Saturday, July11, 2020
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Marine Weather and Tides
Chelsea, 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 5:16AMSunset 8:23PM Saturday July 11, 2020 5:47 PM EDT (21:47 UTC) Moonrise 12:00AMMoonset 11:41AM Illumination 61% Phase: Waning Gibbous; Moon at 21 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- 445 Pm Edt Sat Jul 11 2020
.small craft advisory in effect until 6 pm edt this evening...
Today..S winds 10 to 15 kt with gusts up to 25 kt. Waves 2 to 3 ft.
Tonight..S winds 10 to 15 kt. Gusts up to 25 kt in the evening. Waves 2 to 3 ft. Patchy fog.
Sun..SW winds 10 to 15 kt. Gusts up to 20 kt in the afternoon. Waves around 2 ft.
Sun night..SW winds 5 to 10 kt. Waves around 2 ft.
Mon..S winds 5 to 10 kt. Waves 1 foot or less. A chance of showers.
Mon night..W winds 5 to 10 kt. Waves 1 foot or less. A chance of showers.
Tue..NW winds around 5 kt. Waves 1 foot or less. A chance of showers.
Tue night..W winds around 5 kt. Waves 1 foot or less. A chance of showers.
Wed and Wed night..NE winds around 5 kt, becoming s. 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 445 Pm Edt Sat Jul 11 2020
Synopsis for massachusetts and rhode island coastal waters.. High seas and gusty winds from tropical storm fay will impact mostly the south coast and outer eastern waters this evening and Sunday with high surf and dangerous rip currents. A cold front will cross the waters early Sunday and another cold front crosses the water Monday. Warm front lifts north on Wednesday. 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 Chelsea, MA
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location: 42.37, -71.06     debug


Area Discussion for - Boston, MA
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FXUS61 KBOX 111933 AFDBOX

Area Forecast Discussion National Weather Service Boston/Norton MA 333 PM EDT Sat Jul 11 2020

SYNOPSIS. An upper level disturbance tracks from western New York into northern New England tonight into early Sunday. Scattered thunderstorms are possible through early evening, and a few may become locally strong with gusty winds and heavy rainfall. It will still be quite warm and still fairly humid on Sunday, with another chance for showers and embedded thunderstorms overnight into early Monday morning. Scattered showers and thunderstorms return on Monday afternoon and Tuesday. High pressure then brings fair weather for Wednesday and possibly Thursday. Scattered showers and thunderstorms return on Friday and Saturday.

NEAR TERM /UNTIL 6 AM SUNDAY MORNING/. 230 PM Update:

A shortwave trough currently spiraling across northwestern PA is resulting in scattered to numerous showers and thunderstorms across much of the Southern Tier of NY eastward into the Catskills and lower Hudson Valley. Though a few showers have popped up in what is best characterized by moderately strong convective instability (SBCAPEs 2000-2500 J/kg with lifted indices -4 to -6 units per SPC's mesoanalysis), expecting a greater threat for scattered thunderstorms moving into the CT River Valley eastward into portions of central MA and eastern CT. The upper trough will lift northeastward toward the Adirondacks through mid-evening, and while this system more or less glances our area, related height falls and the strongly heated air mass should maintain scattered storms as they move into the CT Valley. Mid-level lapse rates are poor and as such, storms may be a bit slower to grow, and weak wind shear values will support pulse updrafts. However the strongly-heated low-levels and high PWAT values could support strong to localized damaging winds and wet microbursts. Will also have to keep tabs on rain rates with some concerns for localized street flooding, especially if storms can move over the same areas. Lacking a trigger and given somewhat less unstable southerly flow off the water, appears eastern MA into RI should stay dry.

Southerly flow tonight may become slightly more onshore, and this may draw a field of stratus back northward, reflected in most model guidance RH forecasts. Bigger question is how far west will this stratus later extend, with evolving drier SWly flow looking to help serve as a western bound to the stratus layer. Winds do become more SW late in the overnight into early Sunday morning so not thinking the stratus will be with us any longer than the overnight hrs. Mild and muggy lows in the mid 60s to lower 70s.

