Monday, August21, 2017 L-36.com


Marine Weather and Tides
Popponesset Island, 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 11:59 AM EDT (15:59 UTC) Moonrise 5:38AMMoonset 7:37PM Illumination 0% Phase: New Moon; 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- 1045 Am Edt Mon Aug 21 2017
.small craft advisory in effect from Tuesday afternoon through late Tuesday night...
This afternoon..SW winds 5 to 10 kt. Gusts up to 20 kt. Seas 1 to 2 ft.
Tonight..SW winds 5 to 10 kt with gusts up to 20 kt. Seas around 2 ft.
Tue..SW winds 10 to 15 kt with gusts up to 25 kt. Seas 2 to 3 ft. Patchy fog. Vsby 1 to 3 nm.
Tue night..SW winds 15 to 20 kt with gusts up to 25 kt. Seas 2 to 4 ft. Patchy fog. Showers likely with a chance of tstms. Some tstms may produce heavy rainfall. Vsby 1 to 3 nm.
Wed..SW winds 10 to 15 kt, diminishing to 5 to 10 kt in the afternoon. Gusts up to 25 kt. Seas 2 to 3 ft. Showers likely with a chance of tstms. Some tstms may produce heavy rainfall.
Wed night..W winds 5 to 10 kt, becoming nw after midnight. Seas around 2 ft.
Thu..NW winds 5 to 10 kt. Seas 1 foot or less.
Thu night..W winds 5 to 10 kt. Seas 1 foot or less.
Fri..NE winds 5 to 10 kt. Seas 1 foot or less.
Fri night..NE 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 1045 Am Edt Mon Aug 21 2017
Synopsis for massachusetts and rhode island coastal waters.. High pres will move offshore of the mid-atlantic coast today and Tue. A cold front will follow and approach the waters from the west late Tue night, then sweep across the waters Wed morning. Large high pres will build east from the great lakes 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 Popponesset Island, MA
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location: 41.59, -70.46     debug


Area Discussion for - Boston, MA
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Fxus61 kbox 211426
afdbox
area forecast discussion
national weather service taunton ma
1026 am edt Mon aug 21 2017

Synopsis
High pressure moves offshore today. Southwest winds bring warm
humid air Tuesday night, which will feed developing showers and
thunderstorms. The wet weather will continue into Wednesday,
until a cold front sweeps across southern new england. High
pressure brings dry weather Thursday through Sunday.

Near term until 6 pm this evening
No major changes to the forecast this morning. Some high clouds
wafting by. Looking out the window, some of this cirrus was
fairly thick, especially across southeast ma. Expecting it to
briefly thin over the few hours, before more clouds arrive later
this afternoon.

Otherwise, just brought the forecast back in line with observed
trends.

Previous discussion...

temperatures will rebound quickly this morning thanks to plenty
of sunshine. Model cross sections show enough low level
moisture to result in diurnal cumulus once again today, but
coverage should not be enough to affect viewing of the partial
solar eclipse this afternoon (unless one of those clouds ends up
in the wrong place at the wrong time!) any higher clouds will
remain thin enough to allow good viewing. Remember to wear safe
glasses in order to protect your eyes.

The only other issue today is whether or not a weak sea breeze
develops for a few hours from late morning into early afternoon,
before gradient tightens and SW flow gets underway. Forecast
soundings show deep enough mixing in boston which should prevent
sea breeze from making it onto land, although it's certainly
possible any sea breeze could stay parked over boston harbor.

Highs will top out in mid to upper 80s across much of area.

Short term 6 pm this evening through 6 pm Tuesday
Mid level short wave is expected to dampen out as it reaches sne
tonight. This will cause any convection that develops to our
west today to weaken as it reaches out area, especially given
loss of daytime heating and little overall support for
convection this far east. It's still possible that a few showers
survive the trip, especially given increase in low level
moisture, mainly in western new england and near south coast.

Cold front approaches from great lakes Tuesday, but will be far
enough to our west to keep better chances of convection outside
of sne. Models are fairly aggressive in trying to bring at least
scattered showers storms into region, especially given surface-
based CAPE in excess of 1000 j kg and plenty of low level
moisture as precipitable water values climb to nearly 2 inches.

However better large scale lift should be located closer to cold
front, so we're not convinced we'll see much in way of
showers storms until very late in day across western new
england. It's possible a few showers develop due to heating and
moist airmass in place however.

