textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Updated key messages and marine section.

KEY MESSAGES

1. Subtropical Storm Josephine located well off the Mid- Atlantic coast will move even farther away today, with coastal impacts and hazardous marine conditions gradually dwindling.

2. Elevated tide cycles persist due to Subtropical Storm Josephine well of the coast resulting in widespread minor coastal flooding continuing in Ocean County, NJ and Sussex County, DE.

3. Frost impacts possible Friday night and Saturday night where the growing season continues.

DISCUSSION

KEY MESSAGE 1...Subtropical Storm Josephine located well off the Mid-Atlantic coast will move even farther away today, with coastal impacts and hazardous marine conditions gradually dwindling.

Subtropical Storm Josephine located well off the Mid-Atlantic coast will gradually turns more to the northeast today. Meanwhile, strong surface high pressure is re-centering across the Canadian Maritimes. This is allowing the pressure gradient to begin relaxing.

Impacts will continue to dwindle for our coastal and marine areas. The multi-day north-northeast wind has resulted in 10+ foot waves just offshore. These big waves breaking onto the beaches will result in some additional beach erosion especially during times of high tide. Peak wind gusts should be notably lower today, more like 20-30 mph even at the coast. Any lingering mid and high clouds should dissipate.

As Subtropical Storm Josephine moves farther out to sea, an incoming system from the northwest will push across the region, but no precipitation and few clouds are expected with it... its main function is to move Josephine away. This will further reduce the marine and coastal impacts, while providing a fresh shot of chilly air. There will still be a notable north- northwest breeze today as the pressure gradient tightens again as another strong surface high moves towards us from Canada.

KEY MESSAGE 2...Elevated tide cycles persist due to Subtropical Storm Josephine well of the coast resulting in widespread minor coastal flooding continuing in Ocean County, NJ and Sussex County, DE.

As Subtropical Storm Josephine lingers well off the coast elevated tide cycles are persisting some areas.

In Ocean County, New Jersey and Sussex County, Delaware, water levels remain elevated and minor tidal flooding is continuing, particularly in the back bays. A the day wears on however, Josephine's gradual departure to the northeast away from the region will help water levels diminish, though another round of spotty minor coastal flooding is possible this evening.

At this time we are not forecasting any coastal flooding for the Maryland eastern shore.

KEY MESSAGE 3...Frost impacts possible Friday night and Saturday night where the growing season continues.

As an upper-level trough pivots across the Northeast on Friday, a potentially strong mid level ridge in the Plains to Midwest shifts eastward some into the weekend. This will support strong surface high pressure initially centered near the Great Lakes and portions of eastern Canada, which then shifts eastward into the Northeast and Mid-Atlantic Friday and over the weekend.

A chilly and dry air mass will accompany this strong surface high, and as the high itself settles more overhead the winds will decouple. This will set the stage for efficient radiational cooling both Friday night and Saturday night. The forecast lows are in the 30s for much of the area (away from the coasts and outside of the urban centers) with a frost potential. It is possible that if the radiational cooling ends up being stronger, then some areas could get to freezing or a little below. Overall though, frost impacts are possible where the growing season remains active.

AVIATION /07Z THURSDAY THROUGH MONDAY/

The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.

Thru 12Z this morning...VFR. North winds around 4-8 kt (becoming locally light and variable). High confidence.

Today...VFR. North-northwest winds around 10-15 kt with a few gusts up to 18-23 kt possible. Moderate-high confidence overall.

Tonight...VFR. North-northwest winds diminishing to 10 knots or less. High confidence.

Outlook...

Friday through Monday...VFR.

MARINE

A Small Craft Advisory continues for the New Jersey and Delaware nearshore waters and lower Delaware Bay as Subtropical Storm Josephine gradually moves farther out to sea today. A tightened pressure gradient will remain in place however due to strong high pressure to our north. Seas 8-15 feet on the ocean, with 5-8 foot waves into portions of lower Delaware Bay (more likely closer to the mouth of the bay). The winds are forecast to weaken some tonight, with gradual diminishing of seas beginnign as well.

Outlook...

Friday...Small Craft Advisory conditions probable, mainly on the ocean zones due to lingering 5+ foot seas.

Saturday...Winds are forecast to be below Small Craft Advisory criteria, however seas around 5 feet may linger for a while longer especially for our southern Atlantic coastal waters.

Sunday and Monday...The conditions should be below Small Craft Advisory criteria..

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...Coastal Flood Advisory until 10 AM EDT this morning for NJZ020- 026. DE...Coastal Flood Advisory until 10 AM EDT this morning for DEZ003- 004. MD...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ431. Small Craft Advisory until 8 PM EDT Friday for ANZ450>455. Gale Warning until 6 AM EDT early this morning for ANZ480>483- 485.