Marine Weather Net

Cape Henlopen to Fenwick Island DE out 20 nm Marine Forecast


10 - 15







The Marine Weather Forecast In Detail:
ANZ455 Forecast Issued: 1018 AM EDT Sun Sep 19 2021

Rest Of Today...Ne Winds 10 To 15 Kt. Seas 3 To 4 Ft. Swell Mainly From The Ne With A Dominant Period Of 9 Seconds.
Tonight...E Winds Around 10 Kt. Seas Around 3 Ft. Swell Mainly From The E With A Dominant Period Of 8 Seconds.
Mon...E Winds Around 10 Kt, Increasing To Around 15 Kt In The Late Morning And Afternoon. Seas 3 To 4 Ft. Swell Mainly From The E With A Dominant Period Of 8 Seconds.
Mon Night...E Winds Around 15 Kt. Gusts Up To 20 Kt In The Evening. Seas 3 To 4 Ft. Patchy Fog After Midnight With Vsby 1 To 3 Nm. Swell Mainly From The E With A Dominant Period Of 7 Seconds.
Tue...E Winds Around 15 Kt. Seas Around 4 Ft. Patchy Fog In The Morning With Vsby 1 To 3 Nm.
Tue Night...Se Winds 10 To 15 Kt. Seas Around 4 Ft. Patchy Fog After Midnight With Vsby 1 To 3 Nm.
Wed...Se Winds 10 To 15 Kt. Seas Around 4 Ft. Patchy Fog In The Morning. A Chance Of Showers In The Afternoon. Vsby 1 To 3 Nm In The Morning.
Wed Night...Se Winds Around 15 Kt. Seas 4 To 5 Ft. A Chance Of Showers In The Evening, Then Showers Likely After Midnight.
Thu...Se Winds Around 15 Kt. Seas 4 To 5 Ft. Showers Likely In The Morning, Then Showers Likely With A Chance Of Tstms In The Afternoon.
Thu Night...Se Winds 10 To 15 Kt, Becoming Sw After Midnight. Seas 3 To 4 Ft. A Chance Of Tstms In The Evening, Then A Chance Of Showers After Midnight. Winds And Seas Higher In And Near Tstms.
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Area Forecast Discussion
National Weather Service Mount Holly NJ
956am EDT Sunday September 19 2021

High pressure builds over eastern Canada and the Northeast United States later today and tonight, then moves into the Gulf of Maine on Monday. High pressure remains over the western Atlantic through the end of next week. A frontal boundary approaches for the middle of the week, and slowly crosses the region at the end of the work week. Another front may pass through next weekend.

Near Term - Through Tonight
A surface cold front has cleared the area this morning with drier and cooler air moving in behind. High pressure is currently over southeastern Ontario and will slowly head east towards Maine this evening. Temperatures today will be 5 to 10 degrees lower than Saturday's highs, with highs mostly in the 70s (though a few places could be near 80 F).

Winds will be gradually veering from northerly to easterly, primarily late in the day into tonight. With onshore flow, risk for fog and/or low stratus increases. However, the risk for fog appears rather low tonight as the most likely areas to get close to saturation (SE NJ and northern Delmarva) should have winds stay up near 5 kt. Across NW NJ and E Central PA, where winds will be lighter, dew points should also be lower. Thus, for now I don't have a mention of fog in the forecast. As for low stratus clouds, that is possible, but given how late the onshore flow develops, it is unlikely that we will see widespread low clouds.

Short Term - Monday Through Tuesday
High pressure will move into the Gulf of Maine on Monday and remains there through Tuesday. Onshore flow sets up across the region, and low level moisture will gradually increase across the region. Surface dew points will start out in the 50s on Monday, gradually rising through the 60s once again on Tuesday.

Plenty of sunshine and seasonal conditions expected on Monday with highs generally in the 70s. With increasing low level moisture, patchy fog possible late Monday night. On Tuesday, high temperatures will once again be in the 70s, but with increasing clouds as a frontal boundary approaches from the west.

Long Term - Tuesday Night Through Saturday
Surface cold front with a deep upper trough dig through the central U.S., but with high pressure anchored offshore, the front looks to slow down over the eastern Great Lakes and Ohio Valley Tuesday night.

A period of unsettled weather is on tap for the midweek period, however, there is a good deal of uncertainty with specifics given the differences among the models.

A closed H5 low will pinch off of the upper trough over the great Lakes and Ohio Valley late Wednesday. The first wave of showers will approach the region Wednesday and Wednesday night. The issue over the following couple of days is that the 00Z/19 GFS, ECMWF, and Canadian all have different solutions regarding the timing and placement of the upper low. Overall, a period of showers is likely Wednesday night through Thursday, but showers may continue Thursday night and if the slower models pan out. Another concern is convection. Models indicating minimal MUCAPE, with the 00Z ECMWF (European Centre for Medium-Range Weather Forecasts) on the more robust side, but still only around 600 J/kg. Given that surface dew points will be well in the 60s, possibly approaching 70, there is enough moisture available. The concern is that all of the ingredients might not come together. ECMWF indicating 80-100 kt jet, but the jet stays north of the region. GFS indicates this jet, but it is more over the Northeast, and is producing a period of heavy rain right over western and central New York and central and eastern Pennsylvania Wednesday night, then over New Jersey Thursday morning. The Canadian brings this rain which could be heavy to the region late Thursday and Thursday night. The ECMWF is not as progressive with that heavy rain, but is slower, bringing it Thursday night/Friday morning.

Feel best course of action is to cap Probability of Precipitation at chance on Wednesday, then carry likely Probability of Precipitation Wednesday night and Thursday. Will also add a chance for thunder Thursday afternoon, but it remains uncertain.

Cold front passes through the region by Friday morning, unless the ECMWF is correct, and in that case, it will not be until late Friday. Conditions dry out sometime Friday and Saturday as high pressure builds in from the north.

Winds and seas should stay below Small Craft Advisory criteria through tonight. Some guidance shows seas on the NJ coastal waters getting to 5 feet this afternoon. However, that guidance is too high with current conditions, so expect that bias to continue and thus think seas should stay just below SCA (Small Craft Advisory) criteria.

Outlook... Tuesday-Thursday...Although winds should remain below advisory levels through the period, seas could increase to 5 feet or higher by Tuesday night and continue into Thursday.

Rip currents... The combination of lingering swells from Odette, with developing onshore flow later today, and the full moon on Monday will result in a moderate risk for rip currents today and Monday. Although the swells should start to diminish, this tendency will be offset by the increasing onshore flow.

Tides / Coastal Flooding
Spotty minor tidal flooding is possible centered around the highest astronomical tides through Monday. The combination of increased swells from Odette, higher astronomical tides with the full moon on Monday, and developing onshore flow will all contribute to this. The highest astronomical tides, and thus the higher risk for spotty minor flooding, will be the evening/overnight high tides. At this point, tidal levels just should fall just shy of advisory criteria. However, if the onshore flow develops faster than what is currently expected, there could be an increased risk for widespread minor flooding, especially with the evening/night high tide tonight.

Notably, forecasts have increased slightly for portions of the Atlantic coast in southern New Jersey and Delaware for the evening/night high tide tonight, and there is a chance an advisory may be required for these areas as well as adjacent portions of Delaware Bay during this time frame.

NOAA Mount Holly NJ Office: Watches - Warnings - Advisories
PA...None. NJ...None. DE...None. MD...None.