Other issue is with high temperatures. NAM keeps much more low
level moisture locked in which keeps highs in low to mid 80s,
while GFS does not and highs end up closer to 90. Persistent sw
flow certainly favors NAM and it also has support from high-res
models (nmm in particular). It may end up that south coastal
areas hang onto clouds fog for much of day, while areas farther
inland are able to break out into sunshine. Based upon model
consensus, nudged highs down slightly (mid to upper 80s).

Long term Tuesday night through Sunday
Big picture...

low pressure from central canada digs over quebec Tuesday night and
swings the trough axis across the northeast usa during the late
week. Cyclonic flow lingers over new england through next
weekend. With upper heights lowering after midweek, expect
temperatures to trend seasonably cool during the period.

Gfs and ECMWF mass and thermal fields are similar through the
period, although with small differences developing Saturday and
Sunday. Thus, forecast confidence is moderate to high.

Details...

Tuesday night and Wednesday...

upper shortwave moving up the st lawrence valley will swing a cold
front across the northeast usa. Consensus of timing would bring the
front across new york state Tuesday night and across southern new
england on Wednesday morning. Deep moisture along with pw values of
2+ inches will be acted on by favorable dynamics in the right
entrance region of the upper jet. This suggests potential for
thunderstorms with locally heavy downpours. Winds at 850 mb are
forecast at 35-40 knots and 500 mb winds around 50 knots. So there
is also a potential for a few strong wind gusts.

Thursday through Sunday...

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 Friday. Temperatures at 500-mb will minimize at
-16c to -18c 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 partly cloudy and dry pattern, but the
instability shows some potential for a few showers. For now we will
maintain pops at less than 15 percent.

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. Dew points
will be in the 50s Thursday-Friday and 45-55 over the weekend... With
light winds allowing min temps in the 50s each night.

The light wind flow will allow sea breezes to develop each late
morning and afternoon Friday through Sunday.

Aviation 14z Monday through Friday
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Tuesday ...

vfr today, with W winds becoming SW this afternoon. It's
possible a weak seabreeze develops near eastern ma coast 15z-
18z, but confidence is not high enough to include a seabreeze
in the forecast.

Vfr conditions persist through midnight, but MVFR ifr ceilings
should develop overnight, especially from western new england
to south coast. Ceilings should slowly lift Tuesday toVFR,
except along south coast, cape, and islands where ifr may last
much of the day due to persistent SW flow.

Scattered thunderstorms are possible Tuesday afternoon across
interior, mainly near berkshires.

Kbos terminal... High confidence in taf. Low chance of a weak
seabreeze 15z-18z but currently expecting it to remain just
offshore.

Kbdl terminal... High confidence in taf.

Outlook Tuesday night through Friday ...

areas of MVFR CIGS vsbys in showers thunderstorms Tuesday night and
Wednesday morning.

OtherwiseVFR all areas, with patchy ifr CIGS vsbys in fog Wednesday
night early Thursday and Thursday night early Friday.

Marine
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Tuesday ... High confidence.

Sw flow gets underway today as high pressure moves offshore.

That said, gradient may weaken enough to allow for local
seabreezes to develop on eastern ma waters from late morning
into early afternoon before winds shift to S sw.

Small craft advisories are being posted from Tuesday afternoon
into Tuesday night for south coastal and outer coastal waters.

Gusts should reach 25 to perhaps 30kt, along with building seas
up to 6-7 ft offshore.

Outlook Tuesday night through Friday ...

Tuesday night...

southwest winds near 25 knots Tuesday night will maintain building
seas with heights 5 to 7 feet on the outer waters and on ri sound
and block island sound.

Wednesday through Friday...

cold front moves across the waters, turning winds from the west-
northwest. High pressure then builds in with winds diminishing to
less than 20 knots. Winds further turn from the north on Friday.

Diminishing wind will bring diminishing seas, with some leftover 5
foot seas Wednesday followed by seas 3 feet or less Thursday and
Friday.

Box watches warnings advisories
Ct... None.

Ma... None.

Ri... None.

Marine... Small craft advisory from 2 pm Tuesday to 6 am edt Wednesday
for anz231>235-237-250-254>256.

