Wednesday, September30, 2020
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Marine Weather and Tides
West Yarmouth, MA

Version 3.4
NOTICE
8/26/2020 The 7 day forecast is taking about 5 seconds to load but it will eventually load. NOAA is still working on it.
8/18/2020 NOAA continues to have trouble. Wind guest will occasionally be left off graphs. I am working with NOAA to resolve the issue.
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 6:36AMSunset 6:25PM Wednesday September 30, 2020 10:21 AM EDT (14:21 UTC) Moonrise 6:20PMMoonset 5:08AM Illumination 97% Phase: Waxing Gibbous; Moon at 13 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- 1016 Am Edt Wed Sep 30 2020
.gale warning in effect until 2 pm edt this afternoon...
This afternoon..SW winds 20 to 25 kt with gusts up to 30 kt. Seas 4 to 6 ft. A chance of showers this morning. Patchy fog.
Tonight..SW winds 15 to 20 kt, diminishing to 10 to 15 kt after midnight. Gusts up to 25 kt. Seas 2 to 4 ft.
Thu..SW winds 10 to 15 kt with gusts up to 20 kt. Seas around 2 ft.
Thu night..SW winds 10 to 15 kt with gusts up to 20 kt, diminishing to 5 to 10 kt after midnight. Seas around 2 ft.
Fri..SE winds around 5 kt, increasing to around 10 kt in the afternoon. Seas around 2 ft. A chance of showers.
Fri night..SE winds 5 to 10 kt, becoming nw 10 to 15 kt with gusts up to 20 kt after midnight. Seas around 2 ft. A chance of showers.
Sat through Sun night..E winds 10 to 15 kt with gusts up to 20 kt. Seas around 2 ft. 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 1016 Am Edt Wed Sep 30 2020
Synopsis for massachusetts and rhode island coastal waters.. A strong cold front sweeps across the waters Wednesday morning with southerly gales ahead of the front. The front moves east of the waters Wednesday afternoon with winds becoming west and subgale. Improving weather with dry conditions and good visibility behind the front. Dry, tranquil boating weather continues tonight and Thursday. Weak low pressure tracks across the new england waters Fri from southwest to northeast. Behind the low, dry west winds follow Saturday. Tranquil boating weather continues Sunday as high pressure builds over the area. For additional information on possible hazardous weather for the week ahead, please visit www.weather.gov/boston/ehwo .


7 Day Forecast for Marine Location Near West Yarmouth, MA
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location: 41.6, -70.27     debug


Area Discussion for - Boston, MA
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FXUS61 KBOX 301208 AFDBOX

Area Forecast Discussion National Weather Service Boston/Norton MA 808 AM EDT Wed Sep 30 2020

SYNOPSIS. A cold front sweeps across the area this morning, bringing widespread heavy rain and strong to possibly damaging winds, with highest rainfall totals across western Massachusetts and Connecticut. Cooler, less humid and drier air then overspreads the region this afternoon and lingers into Thursday. A round of showers is likely Friday, with showers most numerous and heaviest northwest of the I- 95 corridor. Dry and cooler weather returns for the weekend. Another round of showers is possible Sunday night into early next week.

NEAR TERM /UNTIL 6 PM THIS EVENING/.

745 am update .

The forecast is largely on track. High Wind Warnings across most of RI and southeast MA look to have verified. Over 50K power outages have been reported so far across S New England with numerous reports of downed trees. Blue Hill Observatory reported a gust of 61 kts just before 7 am. A fine line of low-top convection has developed along the cold front as the surface low pressure rapidly intensifies and lifts to the north. This line is expected to clear Eastern MA by around 9 am so the main change to the near term forecast is to lower the PoPs for the next few hours. Most of S New England should be dry by mid to late morning with breezy SW winds behind the front, although these winds will be considerably lower than the damaging winds that some areas experienced this morning.

PREVIOUS DISCUSSION .

430 am update .

* High Wind Warning for most of RI and southeast MA. Other headlines remain the same. Heavy downpours can lead to localized brief urban ponding. * Turning partly sunny albeit breezy and much more refreshing in the afternoon hours.

A rather impressive fine line of convection is moving into Northern NJ and just north of NYC at this time. NYC area airports are reporting gusts of up to 46 mph so the heavy rain is bringing down some of the strong winds aloft. Meanwhile, temperatures across RI and southeast MA are in the low to mid 70s, while a few degrees cooler on the immediate coast. That couple of degrees difference would likely mean that the Cape and Islands escape the worst of the damaging winds. The current timing and spatial coverage of the High Wind Warning still looks good. Aside from strong to damaging winds, there could be localized nuisance urban poor drainage flooding during the heaviest of downpours but most locations would receive some beneficial rain.

Below is our consideration for upgrading most of RI and SE MA to High Wind Warning between 4 and 10 AM:

1) Models have trended even more robust with the low level jet, with 850mb winds up to 80 kts and 925 mb up to 70 kts. GEFS show 850 and 925mb winds at 5 to 6 standard deviations above normal.

2) Highly impressive pressure rise/fall couplet exceeding 14 mb between 09z and 12z. The surface cyclone will race to the north and likely undergo bombogenesis, i.e. see a fall of 24 mb over 24 hours.

