textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Updated the rip currents section of the Marine discussion.

KEY MESSAGES

1. Unsettled conditions tonight and thru Saturday as a front and weak upper systems move through.

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 to around 100 degrees, with maximum heat index values exceeding 100 degrees.

DISCUSSION

KEY MESSAGE 1... Unsettled conditions tonight and thru Saturday as a front and weak upper systems move through.

A weak cold front will continue across the region tonight and the front will meander back through Saturday. The front will interact with an upper short wave tonight and another Saturday. These factors will lead to the development of showers and a few tstms through the period. Higher POPS will be across Delmarva and south NJ both tonight and Saturday. While severe weather is not expected, a few tstms with gusty winds may occur. It'll remain mild and humid tonight with lows in the low/mid 60s N/W and upper 60s/low 70s S/E. Highs on Saturday will generally be in the 70s with some low 80s for Delmarva and south NJ.

The cold front slowly sags south into the Mid-Atlantic Saturday night. High pressure begins to build in from the north and west, but with that front nearby, and shortwave energy on the base of a mid- level trough diving into the Mid-Atlantic, showers with isolated thunderstorms will linger over the area Saturday night, with the bulk of the activity over Delmarva and extreme southern New Jersey. While most of the area dries out on Sunday, some lingering showers, and even a few thunderstorms, may continue to impact Delmarva into Sunday afternoon.

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 in the 90s to around 100 degrees, with maximum heat index values exceeding 100 degrees.

Strong mid-level ridging will develop over the Great Lakes and Ohio Valley early in the new week, then will build into the Northeast and Mid-Atlantic starting on Wednesday and continuing through the end of next week. Hot and humid conditions will return with high temperatures well into the 90s to around 100 degrees with and max heat index values over 100 degrees.

13Z/26 NBM probabilities indicate a 70 to 90 percent probability of high temperatures exceeding 95 degrees on both Thursday and Friday, with a 30 to 50 percent probability of high temperatures exceeding 100 degrees from the Lehigh Valley north on Thursday and a 60 to 80 percent probability of high temperatures exceeding 100 degrees across the Delaware Valley, including Philadelphia, southern New Jersey, and Delmarva on Thursday. Max heat index values could exceed 105 degrees, which would necessitate potential Extreme Heat Warnings.

Saturday

Overall a cloudy fcst with greater chances for showers/tstms across south NJ and Delaware Valley sites. Lower CIGs/VSBYs (mostly MVFR) for the morning with some improvement into the afternoon. Light and variable winds early then switching around to NE/E at times during the afternoon. Confid is low/medium overall.

Outlook...

Saturday night...MVFR and IFR conds in low CIGs, SHRA, fog.

Sunday...VFR. Lingering MVFR/IFR conds in the morning, improving to VFR by midday. Cannot rule out a SHRA or TSRA at KILG, KMIV, KACY.

Sunday night...VFR.

Monday through Wednesday...VFR. NSW.

MARINE

A weak cold front will cross the waters early tonight and then return as a warm front Saturday. Overall, winds and seas will remain sub-SCA tonight and Saturday. A few showers or a TSTM are possible this evening and into the early overnight Another period of possible showers/tstms will be around Saturday with chances in the high chance/low likely category.

Outlook...

Saturday night through Sunday...Sub-SCA conditions. VSBY restrictions in showers, scattered thunderstorms, and fog Saturday night through Sunday morning.

Monday through Wednesday...Overall, sub-SCA conditions. Cannot rule out a brief period of southerly 25+ kt gusts late Tuesday afternoon north of Barnegat Light.

Rip Currents...

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 mainly southeast around 10 mph. Given these conditions we'll continue with a LOW risk for the development of dangerous rip currents for both the Jersey Shore and Delaware Beaches.

For Sunday, winds shift to mainly northeasterly around 10 mph with continuing breaking waves in the surf zone around 2 feet with a 6 second period and southeast swell. So we'll continue with a 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.