Wednesday, August4, 2021
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Marine Weather and Tides
Harwich Port, MA

Version 3.4
NOTICE
3/30/2021 -- ANZ330 has been split into ANZ331 and ANZ332. Click EDIT in Marine Forecast and select your new zone.
1/26/2021 -- The West Coast Satellite images havd been updated. They now use GEOS-17.
1/1/2021 -- The 7 day forecast are now working well. Thank you NOAA for your support.

Sunrise 5:37AMSunset 7:56PM Wednesday August 4, 2021 3:27 PM EDT (19:27 UTC) Moonrise 1:40AMMoonset 5:24PM Illumination 13% Phase: Waning Crescent; Moon at 26 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- 127 Pm Edt Wed Aug 4 2021
.small craft advisory in effect from late tonight through Thursday evening...
This afternoon..SE winds around 10 kt. Seas around 2 ft. Patchy fog. Showers likely. Vsby 1 to 3 nm.
Tonight..E winds 10 to 15 kt, becoming se after midnight. Gusts up to 25 kt. Seas 2 to 3 ft. Patchy fog. Showers with tstms likely. Vsby 1 to 3 nm.
Thu..S 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. Vsby 1 nm or less.
Thu night..S winds 15 to 20 kt, becoming sw around 10 kt after midnight. Seas 2 to 4 ft. Patchy fog. A chance of showers. Vsby 1 to 3 nm.
Fri..SW winds 5 to 10 kt. Seas 2 to 3 ft. Patchy fog.
Fri night..SW winds around 10 kt. Seas 2 to 3 ft.
Sat through Sun night..S winds 5 to 10 kt. Seas around 2 ft. 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 127 Pm Edt Wed Aug 4 2021
Synopsis for massachusetts and rhode island coastal waters.. A frontal boundary offshore near 40n/70w, will begin drifting northward Wednesday, and then onshore Wed night into Thu morning as low pressure tracks along the front. The weak low departs into maine Thu and then the maritimes Thu night. The bermuda high then builds towards the east coast, providing a drying trend Fri and Sat. Another frontal boundary crosses the waters Sun, introducing a risk for showers and Thunderstorms Sunday. Behind this departing surface wave, improving weather is expected Monday. 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 Harwich Port, MA
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location: 41.57, -70.05     debug


Area Discussion for - Boston, MA
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FXUS61 KBOX 041738 AFDBOX

Area Forecast Discussion National Weather Service Boston/Norton MA 138 PM EDT Wed Aug 4 2021

SYNOPSIS. A front moves onshore late today into Thursday, bringing showers/thunderstorms with locally very heavy rainfall and possible flooding. Drying out Thu night, Friday and into Sat along with warmer weather. Not as warm Sunday as a front enters the region along with scattered showers. Summer warmth returns early next week.

NEAR TERM /UNTIL 6 PM THIS EVENING/.

130 PM update .

Rain showers have moved up to the Cape Cod Canal at this hour and will continue their slow march northward. Forecast is favoring the NAM3K timing as it is most representative of the current radar situation. This would mean rain making it up to northeast MA by 5-6 pm.

1030 AM update .

Forecast is on track this morning with minimal changes necessary. Impressive satellite this morning featuring a nice baroclinic leaf over the Mid Atlantic along that frontal wave. As warm air advection continues clouds will continue to thicken and lower through the day ahead of the rain. Nantucket is the only location seeing rain at the moment but is will move north through the morning and early afternoon.

Previous Discussion .

Lead wave of low pres moves offshore this morning. Bulk of shower activity has remained offshore and the morning will feature dry conditions although with lots of cloud cover. Stronger low pres lifts north from the NC coast this afternoon with deeper moisture and increasing PWATs moving up along the coast this afternoon. This will result in area of showers developing and moving up along the south coast and Cape/Islands through this afternoon, possibly reaching I-95 corridor toward evening. However, much of interior SNE west of I-95 should remain dry. Temps in the interior should reach mid/upper 70s with some sunshine this morning through high clouds, but cooler near the coast and SE New Eng.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/. Highlights .

* Heavy rainfall and localized flash flooding possible across RI and eastern MA tonight into early Thu * Axis of heaviest rainfall remains uncertain and may still shift west or east

SNE will remain between western Atlantic subtropical ridge and slow moving trough across the Great Lakes tonight. Result is deep SW flow into New Eng with a tropical connection in place. During Thu as the upper trough approaches, the deeper moisture will gradually move to the east.