3) 00z Bufkit soundings show over 40 kt winds mixed down to well below 1000 ft. 00z CAM guidance shows mixed signal with regards to a well-defined fine line of convection, which would have been very favorable in bringing down the damaging winds. Nonetheless, with the nose of the LLJ pointed at RI and SE MA, we have increased confidence that at least parts of the area will see some kind of wind damage.

4) Leaves are still fully leaved and drought-stressed. Even if winds fall just shy of High Wind Warning criteria (sustained 35 kts or gusts over 50 kts), the potential high-end damage (even if widely scattered) warrants a headline higher than an advisory.

Following the cold front passage, dew points fall rapidly into the 50s during the day. Expect breezy conditions to persist through much of the day as lapse rates steepen though risk for damaging winds should decrease as jet dynamics become less impressive. Currently have used a blend of guidance to derive the forecast daytime highs, with Western MA topping out in the 60s and Eastern MA in the low to mid 70s. The highs could well be reached early in the day as cold air advection commences in earnest. Should be a mostly dry day but with plenty of cold stratocumulus clouds. 00z CAM guidance did suggest that there could be more sun than clouds albeit with breezy west winds by the afternoon hours.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/. 430 am update .

Tonight:

With diminishing winds and mostly clear skies, used MOS guidance to derive overnight lows. Lows range from mid 40s in the high terrain of Western MA to low to mid 50s for much of Eastern MA and RI, except for low 60s on the Cape.

Thursday:

* Comfortable day with breezy conditions. Afternoon highs about 5 degrees above average for late Sep/early Oct

A positively tilted H5 trough runs from the Great Lakes into Missouri. This means that S New England remains in a predominant SW flow with the bulk of the cold air staying well west of us. With mixing up to 850mb and 850mb temps around +7 to +9C on Thursday, expect highs to range between upper 60s to mid 70s, with downslope flow potentially leading to highs overperforming in Eastern MA and RI. Dew points remain in the 40s and 50s so it will be a very comfortable day for outdoor activities.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/. 430 am update .

Highlights .

* Showers likely Thu ngt and Fri, most numerous NW of I-95 corridor

* Dry and cool weather returns for the weekend

* Showers may return Sunday night into early next week

Precipitation .

Good model agreement on next short wave trough moving across the northeast Thu ngt into Fri. Deepest moisture and lift track across CT and northern MA, yielding highest pops and qpf north and west of the I-95 corridor. Short wave is progressive so dry weather quickly returns Fri night and persist into the weekend. A low amplitude short wave does move across New England Sat, but column is fairly dry so not expecting any showers, just some extra diurnal clouds Sat. Amplifying mid level trough over the Great Lakes Sunday results in downstream ridging across New England, yielding dry pleasant weather over the region. Then by Sunday night and especially into early next week, amplifying Great Lakes/OH Valley trough begins to advect eastward. However models differ on amplitude of trough with EC and its ensembles more robust than the GFS/GEFS/CMC/UKMET. Given spread here followed a model blend yielding a chance of showers from Sunday night into early next week. If the EC solution verifies a coastal storm with a soaking wind swept rain would occur here. But again, the EC and its ensembles are on the stronger side of all model outcomes.

Temperatures .

Seasonably cool Thu ngt and Fri given cloud cover and showers. Behind this departing short wave, cold air advection increases with cooler weather Sat. 925 mb temps around +10C will support highs in the low to mid 60s. Temps aloft about the same Sunday so expecting similar highs, low to mid 60s. These values are a few degs cooler than average, with normal highs in the mid to upper 60s. It will be pleasant with light winds both days, especially Sunday as 1026 mb high crest over the region. Also a mix of clouds sunshine both weekend days. Temps early next week remain uncertain pending amplitude of mid level trough and associated surface low. Wetter EC and its ensembles offer cool temps, while GFS and its ensembles are drier, thus milder temps. Given uncertainty derived temps here from a model blend.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/. Forecaster Confidence Levels .

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

Today: High confidence.

IFR and local LIFR to start, improving rapidly to VFR by 15z. Winds turning WSW at 10 to 15 kts with gusts up to 25 kts.

Tonight: High confidence.

VFR conditions. SW winds at 5 to 10 kts with gusts 15 to 20 kts possible for coastal terminals.

Thursday: High confidence.

VFR conditions. SW winds at 5 to 10 kts except up to 15 kts with gusts 20 to 25 kts possible for coastal terminals.

KBOS Terminal . High confidence in TAF.

KBDL Terminal . High confidence in TAF. Outlook /Thursday Night through Sunday/ .

Thursday Night: VFR.

Friday: Mainly VFR, with areas MVFR possible. Chance SHRA.

Friday Night: Mainly VFR, with local MVFR possible. Breezy. Chance SHRA.

Saturday through Sunday: VFR.

MARINE.

* Gale Warnings for all waters this morning.

A rapidly intensifying low pressure system passing well west of the waters has allowed a very strong southerly LLJ to develop ahead of an approaching cold front. The strongest of the winds has occurred early this morning, especially between 5 AM to 9 AM. Despite the inversion, a period of southerly wind gusts of 30 to 40 knots have been observed during this time. Seas build to between 7 and 11 feet across our open waters. Gale Warnings continue for all waters this morning.

