Sunday, April22, 2018 L-36.com


Marine Weather and Tides
Dennis Port, MA

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 5:47AMSunset 7:31PM Sunday April 22, 2018 2:21 PM EDT (18:21 UTC) Moonrise 11:30AMMoonset 1:33AM 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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ANZ232 Nantucket Sound- 116 Pm Edt Sun Apr 22 2018
This afternoon..SW winds 5 to 10 kt. Seas 2 to 3 ft.
Tonight..SW winds 5 to 10 kt, becoming nw after midnight. Seas around 2 ft.
Mon..N winds around 5 kt, becoming E with gusts up to 20 kt in the afternoon. Seas 2 to 3 ft.
Mon night..S winds 5 to 10 kt. Gusts up to 20 kt in the evening. Seas 2 to 3 ft.
Tue..S winds 5 to 10 kt. Seas around 2 ft.
Tue night..SE winds 10 to 15 kt. Seas 2 to 3 ft. A chance of rain.
Wed..SE winds 15 to 20 kt with gusts up to 25 kt. Seas 2 to 4 ft. Rain.
Wed night..S winds 15 to 20 kt with gusts up to 25 kt. Seas 2 to 4 ft. A chance of rain.
Thu..SW winds 10 to 15 kt with gusts up to 20 kt. Seas 2 to 3 ft.
Thu night..SW winds 10 to 15 kt with gusts up to 20 kt. Seas 2 to 4 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 116 Pm Edt Sun Apr 22 2018
Synopsis for massachusetts and rhode island coastal waters.. High pressure remains over the waters through Monday, then shifts the the east on Tuesday. Low pressure will move north along the eastern seaboard Tuesday night and Wednesday, lifting over the waters on Thursday. 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 221739
afdbox
area forecast discussion
national weather service boston norton ma
139 pm edt Sun apr 22 2018

Synopsis
High pressure remains in control through Tuesday bringing dry
weather with moderating temperatures. Wet weather returns
Wednesday into Thursday as low pressure moves through our
region. Unsettled weather continues into the weekend, but not a
washout.

Near term through tonight
Just about as quiet as it gets around here weatherwise with high
pressure in control. Satellite imagery shows clear skies around
region with nearest (high) clouds in pa and southern nj.

Deep mixing to nearly 850 mb has prevented sea breezes from
developing so far this afternoon. However, model guidance
suggests winds aloft will weaken just enough to allow a weak sea
breeze to develop along E ma coast and a slightly stronger sw
sea breeze along south coast from mid to late afternoon.

Mixing has also brought drier air to surface, as dewpoints have
fallen into teens and lower 20s, resulting in relative humidity
values dropping to less than 20 percent. Dewpoints will
gradually recover through this evening as mixing subsides.

Otherwise, clear skies and light winds tonight with patchy
valley fog. Leaned closer to MOS for lows which tend to perform
well in these situations. Lows drop back into 30s to around 40
with some patchy frost inland.

Short term Monday through Monday night
High pressure becomes centered over sne Monday. Once again
plenty of sunshine with light winds, and coastal sea breezes
will get underway by their usual late morning time frame. This
will give way to S SW flow Monday night as the high shifts
offshore, with some increase in high clouds late.

Stayed close to MOS with highs in the 50s 60s Monday, perhaps
approaching 70 in ct valley, and lows falling back into 30s to
near 40 Monday night.

Long term Tuesday through Saturday
* highlights...

- wet and breezy midweek
- perhaps a reprieve Friday
- more showers possible Saturday
overview and model preferences...

phasing S stream and pacific waves will lead to gradual height
falls and reduction of the ridge across NE throughout the day on
tue and into wed. Another longwave trof gradually develops
across the CONUS as a result during the latter half of the week.

