Sunday, December15, 2019
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Marine Weather and Tides
Siasconset, MA

Version 3.4
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10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
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Sunrise 7:02AMSunset 4:17PM Sunday December 15, 2019 6:01 AM EST (11:01 UTC) Moonrise 8:57PMMoonset 10:53AM Illumination 86% Phase: Waning Gibbous; Moon at 18 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 151032 AFDBOX

Area Forecast Discussion National Weather Service Boston/Norton MA 532 AM EST Sun Dec 15 2019

SYNOPSIS. Mainly dry but windy weather is on tap for the region today. Low pressure moves out of the mid Mississippi and Ohio River valleys Monday. This low will push south of the region Monday night and Tuesday, bringing light snow, ice and rain. An arctic front moves across Wednesday with patchy light snow across western areas as well as Cape Cod and the islands. Dry conditions move in for late this week, with very cold temperatures on Thursday, then readings may moderate a little Friday.

NEAR TERM /UNTIL 6 PM THIS EVENING/.

4 AM Update .

* Westerly wind gusts of 40 to 50 mph today.

Powerful low pressure dropping below 970 mb will continue to lift northward through eastern Canada today. The resultant pressure gradient along with steepening lapse rates with the cold pool aloft will result in windy conditions today. Bufkit soundings continue to support 40 to 50 mph wind gusts across much of the region. Therefore, Wind Advisories will continue for most areas north of the CT/RI and MA border. We will come close to meeting criteria across CT/RI too, but not confident enough to extend southward at this time. Regardless, 40 to 50 mph wind gusts expected today with the strongest across the high terrain as well as as portions of the Cape/Islands.

Impressive cold pool aloft will result in a scattered to broken deck of cloudiness, but still expect peeks of sunshine. Westerly flow coupled with steep lapse rates and lake moisture will result in scattered snow showers in the Berks. Across the rest of our region, dry weather will dominate but a few passing sprinkles/flurries can not be ruled out given the steep lapse rates.

High temps will range from the upper 30s in the high terrain, to the lower to middle 40s elsewhere. Although it will feel colder given the windy conditions.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/.

Tonight .

The powerful low pressure system will lift further into northern Canada and the pressure gradient begins to relax. Westerly wind gusts of 35 to 45 mph are still possible into the first half of the evening, but should see a downward trend especially after midnight as a ridge of high pressure gradually builds in from the west. Low temps are expected to drop into the upper teens to middle 20s in most locations by daybreak Monday in the cold air advection pattern.

Monday .

A ridge of high pressure over our region will keep us dry during the day on Monday. We will see some mid level cloudiness overspread the region in advance of low pressure lifting northeast across the mid Atlantic. High temps will be colder than today, remaining in the 30s but with much less wind than today.

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/.

Highlights .

* Confidence moderate to high for a plowable snow as well as icy roads, Monday night through Tuesday, with the best chance across interior MA/CT into northern RI. Impact to the Tuesday AM commute from snow, sleet and/or freezing rain. Details remain uncertain on snow and ice accumulations which will depend upon the thermal structure and precipitation type changes. * Scattered snow showers from midday Wednesday into early evening ahead of Arctic cold front, with some snow squalls possible.

* Temperatures fall to between 10 and 20 degrees below normal late Wednesday night and Thursday with Wind Chill values from zero to around -10 possible.

* Some gradual temperature moderation on Friday, but readings remain below normal. Details .

After a period of light snow and/or rain showers today as a couple of fronts push across, a high pressure ridge builds across tonight as temperatures fall close to seasonal levels. Low pressure will shift east out of the central Mississippi into the Ohio River valleys. High pressure will linger to the north and, as the low approaches late Monday, clouds will increase. The cold air will remain Monday night, so light snow will develop. However, milder air will slide above the cold dome, so will see a change over to a wintry mix mainly across southern areas after midnight, then will slide north through Tuesday while enough milder air works in mainly near and S of the Mass Pike that the precip should change to rain. the low will pass close to or south of the S coast late Tue, so will see the precip change back to snow as colder air returns then will taper off during Tuesday night.

