textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Updated Rip Current section.

KEY MESSAGES

1. A cold front will approach the region through this morning, eventually progressing through the Northeast and Mid-Atlantic tonight through Saturday. Isolated showers are possible through early this morning, with more widespread activity expected during the day on Saturday. Some isolated thunder is possible late tonight through Saturday.

2. Heat builds back into the region for the middle and end of next week. There is increasing confidence that high temperatures will be well in the 90s, with maximum heat index values around 100 degrees.

DISCUSSION

KEY MESSAGE 1...A cold front will approach the region through this morning, eventually progressing through the Northeast and Mid-Atlantic tonight through Saturday. Isolated showers are possible through early this morning, with more widespread activity expected during the day on Saturday. Some isolated thunder is possible late tonight through Saturday.

A band of showers with isolated embedded thunder will continue to progress generally to the east-northeast through eastern PA and far northern NJ through daybreak. Expect that this activity will gradually weaken and wither through the predawn hours, but the southern trailing axis of light showers may extend as far south as the Philly metro area by daybreak.

Although some brief downpours may lead to rainfall amounts around an inch, isolated heavier pockets around 1.5 inches are certainly possible, mainly in far eastern PA and northern NJ through sunrise. Suppose some brief ponding of water is possible in low- lying areas, but the overall flood threat is fairly low. The severe threat remains very low.

There will likely be a lull in the precip through the day today in the wake of the departing S/W, especially as some drier air begins to filter in to far eastern PA and northern NJ by late afternoon. There will be some filtered sunshine through the daytime, allowing temperatures to reach into the upper 80s and low 90s with surface dew points in the 60s. However, further north across eastern PA and far northern NJ, highs will generally top out in the lower to mid 80s.

The front will slowly drift southeast through the local area this evening into tonight as a low pressure system in the OH Vly slowly crawls to the E. This approaching low will cause the front to stall, with a gradual increase in showers expected once again late tonight into the day Saturday. The greatest coverage will be focused near/S of the I-78 corridor, but this activity may linger through quite a bit of the day Saturday, keeping temps below seasonal norms.

Rainfall will generally be around 1/2 inch late tonight through the day Saturday for locales near/S of I-78 (with much less further north). Locally heavier amounts are possible in Delmarva where deeper moisture will linger the longest and persistence of activity may allow for amounts near/greater than an inch.

The front sags south into the Mid-Atlantic Saturday night through Sunday. High pressure builds in from the north, and conditions dry out for Sunday.

KEY MESSAGE 2...Heat builds back into the region for the middle and end of next week. There is increasing confidence that high temperatures will be well into the 90s, with maximum heat index values around 100 degrees.

There is increasing confidence in strong mid-level ridging developing over the Great Lakes and Ohio Valley, building into the Northeast and Mid-Atlantic starting on Wednesday and continuing through the end of next week. Hot and humid conditions look to return with high temperatures well into the 90s and max heat index values around 100 degrees.

Latest ensemble guidance points to high probabilities (>50%) of high temperatures of at least 95 degrees for much of the region, beginning as early as Wednesday, continuing through Friday of next week. This would likely translate to maximum heat index values near or greater than 100 degrees, particularly Thursday and Friday afternoons.

AVIATION /07Z FRIDAY THROUGH TUESDAY/

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

Through 12z this morning...VFR conditions are expected to prevail at the sites, except for the brief potential of visibility reductions to MVFR coincident with some showers, especially at KABE and perhaps KRDG. Vicinity showers will be possible for TTN/PNE/PHL in the several hours around daybreak, but most activity will dissipate as they approach the Philadelphia area by sunrise. There is a chance for ISO TS, but will keep out of the TAFs for now due to low probabilities. Light southerly winds around 5kts may go light/VRB. Medium confidence on coverage and maintenance of SHRA/TSRA.

Today...VFR conditions prevail as cloud cover generally decreases through the morning. A few showers may linger past 12z, but conditions will trend increasingly drier by mid morning and beyond. Increasing mid/high clouds will overspread the region toward late in the daytime. Southerly winds early in the morning will go more out of the WSW, or perhaps even the W, by the afternoon, generally staying around 10kts for the afternoon. Winds subside toward/past 00z, going light/VRB as clouds gradually lower with a moistening profile.

Outlook...

Tonight through Saturday night...MVFR CIGs possible, with brief MVFR VSBY possible in heavier pockets of pcpn with scattered SHRA/TSRA. There is the potential for some MVFR VSBY with BR tonight into Saturday morning, but confidence on this occurring is rather low.

Sunday through Tuesday...VFR. No significant weather.

MARINE

Conditions will remain below advisory levels through tonight. Winds will likely gust around 15 to 20 knots through this afternoon before subsiding to less than 10kts tonight.

Outlook...

Friday night through Tuesday...Sub-SCA conditions expected. VSBY restrictions in showers and scattered thunderstorms.

Rip Currents...

For today, south-southwest winds around 10 mph with breaking waves in the surf zone of mainly 1-2 feet, with up to 2 to 3 feet with an 8 second period near the Atlantic City and Ocean City shores. This will continue the LOW risk for the development of dangerous rip currents for the Jersey Shore and Delaware Beaches.

For Saturday, breaking waves in the surf zone are forecast to be around 2 feet with around a 6 second period and southeast swell. Winds should be more easterly around 10 mph across the northern Jersey Shore beaches while more southerly farther south. Despite a more onshore component to the wind at some beaches, continued the LOW risk for the development of dangerous rip currents for both the Jersey Shore and Delaware Beaches.

For specific beach forecasts, visit weather.gov/beach/phi

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...None.