A High Surf Advisory continues until 6 PM today. Given the continued long-period southerly swell and the continued threat for rip currents, either a High Surf or Rip Current Statement will likely be needed for Sunday as well.

SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/. 230 PM Update:

Sunday:

Shortwave trough will be moving into northern New England on Sunday. A related fairly weak surface low will move through the St. Lawrence Valley, with troughing extending down into northwestern MA and the Berkshires. High pressure should maintain itself over southeastern New England.

Sunday should be another very warm day and while dewpoints are lower it will still feel quite muggy again. Once the sun comes out to erode any residual stratus from overnight, looking at mostly sunny conditions and it should also become fairly breezy for a typical mid- July day. Gusts to 25 mph not out of the question with strong heating allowing for mixing to occur. A few higher res models simulate isolated to widely scattered thunderstorms near the weak trough axis over northwest into north-central MA. Better large-scale support for storms looks north of our area, instability looks to be less than prior days due to slightly lower dewpoints, weak lift/convergence and dry air in the mid-levels should keep most storms fairly isolated if any develop at all. Wouldn't necessarily cancel any plans but certainly keep an eye to the sky if in towns north and west of a Worcester to Springfield line. Highs will again top out in the lower 90s in the interior, though slightly lower dewpoints due to mixing and some downsloping should keep heat indices from reaching Advisory levels.

Sunday Night:

Any thunderstorms which may have developed across western into north- central MA should dissipate after sunset. A brief period of shortwave ridging and dry weather then resumes for most of the overnight. However late in the overnight into the pre-dawn hours, 500 mb heights again start to fall as the next shortwave trough moves through east-central PA into southern NY. While low-levels are stable, seasonably-strong 850-500 mb WSW flow advects in some modest elevated instability into early Monday morning across northern CT, northwest RI into western and central MA (Showalter indices -1 to -2 units, associated with 6-6.5 C/km 700-500 mb lapse rates). Though timing remains a question - it could be more focused into Monday morning as opposed to very late Sunday night - the potential exists for early-morning thunderstorms in the Springfield-Hartford to Worcester corridor. While it is the exception and not the rule, an upper-end outcome could feature thunderstorms with small sub-severe hail given MUCAPEs increasing to around 500-900 J/kg. Otherwise, still a muggy evening ahead with lows in the upper 60s to lower 70s.

LONG TERM /MONDAY THROUGH SATURDAY/. Big Picture .

High pressure in control coast-to-coast across the Southern USA. One trough moves across New England Monday and Tuesday, followed by a weak ridge Wednesday. Another shortwave trough based in Canada moves across the Nrn Tier of the USA, crossing New England Thursday or Friday.

Height contours at 500-mb, refecting the deep layer, are forecast near normal Monday-Tuesday, trending above normal the remainder of the week. Surface high pressure passing north of the region midweek may generate a low-level easterly flow that would buffer the warming trend, but the high pressure moves east and the surface flow returns to a west-southwest direction late in the week.

Mass fields are similar through Thursday morning, then show differences in handling the late week trough. Confidence is moderate- high through Thursday, then lower confidence Friday-Saturday.

Daily details .

Monday-Tuesday .

A leading shortwave trough sweeps across Srn New England Monday, supporting a surface cold front that crosses the region late in the day or evening. An associated 100-kt jet in the southwest upper flow moves across New England with Srn New England under the right entrance region of the jet, supporting lift. The airmass will be unstable with LI of -3 to -5 and CAPE of 1000-1500 J/Kg. And 0-3 Km Helicity will be around 100. Expect showers and scattered t-storms with the front. PW values are forecast around 1.9 inches, so local downpours are also expected.

The main trough axis sweeps overhead late Monday night and Tuesday, cooling temps at 500 mb by 2-3C from Monday. CAPE of 500 J and LI of minus 1 to minus 2 extend south into Eastern MA during Tuesday. This may be enough to generate scattered showers/thunder Tuesday, with most favorable conditions in Eastern MA. PW values diminish to 1.3 inches, so less favorable for downpours.

Wednesday-Thursday .

High pressure builds south from Quebec, and combined with a shortwave upper ridge this should bring rain-free weather and lower dew points. The surface high remains centered to our north, which suggests an east flow over the region and cooler temperatures along the eastern coast.

