Marine Weather Net

Cape Henlopen to Fenwick Island DE out 20 nm Marine Forecast


TONIGHT

E
WINDS
15 - 20
KNOTS

MON

E
WINDS
10 - 15
KNOTS

MON NIGHT

NW
WINDS
5 - 10
KNOTS

TUE

NW
WINDS
5 - 10
KNOTS

The Marine Weather Forecast In Detail:
ANZ455 Forecast Issued: 401 PM EDT Sun Oct 25 2020

SMALL CRAFT ADVISORY IN EFFECT THROUGH MONDAY AFTERNOON
Tonight...E Winds 15 To 20 Kt, Diminishing To 10 To 15 Kt Late. Seas 4 To 6 Ft. Patchy Drizzle This Evening. Rain. Areas Of Drizzle After Midnight. Patchy Fog Late This Evening. Areas Of Fog After Midnight. Vsby 1 To 3 Nm Late This Evening And Overnight. Swell Mainly From The E With A Dominant Period Of 9 Seconds.
Mon...E Winds 10 To 15 Kt, Becoming Ne 5 To 10 Kt In The Afternoon. Seas 3 To 5 Ft. A Chance Of Rain With Areas Of Drizzle Early In The Morning, Then Patchy Drizzle Late In The Morning. Areas Of Fog Early In The Morning, Then Patchy Fog Late In The Morning. Vsby 1 To 3 Nm In The Morning. Swell Mainly From The E With A Dominant Period Of 8 Seconds.
Mon Night...Nw Winds 5 To 10 Kt. Seas 3 To 4 Ft. Swell Mainly From The E With A Dominant Period Of 7 Seconds.
Tue...Nw Winds 5 To 10 Kt. Seas 3 To 4 Ft. Swell Mainly From The E With A Dominant Period Of 7 Seconds.
Tue Night...N Winds 5 To 10 Kt. Seas Around 3 Ft. A Chance Of Showers.
Wed...Ne Winds 5 To 10 Kt. Seas Around 3 Ft. A Chance Of Showers In The Morning.
Wed Night...S Winds 5 To 10 Kt. Seas Around 3 Ft In The Evening, Then 2 Ft Or Less. A Chance Of Rain After Midnight.
Thu...S Winds 5 To 10 Kt, Increasing To 10 To 15 Kt In The Afternoon. Seas 3 To 4 Ft. Rain Likely.
Thu Night...S Winds 15 To 20 Kt, Becoming Ne After Midnight. Seas 4 To 6 Ft. Rain Likely.
Fri...N Winds 20 To 25 Kt. Seas 5 To 8 Ft, Building To 7 To 10 Ft In The Afternoon. Rain Likely In The Morning, Then A Chance Of Showers In The Afternoon.
Fri Night...N Winds 20 To 25 Kt. Seas 7 To 10 Ft. A Chance Of Showers.
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Area Forecast Discussion
National Weather Service Mount Holly NJ
324pm EDT Sunday Oct 25 2020

Synopsis
High pressure will then build across to the north of our area and off the northeastern coast through Monday. A cold front will cross the region Monday night. A weak area of high pressure will cross to our north and east Tuesday through Wednesday. Low pressure will move up through the southeastern states and into the Mid-Atlantic late Thursday. High pressure then returns for the end of the week.

Near Term - Until 6am Monday Morning
Fairly classic cold-air damming setup occurring today across the Mid- Atlantic, with a strong surface high moving into the Canadian Maritimes while a weak surface wave attendant to a midlevel perturbation approaching the East Coast attempts to organize near or off the coast. Steady onshore flow upstream of yesterday's cold front has allowed ageostrophic acceleration to occur to the east of the Appalachians, producing the typical equatorward surge of colder air. Meanwhile, areas of rain have developed in association with large-scale ascent downstream of the aforementioned perturbation across the central Appalachians and the Mid-Atlantic. The steadiest rain has remained south of the CWA today, with Delmarva and far southern New Jersey seeing the most precipitation in our area. Closer proximity to the surface high farther north has prevented much measurable precipitation from occurring, though some sporadic tips of the bucket are being reported with bands of light rain extending into southeast Pennsylvania and central New Jersey at this time.

