Marine Weather and Tide Forecast for Millbourne, PA

KEY MESSAGES
1. Gusty winds through today with a brief cool down through Friday.
Milder temperatures this weekend and especially next week.

2. Low pressure sliding by to our south later Sunday into Monday.

DISCUSSION
KEY MESSAGE 1...Gusty winds through today with a brief cool down through Friday. Milder temperatures this weekend and especially next week.

It remains breezy overnight as there's a fairly tight pressure gradient over the area in between low pressure off to our east and high pressure gradually approaching from the west. This gradient is expected to linger through Thursday, keeping breezy NW winds in the forecast. The gustiness should diminish some overnight and then pack back up again through Thursday morning with gusts of 20 to 25 mph likely. Temperatures will be cooler than Wednesday but not as cold as what we've dealt with for much of the past few weeks. However the wind chill will still make it feel rather cold. Highs Thursday will generally be in the 30s (20s over the Poconos) but with the wind chill it will feel a good 10 degrees or so colder than this. There will also be considerable cloudiness around.

The winds diminish for Thursday night and Friday as high pressure builds in and the pressure gradient slackens. Lows Thursday night will be mainly in the teens to low 20s with highs Friday once again mainly in the 30s except 20s over the Poconos. Friday should also feature mainly sunny conditions.

The air mass over the area moderates this weekend as high pressure slowly shifts off to the east. High temperatures both Saturday and Sunday generally range from the 30s north to the mid/upper 40s south. Overnight lows, at least for Saturday night, will be below freezing (in the 20s). The overall moderating trend looks to continue into next week, although low pressure sliding by to our south later Sunday into Monday could result in some cooling on Sunday (see Key Message 2 below). Regardless of what happens with the storm, it will have departed by next Tuesday and Wednesday with highs by then looking to be well into the 40s for most areas with even some 50s over parts of the coastal plain.

KEY MESSAGE 2...Low pressure sliding by to our south later Sunday into Monday.

The model guidance continues to depict an area of low pressure affecting portions of the East Coast later Sunday into Monday. While there remains some uncertainty in the intensity and track details of this system, the surface low itself does look to slide by to our south. The air mass in place prior to this system will be on the milder side (highs Saturday mostly in the 40s), with rain or snow changing to rain would tend to be favored. A weaker system would tend to favor less snow, however some previous model runs have shown phasing occurs which resulted in a much stronger storm. If this were to pan out, dynamic cooling due to robust forcing for ascent along with just enough cold air could result in accumulating snow across much of the area excluding most of the coast. A strong storm solution continues to be a low probability based on the overall trends in deterministic and ensemble guidance.

Given some uncertainty in how far north the associated precipitation shield gets, opted to maintain the official forecast with the NBM guidance which has chance to likely PoPS (30-70 percent) from north to south Sunday afternoon into early Monday. The areas farther north that have a better chance of seeing any precipitation fall as snow also have the lower PoPs at this time.

AVIATION /06Z THURSDAY THROUGH MONDAY/
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.

Overnight...VFR with a scattered to broken deck of cloud cover around 4-5 thousand feet. Northwest winds around 10 to 15 knots with some gusts up to 20-25 knots at times. Gusts should generally diminish in frequency overnight. Moderate confidence.

Thursday...VFR with increasing clouds by midday. Northwest winds around 10-15 knots with gusts up to 20-25 knots in the afternoon. High confidence.

Thursday night...VFR. Northwest winds diminishing to less than 10 knots. High confidence.

Outlook...

Friday and Saturday...VFR.

Sunday and Monday...A period of sub-VFR conditions and rain/snow possible.

MARINE
A Small Craft Advisory remains in effect for all marine zones through Thursday. As colder air continues to move in, expect NW winds gusting 25 to 30 knots through the first half of Thursday before winds slowly subside through the afternoon and evening. The Small Craft Advisory runs until 6 PM Thursday. Beyond this time expect sub SCA conditions through Friday.

Regarding the river/bay ice...Significant ice cover continues across many area bay waters and inland estuaries. This includes, but is not limited to the Delaware estuary. On rivers, the ice thickness is enough to cause some restrictions in the flow. Per satellite imagery and ice analysis data, the Delaware River is mostly ice covered from the entrance to Delaware Bay northward, or upstream, to at least Washington Crossing. Delaware Bay has quite a bit of ice cover, however satellite imagery the last few days has shown icing flowing out of Delaware Bay into the Atlantic Ocean.

The most common ways river ice can break up is either through a thermal or mechanical means. We would like to see temperatures rise into the 40s for a few days, which parts of the region are forecast to get to once again over the weekend with some areas getting into the 50s early next week. Significant rainfall, producing river rises, can also break up ice but that is not in the forecast this week.

As a result, ice cover will continue. There may be a pause in the ice growth during the daylight hours as temperatures rise to and above freezing, however temperatures at night will continue to support some ice expansion.

Outlook...

Friday night and Saturday...The conditions are anticipated to be below Small Craft Advisory criteria.

Sunday and Monday...The conditions are currently forecast to be below Small Craft Advisory criteria, however this will depend on the track and strength of low pressure sliding by to our south.

PHI WATCHES/WARNINGS/ADVISORIES
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ430- 431-450>455.