Anomalous PWATs 2"+ will lift north across eastern New Eng tonight at the nose of a 40-50 kt low level jet. Right entrance region of a robust upper jet will provide large scale forcing for ascent leading to widespread showers lifting north across SNE tonight into Mon morning. Meanwhile, sfc low pres lifts north along a frontal boundary which moves into SNE from the SE. Strong low level convergence along the boundary acting on anomalous moisture will lead to potential for very heavy rainfall, along with a few t-storms given marginal elevated instability and strong forcing. Potential for 2-4 inches of rain within the axis of heaviest rainfall, with max rainfall rates of 1-2"/hour possible. This could lead to significant urban street flooding and rapid rises on small rivers and streams.

The challenge for this forecast is where the axis of heavy rainfall will set up which will be dependent on the boundary location. Global and hi-res guidance offer differing solutions so forecast confidence is lower than what is ideal at this time range. Consensus of the guidance favors the I-95 corridor including BOS and PVD for axis of heaviest rainfall but the ECMWF is further west into CT and central MA while HRRR and hi- res RGEM are further east and focused more across SE MA and Cape Cod. We leaned toward the HREF LPMM which targeted the I-95 corridor into eastern MA which is also closer to the low level jet and PWAT axis so we issued a flash flood watch for RI and eastern MA where confidence is highest at this time. However, the axis of heavy rainfall may still shift to east or west given envelope of deterministic and ensemble solutions.

Rainfall rates will be diminishing Thu morning as higher PWATs shift east with rainfall focused across eastern New Eng. Some improvement is expected Thu afternoon from west to east.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/. Highlights .

* Fri-Sat: mainly dry weather with summer heat & humidity

* Sunday: Not as hot along with scattered showers

* Early Next Week: Summer heat and humidity return

Precipitation .

Mid level trough exits southern New England early Fri with good column drying, as PWATs decrease AOB 1 inch! This will combine with short wave ridging to support dry weather Fri into Sat. Next short wave approaches from the west late Sat, thus low risk for a few showers/T-storms late in the day across western CT/MA. Otherwise dry weather prevails thru Sat. Short wave trough and attending surface boundary Sunday yields more clouds and risk of scattered showers/T- storms. Subtropical ridge then begins to surge northward, yielding rising heights into southern New England early next week. Although, some of the guidance suggest potential robust short wave possible impacting the region around Tue, with an increase risk for scattered showers/T-storms.

Temperatures .

Ensembles show a fairly warm signal with 850 mb temps above normal much of this period. 850 mb ensemble mean temp is +14C Fri, then warming to +17C Sat ahead of approaching s/wv trough. This should support highs 80-85 Fri and 85-90 Sat. These temps combined with dew pts in the 60s will definitely provide a summer feel. Then Sunday, short wave energy, lower heights, more clouds and scattered showers will result in temps not quite as hot, with highs 80-85. Still humid with dew pts in the 60s. Then trending warmer/hot early next week as subtropical ridge builds northward. Ensemble mean 850 mb temps around +17C Monday, supporting highs well into the 80s, then with 850 mb temps warming to +19C Tue, highs in the upper 80s to lower 90s seem plausible.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/. Forecaster Confidence Levels.

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

18z update .

This afternoon . High confidence.

Mainly VFR cigs, but lowering to MVFR along the south coast later today as showers lift north into the region.

Tonight . Moderate confidence.

Becoming MVFR/IFR in for terminals east of the CT valley overnight with moderate to heavy rain in the PVD to BOS corridor especially 05-11Z. A few thunderstorms are possible as well. Gusty southerly winds develop over Cape Cod and the islands early Thursday morning, remaining light and NE elsewhere.

Thursday . Moderate confidence.

Areas of MVFR/IFR in the morning with showers focused across eastern New Eng. Improvement expected in the afternoon but will be slow, especially for ORH and east.

Thursday night . moderate confidence.

Mostly dry and VFR, but some showers may linger, especially for eastern MA terminals with embedded MVFR.

KBOS Terminal . High confidence in trends, lower confidence in timing. Lowering cigs to MVFR this evening as showers develop. Heavy rainfall and isolated t-storm possible after midnight.

KBDL Terminal . Moderate confidence in TAF. Mainly VFR cigs through the period, but a period of MVFR is possible tonight with a few showers. More widespread rainfall should remain to the east.

Outlook /Thursday Night through Sunday/ .

Friday through Friday Night: VFR.

Saturday: Mainly VFR, with local MVFR possible. Slight chance SHRA, slight chance TSRA.

