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Marine Weather and Tides
Siasconset, MA

Version 3.4
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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 7:07AMSunset 4:43PM Sunday January 16, 2022 5:41 AM EST (10:41 UTC) Moonrise 4:24PMMoonset 7:11AM Illumination 98% Phase: Waxing Gibbous; Moon at 14 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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7 Day Forecast for Marine Location Near Siasconset, MA
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location: 38.84, -69.85     debug


Area Discussion for - Boston, MA
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FXUS61 KBOX 160946 AFDBOX

Area Forecast Discussion National Weather Service Boston/Norton MA 446 AM EST Sun Jan 16 2022

SYNOPSIS. High pressure builds across New England today. A strong storm will impact the region late Sunday night into Monday, with heavy snow over the interior high terrain and brief snow changing to heavy rain in Rhode Island and eastern Massachusetts. Strong to damaging winds along the coast as well as coastal flooding will also impact the region. Blustery and cold weather returns Tuesday followed by milder air Wednesday. A weak frontal system moves through the region Wednesday night followed by colder weather Thursday and Friday.

NEAR TERM /UNTIL 6 PM THIS EVENING/. High pres in control today with sunshine giving way to more clouds later in the afternoon as the high slides to the east. After a frigid start this morning, temperatures will recover into the mid 20s to lower 30s this afternoon. Winds will be light.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/. Tonight and Monday .

* Strong to Damaging Winds late tonight and Monday Morning * Heavy snow interior high terrain with brief snow changing to heavy rain in the coastal plain * Widespread minor to moderate Coastal Flooding Monday Morning

Overview .

Potent southern stream low pres lifts north across eastern US with excellent model agreement on track of surface and mid level low across eastern NY to interior New Eng. There are signals for a secondary low development further to the east which seems reasonable given impressive height falls that develop. Strong southerly mid level jet and E/SE low level jet will bring quick warming into the low to mid levels which will result in snow changing to rain overnight into Mon morning. However, not before a decent front end thump of snow over the higher terrain. Farther south and east, the greater concern is the risk of strong to damaging wind along the coast late tonight into Mon morning as well as minor to moderate coastal flooding during the Mon morning high tide.

Ptype/Snow Accumulation .

Given deep cold airmass in place ahead of the storm, precip will start as snow in most locations, with onset between 10 pm and 1 am from west to east. Along the immediate coastline and far SE MA, quickly warming boundary layer may lead to precip starting as rain or a rain/snow mix with no accum. Further inland, snow will gradually change to rain with the rain-snow line advancing north and west across SNE after midnight through about daybreak.

The nose of a strong mid level jet will lead to strong forcing for ascent with a period of heavy snow likely for Berkshires and northern Worcester Hills. Easterly low level jet will provide upslope which will enhance snowfall rates along the eastern slopes of the Berkshires and possibly the Worcester Hills. In fact, HREF indicating up to 2"/hr snowfall rates here overnight, especially in the Berkshires. Much of the 00z guidance trended a bit higher with snow accums. Incorporated hi-res guidance QPF to derive snow accum which yields 6-12 inches accum for the Berkshires and 4-8 inches for the northern Worcester Hills. Fortunately, bulk of the snow over the high terrain will be on the dry side as temps will be cold to start. For the rest of SNE, expecting snow accum of 1-4 inches in the interior low elevations before changing to rain, with up to an inch for I-95 and 128 corridor before it gets washed away by heavy rain. Issued a winter weather advisory for interior locations from northern CT to interior NE MA. There may be also be a brief period of freezing rain during the rain to snow transition. All locations except for the high terrain near the VT/NH border will be rain by daybreak, with snow changing to rain here 6-9 am. Not expecting much wintry impacts to the morning commute outside of the high terrain, except for heavy rain impacts.

Heavy Rain Threat .

Anomalous PWATs combined with 80-90 kt low level jet will result in a 3-6 hr period of heavy rainfall late tonight into Mon morning across RI and eastern MA. Hi-res CAMs also indicating some convective elements with a possible fine line further south over the ocean where there is marginal instability. Rainfall of 1-2 inches is expected which will result in areas of urban and poor drainage street flooding.

Strong to Damaging Winds .

Very anomalous low level jet 80-90 kt lifts along the south coast then northward along eastern MA late tonight into Mon morning. The jet is strengthening as it moves off the coast and into the Gulf of Maine with 850 mb winds increasing to 100 kt from east of Cape Cod to Gulf of Maine. Bufkit time section show 60-70 kt down to near 500 ft along the immediate coast. Given impressive pressure falls exceeding 12 mb/3 hr and convective elements, expect a decent chunk of this to mix down to the surface with gusts 55-65 mph along the immediate coast, first along the south coast toward daybreak then lifting north along eastern MA coast 7-10 am. The strongest gusts will be from the outer Cape to Cape Ann where a few gusts to 70 mph are possible. Wind damage and power outages are likely. High wind watches along the coast were converted to warnings, and wind advisories were issued for the rest of RI and eastern MA for gusts to 50 mph.

