textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Aviation section updated for the 06Z TAFs. Few changes for the other sections during the evening update. Strong Nor'easter continues to deepen and move towards our coastal waters.

KEY MESSAGES

1. A developing Nor'easter east of the Mid-Atlantic coast lifts to the north, then retrogrades back towards New Jersey over the weekend before finally departing on Tuesday. This will bring periods of rain and strong winds at the coast to the region.

2. Multiple rounds of significant tidal flooding expected into this weekend. Major Coastal Flood levels expected for New Jersey Atlantic Coast, Delaware Atlantic Coast, and portions of southern Delaware Bay. Coastal Flood Warning expanded to northern portions of Delaware Bay.

3. Dangerous rip currents and high surf are expected at the Jersey Shore and Delaware Beaches through Sunday. Beach erosion is likely and breaching of sand dunes is possible.

DISCUSSION

KEY MESSAGE 1...A developing Nor'easter east of the Mid-Atlantic coast lifts to the north, then retrogrades back towards New Jersey over the weekend before finally departing on Tuesday. This will bring periods of rain and strong winds at the coast to the region.

Broad high pressure remains centered over eastern Canada and extends back into the Great Lakes. While the high will weaken and lift into northern portions of the Province of Quebec, it will still be strong enough to create a tight pressure gradient between it and low pressure east of the Mid-Atlantic. The trend with the last run of models has been to bring the storm closer to the shore, and even have the center of the Nor'easter move into New Jersey Saturday night.

A tight north to northeast pressure gradient develops tonight and will persist through the weekend as this Nor'easter retrogrades back towards New Jersey Saturday through Saturday night. Winds increase tonight, generally to 25 to 35 mph with 40 to 50 mph inland, and gusts up to 60 mph at the coast. Will keep High Wind Warnings and Wind Advisories in effect through Saturday night, but additional headlines may be needed on Sunday depending on the strength and position of the low on Sunday. This trend may result in stronger winds farther west as well. Given that trees still have their leaves, the combination of these winds and heavy rain (more on that in a bit) will result in tree damage, as well as power line and potentially roof damage with highest impacts at the coast.

The farther inland trend also results in higher PoPs inland as well as and higher rainfall over the area. Rain spreads into the region from east to west starting later tonight, and then on Saturday, PoPs will be 60 to 70 percent across the southern Poconos, Lehigh Valley, and far northwest New Jersey and 80 to 90 percent across the rest of New Jersey, southeast Pennsylvania, and Delmarva. PoPs will then be 90 to 100 percent across the whole area Saturday night and Sunday. QPF has also increased, with 1 to 2 inches of QPF north and west of Philadelphia and across Delmarva, and 2 to 4 inches along the I-95 corridor, and as much as 3 to 5 inches over much of eastern New Jersey. This will be over a 48 to 60 hour timeframe, so widespread flooding is nor anticipated at this time, though there may be some flooding concerns by late Sunday and Sunday night. In addition, runoff from this rain may exacerbate coastal flooding, which will be covered by Coastal Flood Warnings. Cannot rule out a few embedded thunderstorms, mainly at the coast, during this time.

KEY MESSAGE 2...Multiple rounds of significant tidal flooding expected into this weekend. Major Coastal Flood levels are now expected for the New Jersey Atlantic Coast, the Delaware Atlantic Coast, and portions of central and southern Delaware Bay. The Coastal Flood Warning has been expanded to northern portions of Delaware Bay.

With a slow moving nor'easter and multiple days of strong northeast winds expected, the confidence in the threat for tidal flooding remains high. In fact, the threat for the New Jersey Atlantic Coast, Delaware Atlantic Coast, and portions of southern Delaware Bay to reach Major Flood levels around the time of high tide Saturday morning has increased, so we have increased the forecast for these areas to reach Major Flood levels. Strong onshore flow that has persisted for several days is resulting in water piling up across tidal tributaries and within back bays of coastal communities. Tidal levels will also be enhanced with astronomical tides increasing with the upcoming Full Moon Saturday.

For Delaware Bay communities, north/northeast winds will keep pushing water to the west side of the Bay and onto the Delaware coast. This will increase the forecast for Major Flood levels around southern and central Delaware. The Coastal Flood Warning remains 2 AM Sunday for Kent and Sussex, DE. The forecast is now expected to reach the Moderate Flood level for Cumberland and Salem, NJ as well as New Castle, DE, so the Warning was expanded to these area.

For the tidal Delaware River, widespread minor tidal flooding continues to be forecast, so the Coastal Flood Advisory remains in effect through Saturday Night for the tidal Delaware River. While not currently expected, we cannot rule out Moderate tidal flooding getting to Delaware River communities.

