textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Updated aviation section for 12z TAFs

Small Craft Advisory extended for Delaware Bay through 6PM today.

KEY MESSAGES

1. A cold front continues to approach this afternoon and evening bringing some showers and perhaps a rumble of thunder, though no significant impacts are expected.

2. The overall weather pattern remains unsettled through the weekend with cool temperatures late week giving way to a warming trend over the weekend.

DISCUSSION

KEY MESSAGE 1...A cold front continues to approach this afternoon and evening bringing some showers and perhaps a rumble of thunder, though no significant impacts are expected.

A cold front currently draped over central Pennsylvania continues to slowly inch its way toward our region. The initial round of light rainfall has come and gone.

As the front comes through this evening, there could be some isolated low topped thunderstorms right along the front. Storms will be mainly for South Jersey and Delmarva, but we cannot rule out a rumble of thunder for eastern PA early in the evening. No severe weather is expected from any storms. The front slowly sags south and east, with some showers possible overnight south/east of I-95, but nothing significant expected. With the slow progression of the front, high res guidance is suggesting some showers will linger across southeast NJ and the Delmarva come Thursday morning. Overall rainfall amounts from this evening forward will only add on a few hundredths across the I-95 corridor and points north and west to perhaps 0.25-0.35 inches across the southeast NJ and southern Delmarva.

KEY MESSAGE 2...An unsettled pattern for Friday and the weekend.

An upper trough will remain across the Great Lakes and Northeast this weekend before heading off the coast early next week. The trough will allow several weak shortwaves to move across the Middle Atlantic and bring opportunities for showers or perhaps a thunderstorm (Sat afternoon). Pops are greatest for Saturday and then after a break (Sat night/Sun, morning) they climb again for Sunday (late afternoon and night and into Monday). These rains will bring additional relief for the overall dry conditions over our region.

Temperatures will generally be cooler than normal. One exception will be for Sunday when readings will climb into the mid/upper 70s for the N/W areas and upper 70s/low 80s elsewhere. The rest of the Fri-Tue. period will have highs in the mid/upper 60s with low 70s S/E. These temps are 2 to 4 degrees below normal.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

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

Rest of today (through 00Z)...MVFR cigs will prevail across the region. A period of IFR cigs are possible for RDG/ABE/TTN/PNE, mainly before 00Z. VCTS possible for RDG/ABE before 00Z, but confidence and coverage is low. Brief periods of MVFR VSBYs possible at times, though have highest confidence in lower visibilities for the Lehigh Valley terminals. Winds out of the south/southeast around 10-15 kt and gusts 20-25 kt. Low confidence.

Tonight...Winds shift and become west/northwesterly early this evening as a cold front passes. Winds should diminish with the frontal passage and hover around 10 kt or less. While some stratus may hang on as the front passes, would expect improvement to VFR by 04z-07z. Moderate confidence.

Thursday...VFR. Northwest winds 5 to 10 kt. High confidence.

Outlook...

Thursday night/Friday... VFR expected.

Friday night/Saturday... Showers with lower CIGs/VSBYs possible.

Saturday night/Sunday morning... VFR expected.

Sunday night/Monday... Widespread lower CIGs/VSBYs possible with frequent showers.

MARINE

A Small Craft Advisory is in effect for all marine zones through early this evening. Winds out of the south/southwest around 15-20 kt with gusts near 25 kt on Delaware Bay and near 30 kt over the open ocean. Seas of 4 to 7 feet.

Winds diminish this evening as a cold front passes, and become northwesterly around 10-15 kt overnight. This will allow the SCA to expire for Delaware Bay at 6 PM tonight, but seas within the ocean zones remain in the 4 to 6 foot range until 8AM Thursday.

Marine conditions will remain below SCA criteria for the remainder of Thursday.

Outlook...

Overall, winds and seas look to remain below SCA levels for Friday and into the weekend. The synoptic systems look to be weak and show little impact on seas. A few solutions have shown a possibly stronger low offshore Sunday/Monday and this may create SCA conditions if it develops. Fair Friday. Showers Saturday and again Sunday night/Monday.

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ430- 431. Small Craft Advisory until 8 AM EDT Thursday for ANZ450>455.