Thursday, July27, 2017 L-36.com


Marine Weather and Tides
Dennis Port, 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 5:29AMSunset 8:05PM Thursday July 27, 2017 8:51 PM EDT (00:51 UTC) Moonrise 10:10AMMoonset 10:46PM Illumination 20% Phase: Waxing Crescent; Moon at 4 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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ANZ232 Nantucket Sound- 716 Pm Edt Thu Jul 27 2017
.gale watch in effect from Saturday morning through late Saturday night...
Tonight..SW winds 5 to 10 kt. Gusts up to 20 kt this evening. Seas 1 to 2 ft. Isolated showers. Patchy fog after midnight with vsby 1 to 3 nm.
Fri..SW winds around 5 kt, becoming S in the afternoon. Seas 1 foot or less. Patchy fog. Vsby 1 to 3 nm.
Fri night..E winds 5 to 10 kt. Seas 1 to 2 ft. Patchy fog. Scattered showers. Vsby 1 nm or less.
Sat..NE winds 10 to 15 kt, increasing to 15 to 20 kt in the afternoon. Gusts up to 30 kt. Seas 2 to 3 ft. Patchy fog. Rain likely. Vsby 1 nm or less.
Sat night..NE winds 15 to 20 kt with gusts up to 30 kt. Seas 3 to 5 ft. A chance of rain. Vsby 1 to 3 nm.
Sun..NE winds 15 to 20 kt with gusts up to 35 kt. Seas 3 to 5 ft.
Sun night..NE winds 15 to 20 kt. Gusts up to 30 kt in the evening. Seas 2 to 4 ft.
Mon..NE winds 15 to 20 kt with gusts up to 25 kt. Seas 2 to 4 ft. A chance of rain.
Mon night..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 to 3 nm.
Tue..N winds 10 to 15 kt with gusts up to 20 kt. Seas 2 to 4 ft. A chance of rain. Vsby 1 to 3 nm.
Tue night..NW winds around 10 kt. Seas 2 to 3 ft. 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 Pm Edt Thu Jul 27 2017
Synopsis for massachusetts and rhode island coastal waters.. A cold front will approach the waters from the west tonight then stall across the waters Fri. Low pres will move off the mid atlantic coast Fri night and track south of new england this weekend which may bring a period of gale force ne winds. This early season gale will linger south of new eng into Mon then finally head northeast Tue. 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 Dennis Port, MA
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location: 41.65, -70.12     debug


Area Discussion for - Boston, MA
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Fxus61 kbox 272340
afdbox
area forecast discussion
national weather service taunton ma
740 pm edt Thu jul 27 2017

Synopsis
A cold front moves into the region this evening and will be
accompanied by scattered showers followed by a drying trend behind
the front later tonight. The front weakens or washes out Friday
giving way to mainly dry weather along with seasonably warm
temperatures and humidity. Low pressure then tracks south of new
england Saturday, likely bringing a windswept rain to the CAPE and
islands but possibly dry weather for the remainder of the region.

A coastal storm will push off the mid atlantic coast and track
south of new england Saturday, which will bring rain and gusty
onshore winds with cool temperatures especially close to the
south coast. Another low passing off the coast may renew the
chance for rain across portions of the region later Monday into
Tuesday.

Near term until 6 am Friday morning
720 pm update...

back edge of precip from passing mid level trough as weak
surface reflection pushing off the mass coast as seen on latest
ne regional 88d radar mosaic. Noting a long of showers and
scattered thunderstorms moving steadily e-se out of upstate ny
and northern vt, but short range models indicating this should
weaken as it moves along.

Short range high res models have been signaling a drier solution
over the last few hours, which seems to be confirmed by radar.

Noting dry conditions into eastern ny state down to nyc where
the last of showers are moving through there as well.

Agree with previous forecast that it will not really dry out in
the low levels as dewpts remain in the mid to upper 60s through
most of the night, so will probably see patchy fog develop by
around midnight and linger through around 11z-12z.

Have updated near term forecast to end the showers along the s
coast by around midnight, and kept fog in forecast. Also updated
remainder of near term to bring conditions current.

