textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Updated aviation section for 12Z TAFs.

KEY MESSAGES

1. Low pressure continues to pass through the region. Additional rounds of showers and thunderstorms with the potential for severe weather and flash flooding are likely for today, though the main risk will shift southward into the Delmarva.

2. Another cold front is expected to approach the region late this week, bringing more chances for showers and storms.

DISCUSSION

KEY MESSAGE 1...Low pressure continues to pass through the region. Additional rounds of showers and thunderstorms with the potential for severe weather and flash flooding are likely for today, though the main risk will shift southward into the Delmarva.

For today, the forecast continues with the theme of slower movement out as the system looks to get hung up over the area. The latest indications continue to show a new low to develop near near Delmarva. This will occur as another piece of energy moves around the base of the upper trough over the east, and will result in more rounds of showers and storms that could once again be on the heavier side by the afternoon. Near the warm sector over the Delmarva and far southern NJ, we can't rule out some storms becoming severe and the SPC now has a MARGINAL risk for severe storms. A heavy rain threat will also persist with a MARGINAL risk for excessive rainfall in this region as well. Further north, cooler more stable air should result in lighter rains and less risk of severe weather, particularly from Philadelphia northwards.

Low pressure with it's associated showers/storms should finally move out through tonight.

KEY MESSAGE 2...Another cold front is expected to approach the region late this week, bringing more chances for showers and storms.

Another cold front is expected to approach our region late in the week (likely crossing through our region Friday into Saturday). More showers/storms are likely beginning as early as late day Thursday and then continuing Friday. Southwesterly flow ahead of the front should allow for plenty of moisture advection ahead of the rain chances. However with the best forcing more centered north of the region, that could limit how widespread significant rain is with this event. As for what hazards to expect with this event, that will be highly dependent on the timing of the showers and storms, which is still uncertain.

The front may linger nearby next weekend and if this occurs it would keep chances for shower/storms going, especially in the afternoon/evening hours. There is uncertainty regarding this though.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

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

Today...Sub-VFR conds in the morning in BR and stratus with another round of SHRA with scattered TSRA will impact most terminals from late morning through late afternoon with MVFR/IFR conds. Winds become N around 10 kt from late morning on. Moderate confidence.

Tonight...Becoming VFR. Winds may gust 20 kts from N-NW in the evening. Moderate confidence.

Outlook...

Wednesday...VFR. No significant weather.

Thursday through Saturday...Chances for shower/storms return (30 to 50 percent chances) beginning late day Thursday and these could bring brief restrictions.

MARINE

Winds have relaxed over the waters and the SCA has been cancelled. Showers and a few more storms are likely today however, a few of which may be gusty. As the low pulls away late today into tonight, another period of SCA conditions will be possible late today into tonight due to gusty N/NW winds.

Outlook...

Wednesday through Saturday...Sub SCA conditions.

Rip Currents...

Today, winds will be out of the south to southwest around 10 mph, turning to the north to northeast at 10 to 15 mph with gusts up to 20 mph in the afternoon. Breaking waves will be 1 to 3 feet with a light southeasterly swell with a period around 6 seconds. As a result, there is a LOW risk for the development of dangerous and life threatening rip currents for the Jersey Shore and Delaware Beaches.

On Wednesday, winds will be northwest in the morning, turning southwest around 10 mph in the afternoon. Breaking waves will be 1 to 2 feet with a light southeast swell with a period around 7 seconds. As a result, there is a LOW risk for the development of dangerous and life threatening rip currents for 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.