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/. Big Picture .

Shortwave moves over New England tonight and Tuesday. Brief ridge slips over the region Wednesday. Shortwave drops down from Northern Canada to cross New England late in the week.

Upper heights are below normal values Tuesday, then normal Wednesday. The GFS brings colder than normal values for Thursday and Friday, while the ECMWF is on the cold side of the normal range. Expect variable temperatures through the period, although colder than normal Tuesday and Thursday-Friday.

Model mass fields are in agreement Tuesday and Wednesday, then diverge late week and are in disagreement Saturday. Confidence is moderate-high midweek, trending to low by Saturday.

Details .

Monday night-Tuesday .

Upper trough trailing the Monday system will move over New England Monday night, then move off to the east Tuesday. The trough carries a minus 36C cold pool, cold enough to produce instability. But the airmass will be dry, with PW values at 0.2 inches Monday night and below 0.1 inches Tuesday. Expect lingering clouds and showers early Monday night, then clearing skies late at night and on Tuesday. Winds at 2000 feet are forecast at 25 to 35 kt/30 to 40 mph, so expect gusty west to northwest winds, especially on Tuesday.

Pressure gradient relaxes later in the day as high pressure builds in from the west.

Wednesday through Friday .

Weather system races across the northern tier of the USA, crossing the Great Lakes Wednesday and turning up the St Lawrence Valley Wednesday night. Warm front leading this system will move through Srn New England Wednesday midday. The passing low will then swing a cold front through during Wednesday night. PW values climb along and ahead of the front, reaching 0.75 inches. This is well above the January average near 0.4 inches, so will go with chance pops for rain/snow showers Wednesday night.

Northwest winds behind the cold front will bring colder air into the region for Thursday and Friday. Colder drier air will mean clearing skies for both days. However, the movement of the cold air over the warmer ocean water may lead to ocean-effect clouds and snow showers. High temperatures will be below freezing northwest Thursday and everywhere Friday, while min temps will be in the single numbers Thursday night and Friday night.

Mixing reaches near 925-mb, with temperatures at that level near minus 2C Wednesday, minus 6 to 12C Thursday, and minus 14 to 18C Friday. Expect max temps 35 to 45 Wednesday, 25 to 40 Thursday, and 15 to 30 on Friday. Min temps in the single numbers and teens Thursday night and Friday night.

Saturday .

The Wednesday night cold front will stall over the deep south. A shortwave moves through the Deep South Friday and may generate surface low pressure along the stalled front. Of the operational models . the 00Z GFS shows that low moving east out to sea with just ocean-effect snow showers near Cape Cod. On the other hand, the 00Z ECMWF shows the low pressure moving up the coast, then crossing the 40N/70W benchmark. The ECMWF forecasts a broad shield of roughly 1.2 inches precipitation in an area of below-freezing temperatures across Srn New England. The 00Z GGEM runs the storm center right up to the South Coast, with measurable pcpn covering all of New England.

The forecast will bring either slight chance pops or low-end chance pops to the region Saturday, with the highest pops along the South Coast.

This is a Day 7 forecast, with all the uncertainty normally found that far in the future. Will need to keep an eye on future model runs regarding this system . does it move closer or farther away from Srn New England. Forecast confidence for Saturday is low.

AVIATION /10Z SUNDAY THROUGH THURSDAY/. Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent.

06z update .

Through Today . High confidence.

VFR, but areas of low end VFR/MVFR cigs may develop along the south coast and portions of CT late this afternoon. Winds turning SE 5-10 kt this afternoon.

Tonight . High confidence on trends, lower on exact details.

Conditions lowering to MVFR 03-06z from west to east with snow overspreading the region, except rain or a rain/snow mix along the coast. Areas of IFR/LIFR after 06z with snow inland changing to a wintry mix then rain. Rain in the coastal plain. Increasing E wind along the coast with gusts 30-40 kt developing after 06z and up to 50 kt by 12z along the immediate coast. LLWS after 06z as strong ESE jet overspreads the area.

Monday . High confidence on trends, lower on exact details.

IFR/LIFR in the morning in periods of heavy rain, except a wintry mix over the Berkshires. E/SE wind gusts 45-55 kt Cape/Islands and along eastern MA coast in the morning, with 35-45 kt along I-95 corridor, then turning SW with gusts 25-35 kt in the afternoon. LLWS with very strong ESE jet over eastern MA in the morning. Drying trend in the afternoon with cigs improving to MVFR.

KBOS Terminal . High confidence in TAF trends.

KBDL Terminal . High confidence in TAF trends.

