Monday, August21, 2017 L-36.com


Marine Weather and Tides
South Yarmouth, 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 5:55AMSunset 7:32PM Monday August 21, 2017 12:44 AM EDT (04:44 UTC) Moonrise 5:36AMMoonset 7:36PM Illumination 1% Phase: Waning Crescent; Moon at 29 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- 923 Pm Edt Sun Aug 20 2017
Overnight..NW winds around 5 kt. Seas around 2 ft.
Mon..SW winds 5 to 10 kt. Seas 1 foot or less.
Mon night..SW winds 5 to 10 kt. Seas 1 foot or less.
Tue..SW winds 5 to 10 kt, increasing to 10 to 15 kt with gusts up to 25 kt in the afternoon. Seas 2 to 3 ft.
Tue night..SW winds 15 to 20 kt with gusts up to 25 kt. Seas 2 to 4 ft. A chance of showers and tstms.
Wed..SW winds 10 to 15 kt with gusts up to 25 kt. Seas 2 to 4 ft. A chance of showers and tstms.
Wed night..W winds 5 to 10 kt, becoming nw after midnight. Seas around 2 ft. A chance of showers.
Thu..N winds 5 to 10 kt. Seas 1 foot or less.
Thu night..NE winds around 5 kt. Seas 1 foot or less.
Fri..NE winds 5 to 10 kt. Seas 1 foot or less.
Fri night..N winds 5 to 10 kt. Seas 1 foot or less. 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 923 Pm Edt Sun Aug 20 2017
Synopsis for massachusetts and rhode island coastal waters.. High pres will remain over the waters through Mon, then will move offshore Tue, allowing a cold front to approach Wed. Large high pres will build over the region Thu and Fri. 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 South Yarmouth, MA
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location: 41.64, -70.2     debug


Area Discussion for - Boston, MA
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Fxus61 kbox 210126
afdbox
area forecast discussion
national weather service taunton ma
926 pm edt Sun aug 20 2017

Synopsis
High pressure builds over the region tonight and then offshore
Monday, providing dry and comfortable weather. Hot and humid
weather is forecast for Tuesday as the high moves farther
offshore. A cold front will approach the area late Tuesday, then
sweep across the region by mid-afternoon Wednesday, bringing the
risk of showers and thunderstorms. Any storms could produce
locally heavy rain and gusty winds. Skies clear out later
Wednesday. Then strong high pressure brings fall-like weather
with mainly sunny skies and clear nights Thursday through
Sunday... With highs in the 70s and lows in the 50s.

Near term until 6 am Monday morning
930 pm update...

clear skies and light winds will allow temperatures to fall into
50s overnight, except lower 60s along immediate coast and in
urban areas. Patches of valley fog possible as well. Forecast
is on track so only minor changes made.

Short term 6 am Monday morning through Monday night
Updated 4 pm...

Monday...

after a cool start to the day return flow (sw winds) becomes
established by late morning as high pres slips offshore. Low level
waa results in slightly warmer and more humid conditions tomorrow
with highs in the mid to upper 80s away from the south coast. Dew
pts still tolerable (u50s to l60s) as warm sector airmass remains
west-southwest of new england.

Dry weather prevails along with mostly sunny conditions. Thus good
viewing of the solar eclipse (just remember to wear safe glasses)!
could be some mid and high clouds arriving late in the day across
western ma ct, but by then the eclipse will have ended.

Monday night...

low amplitude lead short wave and attending warm sector approach
from the west. Convection over pa ny nj late Monday likely
weakens dissipates as it approaches southern new england given loss
of daytime heating and weak mid level lapse rates. Nonetheless low
pops will be included in the forecast to account for any leftover
showers especially western ma ct.

Much warmer and humid than previous nights given warm sector
overspreads the area. This may be accompanied by stratus patchy fog
and possibly spotty light drizzle.

Long term Tuesday through Sunday
Big picture...

at upper levels, closed low pressure will be moving slowly
across canada, from west of james bay Tuesday to eastern quebec
by Saturday. The trough axis extending southward from the low
will remain to our west until Saturday. The cold pool of air
will arrive over our region around Thursday and remain in place
into next weekend. A weak ridge begins to build over the area on
Sunday, as the trough finally exits.

At the surface, high pressure will pass southeast of the region
Tuesday. A cold front moves through Wednesday. Then strong high
pressure builds over the great lakes states, with its influence
extending eastward into new england Thursday into Saturday.

The strong high pressure becomes centered around new brunswick
on Sunday.

As the previous forecaster noted, there has been a tendency for
the canadian model to generate a tropical system off the
southeast coast of the u.S. Then head northeast towards us for
the past several runs. Now, the ukmet, gfs, and to some extent
the ECMWF all show the potential for tropical development late
in the week, off the florida coast. However, the significant
change is that they all now focus the northeastward movement
more along a persistent frontal boundary that currently exists
several hundred miles south of new england. That would appear to
make more meteorological sense, as tropical systems sometimes do
form on the tail end of old frontal boundaries. The strong high
pressure over the northeast states is expected to dominate our
weather. However, it is possible that late next weekend there
could be increasing potential for rip currents once again on
southern beaches. Anyway, that's a week away.