Previous discussion...

later this evening and especially overnight the short wave trough
moves east of the region with its attending cold front sliding south
and reaching the south coast by sunrise. Good drying through the
column from top down as k indices fall from the mid 30s this evening
to mid teens by 12z fri. This will result in a drying trend from
north to south tonight. However this mid level dry air will not
reach the surface with dewpts remaining in the 60s regionwide
overnight. So while showers will taper off fog will likely
develop as the night progresses.

Given the relatively high dewpt air it will be much milder
tonight than previous nights with lows in the 60s.

Short term 6 am Friday morning through Friday night
4 pm update...

Friday...

behind departing short wave tonight mid level confluent flow
develops across the area. This provides mid level subsidence over
the region weakens or washes out the frontal boundary near the south
coast. This mid level drying and associated subsidence provides a
cap tomorrow and should yield a mainly dry day. Given dew pts will
remain in the 60s there will be some sb instability present tomorrow
afternoon along with some weak low level convergence from
seabreezes. Thus can't rule out an isolated low top shower during
the afternoon. Given the mid level cap and limit instability (sb and
aloft) decided not to include any thunder.

So much of the day looks dry tomorrow along with seasonably warm
temps in the upper 70s to low 80s and typical summer humidity with
dew pts in the 60s. A combination of some mid level cloudiness along
with diurnal clouds should allow for at least a few breaks of
sunshine.

Friday night...

other than an isolated low top shower the evening hours should be
mainly dry as mid level cap and dry air aloft hold til about 03z or
so. However thereafter closed mid level low near pittsburgh moves
east and backs the mid level flow along the eastern seaboard,
advecting deeper moisture northward into southern new england,
especially the south coast. This will result in the risk of
overrunning rain yeah, it really is late july to invade the south
coast including CAPE cod and the islands. The remainder of the
region likely remains dry especially north of the ma pike.

Seasonably mild with lows in the 60s.

Long term Saturday through Thursday
Highlights...

* risk continues for showers and a few thunderstorms possible fri
night and sat, best chance S coast
* long e-ne fetch off the gulf of maine leads to continued strong
winds especially along the coast from S of boston to the S coast
this weekend into early next week
* another low passes offshore late Monday into Tuesday with
more light rain for eastern areas
overview and model preferences...

while examining the 12z operational models, noted changes to a
slower solution along the mid atlantic and northeast u.S. With
respect to overall motion of surface systems especially from
Sunday through Tuesday. Continued wide solution spread, however,
though in the broad sense they keep an overall e-ne wind flow
in place with a front stalled to the S and high pressure, albeit
weak, to the north. Timing of surface waves along the front
remains tough, as some guidance has a couple of waves early in
this period, while others have only one from late Sat into early
mon.

The biggest question appears to be how each individual model member
handles the h5 pattern, with some developing a broad cutoff h5 low
(12z GFS 00z ecmwf) generally across the mid atlc states to about
the S coast of ct long island, while others keep broad positive
tilted troughing. What really makes this forecast particularly
difficult is, even if cutoff h5 low forms, there is still quite a
bit of dry air to the N which could lead to variable sensible
weather into early next week. Where this all sets up, and where the
dry vs. Somewhat wetter conditions develop, is another big dilemma.

At this point, with so much uncertainty in place, will be leaning
toward available model and ensemble guidance blend for this forecast
package. Depending upon the final blend, may enhance with some more
agreeable model blending, such as around the Sunday-Monday timeframe
which does overall appear drier for most areas. Then, may see
another low pres wave move along the stalled front, but could lift a
bit further N which could affect the eastern part of the forecast
area Monday night and Tuesday.

Beyond Tuesday, looks like broad trough continues across the eastern
u.S., though weak surface ridge should keep mainly dry conditions in
place for Wednesday and next Thursday.

Details...

Saturday through Sunday night...

as low pres slowly passes S of the region sat, will see area of
rain move in across N ct ri SE mass, with some patchy light
rain further N from there. Pretty sharp dry are across N mass,
though, so may remain dry there. Precip pushes offshore sat
night with drier conditions.