A shot of Arctic air will push out of central Canada with another high pressure center. So, will see dry conditions but the coldest air so far this season on Thursday. The arctic dome will shift slowly east Thursday night into Friday so temperatures will moderate somewhat but it will remain cold to end the work week.

Monday Night Through Tuesday Night:

** Low to Moderate Confidence for Winter Weather conditions Monday Night through Tuesday **

Light west winds will linger across the region Monday night as low pressure moves slowly E out of the Ohio and central Appalachians. With a generally flat mid level flow, which will start to tilt SW as a long wave trough digs across the central and western Plains, will see leading edge of light snow will push S-N across CT/RI Monday evening.

Noting a classic cold dome of air lingering across the region Mon night, while milder air will ride above it. This will allow for mixed precip to start to work in late Monday night as the precip lifts N-NE. Temps will start off in the mid 20s to mid 30s, coldest across the interior and higher terrain, then transitions into a non-diurnal temp trend as readings slowly rise overnight into Tuesday morning.

Still some uncertainty on the snow accumulations and especially how much icing will be realized leadings into the Tuesday morning commute. Looks like the best chances for freezing rain and/or sleet will occur away from the immediate coast to start the commute, then should change to rain by around mid to late morning from around the Boston-Providence corridor southward to the S coast. A wintry mix should continue through the afternoon well inland, which could be the biggest impact especially across untreated roadways and other outdoor surfaces.

As the low pushes S and E of Cape Cod and the islands late in the day, should see a change back over to snow toward Tuesday evening except across the S coast, Cape Cod and the islands. Should see the precip taper off Tuesday evening, though snow showers may linger across the E slopes of the Berkshires from time to time overnight.

Current forecast suggests snow amounts on the order of less than an inch along the S coast to around 2-4 inches from around the Mass Pike northward, but still quite a bit of uncertainty on the timing of the mixing and/or changeover to rain and how far that will lift northward. Another issue will be the icing and its impacts. Could see about 0.1 to 0.2 inches across portions of N CT, N RI into most areas of Massachusetts.

Headlines for at least Advisory level conditions across the interior remain possible (at least), but still questions on placement of the PTYPES and how long they will last overnight into Tuesday.

Pretty confident for impacts across most roadways for the Tuesday morning commute, especially areas near/north of Route 6 in CT and RI and near/NW of I-95, and especially across from Hartford to NW of Providence to Boston and the interior SE Mass areas. Coastal MA/RI into part of SE MA should see a shorter period of winter weather before changing to a cold rain.

Wednesday .

Will see mainly dry conditions except for some spotty snow showers across the higher terrain and possibly across Cape Cod and the islands. Another weak trough moves across which may enhance some light snow showers elsewhere, but will be tough with lack of moisture away from the higher terrain and near the coastline. Something to keep an eye on, though.

Wednesday Night into Thursday Night .

Arctic airmass dives SE across the region after the front passes during early Wed night. Models continue to signal H85 temps diving to -14C to -18C through the night. Light snow lingers across outer Cape Cod and the island through around midnight then should push offshore.

The coldest air of the season arrives Wed night and Thu. Lows Wed night will bottom out in the single digits and teens, except around 20s across outer Cape Cod and the islands. However, with W-NW winds at 10-20 mph, maybe a bit higher along the immediate coast, could see wind chill values bottom out from -5 to -10 well inland and especially across the higher terrain to zero to 5 above along the coast by daybreak Thursday. May see some dangerous wind chills especially for the children waiting for buses out of doors. Bundle up!

As high pressure approaches Thursday, winds will diminish but the cold air will remain in place. While temperatures moderate some, it will remain cold though the wind chills will not be quite as cold. Highs will be in the mid teens to around 20 inland and in the 20s across the coastal plain.

Friday and Saturday .

Large high pressure will dominate across the mid Atlc and northeast both Friday and Saturday. It will remain cold on Friday with highs in the 20s to around 30, though NW winds will be in the 5-10 mph range. Winds shift to N-NE but remain light on Saturday with temps in the mid 20s and 30s with winds veering to NE.