Outlook /Monday Night through Thursday/ .

Monday Night: MVFR/IFR conditions possible. Strong winds with local gusts up to 40 kt. Slight chance SN.

Tuesday: VFR. Windy with gusts up to 35 kt.

Tuesday Night: VFR. Windy with areas of gusts up to 30 kt.

Wednesday: Mainly VFR, with local IFR possible. Breezy.

Wednesday Night: Mainly VFR, with areas IFR possible. Breezy. Slight chance RA, slight chance SN.

Thursday: VFR. Breezy. Slight chance SN.

MARINE. Forecaster Confidence Levels.

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

* Storm Warnings in effect for all waters for late tonight into Mon morning.

Light winds and seas below SCA today. increasing E/SE winds tonight with peak of wind late tonight into Mon morning as anomalous low level jet lifts north across the waters. Gusts 50-60 kt likely with a few gusts to 65 kt possible over waters east of Cape Cod. Seas build to 25+ ft over the eastern MA waters. Vsbys reduced in heavy rain and fog late tonight into Monday morning, improving in the afternoon.

Outlook /Monday Night through Thursday/ .

Monday Night: Strong winds with gusts up to 40 kt. Rough seas up to 19 ft. Slight chance of rain. Visibility 1 to 3 nm.

Tuesday: Strong winds with gusts up to 35 kt. Rough seas up to 15 ft. Local visibility 1 to 3 nm.

Tuesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 12 ft.

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

Wednesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Slight chance of rain. Visibility 1 to 3 nm.

Thursday: Winds less than 25 kt. Areas of rough seas. Slight chance of rain, slight chance of snow. Areas of visibility 1 to 3 nm.

TIDES/COASTAL FLOODING. *** Coastal Flood Warning in effect Monday Morning for the East Coast from Plymouth county northward *** Coastal Flood Advisory in effect Monday morning for Cape/Islands and the South Coast***

ESE wind gusts 55-65 mph will result in storm surge up to 3 ft along eastern MA coast. This combined with seas up to 25 ft just offshore will result in widespread minor to moderate coastal flooding. The greatest risk of moderate flooding is along the north shore, especially Cape Ann and Plum Island as peak of wind/surge likely to coincide with high tide for these locations. Surges are expected to be a bit lower near Cape/Islands where minor flooding is expected.

Along the coast, a storm surge of 3 ft is possible with up to a 4 ft surge at PVD, but the timing of the peak surge may occur just after high tide. Still, we expect areas of minor coastal flooding along the south coast and Narragansett Bay during the high tide.

Storm surge values for this forecast were derived from a blend of ESTOFS and Stevens Institute ensemble storm surge guidance.

BOX WATCHES/WARNINGS/ADVISORIES. CT . Winter Weather Advisory from midnight tonight to 7 AM EST Monday for CTZ002>004. MA . High Wind Warning from 1 AM to 10 AM EST Monday for MAZ020-021. High Wind Warning from 1 AM to noon EST Monday for MAZ007-015- 016-019-022>024. Coastal Flood Warning from 9 AM to 1 PM EST Monday for MAZ007- 015-016-019. Wind Advisory from 4 AM to 10 AM EST Monday for MAZ005-006-013- 014-017-018. Winter Weather Advisory from midnight tonight to 7 AM EST Monday for MAZ003-005-010>012. Coastal Flood Advisory from 6 AM to 9 AM EST Monday for MAZ020. Winter Storm Warning from midnight tonight to noon EST Monday for MAZ002-004-008-009-026. Coastal Flood Advisory from 9 AM to 1 PM EST Monday for MAZ022>024. RI . High Wind Warning from 1 AM to 10 AM EST Monday for RIZ006>008. Wind Advisory from 4 AM to 10 AM EST Monday for RIZ001>005. Coastal Flood Advisory from 6 AM to 9 AM EST Monday for RIZ002- 004>007. MARINE . Storm Warning from 1 AM to 11 AM EST Monday for ANZ232>237-255- 256. Storm Warning from 2 AM to 11 AM EST Monday for ANZ230. Storm Warning from 1 AM to 1 PM EST Monday for ANZ231-250-251- 254.

SYNOPSIS . WTB/KJC NEAR TERM . KJC SHORT TERM . KJC LONG TERM . WTB AVIATION . WTB/KJC MARINE . WTB/KJC TIDES/COASTAL FLOODING .


Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Nantucket, Nantucket Memorial Airport, MA168 mi48 minN 510.00 miMostly Cloudy22°F14°F71%1028.4 hPa

Link to 5 minute data for KACK

Wind History from ACK (wind in knots)
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2 days ago0E3E5E5SE7SE8SE8SE6SE7SE9E7E6E7E7E7E7E7NE6NE6NE8NE9NE9NE11NE10

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