Following the initial development, a second stronger wave
connected to the aleutian vortex will likely deepen the trof by
next weekend, yielding a return to cooler, and maintaining the
unsettled and wet conditions that look to begin on wed. Noting a
better agreement between deterministic runs in the phasing
process and deepening of the wave for mid week than previous
runs. Therefore, although ensemble means will still be used,
will blend in more operational guidance with this forecast
update.

Details...

tue...

high pres slips E but remains in control through the day and
much of the evening. However, a combination of developing return
flow, and increased moisture loading aloft will likely yield
increasing clouds. Dry wx prevails. H85 temps near +4c should be
mixed too, so expecting another day in the 60s in spite of the
clouds. S shore sea breezes likely, with a risk on the E coast
as well, but increase pres gradient may preclude this.

Wed and thu...

low pres develops out of the remnant cold pool from convection
across the se, as S stream wave develops. Guidance in fair
agreement on track, E of the spine of the appalachians as low
pres deepens enough to draw it more N of e. With it, pwats
increase to nearly 200 percent of normal. As the low deepens, an
llj of 40 kt also develops through the morning wed. This will
lead to a period of rain, potentially heavy at times as k
indices exceed 30 and soundings become conditionally unstable.

Initial overrunning followed by mid low and mid lvl convergence
will lead to rain most of the day. With the wave continuing to
deepen, the low pres will deepen and slow, leading to wet
conditions persisting into the overnight hours, with wrap around
shra possible into thu, but with some improvement. Probs of qpf
exceeding 1.00 inches rather high. Clouds along with a dip in
h85 temps will yield cooler temps each day, with highs mainly in
the 50s and lows in the 40s.

Fri and sat...

although trof remains in place, a brief period of rising
heights looks possible ahead of a secondary acute wave
traversing the CONUS from the aleutian low and NW territory
origins. Therefore, a period of more dry-than-wet conditions
looking more likely per ensemble operational guidance. Still
with cyclonic flow and some moisture clouds and a spot shower
can be ruled out. Temps near seasonal normals, although
potentially cooler if more cloud than Sun is observed.

Early next week...

the aforementioned wave reinforces the trof across the e, with
a return to cooler and wetter wx possible. Still several details
to iron out, but confidence rises based on ensemble
means operational runs showing at least some synoptic agreement.

Aviation 17z Sunday through Thursday
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Monday night ... High confidence.

Sea breeze potential still questionable along E ma coast this
afternoon as winds aloft have been just strong enough to
maintain W NW flow. However, there should be some weakening in
winds later this afternoon to allow sea breeze to develop
between 20z-23z. Confidence is higher for south coastal sea
breeze which should get underway around 20z as well.

Vfr. Light W NW winds prevail tonight with local MVFR ifr
visibility in patchy valley fog. Higher confidence in sea
breezes along both coasts mon.

Kbos terminal... Moderate confidence in taf. E sea breeze
expected 20z-23z but if it does not occur, winds will veer to n.

Kbdl terminal... High confidence in taf.

Outlook Tuesday through Thursday ... High confidence.

Tuesday:VFR.

Tuesday night: MVFR ifr conditions possible. Breezy. Chance ra.

Wednesday: mainly MVFR, with areas ifr possible. Breezy. Ra.

Wednesday night: mainly MVFR, with areas ifr possible. Breezy.

Chance shra, chance ra.

Thursday: mainly MVFR, with areasVFR possible. Breezy. Chance
shra.

Marine
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Monday night ... High confidence.

High pressure builds over waters with light winds, flat seas,
and good visibility.

Only concern for recreational boaters is for sea breezes along
south coast this afternoon with 15-20kt gusts and choppy seas
near shore, especially when opposing outgoing tide. Similar
conditions Monday.

Outlook Tuesday through Thursday ... High confidence.

Tuesday: winds less than 25 kt.

Tuesday night: winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain.

Wednesday: low risk for small craft advisory winds with gusts
up to 25 kt. Areas of rough seas. Rain.

Wednesday night: winds less than 25 kt. Rough seas up to 12 ft.

Chance of rain showers, chance of rain.