Details...

Tuesday...

summer is back. It will be hot and humid as high pressure
shifts offshore and southwest breezes increase, well in advance
of an approaching cold front. With 925 mb temperatures reaching
25-26c and a good deal of sunshine, expecting highs to soar to
90-95. Dewpoints will be rising to near 70 by late afternoon and
heat indices will be reach the mid 90s. Our new criteria for
heat advisories is 95 degrees, but it needs to be for 2
consecutive days, unless it hits 100, which would only require
1 day. Since it will probably not be reached on Monday, we may
issue a special weather statement to draw attention to it, as
opposed to a heat advisory.

Southwest winds increase to 30-40 kts at 925 mb Tue afternoon,
so expect gusts at the surface to 20-25 mph at times, especially
in southeast ma and ri. CAPE is maximized over ny state, well
to our west, close to the cold front and that is where the best
potential exists for strong severe thunderstorm activity.

However, a few showers and thunderstorms could form over the
higher terrain of western ma and northwest ct in the mid-late
afternoon hours.

Tuesday night...

precipitable water values increase to 2.0 to 2.2 inches across
the region Tue night, becoming maximized in eastern sections
toward daybreak. We will have lost some heating as the front
moves into western sections Tue night. Nevertheless the 12z ecmwf
keeps 1000+ j kg CAPE overnight. There will be increasing wind
fields aloft, mainly unidirectional. The storm prediction center
has a "marginal risk" of severe weather the western part of our
area. Expect that we will mainly have remnants of the strong
convection that had been to our west southwest during the day,
but there should be some new development as well. Any storm
could produce locally heavy rainfall and gusty winds. Any
training of storms or clusters of storms could lead to a
flooding flash flooding threat.

Wednesday...

cold front swings across southern new england. Timing is still in
question, but consensus would have the front exiting the coast
in the afternoon. Southern new england will be in the right rear
quadrant of a 300 mb jet MAX of 100-110 kts, which would be
favorable for strong thunderstorm development, especially given
high pw values still in place in eastern ma and ri through early
afternoon. Skies will become mostly sunny from west to east
during the mid and late afternoon. Highs in the 80s.

Thursday through Saturday...

high pressure builds in at the surface while an upper trough digs
south from quebec. The trough will carry a cold pool with cold
advection aloft on Thursday and Friday. Temperatures at 500 mb
will minimize at around -16c early Saturday morning. Moisture
fields show a moist layer between 850 and 700 mb during this
period, but dry air above and below. This looks like a mostly
sunny and dry pattern, but the instability shows some potential
for a few showers on Saturday. The mixed layer reaches to
between 850 and 800 mb, with temps at the top of the layer
supporting MAX sfc temps in the 70s... Giving a fall-like feel.

Overnight low temperatures will be in the 50s each night.

Sunday...

high pressure becomes centered over new brunswick. Sunny, cool
weather will continue across southern new england with highs in
the 70s and northeast to east wind flow. It is possible that
southernmost coastal waters could see increasing swell and
potential rip currents if there is any tropical development
several hundred miles south of the region.

Aviation 02z Monday through Friday
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.

715 pm update...

tonight...VFR. Light wnw winds becoming calm. Patchy MVFR fog
possible across interior valleys.

Monday...VFR and winds becoming sw. Afternoon t-storms across
ny pa should diminish before entering western ma ct late in the
day.

Monday night...VFR to start but lowering to MVFR and or ifr as
low clouds and fog overspread the area after midnight and
especially toward Tue morning. Low risk of spotty light drizzle
late.

Kbos terminal... High confidence in taf.

Kbdl terminal... High confidence in taf.

Outlook Tuesday through Friday ...

Tuesday into early Wednesday afternoon... Moderate confidence.

Vfr except areas of MVFR ifr in showers and scattered strong
thunderstorms mainly Tuesday night and Wednesday morning to
early afternoon. Patchy fog.

Later Wednesday afternoon through Friday... High confidence.

Vfr. The only exception will be patchy ifr in fog Wednesday
night and early Thursday morning.

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.

715 pm update...

tonight... Modest west winds become light and variable
overnight. Good vsby and dry weather prevails.

Monday... High pres moves offshore yielding modest SW winds.

Dry weather and good vsby continue.

Monday night... Modest SW winds continue and will likely be
accompanied by low clouds patchy fog along with a low risk for
spotty drizzle. Thus vsby may be reduced at times especially
southern waters.

Outlook Tuesday through Friday ...

Tuesday... High confidence.