Winds will diminish behind the front during the afternoon, but still expect SW wind gusts around 25 knots.

Outlook /Thursday Night through Sunday/ .

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

Friday through Friday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers.

Saturday through Sunday: Winds less than 25 kt.

BOX WATCHES/WARNINGS/ADVISORIES. CT . Wind Advisory until 1 PM EDT this afternoon for CTZ002>004. MA . Wind Advisory until 1 PM EDT this afternoon for MAZ004>007-011- 012-014-015-022>024-026. High Wind Warning until 10 AM EDT this morning for MAZ013- 016>021. RI . Wind Advisory until 1 PM EDT this afternoon for RIZ008. High Wind Warning until 10 AM EDT this morning for RIZ001>007. MARINE . Gale Warning until 2 PM EDT this afternoon for ANZ231-232-250- 254>256. Gale Warning until noon EDT today for ANZ230-233>237-251.

SYNOPSIS . Nocera/Chai NEAR TERM . Chai SHORT TERM . Chai LONG TERM . Nocera AVIATION . Nocera/Chai MARINE . Nocera/Chai


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
44020 - NANTUCKET SOUND 7 mi32 min SSW 25 G 35 66°F5 ft
WAXM3 - Waquoit Bay Reserve, MA 14 mi97 min SSE 8 73°F 1002 hPa73°F
44090 17 mi25 min 61°F4 ft
CHTM3 18 mi52 min 72°F 65°F
BZBM3 - 8447930 - Woods Hole, MA 22 mi52 min 69°F 67°F
NTKM3 - 8449130 - Nantucket Island, MA 24 mi52 min 70°F 67°F
44018 - SE Cape Cod 30NM East of Nantucket, MA 42 mi32 min SSW 25 G 31 68°F 7 ft1000.3 hPa (-0.0)64°F
BUZM3 - Buzzards Bay, MA 43 mi82 min SSW 28 G 30 1001.9 hPa (+1.3)
BLTM3 - 8447387 - Borden Flats Light at Fall River, MA 48 mi52 min 71°F
FRVM3 - 8447386 - Fall River, MA 48 mi52 min 71°F 67°F
FRXM3 49 mi52 min 71°F 67°F

Wind History for Nantucket Island, MA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hyannis, Barnstable Municipal-Boardman Airport, MA6 mi26 minSSW 18 G 297.00 miOvercast and Breezy71°F66°F87%1002.3 hPa
Otis Air National Guard Base, MA14 mi37 minSW 21 G 295.00 miFog/Mist and Breezy72°F71°F100%1002.7 hPa
Chatham, Chatham Municipal Airport, MA16 mi30 minSSW 16 G 307.00 miOvercast72°F66°F84%1003.3 hPa
Marthas Vineyard Airport, MA23 mi29 minSSW 18 G 245.00 miFog/Mist and Breezy69°F66°F90%1003.5 hPa

Link to 5 minute data for KHYA

Wind History from HYA (wind in knots)
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Last 24hrS5S5S6SW9S10S7S7S7S5SE4S5S5S566S8
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1 day agoS5S5S8S7
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2 days agoS8S86S9S9S7S8S65S4S4S4S54SE5S5S55S76S5S6S76

Tide / Current Tables for Hyannis Port, Nantucket Sound, Massachusetts
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Hyannis Port
Click for Map
Wed -- 05:08 AM EDT     Moonset
Wed -- 05:33 AM EDT     0.09 feet Low Tide
Wed -- 06:37 AM EDT     Sunrise
Wed -- 12:11 PM EDT     3.20 feet High Tide
Wed -- 05:46 PM EDT     0.15 feet Low Tide
Wed -- 06:20 PM EDT     Moonrise
Wed -- 06:23 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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3.332.31.50.60.20.10.40.81.52.32.93.23.12.51.70.90.30.20.40.81.42.22.9

Tide / Current Tables for Pollock Rip Channel, Massachusetts Current
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Pollock Rip Channel
Click for Map
Wed -- 12:00 AM EDT     -1.75 knots Max Ebb
Wed -- 02:56 AM EDT     0.00 knots Slack
Wed -- 05:07 AM EDT     Moonset
Wed -- 06:30 AM EDT     2.25 knots Max Flood
Wed -- 06:36 AM EDT     Sunrise
Wed -- 09:28 AM EDT     -0.00 knots Slack
Wed -- 12:27 PM EDT     -1.76 knots Max Ebb
Wed -- 03:25 PM EDT     0.00 knots Slack
Wed -- 06:19 PM EDT     Moonrise
Wed -- 06:22 PM EDT     Sunset
Wed -- 06:51 PM EDT     2.07 knots Max Flood
Wed -- 09:41 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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-1.7-1.5-0.90.111.72.22.21.60.5-0.6-1.3-1.7-1.7-1.2-0.40.51.31.92.11.70.8-0.3-1.2

Weather Map
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GEOS Local Image of    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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Ground Weather Radar Station Boston, MA
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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.