AVIATION /10Z SUNDAY THROUGH THURSDAY/. Forecaster Confidence Levels .

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

Short Term /through Monday/ .

Today . High confidence. Mainly VFR conditions despite a scattered to broken deck of mid level cloudiness. A sprinkle/flurry or two is possible, but the main story will be the winds. W winds will increase this morning with gusts of 35 to 40 knots in most locations. 40-45 knot gust possible over the high terrain, as well as portions of the Cape/Islands.

Tonight . High confidence in VFR conditions. W winds gusts diminish a bit, but still expect many locations to gust between 25 and 35 knots during the first half of the evening.

Monday . High confidence. VFR conditions despite some mid level cloudiness, especially south of the MA Turnpike. W winds of 5 to 15 knots.

KBOS Terminal . High confidence in TAF.

KBDL Terminal . High confidence in TAF.

Outlook /Monday Night through Thursday/ .

Monday Night: MVFR/IFR conditions possible. FZRA, chance SN, chance PL.

Tuesday: Mainly IFR, with areas MVFR possible. Breezy. RA, SN, PL, FZRA.

Tuesday Night: Mainly VFR, with local IFR possible. Breezy. Slight chance SN.

Wednesday: VFR. Breezy.

Wednesday Night through Thursday: VFR. Windy with gusts up to 35 kt.

MARINE. Short Term /through Monday/ .

Today and tonight . High confidence. Powerful storm in eastern Canada will continue to lift north with the pressure dropping below 970 mb. The result will be strong westerly gales with gusts of 40 to 45 knots today and a good portion of tonight. High pressure will begin to build in from the southwest after midnight, which should allow winds to gradually trend downward after that time. Seas 8 to 15 feet across the outer-waters today, gradually diminishing tonight.

Monday . High confidence. Lingering SCA wind gusts across the eastern waters in the morning will diminish by afternoon as high pressure builds over the waters. Seas will also diminish, but some 5 foot seas may linger across the eastern outer-waters into Mon afternoon.

Outlook /Monday Night through Thursday/ .

Monday Night: Winds less than 25 kt. Rain likely, freezing rain likely, chance of snow. Local visibility 1 to 3 nm.

Tuesday: Winds less than 25 kt. Local rough seas. Rain.

Tuesday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Rough seas up to 9 ft. Chance of rain. Local visibility 1 to 3 nm.

Wednesday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Rough seas up to 9 ft. Slight chance of snow. Areas of visibility 1 to 3 nm.

Wednesday Night: Strong winds with gusts up to 35 kt. Rough seas up to 11 ft. Slight chance of snow. Visibility 1 to 3 nm.

Thursday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 11 ft.

BOX WATCHES/WARNINGS/ADVISORIES. CT . None. MA . Wind Advisory until 9 PM EST this evening for MAZ023-024. Wind Advisory until 7 PM EST this evening for MAZ002>016-018- 019-021-022-026. RI . Wind Advisory until 9 PM EST this evening for RIZ008. MARINE . Gale Warning until 1 AM EST Monday for ANZ231>234-251-255-256. Gale Warning until 10 PM EST this evening for ANZ230. Gale Warning until 7 PM EST this evening for ANZ236. Gale Warning until 11 PM EST this evening for ANZ235-237. Gale Warning until 4 AM EST Monday for ANZ250-254.

SYNOPSIS . Frank/EVT NEAR TERM . Frank SHORT TERM . Frank LONG TERM . EVT AVIATION . Frank/EVT MARINE . Frank/EVT


Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Nantucket, Nantucket Memorial Airport, MA168 mi68 minW 18 G 2810.00 miFair and Breezy45°F37°F74%996.4 hPa

Link to 5 minute data for KACK

Wind History from ACK (wind in knots)
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2 days agoNW18
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Tide / Current Tables for
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Wind Forecast for Boston, MA (6,6,7,8)
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