Monday, July6, 2020
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Marine Weather and Tides
Nantucket, 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 5:11AMSunset 8:19PM Monday July 6, 2020 4:53 AM EDT (08:53 UTC) Moonrise 9:47PMMoonset 6:25AM Illumination 99% Phase: Waning Gibbous; Moon at 16 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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ANZ255 Coastal Waters Extending Out To 25 Nm South Of Marthas Vineyard And Nantucket- 416 Am Edt Mon Jul 6 2020
Today..W winds 5 to 10 kt, becoming N with gusts up to 20 kt this afternoon. Seas 2 to 4 ft. Patchy fog this morning with vsby 1 nm or less.
Tonight..E winds 5 to 10 kt. Seas 2 to 4 ft.
Tue..SE winds 5 to 10 kt, increasing to 10 to 15 kt with gusts up to 20 kt in the afternoon. Seas 2 to 3 ft.
Tue night..SE winds 10 to 15 kt with gusts up to 20 kt, becoming S 5 to 10 kt after midnight. Seas around 3 ft. A chance of showers. Vsby 1 to 3 nm.
Wed and Wed night..SW winds 5 to 10 kt. Seas 2 to 3 ft.
Thu and Thu night..S winds 5 to 10 kt. Seas 2 to 4 ft.
Fri..S winds 10 to 15 kt with gusts up to 20 kt. Seas 4 to 6 ft.
Fri night..S winds 10 to 15 kt with gusts up to 25 kt. Seas 7 to 10 ft. A chance of showers. 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 Edt Mon Jul 6 2020
Synopsis for massachusetts and rhode island coastal waters.. High pres to build over the waters through Sunday. A cold front will push across the waters by Monday morning. High pressure returns for Monday afternoon into Tuesday. 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 Nantucket, MA
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location: 41.27, -70.06     debug


Area Discussion for - Boston, MA
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FXUS61 KBOX 060827 AFDBOX

Area Forecast Discussion National Weather Service Boston/Norton MA 427 AM EDT Mon Jul 6 2020

SYNOPSIS. A cold front will sag southward across Southern New England this morning, stalling along the waters south of Cape Cod into southern Connecticut. While a few thunderstorms are possible across northern Connecticut into southern Rhode Island today, most areas should trend dry and cooler than normal with onshore flow. The cold front returns back northeast as a warm front on Tuesday, with considerable cloudiness and cooler temperatures for Tuesday. Very warm, very humid conditions move in for the late week. Showers/thunderstorms will be possible each day with some heavy downpours.

NEAR TERM /THROUGH TONIGHT/. Early this morning, remnant thunderstorms from yesterday's late- evening severe weather episode were located east of Nantucket and will continue to move into the outer waters. A surface cold front was positioned along a rough line from North Smithfield to Marshfield to near buoy 44018. Northerly flow north of the boundary was advecting in cooler and somewhat lower theta-e air across northeastern MA. South of it southerly flow continued to pump in dewpoints in the mid to upper 60s. The higher dewpoint air across southeast MA and much of RI was leading to areas of fog and low stratus, while north of the cold front a cooling PBL with northerly flow is drawing southward stratus and fog from coastal ME/NH. Though the meteorological factors leading to the fog is different in both areas, will be issuing a fog SPS through the morning commute to address the foggy conditions across all of eastern MA/Cape Cod and into RI. Visibilities are low enough that difficult travel is possible, although visibilities of a quarter mile or less are not anticipated to be sustained long enough to warrant a dense fog advisory. In the interior, clear conditions were still prevalent, though will have to watch for brief periods of fog in the river valleys.

The cold front/backdoor front will continue to advance southward today. However this cold frontal boundary will become more stationary near southern RI into parts of central and southern CT as it runs into the hot, humid and conditionally unstable air building over the lower Hudson Valley and northern mid-Atlantic states. The backdoor cold front will lead to a prevailing onshore northeast flow advancing southwestward as the day progresses. Though areas of low clouds and fog should begin to scatter through the day, the onshore flow especially eastern MA, Cape Cod into RI will likely lead to early-day to early-afternoon highs before hovering/cooling. It is a challenging high temperature forecast for these central and eastern sections of Southern New England. While most of the CT Valley stands to reach the mid 80s to lower 90s, high temps further east will be some 10 degrees cooler with lower/somewhat more comfortable dewpoints.