Friday-Saturday .

The next shortwave approaches from the Great Lakes, but timing remains in question due to the variety of model timings. Expect increasing instability with LI falling to near -5 by Saturday and CAPE increasing to near 2000 J/Kg. PW values climb to 2 inches. The question remains whether the convection reaches Srn New England Friday, or waits until Saturday. When it arrives, expect scattered showers and thunder, with local downpours.

AVIATION /20Z SATURDAY THROUGH THURSDAY/. Forecaster Confidence Levels .

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

18z TAF Update:

Rest of Today: High confidence.

VFR for most of the interior and towards BOS-BED, but continued IFR to MVFR across the Cape. Possible strong thunderstorms BAF- CEF-BDL-HFD, perhaps to ORH as soon as 19z, but best chance after 20z. Brief sub-VFR visby and gusty winds main threats in thunderstorms. South winds 10-15 kt gusts to 25 kt.

Tonight: Moderate to high confidence.

Early iso-sct TSRA from ORH westward should dissipate after 02z. Deteriorating flight categories toward MVFR/IFR after 03z due to another period of lower stratus. Best chance IFR across the Cape/ACK with possible mist/fog. Should see improvement toward MVFR-VFR ceilings late overnight to pre-dawn. South winds around 10 kt.

Sunday: High confidence.

Any sub-VFR to become VFR by mid-morning. Isolated SHRA/TSRA N/W of CEF-ORH-BED after 17z but confidence on development is not high and may stay dry. Southwest winds pick up with gusts 20-25 kt by late-AM/early-PM.

Sunday Night: High confidence on trends, moderate on thunder potential.

VFR through about 04z, then better chances for showers move in after midnight and especially pre-dawn to early Monday AM. Could see periods of thunder embedded at times, timing and coverage is less clear. SW winds decrease to around 5-10 kt.

KBOS Terminal . High confidence in TAF.

KBDL Terminal . Moderate to high confidence in TAF. VCTS for SCT TSRA threat after 20z.

Outlook /Monday through Thursday/ .

Monday: Mainly VFR, with areas MVFR possible. Breezy. Chance SHRA, slight chance TSRA.

Monday Night: Mainly VFR, with local MVFR possible. Slight chance SHRA, isolated TSRA. Patchy BR.

Tuesday: Mainly VFR, with areas MVFR possible. Chance SHRA, slight chance TSRA.

Tuesday Night: Mainly VFR, with local IFR possible. Patchy BR.

Wednesday: VFR.

Wednesday Night: Mainly VFR, with local IFR possible. Patchy BR.

Thursday: Mainly VFR, with local MVFR possible. Slight chance SHRA.

MARINE. 230 PM Update:

Tonight through Sunday Night: High confidence.

Small craft advisories remain in effect for all waters due to southerly winds 25-30 kt and/or seas over 5'. Winds should subside early this evening across Boston Harbor and Narragansett Bay. However SCA conditions then continue through Sunday afternoon, with SW gusts in the 20-25 kt range and longer period 5-6' seas. Areas of low clouds and fog again set in for most waters tonight.

A High Surf Advisory continues until 6 PM today. Given the continued long-period southerly swell and the continued threat for rip currents, either a High Surf or Rip Current Statement will be needed for Sunday as well.

Outlook /Monday through Thursday/ .

Monday through Monday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, slight chance of thunderstorms.

Tuesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers, isolated thunderstorms.

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

Wednesday through Thursday: Winds less than 25 kt.

BOX WATCHES/WARNINGS/ADVISORIES. CT . None. MA . High Surf Advisory until 6 PM EDT this evening for MAZ020-023- 024. RI . High Surf Advisory until 6 PM EDT this evening for RIZ006>008. MARINE . Small Craft Advisory until 8 PM EDT Sunday for ANZ231>235-237- 250-251-254>256. Small Craft Advisory until 6 PM EDT this evening for ANZ230. Small Craft Advisory until 8 PM EDT this evening for ANZ236.

