textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Precipitation has ended across the area. Chances for fog have decreased overnight.

KEY MESSAGES

1. An arctic front late Saturday night into Sunday may bring some snow to our northern areas.

2. An area of low pressure may impact our region early next week with wintry precipitation possible.

DISCUSSION

KEY MESSAGE 1...An arctic front late Saturday night into Sunday may bring some snow to our northern areas.

The warmth will come to an end Saturday night into Sunday as an arctic front crosses the region. There is limited moisture with this front with the main forcing for ascent lifting to our north, however a ribbon of forcing with the wind shift should generate some light precipitation. The main precipitation may end up being behind the front with cooling aloft taking place, therefore some snow is possible north of I-78 late Saturday night and Sunday morning. South of I-78, even less precipitation may occur and it also may end up being a little to warm and therefore some light rain or rain/snow mix for a time. Given limited moisture and quick movement of the system, any snow accumulations at this point look to be rather light. It will be noticeably colder Sunday with an increasing northerly breeze.

KEY MESSAGE 2...An area of low pressure may impact our region early next week with wintry precipitation possible.

A much colder air mass is forecast to be in place early next week as arctic high pressure from Canada builds nearby. There will be one or more ripples of energy in the northern stream that will initiate some precipitation. The timing and strength of these features within a trough aloft will determine the details. Some guidance is weaker with the trough and associated energy and therefore less precipitation, while focusing on a secondary short wave that delivers more of the precipitation on Tuesday compared to Monday. There still remains the potential for a period of wintry precipitation Monday and/or Tuesday, however uncertainty remains as the model guidance continues to differ on the handling of the upper- level features. The pattern does look conducive though for an overrunning snow or wintry mix setup with arctic high pressure to the north and energy arriving from the west. It is a matter of how much the moisture attacks the cold air across our region, with also how far south the arctic high pushes. Given the continued uncertainty, did not make any changes to the latest NBM guidance which has 30-50 PoPs across the area Monday and Tuesday.

AVIATION /01Z FRIDAY THROUGH TUESDAY/

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

Tonight... VFR conditions are expected overnight. Winds will be light and variable overnight.

Friday...VFR conditions expected through the day once any early morning fog lifts. Light and variable winds early will become southeast through the morning, then southwest by the afternoon with speeds around 5-10 knots or less. Confidence is the forecast is high after any early morning fog.

Outlook...

Friday night...VFR overall. Some fog/low clouds possible late.

Saturday and Sunday...Some fog/low clouds possible to start Saturday. Some snow possible near KRDG and KABE late Saturday night into Sunday morning. Otherwise, mainly VFR. Northwest wind gusts to 20 knots possible on Sunday.

Monday and Tuesday...A period of sub-VFR conditions along with snow and/or rain possible.

MARINE

Conditions will remain below advisory levels through Friday.

Outlook...

Friday night and Saturday...No marine headlines are anticipated.

Sunday and Monday...Small Craft Advisory conditions possible.

Tuesday...The conditions should be below Small Craft Advisory criteria.

PHI WATCHES/WARNINGS/ADVISORIES

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