Monday, August21, 2017 L-36.com


Marine Weather and Tides
Groton, 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 6:00AMSunset 7:39PM Monday August 21, 2017 11:15 PM EDT (03:15 UTC) Moonrise 5:41AMMoonset 7:44PM 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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ANZ230 Boston Harbor- 901 Pm Edt Mon Aug 21 2017
Overnight..SW winds around 5 kt. Waves 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. Waves around 2 ft.
Tue night..SW winds 10 to 15 kt with gusts up to 25 kt. Waves around 2 ft. Patchy fog. Showers likely with a chance of tstms. Some tstms may produce heavy rainfall. Vsby 1 to 3 nm.
Wed..W winds 5 to 10 kt. Gusts up to 20 kt in the morning. Waves around 2 ft. Patchy fog. A chance of showers. Vsby 1 to 3 nm.
Wed night..W winds around 5 kt. Waves 1 foot or less.
Thu..NW winds around 5 kt, becoming sw in the afternoon. Waves 1 foot or less.
Thu night..SW winds around 5 kt, becoming nw after midnight. Waves 1 foot or less.
Fri..N winds around 5 kt. Waves 1 foot or less.
Fri night..N winds around 5 kt. Waves 1 foot or less.
Sat..NE winds around 5 kt. Waves 1 foot or less.
Sat night..NE winds around 5 kt. Waves 1 foot or less. Winds and waves 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 901 Pm Edt Mon Aug 21 2017
Synopsis for massachusetts and rhode island coastal waters.. High pres will continue to move east of the waters overnight into 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 through 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 Groton, MA
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location: 42.6, -71.63     debug


Area Discussion for - Boston, MA
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Fxus61 kbox 220111
afdbox
area forecast discussion
national weather service taunton ma
911 pm edt Mon aug 21 2017

Synopsis
High pressure moves farther offshore tonight. 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 am Tuesday morning
910 pm update...

high pressure will continue to move east and further away from
our region overnight. The result will by dry but muggy
conditions with low temps only dropping into the upper 60s to
around 70 in most locales as low level moisture continues to
gradually increase. Dewpoints well into the 60s along with
light winds will allow for patchy ground fog to develop in the
typically prone locations late. May even see some very localized
areas of dense fog develop if winds decouple enough, but that
remains uncertain.

Short term 6 am Tuesday morning through Tuesday night
A cold front will approach our region from the west Tuesday.

With a strong high pressure off to the east, thinking this
front will be delayed from entering our region until Tuesday
night. This front should not move off the coast until sometime
after daybreak Wednesday morning.

Despite the expected timing of this front, our region should see
an increasing risk for showers and thunderstorms from west to
east through Tuesday morning into the afternoon. Latest
guidance suite continues to CAPE values of 1,000-1,600 j kg
during the afternoon and evening, with mid level wind speeds of
40-50 kt. These values are supportive of the risk for a few
strong to sever storms. The greatest threat is across western
and central ma, and northern ct.

Showers and a few thunderstorms should continue into Tuesday
night as a cold front pushes across southern new england.

Precipitable water values are anticipated to be around 2.00
inches. Locally heavy rainfall is possible within any
thunderstorms.

Above normal temperatures continue through this period.

Long term Wednesday through Monday
Big picture...

long term starts off with an upper trough centered over quebec on
Wednesday. Although the upper trough center pulls somewhat
northeastward on thu, cyclonic flow remains over our region thru
this weekend. Expecting temperatures to trend seasonably cool thru
the period.

During early next week GFS and ECMWF show signs of the upper trough
moving east, placing us in upper level ridging. Thus we could see a
warmup for next mon.

Details...

Wednesday...

upper level short wave will push a cold front eastward during
Wednesday. Depending on the exact timing of the cold front, western
portions of the area could start the day off dry. However to the
east and ahead of the cold front, precipitable water is 1.5 to 2
inches, allowing for locally heavy rain. Instability ahead of the
cold front with lis 0 to -2 and CAPE generally 500 to 1000 j kg,
accompanied by the right entrance region of the upper jet. So some
rumbles of thunder are probable ahead of the cold front Wed morning.

Wed afternoon expected to bring a drying trend as the deeper
moisture and better dynamics move offshore. Increasing sunshine
anticipated, allowing high temps to reach the upper 70s to low 80s
for most locales. Dew points will gradually dip into the 50s during
the day and evening.

Wednesday night...

surface ridging starts to build into southern new england and quite
dry airmass in place. Thus mostly clear skies are expected.

Thursday through Sunday...

high pressure builds in at the surface, while upper trough lingers
over southeast canada and into our area. Not much available moisture
thru this period except mainly between 700 and 850 mb. So cold pool
aloft will likely allow for partly cloudy skies and mainly dry
conditions. Short wave crossing the base of the trough Thu night fri
could bring some additional clouds. Could see a few showers here or
there during the long term timeframe, but again moisture looks quite
limited.

Temps will range from near normal to several degrees below normal.

High temps ranging mainly from 70 to 80 degrees f. Dew points range
mainly from the upper 40s to mid 50s, so quite comfortable from a
humidity standpoint. With light winds each night, min temps in the
50s to low 60s are expected, with the warmest overnight temps near
the shoreline, coolest in sheltered valleys.

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

Monday...

models indicate weak upper level ridging in our area, while surface
high pressure lingers. Should be a dry day accompanied by warmer
temps.