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


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BHBM3 - 8443970 - Boston, MA 1 mi53 min 68°F1004.3 hPa
44013 - BOSTON 16 NM East of Boston, MA 22 mi57 min SSE 14 G 18 73°F 68°F3 ft1004.4 hPa (-1.1)73°F
44029 - Buoy A0102 - Mass. Bay/Stellwagen 28 mi103 min S 18 G 19 71°F 4 ft1003.5 hPa
FOXR1 - 8454000 - Providence, RI 43 mi53 min SSW 18 G 22 76°F1006.3 hPa
PVDR1 44 mi53 min SSE 16 G 18 1006.3 hPa
BLTM3 - 8447387 - Borden Flats Light at Fall River, MA 46 mi53 min SSW 13 G 18 1006.7 hPa
FRVM3 - 8447386 - Fall River, MA 46 mi53 min 75°F1007 hPa
FRXM3 47 mi59 min 77°F 74°F
IOSN3 - Isle of Shoals, NH 47 mi47 min SSE 28 G 29 72°F 1004.1 hPa72°F
CPTR1 - 8452944 - Conimicut Light, RI 48 mi53 min 77°F1006.4 hPa
BGXN3 - Great Bay Reserve, NH 49 mi62 min SE 4.1 84°F 1005 hPa75°F

Wind History for Providence, RI
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Boston, Logan International Airport, MA2 mi53 minS 1510.00 miPartly Cloudy84°F72°F67%1005.2 hPa
East Milton, MA11 mi56 minS 17 G 29 mi80°F71°F74%1006.6 hPa
Norwood, Norwood Memorial Airport, MA14 mi54 minS 8 G 1810.00 miPartly Cloudy84°F73°F70%1005.3 hPa
Laurence G Hanscom Field Airport, MA14 mi56 minS 1510.00 miPartly Cloudy88°F72°F59%1005.4 hPa
Beverly, Beverly Municipal Airport, MA16 mi54 minS 14 G 2410.00 miPartly Cloudy85°F71°F63%1004.3 hPa

Link to 5 minute data for KBOS

Wind History from BOS (wind in knots)
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Last 24hrE14E13E13E13E11E14E17E9E10E10E9SE10SE12S11S14S18
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1 day agoSE7S12S11S9S8SW7S5SW7S5S4S5S7S6S5CalmSE3E5E7E9E15E13E14E13E13
2 days agoSW14SW16SW15SW10SW8SW8S5S5SW10SW7SW7SW8SW6W7SW8W54SE9SE7E12E10E8E9E6

Tide / Current Tables for Charlestown Bridge, Charles River, Massachusetts
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Charlestown Bridge
Click for Map
Sat -- 04:20 AM EDT     9.56 feet High Tide
Sat -- 05:18 AM EDT     Sunrise
Sat -- 10:37 AM EDT     0.79 feet Low Tide
Sat -- 11:41 AM EDT     Moonset
Sat -- 04:56 PM EDT     9.13 feet High Tide
Sat -- 08:21 PM EDT     Sunset
Sat -- 10:59 PM EDT     1.55 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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3.14.86.78.59.59.38.26.54.52.51.10.91.83.45.27.18.69.18.67.35.63.82.21.6

Tide / Current Tables for Boston Harbor, Massachusetts Current
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Boston Harbor
Click for Map
Sat -- 01:31 AM EDT     1.00 knots Max Flood
Sat -- 04:02 AM EDT     -0.00 knots Slack
Sat -- 05:17 AM EDT     Sunrise
Sat -- 08:33 AM EDT     -1.09 knots Max Ebb
Sat -- 10:39 AM EDT     0.00 knots Slack
Sat -- 11:41 AM EDT     Moonset
Sat -- 01:58 PM EDT     1.04 knots Max Flood
Sat -- 04:35 PM EDT     -0.00 knots Slack
Sat -- 08:20 PM EDT     Sunset
Sat -- 09:04 PM EDT     -1.06 knots Max Ebb
Sat -- 11:07 PM EDT     0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.9110.60-0.4-0.7-0.9-1.1-1.1-0.60.30.8110.80.3-0.2-0.5-0.8-1-1.1-0.8-0.1

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.
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Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Boston, MA (17,4,5,8)
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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 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.