Marine Weather Net

Montauk NY to Marthas Vineyard out 20 NM South of Block Island Marine Forecast


TONIGHT

N
WINDS
20 - 25
KNOTS

TUE

W
WINDS
5 - 10
KNOTS

TUE NIGHT

NW
WINDS
5 - 10
KNOTS

WED

N
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
ANZ256 Forecast Issued: 745 PM EST Mon Nov 18 2019

GALE WARNING IN EFFECT UNTIL 9 PM EST THIS EVENING
Tonight...N Winds 20 To 25 Kt With Gusts Up To 35 Kt, Becoming Nw 10 To 15 Kt With Gusts Up To 20 Kt After Midnight. Seas 7 To 10 Ft. Patchy Fog. A Slight Chance Of Rain This Evening, Then A Chance Of Rain After Midnight With Vsby 1 To 3 Nm.
Tue...W Winds 5 To 10 Kt, Increasing To 10 To 15 Kt With Gusts Up To 20 Kt In The Afternoon. Seas 4 To 7 Ft.
Tue Night...Nw Winds 5 To 10 Kt. Seas 3 To 5 Ft.
Wed...N Winds 10 To 15 Kt, Increasing To 15 To 20 Kt In The Afternoon. Gusts Up To 25 Kt. Seas 3 To 5 Ft.
Wed Night And Thu...Nw Winds 15 To 20 Kt With Gusts Up To 30 Kt. Seas 4 To 6 Ft.
Thu Night...W Winds 10 To 15 Kt. Gusts Up To 20 Kt After Midnight. Seas 3 To 5 Ft.
Fri...Sw Winds 15 To 20 Kt With Gusts Up To 30 Kt. Seas 5 To 8 Ft. A Chance Of Showers.
Fri Night...W Winds 20 To 25 Kt With Gusts Up To 30 Kt. Seas 7 To 10 Ft.
Sat...Nw Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 5 To 8 Ft.
Sat Night...Nw Winds Around 10 Kt. Seas 4 To 6 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.
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Area Forecast Discussion
National Weather Service Boston/Norton MA
739pm EST Monday Nov 18 2019

Synopsis
The coastal storm will continue to bring spotty light rain and strong winds along the coast early tonight. The rain may become a wintry mix across the interior high terrain late tonight into Tuesday morning. Mainly dry and seasonably chilly weather follows Tuesday afternoon into early Wednesday. Low pressure passing south of the region may push some rain and snow showers across central and eastern areas from midday Wednesday into Wednesday night. Dry conditions and seasonable temperatures for Thursday. An approaching front will bring a chance for showers on Friday, then dry but colder conditions Friday night into Saturday. Another system may approach Saturday night into Sunday, but the details remain uncertain.

Near Term - Until 6am Tuesday Morning
7 PM

Temperatures topped off in the upper 30s and 40s across the region today, with a few spots touching 50 across the outer Cape and islands. Readings remain above freezing across the region, though have slowly fallen over the last few hours. Noting temps in the mid 30s across the E slopes of the Berkshires and Worcester hills, so will start to see the rain start to mix with sleet and/or freezing rain this evening as temperatures continue to slowly fall.

Have continued to mention precipitation across the region, though early tonight will see dry conditions mainly W of the Worcester hills. However, will probably see more moisture wrap S across the CT valley and E slopes of the Berkshires. Latest NE regional 88D radar loop showing a band of precipitation working SWrd out of central and NE Mass, as well as another band of precipitation working eastward out of the Hudson Valley. Also, another short wave works up the coast overnight, which will bring another round of moisture across.

Have continue to mention mixed precipitation after midnight as the colder air drains in on the northerly winds that will become light overnight. With the better shot for mixed precip, especially the threat of freezing rain or drizzle across NW Mass overnight, have held on to the Winter Weather Advisory for western Franklin and Hampshire counties.

Previous Discussion... Through the overnight hours, the next round of precipitation approaches. This is associated with a potent mid level trough lifting north out of the Delmarva, ushering out today's coastal low, while bringing another slug of moisture with it. PWATs (Precipitable Waters) >0.75" together with potent mid-level energy and favorable jet dynamics aloft will bring fairly widespread rain showers to all of southern New England generally after midnight into Tuesday morning, with the greatest Quantitative Precipitation Forecast amounts in western MA/CT.

Surface temperatures have been adjusted slightly warmer in line with the latest hi-resolution guidance which has lessened the magnitude of cold air advection, decreasing the risk of appreciable snow/icing overnight. However, in the highest elevations of the Berkshire slopes, temperatures will hover at or near freezing, so can't rule out a coating of snow or light glaze of ice early Tuesday morning. For the possibility of some light freezing rain, a Winter Weather Advisory continues through Tuesday morning for western Hampshire and Franklin counties.

Short Term - 6am Tuesday Morning Through Tuesday Night
Tuesday starts wet before drying out by late morning/afternoon. By 15Z (10AM) the core of the upper low is over Maine, along with the bulk of the moisture. Looking through the column we see some drier air working in in the mid and upper levels which should allow for peeks of sun Tuesday afternoon. This will help warm temperatures a bit too, even in the Cold Air Advection pattern. High temps should reach into the 40s for most, which, with light winds and the emerging sun will be a nice change from today's wet, raw weather. Tuesday night into Wednesday morning things stay dry but we'll see increasing clouds. This as a deep mid level trough digs to our south, eventually wrapping around enough moisture to bring some rain and snow showers on Wednesday. Cold Air Advection pattern will be evident overnight (850mb temps down to -2 to -3C), with surface lows about 5 degrees colder than the night previous, in the upper 20s and low 30s.