The other forecast challenge for today is the T-storm potential late in the day today across southern RI into our northern CT counties. As mentioned, these areas will be in the vicinity of the stalled frontal boundary, a feature which most convection-allowing models blossom scattered storms after 20z/4 pm. Considerable variation in the progged instability fields across this area, partly a consequence of varied mixing of dewpoints. The NAM largely maintains rather high dewpoints (mid/upper 60s) and it points to moderately strong instability values ; while the HRRR/RAP mix dewpoints out are are only weakly to moderately-unstable. It renders a lower-confidence forecast when it comes to how potent storms may become and the northern extent of the thunder threat. Will point out that upstream 00z RAOBs at BUF, OKX and ALY sampled fairly steep mid-level lapse rates between 6.5-6.8 C/km in the northwesterly flow regime aloft, and that element is present across all models. Weaker mid and upper level NW wind fields as compared to yesterday also lead to lower effective bulk shear of around 25-35 kt, and of note is that the lower- level flow, while weak, is still fairly backed (ESE/SE). The outcomes for the area under some threat (from BDL-IJD-UUU southwest, to include the Hartford metro area) ranges from strong instability but weak/"enough" wind shear supporting at least a credible strong/severe storm risk for these locales, to weaker instability and weaker wind shear with resulting limited to nil strong/severe threat. Possible a few storms could be capable of small hail given the lapse rates aloft in the latter situation, but in a worst-case, a few storms could become strong to severe with hail and localized damaging winds. Though I do have thunder mentioned, the described uncertainties precluded included enhanced wording. But it may need to be considered in later updates with better clarity on instability levels. A Marginal Risk for severe weather lies just west of the forecast area.

SHORT TERM /TUESDAY/. Tonight:

The warm/stationary front moves little from its daytime position over southern CT tonight. Model guidance does advance showers a little further northward, possibly even a rumble or two of what would be elevated thunder on the northern side of the boundary into western and central MA. Coverage of showers varies, but would not likely be a washout in any one area. Meanwhile further offshore, high pressure will allow more of an east-southeast/southeast flow to take hold across most of Southern New England. It's expected that low clouds from this morning, expected to have advanced offshore, will once again return back northwestward. These trends are reflected by the higher-res models and the HREF. The possibility for fog as the lower clouds roll in could be possible as well. Lows should reach the low to mid 60s.

Tuesday:

Tuesday has the look of a persistence type forecast. Considerable cloudiness from the overnight likely hanging tough throughout the bulk of the day, with the nearby warm frontal boundary making some modest northeast inroads into more of interior Southern New England. Thermo profiles look more stable than today, however, so thinking any thunderstorms would be more garden variety and better chances mainly west of ORH/PVD. I sided cloud cover and temperatures more pessimistically towards more overcast and temperatures on the lower side of guidance. Though the 925-850 mb temps progged would argue for much higher, limited heating resulted in keeping highs only in the 70s.

LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/. Big Picture .

Zonal upper flow is featured through most of the week. Closed upper low developing off the Carolinas midweek moves up the coast by Friday or Saturday.

Contours at 500-mb will be above normal through the week, but may drop back to near-normal levels Saturday and Sunday. Expect above- normal temperatures through Thursday, then near normal Friday through Sunday.

Model mass fields are similar through Thursday. GFS moves low pressure up the coast crossing New England Friday, while ECMWF moves that low pressure up the coast Saturday. Confidence is moderate-high Wednesday-Thursday, but then low confidence for Friday through Sunday.

Daily details .

Tuesday night through Thursday .

