MVFR in showers as winds
shift from the northwest.

Saturday... VFR. Diminishing northwest wind.

Sunday... VFR early, trending to MVFR ifr in showers and fog by
Sunday night. Winds from the southeast.

Marine
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Wednesday night ... High confidence.

Tonight and Wednesday...

another coastal low will develop across the mid-atlantic and move
northeastward towards the waters tonight, then pass northeast of the
waters on Wednesday. Visibilities could drop in patchy fog and light
to moderate rainfall late tonight and Wed morning. Improving
visibility and rainfall ending by midday Wednesday as high
pressure builds in the area. However, due to the pressure
gradient between the offshore low and high pressure, a period of
gusty northeast winds is expected during Wednesday and
Wednesday evening. Seas will begin to build during Wed as low
moves further offshore.

Highest confidence of SCA thresholds for winds seas being met during
wed Wed night are along the southern outer coastal waters, and ri bi
sounds. A small craft advisory has been issued for this area.

Outlook Thursday through Sunday ...

Thursday-Friday...

poor vsbys in rain and fog Thursday and Thursday night. Easterly
winds around 25 knots with strongest winds during the afternoon and
evening. These winds then lift north of the waters tonight. Seas 5
to 6 feet on the outer waters Thursday and Thursday night. Low
pressure moves past the waters Friday morning, at which point the
winds shift from the nnw with speeds 20 knots or less. Expect seas 5-
7 feet on the outer waters and ri sound. Small craft advisory may
be needed on some of the waters both days.

Saturday-Sunday...

winds remain below 25 knots through the period. Seas subside below
5 feet early Saturday. Seas may return to 5 feet on the outer waters
late Sunday night. Poor vsbys possible in showers and fog late
Sunday and Sunday night.

Tides coastal flooding
High astronomical tides will occur over several tide cycles along
eastern massachusetts coast from Thursday into memorial day, with
tides around 12 feet in boston and 4 feet on nantucket.

At the very least, minor nuisance flooding will occur in the most
vulnerable locations such as morrissey blvd in boston. Any surge on
top of these tides would lead to more widespread, but minor,
coastal flooding, including on nantucket. Right now, this looks
to be a possibility Thursday into Friday due to expected onshore
winds. Model surge guidance (estofs) shows a potential 0.6 ft
surge, which would give a storm tide near 13 feet Thursday
night in boston and just under 5 ft on nantucket.

Box watches warnings advisories
Ct... None.

Ma... None.

Ri... None.

Marine... Small craft advisory from 10 am Wednesday to 6 am edt Thursday
for anz254>256.

Small craft advisory from 2 pm Wednesday to 6 am edt Thursday
for anz235-237.

Synopsis... Wtb nmb
near term... Dunten nmb
short term... Nmb
long term... Wtb
aviation... Wtb nmb
marine... Wtb nmb
tides coastal flooding... Staff


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
NTKM3 - 8449130 - Nantucket Island, MA 2 mi46 min Calm G 1.9 53°F 60°F1011 hPa
44020 - NANTUCKET SOUND 13 mi74 min 55°F1 ft1010.7 hPa (+0.5)
WAXM3 - Waquoit Bay Reserve, MA 33 mi79 min 1.9 57°F 54°F
BZBM3 - 8447930 - Woods Hole, MA 37 mi46 min 56°F 57°F1010.6 hPa

Wind History for Nantucket Island, MA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Nantucket, Nantucket Memorial Airport, MA1 mi71 minN 010.00 miFair52°F50°F93%1010.9 hPa

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Last 24hrSE18SE17S13S13S8W4N13N9N10N15N14N14N14N14N11N9N7NE4N7N6SW7SW3CalmCalm
1 day agoSW7S6SW7S5S4S3S5S6S8SE10SE11SE13SE12SE12SE12SE11SE11SE9SE12SE11SE12SE14SE17SE19
2 days agoW4NW5NW6NW4NW4NW4N8N10N9N11NE6E8E9SE11SE14SE11SE8S5S4S4S4SW5S5S6

Tide / Current Tables for Nantucket, Nantucket Island, Nantucket Island, Massachusetts
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Nantucket
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Wed -- 04:39 AM EDT     Moonrise
Wed -- 05:05 AM EDT     -0.39 feet Low Tide
Wed -- 05:14 AM EDT     Sunrise
Wed -- 11:35 AM EDT     3.16 feet High Tide
Wed -- 05:11 PM EDT     -0.10 feet Low Tide
Wed -- 06:37 PM EDT     Moonset
Wed -- 08:00 PM EDT     Sunset
Wed -- 11:48 PM EDT     4.05 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
3.62.91.90.9-0-0.4-0.10.51.322.73.13.12.721.10.3-0.10.10.81.82.63.43.9

Tide / Current Tables for Nantucket Harbor Entrance Channel, Massachusetts Current
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Nantucket Harbor Entrance Channel
Click for Map
Wed -- 03:17 AM EDT     -1.49 knots Max Ebb
Wed -- 04:39 AM EDT     Moonrise
Wed -- 05:14 AM EDT     Sunrise
Wed -- 05:30 AM EDT     0.00 knots Slack
Wed -- 07:31 AM EDT     1.42 knots Max Flood
Wed -- 10:32 AM EDT     -0.00 knots Slack
Wed -- 03:43 PM EDT     -1.47 knots Max Ebb
Wed -- 05:54 PM EDT     0.00 knots Slack
Wed -- 06:37 PM EDT     Moonset
Wed -- 07:55 PM EDT     1.40 knots Max Flood
Wed -- 08:00 PM EDT     Sunset
Wed -- 10:43 PM EDT     -0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
-0.5-0.8-1.2-1.5-1.3-0.60.51.31.30.80.2-0.1-0.4-0.6-0.9-1.3-1.4-0.90.11.11.410.4-0.1

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 (0,6,7,8)
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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.