textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1. A cold front will work its way through the Great Lakes and Ohio Valley tonight, slowly crossing the Northeast and Mid- Atlantic Friday night through Saturday. One round of showers and thunderstorms will develop tonight, then more widespread showers will develop on Friday night and 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 work its way through the Great Lakes and Ohio Valley tonight, slowly crossing the Northeast and Mid-Atlantic Friday night through Saturday. One round of showers and thunderstorms will develop tonight, then more widespread showers will develop on Friday night and Saturday.

A cold front will slowly work its way through the Great Lakes and Ohio Valley tonight, and will be just west of the local forecast area Friday morning. With some shortwave energy passing through northeast Pennsylvania, northern New Jersey, and the Hudson Valley out ahead of the front, a round of showers and possible thunderstorms will develop over the southern Poconos and far northwest New Jersey as early as this evening, but the bulk of the activity will hold off until closer to midnight or so. Low level moisture will increase as dew points will creep up into the lower 60s. While the threat for severe weather is low, a few thunderstorms cannot be ruled out. Locally heavy rain may result in minor flooding, but the threat for flash flooding is also quite low.

There will be a lull in the rainfall during the day Friday. Temperatures will creep back up into the upper 80s and low 90s with surface dew points in the 60s.

Low pressure drags that cold front closer to the region Friday night, and low pressure and the cold front will move through the region Friday night through Saturday. Widespread showers with locally heavy rain and a few thunderstorms from time to time are expected. In general, 1/2 to 1 inch of rain will fall, with locally higher amounts possible in any training of thunderstorms. The clouds and rain will keep temperatures cool on Saturday with highs in the 70s to low 80s.

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 in 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 in the 90s and max heat index values around 100 degrees.

13Z/25 NBM has a 50 to 70 percent probability of high temperatures greater than 95 degrees for Thursday and Friday, though as high as 80 percent for portions of Delmarva on Friday.

The Weather Prediction Center currently has a category 2 (Moderate) to category 3 (Major) risk for heat related impacts for New Jersey, southeast Pennsylvania, and Delmarva for Wednesday.

AVIATION /19Z THURSDAY THROUGH TUESDAY/

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

Rest of Today...VFR conditions continue through today. Rainfall is expected to hold off through the daytime hours. Winds gusts of 15-20 knots will continue through the afternoon, before diminishing by sunset. High confidence.

Tonight...VFR conditions are expected to continue through tonight. Showers and thunderstorms are expected to approach the area from the west later this evening. Will begin with vicinity showers by 04z, with PROB30 for showers through 10z, for RDG/ABE/TTN. Vicinity showers will be possible for PHL/PNE, but most activity will dissipate as they approach the Philadelphia area. There is a chance for isolated thunderstorms, but will keep out of the TAFS for now due to low probabilities. Winds will shift to southerly as gusts drop off by sunset, then become light and variable during the overnight hours for most places. Medium confidence on coverage and maintenance of SHRA/TSRA.

Friday...VFR conditions continue as any showers will continue to dissipate through 12z/13z. Winds will shift to southwest, then west, then northwest through the day with speeds 5-10 knots. High confidence.

Outlook...

Friday night through Saturday night...MVFR and IFR in low CIGs/SHRA/scattered TSRA/BR.

Sunday through Tuesday...VFR. NSW.

MARINE

Conditions remain below advisory levels through Friday. Winds may gust around 15 to 20 knots, with a brief gust near 25 knots at times this afternoon and this evening. Winds shift from the south today, to southwest overnight through Friday.

Outlook...

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

Rip Currents...

On Friday, southerly winds around 10 mph with breaking waves in the surf zone on the lower side of mainly 1-2 feet. 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.