textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Updated Aviation section for the 12Z TAFs.

KEY MESSAGES

1. One disturbance passes off the Mid-Atlantic coast today, followed by a cold front late tonight through Sunday morning. A period of showers and thunderstorms is likely with localized flooding.

2. Fair weather is expected to return Monday and should last into the middle of next week.

DISCUSSION

KEY MESSAGE 1...One disturbance passes off the Mid-Atlantic coast today, followed by a cold front late tonight through Sunday morning. A period of showers and thunderstorms is likely with localized flooding.

The base of an upper trough associated with an H5 low over central Canada will move through the Mid-Atlantic later today. Some showers, perhaps a thunderstorm, will impact Delmarva and extreme southern New Jersey later this morning into early afternoon. However, the previous threat for flooding has diminished as the heaviest rain looks to stay south and east of the area. WPC has removed the Slight Risk (2/4) for Excessive Rainfall and the Marginal Risk (1/4) is focused on Delmarva and Cape May county in New Jersey.

A cold front approaches tonight and the upper trough becomes negatively tilted over the Northeast. Another round of showers and possible thunderstorms will develop late tonight and continue into Sunday morning. Instability will be marginal with up to 500 or so J/kg of SBCAPE and MUCAPE, but 0-6 km Bulk Shear values will be upwards of 45 to 50 kt. CAMs showing the potential for some strong to possibly severe thunderstorms mainly north and west of Philadelphia and into northern New Jersey after midnight tonight and into the pre-dawn hours Sunday morning. Locally heavy rain may lead to instances of localized flash flooding in these areas as well.

Cold front passes through the region late Sunday morning, and conditions improve Sunday afternoon.

KEY MESSAGE 2...Fair weather is expected to return Monday and should last into the middle of next week.

More zonal flow with some subtle ridging moves in for the first half of the week. At the surface, high pressure will mainly be in control, resulting in dry and tranquil weather through Wednesday. Temperatures should be seasonable through this stretch.

AVIATION /10Z SATURDAY THROUGH WEDNESDAY/

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

Today...MVFR CIGs in the morning, and MVFR CIGs may persist through the day. Cannot rule out CIGs lifting to VFR at all but KMIV/KACY, but confidence is low. VSBY restrictions in RA/BR at KMIV/KACY from morning through midday or so. E-SE winds 5 to 10 kt. Low confidence.

Tonight...CIGs lower to IFR with MVFR VSBYs. SHRA with TSRA, mainly at the I-95 corridor terminals and KRDG/KABE late. E-SE winds 5 to 10 kt. Low confidence.

Outlook...

Sunday...MVFR or lower in SHRA/TSRA. Improving conds in the afternoon.

Sunday night through Wednesday...VFR. NSW.

MARINE

Sub-Small Craft Advisory conditions on the waters today and tonight. East winds around 10 kt will become SE 10 to 15 kt later today and tonight. Ocean seas will average 2 to 3 ft. VSBY restrictions in showers and perhaps a thunderstorm today, then another round of showers and thunderstorms will impact the waters late tonight.

Outlook...

Sunday through Wednesday...No marine headlines expected. Showers continue Sunday morning, ending Sunday afternoon. Fair weather thereafter.

Rip Currents...

Today...East to southeast winds 10 to 15 mph with breaking waves of 2 to 3 feet and easterly swells with a period of 6 to 8 seconds will result in a MODERATE risk for the development of dangerous and life threatening rip currents for the Jersey Shore and a LOW risk for Delaware Beaches.

On Sunday, winds shift to the southwest at 10 to 15 mph in the morning, then to the west in the afternoon. Breaking waves will be 1 to 2 feet with light southerly swells with a 6 to 8 second period. As a result, there is a LOW risk for the development of dangerous and life threatening rip currents at the Jersey Shore and at 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.