Warm front over NY/PA moves east through New England Tuesday night. Scattered showers/thunder in the lift generated by this warm front. Dew points rise through the 60s overnight as the more humid air trailing the front moves into Srn New England. The temp/dew pt spread will be near zero in many spots, which may form areas of fog. Min temps expected in the mid 60s to low 70s.

Wednesday and Thursday will feature high humidity with dew points near 70. Morning fog gives way to sunshine. Daytime heating will generate CAPE of 1000-2000 J/Kg, with LI values around -3 to -5. PW values will be 1.5 to 2.0 inches each day. This will generate scattered showers/thunderstorms each afternoon/evening, with the high PW values suggesting local downpours. Temps aloft will support max sfc temps in the mid 80s to low 90s. Dew points will support min temps in the mid 60s to low 70s.

Friday-Saturday .

As noted above, two models show differing results for the coastal low forming off the Carolinas. The GFS immediately takes it up the coast, bringing showers/thunder to Srn New England Friday. The ECMWF brings the storm up the coast a little slower, bringing showers/thunder to Srn New England Saturday. Not really a clear favorite at this time, so the forecast goes in-between with showers/thunder moving in Friday night and lingering through Saturday. The very moist southerly/southeast flow draws PW values of 2 inches to 2 5 inches. which suggests showers may be better thought of as downpours.

Sunday .

The coastal low moves off to the northeast into the Maritimes. Upper trough lingers over the Great Lakes. Upper jet of 75 kt coming around the trough swings up past Srn New England, with the forecast area under the left exit region of that jet. This will support lift over the region, and with sufficient instability in place . CAPEs will reach 1000-2000 J/Kg . to generate scattered showers/thunder Sunday midday/afternoon.

AVIATION /09Z MONDAY THROUGH FRIDAY/. Forecaster Confidence Levels .

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

06z TAF Update:

Overnight thru 12z: High confidence in trends, moderate on timing.

Local TSRA/+TSRA for Cape Cod terminals and adjacent waters to build east thru 07-0730z with frequent lightning, MVFR-IFR visby rain and occasional brief wind gusts.

Otherwise, for the rest of this period . along/west of PVD/ORH, VFR to prevail. Expecting degraded flight categories /sub-VFR elsewhere. IFR- LIFR stratus either re-asserts itself (for the Cape/ACK terminals) or builds southward from ME/NH in prevailing northerly flow (for BVY-BOS-BED-OWD). 4-6 SM BR possible in mist. IFR-LIFR BR/FG on the Cape. Confidence on timing IFR-LIFR building south from NH/ME is no better than moderate, but thinking sooner than later.

Today: High confidence in trends, moderate on timing and on development/extent of TSRA in far southwest.

Restricted conditions eastern airports to improve by mid- morning, except late-AM/early-PM across the Cape airports and ACK. Should see ensuing VFR for all after 18z, though potential for TSRA near vicinity of warm front after 20z. Best chance from a HFD-IJD line south/west, but northward extent could be as far as BAF-CEF. Not of the realm of possibility that TSRA here could be strong, but better chances for stronger TSRA further southwest. N to NE winds 4-8 kt will veer to E late, with ESE winds across CT near vicinity of warm front.

Tonight: Moderate confidence.

Possible sub-VFR visby showers/t-storm building north early in the period from ORH west. Flow to turn SE on periphery of warm front and high pressure over the Maritimes, which should allow for returning MVFR-LIFR stratus layer to advance back NW for most. Low to moderate confidence on timing, but thinking after 06z.

Tuesday: Moderate confidence.

Dry conditions, though continued moist SE flow/winds should maintain sub- VFR conditions. While some guidance allows brief VFR intervals, trended ceilings more pessimistically. Could see SHRA/possible TSRA from BDL- WST southwest but low- prob.

KBOS Terminal . Moderate confidence in TAF. Brf VFR to trend IFR/MVFR overnight. Thinking scattering out to VFR after AM push.

KBDL Terminal . Moderate confidence in TAF. Possible VCTS/TSRA after 20z, though better chance HFD-IJD south.