High pressure shifts east of the waters. Winds 20 knots or less, and
seas 4 feet or less.

Tuesday night-Wednesday... Moderate confidence.

A cold front approaches from the great lakes, crossing the waters
late Wednesday afternoon. Showers and scattered thunderstorms
will move across the waters Tuesday night and Wednesday, with
locally heavy rain and gusty winds.

Southwest winds increase with gusts 25 knots. Winds shift from
southwest to northwest Wednesday night and diminish to 15 knots
or less. Seas build Tuesday night and Wednesday reaching 5 to 6
foot heights on the outer waters. The southwest flow may also
nudge those higher seas into ri sound as well. Once the cold
front moves through and winds become northwest, seas will
subside to 3 feet or less Wednesday night.

A small craft advisory may be needed on some of the waters Tuesday
night and Wednesday.

Thursday-Friday... High confidence.

Generally light north to northeast wind flow with seas
below 3 ft.

Box watches warnings advisories
Ct... None.

Ma... None.

Ri... None.

Marine... None.

Synopsis... Nocera gaf
near term... Jwd
short term... Nocera
long term... Gaf
aviation... Nocera gaf
marine... Nocera gaf


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
44020 - NANTUCKET SOUND 14 mi55 min WNW 1.9 G 1.9 73°F 72°F1 ft1019.4 hPa (+1.6)69°F
44090 15 mi41 min 71°F
WAXM3 - Waquoit Bay Reserve, MA 18 mi60 min Calm 71°F 1020 hPa70°F
NTKM3 - 8449130 - Nantucket Island, MA 25 mi45 min WSW 1.9 G 2.9 1019.8 hPa
BZBM3 - 8447930 - Woods Hole, MA 26 mi45 min 70°F 73°F1019.6 hPa (+1.6)
BUZM3 - Buzzards Bay, MA 47 mi45 min WNW 7 G 8 72°F 1020.4 hPa (+1.7)

Wind History for Nantucket Island, MA
(wind in knots)    EDIT      (on/off)   Help
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hyannis, Barnstable Municipal-Boardman Airport, MA5 mi49 minN 010.00 miFair63°F60°F90%1019.3 hPa
Chatham, Chatham Municipal Airport, MA12 mi53 minN 010.00 miFair67°F63°F87%1019.8 hPa
Otis Air National Guard Base, MA17 mi4.8 hrsN 010.00 miFair72°F64°F78%1017.6 hPa

Wind History from HYA (wind in knots)
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Last 24hrSW6SW6SW3SW4CalmSW6SW5W5NW9NW9
G15
N86N7N8N7NE4N4N5N4N4N3CalmCalmCalm
1 day agoS15
G24
NW7SW13
G20
CalmS5SW5SW5S8SW6NW8NW5NW6CalmS7S6S6SW12SW15SW8SW10W8SW5SW7SW6
2 days agoS4S4CalmCalmS43S5S6S9S8S11
G16
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G25
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G22
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G21

Tide / Current Tables for South Yarmouth, Bass River, Nantucket Sound, Massachusetts
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South Yarmouth
Click for Map
Mon -- 12:41 AM EDT     3.49 feet High Tide
Mon -- 05:36 AM EDT     Moonrise
Mon -- 05:55 AM EDT     Sunrise
Mon -- 07:02 AM EDT     -0.44 feet Low Tide
Mon -- 01:18 PM EDT     3.15 feet High Tide
Mon -- 02:31 PM EDT     New Moon
Mon -- 07:17 PM EDT     -0.25 feet Low Tide
Mon -- 07:31 PM EDT     Sunset
Mon -- 07:36 PM EDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
3.43.53.12.51.60.7-0.1-0.4-0.20.41.122.83.13.12.61.910.2-0.2-0.10.41.22.1

Tide / Current Tables for Pollock Rip Channel, Massachusetts Current
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Pollock Rip Channel
Click for Map
Mon -- 03:07 AM EDT     0.00 knots Slack
Mon -- 05:35 AM EDT     Moonrise
Mon -- 05:55 AM EDT     Sunrise
Mon -- 06:44 AM EDT     2.31 knots Max Flood
Mon -- 09:47 AM EDT     -0.00 knots Slack
Mon -- 12:37 PM EDT     -1.81 knots Max Ebb
Mon -- 02:31 PM EDT     New Moon
Mon -- 03:40 PM EDT     0.00 knots Slack
Mon -- 07:07 PM EDT     2.05 knots Max Flood
Mon -- 07:30 PM EDT     Sunset
Mon -- 07:35 PM EDT     Moonset
Mon -- 09:59 PM EDT     -0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
-1.9-1.7-1.1-0.10.91.72.22.31.90.9-0.2-1.2-1.7-1.8-1.4-0.70.31.21.821.91.1-0-1.1

Weather Map and Satellite Images
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Weather Map
wmap_A
IR Satellite Image from GEOS
east_satellite

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.