Long Term - Wednesday Through Monday
Highlights... * Light rain and/or snow showers push across central and eastern areas Wednesday into Wednesday night as an offshore low passes. Gusty northerly winds develop across the coastal waters.

* High pressure brings dry, seasonable weather on Thursday

* Mild temperatures make a brief return ahead of an approaching front, bringing showers Thu night and Fri, then dry but colder weather late Fri night into Sat

* Model solution spread lending to low confidence forecast for potential approaching system sometime next weekend

Overview... An amplified but progressive mid level steering pattern continues across the lower 48. H5 trough may bring some unsettled conditions around mid week, but should push steadily offshore. Will see a brief dry and seasonal day as progressive H5 ridge pushes across the eastern seaboard. Cutoff H5 low crosses eastern Ontario/Quebec, with a trailing surface front swinging across Fri night into Sat.

Solutions amongst the 12Z model suite signaling increasing spread next weekend. This lends to rather low confidence as another system may approach during this timeframe.

Details... Wednesday and Wednesday night... An amplified long wave trough, with a cutoff H5 low passing close to or S of the region, will lift E-NE Wednesday afternoon into Wednesday night. Looks like moisture will shift back across central and eastern areas during the midday and afternoon hours before moving offshore. May see some light snow showers across N central areas, with mainly rain showers across eastern Mass. Mainly northerly winds in place, but temps will top off in the upper 30s to lower 40s as most of the colder air holds back until the trough shifts E.

Leftover showers linger across the mid and outer Cape Wednesday evening, then will exit rather quickly as drier air moves in on NW winds. Temps will bottom out in the mid-upper 20s well inland to the mid- upper 30s along the immediate coast, which are close to seasonal normals. Will see winds gusts up to 20-25 kt across the outer Cape and Nantucket, as well as across the coastal waters.

Thursday and Thursday Night... H5 ridge will steadily shift E, along with large surface high pressure that will cross the eastern seaboard. NW winds will start off gusty especially along the coast, but will diminish as the ridge builds E. Highs will range through the 40s.

As the ridge shifts offshore Thu night, will see light/variable winds to start then becoming S-SW. This will allow temps to bottom out Thu evening, then will slowly rise through the remainder of the night. Clouds will also increase during the night as the next system approaches. May see scattered showers develop and move across mainly around or after midnight, with the best chances across central and western Mass, possibly into N central CT.

Friday through Sunday
Looks like showers will be scattered across the region through Friday as the front pushes across, though there is some question on the timing of this feature with increasing model solution spread. Ahead of the front, temps will be mild. Expect readings topping off from the mid-upper 40s across the higher inland terrain to the lower- mid 50s across the coastal plain.

A lot of question remain in place for the upcoming weekend weatherwise. Model solutions are spread out, mainly with how each member is handling a potential southern stream system that may try to lift NE. This is likely due to wide spread in the handling of the mid level features, namely how fast the next northern stream system moves along as well as a possible southern stream short wave that may merge with the northern stream system. For now, have started off dry, then could see unsettled conditions. However, quite a bit of uncertainty so low confidence forecast.

Marine
Short Term /through Tuesday Night/...Moderate confidence.
Gale warnings remain in effect for all waters except for Small Craft Advisories on Boston Harbor and Narragansett Bay. NE gusts up to around 35 kt this evening, with strongest gusts continuing across the waters south and east of Cape Cod. Seas up to around 15 ft on the eastern outer waters.

The winds and seas will diminish tonight, with winds lowering below small craft levels by late tonight. Vsbys reduced in rain and fog, especially over eastern waters. Seas subside to 6-10 ft by Tuesday morning.

Expect West winds at 5-10 kts on Tuesday. Seas up to 5 to 9 ft, highest on the eastern outer waters early, then slowly subsiding but remaining at or above 5 ft through the day.

W-NW winds at around 10 kt early Tuesday night will shift to N after midnight, with gusts up to around 15 kt. Seas will linger at 5 to 6 ft across the outer waters through most if not the entire night.

Outlook /Wednesday through Saturday/... Wednesday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers.
Wednesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Slight chance of rain showers.
Thursday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft.

Thursday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers.

Friday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas. Chance of rain showers.

Friday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 10 ft. Slight chance of rain showers.

Saturday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Slight chance of rain showers.

Tides / Coastal Flooding
Astronomical high tide at Boston is 10.3 ft MLLW, and 3.7 ft MLLW at Nantucket Harbor. A storm surge of 1.5 to 2 ft is expected during the high tide this afternoon, and current observations show that that is right on track. The combination of the surge and seas up to 15 ft offshore are resulting in pockets of splashover or minor coastal flooding for much of the eastern MA coast during the high tide with the greatest risk at Nantucket. Somewhat lesser risk along the north shore which will be furthest removed from the low level jet.

A Coastal Flood Advisory remains in effect for the eastern Mass coast including Nantucket. However, the winds and storm surge will not be high enough to cause a significant coastal flood event.

NOAA Boston MA Office: Watches - Warnings - Advisories
CT...None. MA...Winter Weather Advisory until 6am EST Tuesday for MAZ002-008. RI...None.
MARINE...
Gale Warning until 9pm EST this evening for ANZ231-232-251- 255-256. Gale Warning until 7pm EST this evening for ANZ233>235-237. Small Craft Advisory until 9pm EST this evening for ANZ230- 236. Gale Warning until 10pm EST this evening for ANZ250-254.