Tuesday, February18, 2020
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Marine Weather and Tides
Groton, MA

Version 3.4
NOTICE
12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed.
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.

Sunrise 6:38AMSunset 5:23PM Tuesday February 18, 2020 7:08 AM EST (12:08 UTC) Moonrise 4:21AMMoonset 1:37PM Illumination 27% Phase: Waning Crescent; Moon at 24 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- 416 Am Est Tue Feb 18 2020
.small craft advisory in effect from Wednesday morning through Wednesday evening...
Today..SE winds 10 to 15 kt with gusts up to 25 kt. Waves around 2 ft. A slight chance of rain this morning, then rain this afternoon.
Tonight..S winds 10 to 15 kt, becoming W 5 to 10 kt after midnight. Gusts up to 25 kt. Waves around 2 ft, except 3 to 5 ft at the outer harbor entrance. Areas of fog. Showers. Vsby 1 nm or less.
Wed..W winds 10 to 15 kt, becoming nw 15 to 20 kt in the afternoon. Gusts up to 30 kt. Waves around 2 ft.
Wed night..NW winds 10 to 15 kt. Gusts up to 30 kt, decreasing to 20 kt after midnight. Waves around 2 ft.
Thu and Thu night..NW winds around 10 kt with gusts up to 20 kt. Waves around 2 ft.
Fri through Sat night..W winds 5 to 10 kt. Waves 1 foot or less. 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 416 Am Est Tue Feb 18 2020
Synopsis for massachusetts and rhode island coastal waters.. High pres across northern new england early this morning moves east of the region today, as low pres across the eastern great lakes lifts into quebec. A strong cold front crosses the waters Wed with gust northwest winds through Wed night. Large high pres over the central states slowly builds east and passes south of our waters this 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 181126 AFDBOX

Area Forecast Discussion National Weather Service Boston/Norton MA 626 AM EST Tue Feb 18 2020

SYNOPSIS. Low pressure will bring a period of rain mainly this afternoon into this evening, which will begin as a wintry mix across the east slopes of the Berkshires and northern Worcester Hills. Dry weather follows later tonight and it becomes windy on Wednesday behind the passage of a cold front. Blustery and colder, dry weather pattern Wednesday night through Friday with even colder wind chills. Temperatures then moderate back to above-normal levels by the weekend. Next Monday or Tuesday offers the next chance for precipitation.

NEAR TERM /UNTIL 6 PM THIS EVENING/. 611 AM Update:

* Slippery travel in the higher terrain of the Berks/northern Worcester Hills late this morning and afternoon

Regional radar mosaic showing some radar returns moving into northwestern MA at this hour. Low-levels remain dry with dewpoint depressions on the order of 8-12 degrees, and this dryness likely extends to a decent depth of lower atmosphere (per 00z RAOB at Albany). If anything is reaching the ground, likely to be nothing more than flurries. Did opt to slow down start of steadier precip by an hour based on the dry atmosphere but not exactly a significant change. Forecast thinking still looks on track regarding the light wintry precip event for locations at and above 1000' today.

Observed temperatures were running several degrees too cold compared to forecast expectations in eastern and SE MA, where early cloud- free skies promoted good radiational cooling. While clouds will continue to fill in areawide, temperatures expected to continue to rise amid warm advection and especially once the radiation inversion mixes out.

Prior discussion follows .

Main concern later this morning and especially this afternoon will revolve around minor snow/ice accumulations in the high terrain along the east slopes of the Berkshires/northern Worcester Hills. This is mainly for elevations near or above 1000 feet, where slippery travel may develop on untreated roadways. We will break things down a bit more below.

Approaching shortwave trough and surface wave lifting from the eastern Great Lakes into Quebec will increase the forcing for ascent today. Some light snow may overspread the east slopes of the Berkshires and northern Worcester Hills late this morning through noon. Steadier precipitation will overspread the rest of the region between about noon and 3 PM as a modest southerly LLJ develops resulting in better forcing.

Ptype should mainly be rain over the majority of the region, perhaps mixed with snow/sleet for a very brief time at the onset with no impacts expected. This a result of the main low pressure system passing well to our west, allowing a milder southeast flow of air into the region. The exception to this is across the high terrain along the east slopes of the Berkshires and northern Worcester Hills. This is mainly for elevations near or above 1000 feet. Thermal profiles appear cold enough to support a brief period of snow. This will be followed by a short period of sleet/freezing rain and a change to all rain by late afternoon/early evening.

In a nutshell, just expecting a coating to 1 inch of snow in the high terrain with perhaps up to 2 inches in extreme northwest MA. This will be followed by a brief period of sleet/freezing rain with the threat of minor ice accretion, less than a tenth of an inch. Given the rather cold temperatures/dry airmass in place early this morning, cold road temperatures certainly may result in slippery travel later today in the high terrain. Opted to issue a Winter Weather Advisory along the east slopes of the Berkshires where confidence was highest in minor snow/ice accretion. Will continue the special weather statement for the northern Worcester Hills for this potential. If confidence increases the next shift may expand the Winter Weather Advisory into this region as well.