Will see gusty NE wind especially along the coast with gusts up
to 30-40 mph, highest along the S coast, CAPE cod and the
islands. May see the northern fringe of heavier rainfall reach
portions of CAPE cod and the islands, with some local rainfall
of around an inch. Have left mention of thunder out of the
forecast with the cooler, stable onshore winds.

Expect temps both days to run up to around 10 degrees below
seasonal normals.

Monday and Tuesday...

h5 long wave trough lingers along the eastern seaboard during
this time. Another low forms offshore and passes close enough to
the 40n 70w benchmark to bring another round of rain across
central E mass into ri and NE ct Monday afternoon through part
of Tuesday. Continued cool NE winds in place, but not quite as
strong as over the weekend. As the low passes Tuesday, rain
should taper off from west to east.

Temps will recover closer to seasonal norms with highs reaching
the lower 80s well inland but will remain cooler along the
shore.

Wednesday and Thursday...

lower confidence due to wide model solution spread. For now,
looks dry and warm on Wednesday, then another front may approach
during Thu though timing is uncertain.

Aviation 00z Friday through Tuesday
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

720 pm update...

tonight... High confidence on trends but lower on exact timing.

Leftover showers will shift E with drier conditions developing
through around midnight. Low level moisture lingers, so will
likely see MVFR-ifr conditions developing in low clouds and
patchy fog.

Friday... Moderate confidence.

Any morning ifr-MVFR conditions should lift toVFR by midday.

Then marginal MVFR-vfr develops in the afternoon regionwide with
isolated shower possible especially near the south coast.

Friday night... Moderate confidence.

MarginalVFR-MVFR in isolated shower threat during the evening
will trend toward ifr late especially south coast as risk of
rain increases.

Kbos terminal... High confidence on trends but some uncertainty
on exact timing of lowering vsbys overnight then timing
improvement Fri morning.

Kbdl terminal... High confidence on trends but lower confidence
on exact timing of changing categories.

Outlook Saturday through Tuesday ...

Saturday and Saturday night... Moderate confidence.

Area of rain across N ct ri SE mass with MVFR-ifr
cigs occasional MVFR vsbys, with patchy heavier rain along the
immediate S coast possible. Patchy fog with local ifr vsbys late
sat Sat night. May see patchy -ra -shra reach across most of
the remainder of the area but should be mainlyVFR. E-ne winds
gusting to 25-35 kt along coast, highest along S coast, CAPE cod
and the islands. Precip may start to taper off from n-s late
sat night with improving vsbys.

Sunday... Moderate confidence.

May see patchy -ra lingering along the S coast through midday
sun with local MVFR-ifr CIGS vsbys. Otherwise, should see mainly
vfr conditions. NE winds gusting to 20-30 kt along the coast,
highest across CAPE cod and the islands, through Sun then should
diminish from n-s Sun night.

Monday-Tuesday... Moderate confidence.

Area of -ra may push back across E mass ri NE ct with local
MVFR CIGS vsbys mainly along the coast Mon afternoon into tue,
then may improve Tue night from w-e. Isold tsra possible along
the coast tue. Otherwise mainlyVFR.

Marine
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Friday night ... High confidence.

720 pm update...

tonight...

light s-sw winds this evening becoming west toward daybreak.

Showers and patchy fog will reduce visibility late this evening
and overnight. Tranquil seas continue.

Friday...

light SE winds and mainly dry weather. Vsby may be reduced in
morning fog but improving by midday. Tranquil seas continue.

Friday night...

winds become NE and increase to 20-25 kt by daybreak sat. Seas
increase rapidly given the long fetch. Chance of rain increases
especially southern waters.

Outlook Saturday through Tuesday ...

Saturday and Sunday... Moderate confidence.

As low pressure passes S of the waters, will likely see NE wind
gusts to 30-35 kt during this timeframe mainly from E of
cape cod southward. Gale watch has been issued for those areas
through Sat night, but could continue into sun. With long
onshore fetch, seas will build up to 6-10 ft, possibly higher
across the outer waters. Area of rain and patchy fog will likely
bring reduced visibilities, which may briefly improve sun
afternoon night.

