Marine Weather and Tide Forecast for Millbourne, PA

KEY MESSAGES
1. A strong cold front will continue cross southern New Jersey and Delmarva this evening with severe weather chances lowering.

2. Frost and freeze conditions are expected for Saturday night into Sunday morning with another round of frost possible for Sunday night into Monday morning.

3. Uncertainty persists regarding a nor'easter developing off the coast of the southern Mid-Atlantic that may cause unsettled conditions and hazardous marine impacts early next week.

DISCUSSION
KEY MESSAGE 1...A strong cold front will cross the region late this afternoon and this evening with severe weather possible.

Low pressure passing north of northern New England will continue to push a potent cold front across southern NJ and Delmarva for the early overnight period. There were some scattered severe thunderstorms earlier across eastern PA and parts of NJ, but the latest radar trends show the activity in most areas diminishing.
The earlier widespread Severe Thunderstorm Watch has been pared back to only include southern/easter areas for a few more hours.
A couple stronger storms may affect the weather shore of MD and Delaware thru 9PM. After that, rains will end overnight with showers hanging on latest across Delmarva. Much cooler temperatures develop overnight.

A tight pressure gradient then develops over the area tonight through Saturday as broad high pressure centered over the Southern Plains begins to build east. Gusty north to northwest winds will develop tonight and will continue through Saturday, with winds ranging from 15 to 25 mph with 30 to 40 mph gusts. Much cooler on Saturday with highs in the 50s and surface dew points falling towards the 30s. Some showers may linger tonight into Saturday morning especially across southern NJ and Delmarva as the front slows for a time, but they should clear out finally later in the day if not before.

KEY MESSAGE 2...Frost and freeze conditions are expected for Saturday night into Sunday morning with another round of frost possible for Sunday night into Monday morning.

The coldest airmass of the season thus far will usher into the region this weekend. With high pressure settling in from the north, skies will become clear by Saturday evening. While it will be a bit breezy early in the night, the pressure gradient is expected to lessen overnight, especially for locales north and west of I-95. In these areas, anticipate a period of good radiational cooling conditions where low temperatures are expected to fall into the upper 20s to low 30s. For this reason, have issued a Freeze Watch for potions of eastern PA and northern NJ for Saturday night.
Further south and east, it appears that winds will remain elevated enough to preclude frost formation where temperatures will be in the mid to upper 30s. At this time, no frost/freeze headlines are expected along the I-95 corridor and points south and east.

High temperatures on Sunday will then only be in the 50s for the entire region despite mostly sunny skies. Temperatures will then begin to slowly moderate Sunday night into early next week. Another round of frost/freeze conditions will be possible for Sunday night into Monday morning, mainly confined to the Lehigh Valley, Poconos and northern New Jersey. Lows are expected to be several degrees warmer than Saturday night mainly in the mid to upper 30s, so this would favor frost over freeze where the growing season remains active. Too early to determine any headlines at this time, but will be considered in future updates.

KEY MESSAGE 3...Uncertainty persists regarding a nor'easter developing off the coast of the southern Mid-Atlantic that may cause unsettled conditions and hazardous marine impacts early next week.

The base of a deep trough axis will pass through the region later Saturday. As it does so, the trough axis will then cutoff into an upper level low which will meander over the southern Mid-Atlantic coast into early next week. At the same time, strong and expansive high pressure will be building over the Ohio Valley. While confidence is increasing regarding a nor'easter developing off the North Carolina coast later this weekend, it must be said there remains a vast amount of uncertainty with regards to potential impacts to our region into next week.

Considerable differences amongst global/ensemble guidance exists with regards to just how close/long this system will get/last in our region. Some guidance keeps the system suppressed further south due to the strong high to the north, which will then minimize potential impacts to our area. However, if the system is further north (and this has been the trend over the past 24 hours), then more in the way of impacts and unsettled weather may occur. At the very least, it is expected that gusty northeast breezes will occur for the majority of the week with the highest gusts located near coastal areas. While it isn't expected to be a washout by any means, there is at least a chance of showers each day for areas south and east of I-95 beginning as early as Sunday night through the end of the week.
More details to come over the weekend once forecast guidance comes into better agreement.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.

Tonight...SHRA/TSRA taper off by 02Z for Delaware Valley and KMIV/KACY. After that, mainly VFR, though showers may linger especially southern terminals. NW winds 10 to 15 kt with 20 to 25 kt. High confidence.

Saturday...Mainly VFR, though showers and perhaps some MVFR cigs may linger southern terminals in the morning. NW winds 15 to 25 kt with 25 to 35 kt gusts. High confidence.

Outlook...

Saturday night through Sunday...VFR. No significant weather expected.

Sunday night...Primarily VFR. A slight chance of rain showers possible near KACY and KMIV.

Monday through Wednesday...Primarily VFR, although sub-VFR conditions possible at times. A chance of rain showers each day for all terminals except KRDG and KABE. Gusty northeast winds up to 20 kt possible with gusts up to 30 kt possible near KMIV and KACY.

MARINE
A Small Craft Advisory remains in effect for the ocean waters.
A line of showers and thunderstorms capable of damaging wind gusts will move across the waters this evening with the passage of a strong cold front.

Winds turn north-northwest tonight and increase to 15 to 20 kt with 25 to 30 kt gusts that will last through Saturday. 30 to 40 kt gusts are likely Saturday. Upgraded Gale Watch to Gale Warning Saturday.

Outlook...

Saturday night...Gale Warnings are in effect for offshore waters and Atlantic coastal waters from Great Egg Inlet to Fenwick Island.
Small Craft Advisory conditions likely for Atlantic coastal waters from Sandy Hook to Great Egg Inlet and Delaware Bay. North-northeast winds of 20-30 kt with gusts of 30-40 kt. Seas of 6-12 feet.

Sunday...A mix of Gales and Small Craft conditions are likely to continue on all waters. Northeast winds of 15-30 kt with gusts of 30- 40 kt possible. Seas of 6-12 feet.

Sunday night through Wednesday...Due to developing nor'easter off the southern Mid-Atlantic coast, a prolonged period of gale force conditions are expected to develop/continue across all marine waters. It should be noted that forecast confidence is low though.
Northeast winds of 25-35 kt with gusts of 35-45 kt are possible.
Seas of 10-16+ feet possible.

PHI WATCHES/WARNINGS/ADVISORIES
PA...Freeze Watch from late Saturday night through Sunday morning for PAZ054-055-060>062-101-103-105.
NJ...Freeze Watch from late Saturday night through Sunday morning for NJZ001-007>009.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ430-431- 450>455.
Gale Warning from 6 AM to 6 PM EDT Saturday for ANZ430-431- 450>452.
Gale Warning from 6 AM Saturday to 6 AM EDT Sunday for ANZ453>455.
Gale Warning from 6 AM Saturday to 7 AM EDT Sunday for ANZ480>483-485.