Across the rest of the region, ptype will just be rain this afternoon. High temperatures will mainly be in the lower to middle 30s across the high terrain, to the upper 30s to the lower 40s elsewhere. Temps may reach the middle 40s across far southeast New England by early evening with increasing southerly flow.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/. * Dry but windy on Wednesday

Tonight .

Showers and areas of fog will linger during the first part of the evening. A secondary wave will develop across southeast New England and then will lift northeast of the region by late evening. Drier air will work in from the west once the wave lifts to our northeast, so any lingering showers and fog should be confined to the south coast by late evening. Improvement should occur along the south coast, Cape and Islands too after midnight. Low temperatures will only drop into the 30s to near 40 by daybreak in most locations with any at or below freezing readings confined to the high terrain.

Wednesday .

The pressure gradient increases significantly on Wednesday. This a result of intensifying low pressure in the Canadian Maritimes and strong high pressure building into the north Central U.S. This coupled with strong cold advection aloft behind a cold front will result in a dry, but windy day. Northwest wind gusts of 25 to 40 mph are anticipated. Plenty of sunshine will attempt to offset the strong cold advection, so expect temperatures to be mainly in the middle 30s to lower 40s much of the day. However, temps may briefly peak in the middle 40s across southeast New England.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/. Highlights .

* Colder, dry weather pattern for mid to late week, with below- normal temperatures and cold wind chills Thurs and Fri.

* Possible ocean-effect snow showers with little accumulation South Shore/Cape Cod late Thu-Fri.

* Warming, moderating temperatures for the weekend with continued dry weather.

Details .

Wednesday Night through Friday:

An upper-level ridge over the west coast of North America results in a period of northwest cyclonic flow aloft across the Great Lakes and Northeast. This northwest flow will draw modified-Arctic air southeastward into the Northeast, leading to a period of colder weather for the latter part of the workweek. Coincident with the colder air mass will be a period of blustery northwest wind conditions which will result in even colder wind chills.

Despite the colder air, the surface pattern is however a dry one as a ridge of high pressure is maintained through this period. Mostly clear to partly cloudy skies should be common in this period, with good radiational cooling at night. Will have to watch for possible ocean-effect SHSN later Thursday night into Friday towards the South Shore and the Cape as low-level flow becomes more favorably NNE and colder air flowing over SSTs in the mid 40s setting the stage for enough instability.

Thermally, 925 mb temps fall to -12 to -14C Wednesday night into Thursday areawide. The coldest period is Thursday night into Friday as the thermal trough builds across New England associated with a potent, though moisture-starved trough in the NW flow. 925 mb temps plummet to around -15 to -17C Thursday night into early Friday, before starting to moderate late in the day on Friday as flow becomes W.

After a cold start with lows in the teens to low 20s Wed night (morning wind chills single digits to 10 above), highs Thurs in the 20s to near freezing. With the coldest air coming in Thurs nite, lows single digits to the teens (Fri AM wind chills around +5 to - 5). Highs Fri in the mid 20s to lower-mid 30s.

Friday Night into Sunday:

Carrying the theme of the winter thus far, the shot of colder air looks to be short-lived/not sustained, with temps moderating back to above-normal levels by the weekend. Surface high pressure builds into the central Appalachians Friday night and then off the mid- Atlantic coast, with a resulting southwest warm advection pattern. A passing Clipper system to our north may increase clouds late Sunday with a wind shift to W but appears to be a dry passage. Highs return into the 40s with lows in the 20s to near freezing for the weekend.

Dry weather pattern looks to continue into the foreseeable future. Per the 00z ECMWF and the Canadian GEM, next chance for precip may not occur until late Monday into early Tuesday as a trough in the southern branch of the jet comes out of the southwest US.

AVIATION /11Z TUESDAY THROUGH SATURDAY/. Forecaster Confidence Levels .

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

12z TAF Update:

Today . Moderate to high confidence.

VFR to continue for another couple hrs, with ceilings continuing to lower to MVFR levels by mid-morning towards BAF. Continued eastward lower of ceilings to MVFR levels late this morning/early afternoon, trending MVFR/IFR levels late afternoon/early evening in many locations. Rain overspreads most locations from 15z to 19z. The exception is mainly the east slopes of the Berkshires and Worcester Hills, where ptype begins as a period of snow/ice with a minor accumulation possible. Ptype should change to rain in all these locations by early evening. Winds shift to E and SE this morning at 10 to 15 knots with some gusts up to 20 knots along the coast and in the high terrain.