Outlook /Tuesday Night through Friday/ .

Tuesday Night: MVFR/IFR conditions possible. Breezy. Chance SHRA, slight chance TSRA, patchy BR.

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

Wednesday Night: Mainly VFR, with local IFR possible. Slight chance SHRA, patchy BR.

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

Thursday Night: Mainly VFR, with local IFR possible. Slight chance SHRA, isolated TSRA, patchy BR.

Friday: Mainly VFR, with areas MVFR possible. Slight chance SHRA, isolated TSRA.

MARINE. Today through Tuesday: High confidence.

Winds/seas to remain below small craft advisory levels. Southeast winds on our northeastern waters on Tuesday may get marginally close to those levels at around 20-22 kt. Seas mainly 2-4'.

Fog and low clouds will continue through most of the day today on eastern waters. Some breaks in lower clouds and fog on the southern waters could result in developing thunderstorms near Block Island Sound today.

Outlook /Tuesday Night through Friday/ .

Tuesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, slight chance of thunderstorms.

Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers, slight chance of thunderstorms.

Wednesday Night: Winds less than 25 kt. Slight chance of rain showers.

Thursday through Thursday Night: Winds less than 25 kt.

Friday: Winds less than 25 kt. Local rough seas. Slight chance of rain showers, isolated thunderstorms.

BOX WATCHES/WARNINGS/ADVISORIES. CT . None. MA . None. RI . None. MARINE . None.

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


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
NTKM3 - 8449130 - Nantucket Island, MA 2 mi60 min SSE 5.1 G 6 67°F 72°F1014.8 hPa
44020 - NANTUCKET SOUND 19 mi34 min S 12 G 14 68°F 70°F1013.6 hPa
CHTM3 29 mi84 min SSW 2.9 G 5.1 65°F 1014 hPa
WAXM3 - Waquoit Bay Reserve, MA 33 mi69 min S 1.9 69°F 1014 hPa69°F
BZBM3 - 8447930 - Woods Hole, MA 37 mi60 min 69°F 70°F1014.4 hPa
44090 42 mi57 min 66°F

Wind History for Nantucket Island, MA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Nantucket, Nantucket Memorial Airport, MA1 mi61 minSE 71.00 miFog/Mist65°F64°F97%1014.8 hPa

Link to 5 minute data for KACK

Wind History from ACK (wind in knots)
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Last 24hrCalmE7SE5SE4S6S4S5S5SE9S7S10S11SE9SE6SE8S7S5S9SW8SW9S10NW8S4SE7
1 day agoNE9NE9N8NE7N9NE8NE10NE10NE11NE12N13NE10NE8N7NE5N6SE33E3E4SE4CalmNW3Calm
2 days agoSW4W5W5N7N9N13N15N16N18N17N16
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Tide / Current Tables for Nantucket, Nantucket Island, Nantucket Island, 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 Nantucket Harbor Entrance Channel, Massachusetts Current
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Nantucket Harbor Entrance Channel
Click for Map
Mon -- 01:12 AM EDT     -0.00 knots Slack
Mon -- 05:14 AM EDT     Sunrise
Mon -- 05:22 AM EDT     -1.61 knots Max Ebb
Mon -- 06:25 AM EDT     Moonset
Mon -- 07:41 AM EDT     0.00 knots Slack
Mon -- 09:38 AM EDT     1.15 knots Max Flood
Mon -- 02:38 PM EDT     -0.00 knots Slack
Mon -- 05:54 PM EDT     -1.57 knots Max Ebb
Mon -- 08:14 PM EDT     0.00 knots Slack
Mon -- 08:16 PM EDT     Sunset
Mon -- 09:47 PM EDT     Moonrise
Mon -- 09:58 PM EDT     0.90 knots Max Flood
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.20-0.2-0.6-1.1-1.6-1.5-0.70.311.10.80.50.40.2-0.2-0.7-1.3-1.6-1.1-0.20.60.90.7

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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Wind Forecast for Boston, MA (4,6,7,8)
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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.