Synopsis... Wtb jwd
near term... Wtb belk jwd
short term... Jwd
long term... Wtb
aviation... Wtb belk jwd
marine... Wtb belk jwd


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WAXM3 - Waquoit Bay Reserve, MA 3 mi75 min 1.9 79°F 1022 hPa67°F
BZBM3 - 8447930 - Woods Hole, MA 12 mi42 min 74°F 73°F1021.4 hPa
44020 - NANTUCKET SOUND 18 mi70 min WSW 5.8 G 5.8 71°F 72°F1 ft1021.3 hPa (-0.4)71°F
44090 19 mi56 min 71°F1 ft
NTKM3 - 8449130 - Nantucket Island, MA 29 mi42 min W 4.1 G 8.9 1021.5 hPa
BUZM3 - Buzzards Bay, MA 33 mi60 min WSW 12 G 12 69°F 1022 hPa (-0.3)
FRVM3 - 8447386 - Fall River, MA 38 mi42 min 76°F 75°F1022.2 hPa
FRXM3 39 mi42 min 78°F 63°F
BLTM3 - 8447387 - Borden Flats Light at Fall River, MA 39 mi42 min SW 6 G 6 76°F 1020.6 hPa
PRUR1 45 mi42 min 75°F 65°F
NWPR1 - 8452660 - Newport, RI 46 mi42 min SSW 5.1 G 7 75°F 69°F1021.4 hPa
NAXR1 - Narragansett Bay Reserve, RI 47 mi75 min NNW 1.9 77°F 1021 hPa64°F
PTCR1 - 8452951 - Potter Cove, Prudence Island, RI 47 mi42 min SW 2.9 G 5.1 78°F 1021.3 hPa
CPTR1 - 8452944 - Conimicut Light, RI 48 mi48 min SSE 6 G 6 74°F 73°F1021.1 hPa

Wind History for Nantucket Island, MA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Otis Air National Guard Base, MA6 mi65 minWNW 510.00 miFair79°F62°F58%1021.7 hPa
Hyannis, Barnstable Municipal-Boardman Airport, MA11 mi64 minWNW 410.00 miFair80°F64°F58%1020.9 hPa
Marthas Vineyard Airport, MA15 mi67 minWNW 510.00 miFair80°F63°F56%1021.4 hPa

Wind History from FMH (wind in knots)
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Last 24hrW11NW9W9
G14
W8
G15
E6N5CalmNE3----------------------NW4--NW6W5W8
1 day agoE3SW5S11SW11SW16SW16SW12SW10
G15
SW7SW7SW6W8W7SW7SW6SW4SW3SW6SW4W7W9NW10W10
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2 days agoS8
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CalmSW18SW11
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W8SW7SW5SW9SW5SW6SW5NE7NE6

Tide / Current Tables for Poponesset Island, Poponesset Bay, Nantucket Sound, Massachusetts
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Poponesset Island
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Mon -- 12:56 AM EDT     2.77 feet High Tide
Mon -- 05:37 AM EDT     Moonrise
Mon -- 05:56 AM EDT     Sunrise
Mon -- 07:07 AM EDT     -0.28 feet Low Tide
Mon -- 01:33 PM EDT     2.52 feet High Tide
Mon -- 02:31 PM EDT     New Moon
Mon -- 07:22 PM EDT     -0.13 feet Low Tide
Mon -- 07:32 PM EDT     Sunset
Mon -- 07:37 PM EDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
2.62.82.62.11.40.70-0.3-0.10.30.91.52.12.52.52.21.710.3-0.1-0.10.30.91.6

Tide / Current Tables for Cape Cod Canal, Massachusetts Current
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Cape Cod Canal
Click for Map
Mon -- 12:12 AM EDT     -4.96 knots Max Ebb
Mon -- 03:27 AM EDT     0.22 knots Slack
Mon -- 05:37 AM EDT     Moonrise
Mon -- 05:57 AM EDT     Sunrise
Mon -- 06:39 AM EDT     4.75 knots Max Flood
Mon -- 09:58 AM EDT     -0.04 knots Slack
Mon -- 12:43 PM EDT     -4.71 knots Max Ebb
Mon -- 02:31 PM EDT     New Moon
Mon -- 03:50 PM EDT     0.21 knots Slack
Mon -- 06:55 PM EDT     4.54 knots Max Flood
Mon -- 07:33 PM EDT     Sunset
Mon -- 07:38 PM EDT     Moonset
Mon -- 10:04 PM EDT     -0.11 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
-4.9-4.8-3.9-2.32.544.64.74.33.3-0.6-3.5-4.5-4.7-4.2-31.33.44.34.54.33.41-3.4

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 (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.