textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Updated rip current section of Marine discussion.

KEY MESSAGES

1. Unsettled tonight and early Sunday morning before slow improvement by Sunday afternoon. 2. Heat and humidity build back into the region for the middle and end of next week. High temperatures will be well in the 90s to as high as 105 degrees, with maximum heat index values exceeding 105 degrees for multiple days.

DISCUSSION

KEY MESSAGE 1...Unsettled tonight and early Sunday morning before slow improvement Sunday afternoon.

A weak front has pushed south into Delmarva as of the early afternoon while high pressure remain across Quebec. A large area of low level moisture is across the area and with light winds, it won't move away much tonight. Showers and a few tstms have developed earlier across eastern PA which have since moved into NJ and Delmarva. One very strong TSTM affected Sussex County DE earlier. The upper system associated with the front will move across the area this evening and the chances for showers will decrease after that happens. Low clouds and some fog will be around much of the night. Lows will drop into the mid/upper 60s N/W and upper 60s to low 70s S/E. Winds will be be light tonight.

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 for multiple days.

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 return with high temperatures well into the 90s starting on Wednesday, then possibly as high as 105 on Thursday and Friday. Combined with surface dew points well in the 60s to low 70s, though dew points should drop a bit in the afternoon hours during peak heating of the day, the max heat index values will be over 100 degrees, likely exceeding 105 degrees. Thursday and Friday. Extreme Heat Warnings would be needed for several days.

13Z/27 NBM probabilities indicate probabilities of high temperatures exceeding 100 degrees of 30 to 50 percent for the southern Poconos, northern New Jersey, and Lehigh Valley both Thursday and Friday, and 70 to 90 percent for southern New Jersey, the Delaware Valley including Philadelphia, and Delmarva on both Thursday and Friday.

The mid-level ridge retrogrades back towards the south and west on Saturday, and a mid-level trough slides down into the Northeast. A back-door cold front will usher somewhat cooler temperatures as well as the potential for showers and thunderstorms next weekend. Convection may even begin as early as Friday evening.

Sunday

Slow improvement thru the day but likely starting with IFR or low-end MVFR at many terminals. Scattered showers are possible at most sites for the morning. Light North to Northwest winds developing. Low confid.

Outlook...

Sunday night...Any lingering SHRA or TSRA taper off. VFR.

Monday through Thursday...VFR. NSW.

MARINE

Winds and seas should continue to be below SCA levels through tonight and for Sunday. There will be a few TSTMs around with locally higher winds and seas possible. Showers will be frequent tonight and Sunday morning then decrease in coverage by afternoon. Seas will be mostly 1 to 2 ft on the ocean and calm to 1 ft for Delaware Bay.

Outlook...

Sunday night through Thursday...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 Sunday, winds shift to mainly northeasterly around 10 mph with continuing breaking waves in the surf zone around 2 feet with a 6 to 7 second period and southeast swell. We will continue with a LOW risk for the development of dangerous rip currents for both the Jersey Shore and Delaware Beaches.

For Monday, we're not expecting much change as breaking waves in the surf zone will be around 1-2 feet with east to northeast winds around 10 mph and a southeast swell. We'll continue with a LOW risk of dangerous rip currents for both the Jersey Shore and Delaware Beaches.

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

CLIMATE

Here is a list of the high temperature records for July 2 (Thursday) and July 3 (Friday):

Thursday July 2 Allentown...102/1968 Atlantic City Airport...100/1966 Atlantic City Marina...97/1968 Georgetown...99/1953 Mount Pocono...93/1911 Philadelphia...103/1901 Reading...102/1966 Trenton...100/1901 Wilmington...98/1966

Friday July 3 Allentown...105/1966 Atlantic City Airport...104/1966 Atlantic City Marina...99/1919 Georgetown...101/1954 Mount Pocono...103/1911 Philadelphia...104/1966 Reading...103/1966 Trenton...102/1966 Wilmington...102/1966

PHI WATCHES/WARNINGS/ADVISORIES

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