Tonight . Moderate to high confidence. Low end MVFR-IFR conditions with localized LIFR conditions into the first half of the evening in showers, low clouds and fog. There will also be LLWS in association with a modest southerly LLJ. Improvement occurs by late this evening and especially after midnight from west to east as drier air works into the region.

Wednesday . High confidence. VFR. NW wind gusts of 25 to 35 knots.

KBOS Terminal . Moderate to high confidence in TAF. VFR this morning, then trending MVFR-IFR for the afternoon push.

KBDL Terminal . Moderate to high confidence in TAF. MVFR by early-aftn, trending towards MVFR-IFR for the afternoon push.

Outlook /Wednesday Night through Saturday/ .

Wednesday Night: VFR. Windy with local gusts up to 30 kt.

Thursday through Saturday: VFR. Breezy.

MARINE. Today . High confidence. A modest southerly LLJ that develops ahead of a shortwave trough should yield SCA SE wind gusts of 25 to 30 knots across most open waters today. Brief 35 knot wind gusts can not be ruled out toward evening across our eastern waters, but felt SCA headlines were more representative. Rain and areas of fog develop later today and especially toward evening. A relatively long southeast fetch should also allow seas to build to between 4 and 9 feet by early evening across the open waters.

Tonight . Moderate to high confidence. Areas of showers and fog this evening should improve after midnight as LLJ shifts east of the region and is replaced by drier air. Some 30 knot southerly gusts early this evening should temporarily diminish and shift more to the west overnight.

Wednesday . High confidence. Northwest wind gusts of 25 to 35 knots develop behind a strong cold front by late morning and afternoon. Opted to go with a Gale Warning for our northeast waters with strong small craft elsewhere. Seas between 4 and 8 feet across the open waters.

Outlook /Wednesday Night through Saturday/ .

Wednesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas.

Thursday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft.

Thursday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of seas approaching 5 ft.

Friday: Winds less than 25 kt. Seas locally approaching 5 ft.

Friday Night: Winds less than 25 kt. Areas of seas approaching 5 ft.

Saturday: Winds less than 25 kt. Seas up to 5 ft.

BOX WATCHES/WARNINGS/ADVISORIES. CT . None. MA . Winter Weather Advisory from 10 AM this morning to 5 PM EST this afternoon for MAZ002-008-009. RI . None. MARINE . Small Craft Advisory until 7 PM EST Wednesday for ANZ232>235- 237-254>256. Small Craft Advisory from 8 AM to 7 PM EST Wednesday for ANZ230-236. Small Craft Advisory from 10 AM this morning to 7 PM EST Wednesday for ANZ231-251. Gale Warning from 7 AM Wednesday to 1 AM EST Thursday for ANZ250.

SYNOPSIS . Frank/Loconto NEAR TERM . Frank/Loconto SHORT TERM . Frank LONG TERM . Loconto AVIATION . Frank/Loconto MARINE . Frank/Loconto


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BHBM3 - 8443970 - Boston, MA 35 mi62 min 35°F 37°F1030.2 hPa
BGXN3 - Great Bay Reserve, NH 53 mi83 min N 1.9 24°F 1032 hPa13°F
44013 - BOSTON 16 NM East of Boston, MA 55 mi78 min E 16 G 19 36°F 41°F3 ft1030.5 hPa (-1.2)24°F

Wind History for Providence, RI
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Fitchburg, Fitchburg Municipal Airport, MA8 mi2.3 hrsN 010.00 miA Few Clouds25°F10°F55%1031.7 hPa
Nashua - Boire Field Airport, NH14 mi2.2 hrsN 010.00 miA Few Clouds25°F12°F60%1032.7 hPa
Laurence G Hanscom Field Airport, MA20 mi2.3 hrsN 010.00 miFair26°F12°F57%1032.9 hPa
Jaffrey Airport-Silver Ranch, NH24 mi2.3 hrsN 010.00 miOvercast24°F9°F52%1031.1 hPa

Link to 5 minute data for KFIT

Wind History from FIT (wind in knots)
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Last 24hrCalmN3NW8NW13
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NW10W13W10NW10NW5CalmCalmCalmCalm--CalmCalmCalmN3NW3CalmCalm
1 day agoSW7SE36S5S7Calm36S4NW6W5SW4CalmS3CalmCalmCalmCalmCalmCalmCalmCalmCalmCalm
2 days ago--NW5CalmCalmCalmSE53SW6S8SW7SW4S4CalmS11S12SE934S6CalmSW8SW8SW6Calm

Tide / Current Tables for Riverside, Merrimack River, Massachusetts
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Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.


Tide / Current Tables for Amelia Earhart Dam, Mystic River, Boston Harbor, Massachusetts
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Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.


Weather Map
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wmap_A
GEOS 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.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Boston, MA (7,2,3,4)
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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 numerous 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.