Aviation 01z Tuesday through Saturday
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Tuesday night ...

tonight... High confidence. MainlyVFR. Low confidence in ifr
stratus developing along the south coast late tonight.

Tuesday... Moderate confidence. MainlyVFR through the day. Any
morning ifr stratus should slowly lift toVFR by mid morning.

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

Tuesday night... Moderate confidence. MainlyVFR with scattered
MVFR is shra tsra.

Kbos terminal... High confidence in taf.

Kbdl terminal... High confidence in taf.

Outlook Wednesday through Saturday ...

areas of MVFR CIGS vsbys in showers thunderstorms Wednesday morning.

Otherwise,VFR all areas thru Saturday, 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 night ... High confidence.

Small craft advisories remain posted from late Tuesday morning
into Tuesday night for south coastal and outer coastal waters.

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

After some more thought, decided to expand the small craft
advisory into massachusetts bay. It possible we might need an
advisory in boston harbor, but don't have enough confidence just
yet.

Winds diminish Tuesday night, although seas may take a bit
longer into Wednesday morning to subside, particularly across
the outer coastal waters.

Outlook Wednesday through Saturday ...

Wednesday...

cold front moves across the waters, turning winds from the west-
northwest. Gusts to 25 kt possible early in the day. Seas 3 to
5 ft on the coastal waters gradually subside during the day.

Thursday through Saturday...

high pressure then builds in with W NW winds diminishing to less
than 20 kt. Winds become north on Friday. Diminishing winds
will bring diminishing seas, generally 3 ft or less through
this period.

Box watches warnings advisories
Ct... None.

Ma... None.

Ri... None.

Marine... Small craft advisory from 11 am Tuesday to 6 am edt Wednesday
for anz231>234-250-254>256.

Small craft advisory from 2 pm Tuesday to 2 am edt Wednesday
for anz236.

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

Small craft advisory from 2 pm Tuesday to 4 am edt Wednesday
for anz251.

Synopsis... Belk nmb
near term... Frank
short term... Belk
long term... Nmb
aviation... Frank belk nmb
marine... Belk nmb


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BHBM3 - 8443970 - Boston, MA 35 mi45 min 77°F 1017.3 hPa
BGXN3 - Great Bay Reserve, NH 53 mi90 min ESE 1.9 66°F 1018 hPa65°F
44013 - BOSTON 16 NM East of Boston, MA 55 mi85 min SSW 12 G 12 73°F 69°F1 ft1017.6 hPa (+0.0)

Wind History for Providence, RI
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Fitchburg, Fitchburg Municipal Airport, MA8 mi23 minN 010.00 miFair69°F64°F87%1018.3 hPa
Nashua - Boire Field Airport, NH14 mi19 minN 010.00 miFair70°F66°F87%1018.7 hPa
Bedford, Hanscom Field, MA20 mi19 minSSW 610.00 miFair72°F62°F71%1018.9 hPa
Jaffrey Airport-Silver Ranch, NH24 mi23 minSSW 510.00 miFair68°F64°F90%1019.4 hPa

Wind History from FIT (wind in knots)
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Last 24hrCalmCalm3CalmCalmN3N44CalmW4NW6W5SW5SW10W10SW5SW54S6SW3CalmNW3CalmCalm
1 day agoCalmCalmCalmNW44W9W7W7W8W8
G18
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NW11NW10NW10NW5CalmNW7CalmN4
2 days agoCalmNE4NW3N4N3NE3N4N4CalmCalmCalmCalmCalmW9SW8W9W6W10W6SW3CalmCalmCalmCalm

Tide / Current Tables for Riverside, Merrimack River, Massachusetts
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Riverside
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Mon -- 12:43 AM EDT     6.90 feet High Tide
Mon -- 05:37 AM EDT     Moonrise
Mon -- 05:57 AM EDT     Sunrise
Mon -- 08:40 AM EDT     -0.39 feet Low Tide
Mon -- 01:20 PM EDT     6.24 feet High Tide
Mon -- 02:31 PM EDT     New Moon
Mon -- 07:36 PM EDT     Sunset
Mon -- 07:41 PM EDT     Moonset
Mon -- 08:53 PM EDT     -0.17 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
6.56.96.55.64.32.81.40.3-0.3-0.30.93.15.16.26.15.64.53.21.90.70-0.20.82.9

Tide / Current Tables for Amelia Earhart Dam, Mystic River, Boston Harbor, Massachusetts
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Amelia Earhart Dam
Click for Map
Mon -- 05:17 AM EDT     -1.13 feet Low Tide
Mon -- 05:38 AM EDT     Moonrise
Mon -- 05:58 AM EDT     Sunrise
Mon -- 11:31 AM EDT     10.58 feet High Tide
Mon -- 02:31 PM EDT     New Moon
Mon -- 05:32 PM EDT     -0.54 feet Low Tide
Mon -- 07:35 PM EDT     Sunset
Mon -- 07:40 PM EDT     Moonset
Mon -- 11:47 PM EDT     11.71 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
10.996.33.20.4-1.1-0.713.46.38.910.410.49.27.14.41.6-0.3-0.31.13.56.49.311.2

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 (23,6,7,8)
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Ground Weather Radar Station Boston, MA
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weather_mapweather_map weather_map

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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.