Current thinking is that the sweet spot for measurable rain across the CWA is this evening, as the perturbation remains just upstream, ejecting northeastward sufficiently to increase large-scale lift and moisten the low-level profiles sufficiently. The highest measurable rain chances will subsequently progress from southwest to northeast and likely become lower in most locations after 06z. This is because once the perturbation/vort max passes late this evening, notable dry advection will occur aloft, and conditions will become more favorable for fog and drizzle (as onshore flow at the surface continues).

Temperatures will be steady overnight and may actually rise slightly as weak near-surface warm advection continues.

Short Term - 6am Monday Morning Through 6pm Monday
The forecast for Monday is tricky, as I am concerned models are scouring the near-surface moisture too quickly. As the developing surface low off the Carolina coast begins to shift east-northeast and the surface high to the north continues quickly eastward, onshore flow will weaken during the day, but there are indications the flow will not entirely abate. Instead, the pressure gradient will simply weaken, with surface flow becoming somewhat light and variable until the arrival of a cold front (which will be after the daytime hours). In such an environment, preexisting cloud cover may be difficult to erode. In fact, lingering fog and drizzle in the morning may be slow to dissipate as well. Cannot completely rule out light rain in the morning either, but think most of the measurable precipitation will be done.

With the above in mind, forecast highs on Monday will be a challenge, as they will hinge largely on the degree of sky cover improvement. Current thinking is the northern CWA will see little improvement, so I have lowered temperatures here somewhat (generally north of I-78). To the south, confidence was too low to change the forecast much, with portions of Delmarva most likely to improve (and possibly being somewhat warmer than the current forecast). It is quite possible a fairly sharp gradient in temperatures exists if (when) the low-cloud shield develops a fairly sharp edge. Bottom line...there is potential for a big bust somewhere in the CWA with daytime highs.

Long Term - Monday Night Through Sunday
A cold front will drop down and move through the area Monday night and linger through at least a part of Tuesday. With limited moisture present, there looks to be some form of showery activity but not likely to be as widespread across the region.

High pressure will slide across the Great Lakes into New England Tuesday through Wednesday, moving off the New England coast late Wednesday. This high is not particularly strong but should help dry us out enough by Wednesday to allow for at least one fully dry day this week. A weak trough will cross the region Tuesday into Tuesday night, which will keep the chance for showers across our area, though it will not be washout and likely just remain cloudy through Tuesday.

Through mid-week, temperatures will be slightly below to near normal for late October, though it will be fairly cloudy through much of that time.

There is some uncertainty as to whether a low will develop near/over the southern plains around midweek. Even so, there will still be the tropical system (Zeta) making landfall along the Gulf Coast around Wednesday. The moisture from Zeta gets pulled up into the Mid- Atlantic state on Thursday. The remnant low will then track up near our area, with the center of the system cross Delmarva. This low will bring copious amounts of moisture with it and we should see some decent rainfall as it moves through our area, with some areas seeing amounts in excess of an inch. There is the potential for a secondary low to form behind the remnant low and this is where the forecast becomes trickier. There will be enough energy to keep precipitation across the region and with the flow turning more to the north and then northwest, colder air will be dragged down into our northern areas. Should the cold air arrive in time, we could see some snow in our forecast area, though it may be confined to northwestern New Jersey and the southern Poconos. Lots of fine tuning still needed as we need to see where Zeta makes landfall and how it progresses as it tracks to the north and east.

The rain will start to move out of the area on Friday as high pressure starts to arrive from the west.

The high pressure arrives as we head into Saturday and will dry us out, allowing us to have some very pleasant fall days through the Halloween weekend. High temperatures will generally be in the 50s across the region with some warming into the lower 60s possible as we head through the weekend.

Marine
A small craft advisory continues for the Atlantic waters, as seas remain near/above 5 feet. Northeast to east winds 10 to 20 kt will slacken on Monday.

Periods of rain are likely through tonight, with localized visibility restrictions possible.

Outlook... Monday night...The Small Craft Advisory may need to be extended into at least part of Monday night. Seas may remain above 5 feet through early Monday night before fully subsiding.

Tuesday through Thursday...Seas should subside by Monday night and then remain below 5 feet Thursday.

Thursday night through Saturday...Seas are expected to build to 5 feet and winds will increase out of the northeast with gusts around 25 to 30 knots Thursday night. Winds and seas will gradually subside through Saturday. A Small Craft Advisory will likely be needed.

NOAA Mount Holly NJ Office: Watches - Warnings - Advisories
PA...None. NJ...None. DE...None. MD...None.
MARINE...
Small Craft Advisory until 6pm EDT Monday for ANZ450>455.