Monday... Moderate confidence.

Ne winds will continue to gust up to 25-30 kt, then start to
back to N Mon night as the low pushes offshore. Seas remain at
or above 5 ft on the outer and southern near shore waters.

Another area of rain and patchy fog moves in during Mon with
reduced visibilities.

Tuesday... Moderate confidence.

N winds gusting to around 25 kt Tue morning, then diminishing.

Seas at or above 5 ft should subside during Tue night. Areas of
rain fog with reduced visibilities should improve from w-e tue
night.

Box watches warnings advisories
Ct... None.

Ma... None.

Ri... None.

Marine... Gale watch from Saturday morning through late Saturday night
for anz231>235-237-254>256.

Synopsis... Nocera evt
near term... Nocera evt
short term... Nocera
long term... Evt
aviation... Nocera evt
marine... Nocera evt


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
44020 - NANTUCKET SOUND 15 mi62 min 67°F1 ft1012.8 hPa (-0.6)
44090 17 mi48 min 61°F1 ft
WAXM3 - Waquoit Bay Reserve, MA 22 mi67 min 1 67°F 1013 hPa64°F
NTKM3 - 8449130 - Nantucket Island, MA 25 mi52 min SSW 5.1 G 9.9 65°F 71°F1013.4 hPa (-0.7)
BZBM3 - 8447930 - Woods Hole, MA 30 mi52 min 68°F 70°F1012.5 hPa (-0.9)

Wind History for Nantucket Island, MA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chatham, Chatham Municipal Airport, MA8 mi60 minSSW 7 G 1510.00 miOvercast67°F64°F91%1013.1 hPa
Hyannis, Barnstable Municipal-Boardman Airport, MA9 mi56 minSSW 1410.00 miMostly Cloudy68°F64°F87%1012 hPa
Otis Air National Guard Base, MA21 mi57 minSSW 99.00 miPartly Cloudy66°F64°F94%1012.9 hPa

Wind History from CQX (wind in knots)
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1 day agoN3CalmN3CalmCalmCalmCalmN3CalmCalmCalmN3NE5NE6NE36SE64S555S4S53
2 days agoN8
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6636355NE66N7N7
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NE11NE75NE64NE8

Tide / Current Tables for Dennis Port, Nantucket Sound, Massachusetts
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Dennis Port
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Thu -- 03:40 AM EDT     4.03 feet High Tide
Thu -- 05:30 AM EDT     Sunrise
Thu -- 09:32 AM EDT     -0.31 feet Low Tide
Thu -- 10:10 AM EDT     Moonrise
Thu -- 04:15 PM EDT     3.77 feet High Tide
Thu -- 08:03 PM EDT     Sunset
Thu -- 09:53 PM EDT     -0.00 feet Low Tide
Thu -- 10:46 PM EDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.62.53.43.943.62.71.60.5-0.2-0.20.20.91.82.73.43.83.632.11.10.300.3

Tide / Current Tables for Pollock Rip Channel, Massachusetts Current
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Pollock Rip Channel
Click for Map
Thu -- 12:46 AM EDT     -0.00 knots Slack
Thu -- 03:33 AM EDT     -1.92 knots Max Ebb
Thu -- 05:29 AM EDT     Sunrise
Thu -- 06:42 AM EDT     0.00 knots Slack
Thu -- 10:09 AM EDT     Moonrise
Thu -- 10:15 AM EDT     2.25 knots Max Flood
Thu -- 01:23 PM EDT     -0.00 knots Slack
Thu -- 04:08 PM EDT     -1.81 knots Max Ebb
Thu -- 07:17 PM EDT     0.00 knots Slack
Thu -- 08:02 PM EDT     Sunset
Thu -- 10:41 PM EDT     1.96 knots Max Flood
Thu -- 10:46 PM EDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.9-0.3-1.3-1.8-1.9-1.5-0.70.31.31.92.22.11.50.5-0.7-1.5-1.8-1.7-1.1-0.30.71.51.91.9

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 (20,4,5,8)
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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.