Thursday: winds less than 25 kt. Rough seas up to 9 ft. Slight
chance of rain showers.

Equipment
Noaa weather radio transmitters serving providence and hyannis
are out of service due to phone line problems. The phone
company has prioritized the issues and is working to get the
weather broadcast back on the air as soon as possible.

Box watches warnings advisories
Ct... None.

Ma... None.

Ri... None.

Marine... None.

Synopsis... Belk jwd
near term... Jwd
short term... Jwd
long term... Doody
aviation... Belk jwd
marine... Belk jwd
equipment... Staff


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
44020 - NANTUCKET SOUND 15 mi91 min SSW 3.9 G 3.9 47°F 46°F1 ft1028 hPa (+0.0)35°F
44090 17 mi51 min 44°F1 ft
WAXM3 - Waquoit Bay Reserve, MA 22 mi96 min 6 57°F 1027 hPa17°F
NTKM3 - 8449130 - Nantucket Island, MA 25 mi51 min N 6 G 9.9 53°F 48°F1027.8 hPa
BZBM3 - 8447930 - Woods Hole, MA 30 mi51 min 49°F 45°F1027.5 hPa

Wind History for Nantucket Island, MA
(wind in knots)    EDIT      (on/off)   Help
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N4
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NW7
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N10
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chatham, Chatham Municipal Airport, MA8 mi29 minVar 510.00 miFair57°F18°F22%1027.6 hPa
Hyannis, Barnstable Municipal-Boardman Airport, MA9 mi25 minNNE 9 G 1510.00 miFair57°F19°F24%1027.1 hPa
Otis Air National Guard Base, MA21 mi46 minVar 410.00 miFair55°F17°F23%1027.4 hPa

Wind History from CQX (wind in knots)
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Last 24hrCalm5S7S7SW5SW6SW7SW4SW3NW3NW3NW4CalmCalmNW4NW4NW45NW856NW7NW75
1 day agoN9
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2 days agoN544Calm3W3CalmW43NW63NW7W9
G18
NW5W566
G14
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G24
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Tide / Current Tables for Dennis Port, Nantucket Sound, Massachusetts
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Dennis Port
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Sun -- 01:32 AM EDT     Moonset
Sun -- 05:46 AM EDT     3.85 feet High Tide
Sun -- 05:49 AM EDT     Sunrise
Sun -- 11:29 AM EDT     Moonrise
Sun -- 11:50 AM EDT     -0.13 feet Low Tide
Sun -- 05:46 PM EDT     First Quarter
Sun -- 06:33 PM EDT     3.41 feet High Tide
Sun -- 07:28 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.411.82.53.23.73.83.52.71.80.80.1-0.10.20.81.52.32.93.33.42.92.21.40.7

Tide / Current Tables for Pollock Rip Channel, Massachusetts Current
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Pollock Rip Channel
Click for Map
Sun -- 01:31 AM EDT     Moonset
Sun -- 02:50 AM EDT     -0.00 knots Slack
Sun -- 05:31 AM EDT     -1.75 knots Max Ebb
Sun -- 05:49 AM EDT     Sunrise
Sun -- 08:40 AM EDT     0.00 knots Slack
Sun -- 11:29 AM EDT     Moonrise
Sun -- 12:04 PM EDT     1.99 knots Max Flood
Sun -- 03:37 PM EDT     -0.00 knots Slack
Sun -- 05:46 PM EDT     First Quarter
Sun -- 06:12 PM EDT     -1.61 knots Max Ebb
Sun -- 07:28 PM EDT     Sunset
Sun -- 09:26 PM EDT     0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.71.40.8-0.2-1.1-1.7-1.7-1.3-0.60.31.21.821.91.40.6-0.4-1.2-1.6-1.5-1-0.40.51.2

Weather Map and Satellite Images
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wmap_A
GOES Local Image of Northeast    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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Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Boston, MA (14,3,4,5)
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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.