Saturday Night: Mainly VFR, with areas MVFR possible. Slight chance SHRA, slight chance TSRA.

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

MARINE. Forecaster Confidence Levels.

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

Moderate Confidence through Thursday.

Wind and seas remain below SCA thresholds today. Approaching low level jet will bring increasing south winds with gusts to 25-30 kt later tonight into early Thu with building seas over south coastal waters. Vsbys reduced in showers and fog tonight into Thu morning. A few t-storms possible.

/Outlook /Thursday Night through Sunday/ .

Thursday Night: Winds less than 25 kt. Areas of rough seas. Chance of rain showers.

Friday through Friday Night: Winds less than 25 kt. Seas up to 5 ft.

Saturday through Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers, slight chance of thunderstorms.

BOX WATCHES/WARNINGS/ADVISORIES. CT . None. MA . Flash Flood Watch from 8 PM EDT this evening through Thursday morning for MAZ005>007-013>021. RI . Flash Flood Watch from 8 PM EDT this evening through Thursday morning for RIZ001>008. MARINE . Small Craft Advisory from 2 AM to 8 PM EDT Thursday for ANZ232>234. Small Craft Advisory from 11 PM this evening to 8 PM EDT Thursday for ANZ235-237. Small Craft Advisory from 8 PM this evening to 8 PM EDT Thursday for ANZ254>256.

SYNOPSIS . KJC/Nocera NEAR TERM . KJC/Nocera/BW SHORT TERM . KJC LONG TERM . Nocera AVIATION . Nocera/BW MARINE . Nocera/BW


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
CHTM3 10 mi57 min S 2.9 G 5.1 66°F 70°F1022.8 hPa
44020 - NANTUCKET SOUND 13 mi37 min E 7.8 G 9.7 68°F 73°F1 ft1022.2 hPa
NTKM3 - 8449130 - Nantucket Island, MA 20 mi57 min E 4.1 G 5.1 68°F 74°F1022.7 hPa
44090 24 mi61 min 70°F
WAXM3 - Waquoit Bay Reserve, MA 25 mi102 min E 1 69°F 1022 hPa66°F
BZBM3 - 8447930 - Woods Hole, MA 33 mi57 min 67°F 73°F1022.6 hPa

Wind History for Nantucket Island, MA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chatham, Chatham Municipal Airport, MA10 mi35 minN 07.00 miLight Rain66°F63°F90%1023.4 hPa
Hyannis, Barnstable Municipal-Boardman Airport, MA14 mi31 minSSE 58.00 miLight Rain67°F63°F87%1022.2 hPa
Nantucket, Nantucket Memorial Airport, MA21 mi34 minE 710.00 miLight Rain69°F63°F81%1022.3 hPa

Link to 5 minute data for KCQX

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Tide / Current Tables for Monomoy Point, Cape Cod, Massachusetts
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Monomoy Point
Click for Map
Wed -- 01:39 AM EDT     Moonrise
Wed -- 03:28 AM EDT     0.54 feet Low Tide
Wed -- 05:37 AM EDT     Sunrise
Wed -- 09:49 AM EDT     3.17 feet High Tide
Wed -- 03:32 PM EDT     0.79 feet Low Tide
Wed -- 05:24 PM EDT     Moonset
Wed -- 07:53 PM EDT     Sunset
Wed -- 09:59 PM EDT     3.68 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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2.51.710.60.60.91.31.92.63.13.232.51.91.30.90.81.21.62.333.53.73.5

Tide / Current Tables for Pollock Rip Channel, Massachusetts Current
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Pollock Rip Channel
Click for Map
Wed -- 12:48 AM EDT     0.00 knots Slack
Wed -- 01:39 AM EDT     Moonrise
Wed -- 04:29 AM EDT     1.87 knots Max Flood
Wed -- 05:37 AM EDT     Sunrise
Wed -- 07:29 AM EDT     -0.00 knots Slack
Wed -- 10:18 AM EDT     -1.37 knots Max Ebb
Wed -- 01:17 PM EDT     0.00 knots Slack
Wed -- 04:49 PM EDT     1.67 knots Max Flood
Wed -- 05:23 PM EDT     Moonset
Wed -- 07:38 PM EDT     -0.00 knots Slack
Wed -- 07:53 PM EDT     Sunset
Wed -- 10:32 PM EDT     -1.54 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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-0.60.20.91.51.81.81.30.5-0.5-1.1-1.4-1.3-0.9-0.20.51.21.61.71.40.6-0.3-1.1-1.5-1.5

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