As mentioned above, more north/northeasterly winds will limit the tidal flooding threat for the Chesapeake Bay. Some spotty minor tidal flooding is anticipated at Claiborne, but nothing higher than that at this time.

KEY MESSAGE 3...Dangerous rip currents and high surf are expected at the Jersey Shore and Delaware Beaches through Sunday. Beach erosion is likely and breaching of sand dunes is possible.

A nor'easter off our coast will bring strong north to northeast winds and high seas for our marine zones. Breaking waves within the surf zone of 6 to 12 feet are expected through Sunday. Dangerous rip currents will accompany the high surf, making it extremely dangerous to enter the water at any time through Sunday. The high surf and strong winds will likely result in areas of beach erosion across the Jersey Shore and Delaware Beaches. Large breaking waves in the surf zone and high water levels may result in breaching of sand dunes.

The High Risk for life threatening rip currents remains in effect through Sunday for all beaches. A High Surf Advisory is in effect for all beaches through Sunday as well.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

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

Rest of tonight (through 12Z)...Most terminals linger at VFR through daybreak with slow increase in clouds and rains from east to west. KACY/KMIV will go MVFR by 08-10Z then the lower conditions continue slowly west towards other sites Sat morning. North to Northeast winds 15 to 25 kts with gusts 30-40 kts. Cannot rule out an occasional gust over 40 kts along the I-95 terminals and east, particularly when showers arrive. Lighter winds for KABE/KRDG. Medium confid.

Saturday...MVFR conditions develop, but IFR conditions along the New Jersey coast. Areas of rain especially east of the Delaware River. Winds northerly 15 to 25 knots gusts to 30-40 knots. Coastal locations gusting to 40+ knots.

Outlook...

Saturday night through Sunday...Widespread MVFR and IFR conds in rain, fog, and low CIGs. A few TSRA may impact KACY and possibly KMIV. N to NE winds 15 to 20 kt with 30 to 35 kt gusts inland and gusts as high as 50 kt from time to time at KACY.

Sunday night...Continued MVFR/IFR conds in lingering SHRA. Diminishing winds.

Monday through Monday night...Conditions improve to MVFR, then to VFR late Monday and Monday night.

Tuesday and Wednesday...VFR.

MARINE

Widespread Storm Force winds developing on the nearshore and offshore waters overnight, and Gale Force winds developing on Delaware Bay. For now, warnings are in effect through Saturday night, but additional headlines are likely to be needed Sunday and possibly Sunday night.

On the ocean, winds will average 35 to 45 kt with gusts as high as 60 kt, and on Delaware Bay, winds will average 20 to 30 kt with gusts as high as 45 kt tonight through Saturday night.

Seas will be very rough, as high as 15 to 20 ft on the ocean during this time. VSBY restrictions in rain.

Outlook...

Sunday night...Conditions expected to improve considerably. Small Craft Advisory conditions likely.

Monday-Monday night...Conditions continue to improve. Seas may remain above advisory levels while winds continue to diminish below 25 knots.

Tuesday...Conditions expected to be below advisory levels.

Rip Currents...Please see Key Message 3 above.

PHI WATCHES/WARNINGS/ADVISORIES

PA...Wind Advisory until 6 AM EDT Sunday for PAZ070-071-101>106. Coastal Flood Advisory until 5 AM EDT Sunday for PAZ070-071- 106. NJ...Coastal Flood Warning until 3 AM EDT Sunday for NJZ016. Wind Advisory until 6 AM EDT Sunday for NJZ008>010-012-013- 015>023-027. Coastal Flood Warning until 2 PM EDT Sunday for NJZ012>014- 020>027. High Wind Warning until 6 AM EDT Sunday for NJZ014-024>026. High Risk for Rip Currents through Sunday evening for NJZ014- 024>026. High Surf Advisory until 8 PM EDT Sunday for NJZ014-024>026. Coastal Flood Advisory until 5 AM EDT Sunday for NJZ017>019. DE...Coastal Flood Warning until 3 AM EDT Sunday for DEZ001. Wind Advisory until 6 AM EDT Sunday for DEZ001>003. Coastal Flood Warning until 2 PM EDT Sunday for DEZ002>004. High Wind Warning until 6 AM EDT Sunday for DEZ004. High Risk for Rip Currents through Sunday evening for DEZ004. High Surf Advisory until 8 PM EDT Sunday for DEZ004. MD...None. MARINE...Gale Warning until 6 AM EDT Sunday for ANZ430-431. Storm Warning until 6 AM EDT Sunday for ANZ450>453-480>483. Storm Warning until 6 PM EDT this evening for ANZ454-455. Storm Warning until midnight EDT tonight for ANZ485.