textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

No significant changes have occurred to the forecast.

KEY MESSAGES

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

2. A couple waves of low pressure may impact the region through the middle of next week with periods of wintry precipitation possible.

3. A significant warm-up is expected late next week.

DISCUSSION

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

Mild temperatures are expected through Saturday under mostly sunny skies. The warmth will come to an end by Saturday night though as an arctic front crosses the region. While moisture is limited with the main forcing for ascent to our north, 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 into Sunday morning where C-1" is possible. For areas south of I-78, PoPs drop off and temps are warmer so precipitation will likely be either a rain/snow mix or plain rain. No accumulations expected south of I-78. After precipitation exits, it will be noticeably colder on Sunday with an increasing northerly breeze and decreasing clouds.

KEY MESSAGE 2...A couple waves of low pressure may impact the region through the middle of next week with periods of wintry precipitation possible.

A cold airmass is forecast to be in place on Monday into Tuesday as arctic high pressure from Canada builds over the Northeast. As of this morning, guidance has become in better agreement that a couple separate systems will pass close to or over the area. The first will come on Monday into Monday evening with the second coming later Tuesday into Wednesday.

Starting with the Monday system, weak low pressure is forecast to track east out of the Tennessee Valley along a stalled frontal boundary. With the strong, arctic high to the north, guidance keeps this system suppressed to the south while tracking off the coast near the Chesapeake region. Suppose a period of light snow may impact the area later Monday, but PoPs have continued to decrease to the 20-40% range. Trends in accumulations with this system continue to decline as well. As this system exits, another disturbance is forecast to ride along this boundary which will then impact the region late Tuesday into Wednesday, though timing differences amongst guidance persists. With temperatures gradually warming on Tuesday into Tuesday night as a southerly flow regime sets-up a rain/snow mix may occur at the onset before changing over to plain rain into Tuesday night. PoPs during this period have increased, now in the 50-70% range.

KEY MESSAGE 3...A significant warm-up is expected late next week.

In wake of wintry systems earlier in the week, a significant warm-up is expected starting late next week into next weekend. GEFS and ECENS guidance are in pretty good agreement that positive height anomalies are forecast over the eastern CONUS with troughing over the western CONUS. CPC probabilities suggest that there is a 60-70% chance that temperatures will be above normal. Current forecast highs for late week are in the 50s and 60s.

AVIATION /07Z FRIDAY THROUGH TUESDAY/

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

Rest of tonight (through 12Z)... VFR conditions are expected overnight. Winds will be light and variable overnight.

Friday...VFR conditions expected through the period. Patchy shallow early morning fog possible, but confidence in coverage is low. Light winds early will vary from the southeast to southwest in the afternoon, staying around 5 knots or less. High confidence overall.

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

Outlook...

Saturday through Saturday night...VFR. No significant weather expected.

Sunday through Sunday night...Sub-VFR conditions possible in the morning, with VFR expected in the afternoon. A chance of light snow or light rain possible in the morning. Winds gusting up to 20 kt in the afternoon, diminishing at night.

Monday through Tuesday...Prevailing VFR with periods of sub-VFR possible. A chance of light snow expected late on Monday with a chance of a rain/snow mix expected on Tuesday.

MARINE

Conditions will remain below advisory levels through Friday night.

Outlook...

Saturday through Saturday night...No marine headlines expected. Winds generally less than 10 kt and seas around 2 feet.

Sunday through Sunday night...Small Craft Advisory conditions possible with winds gusting up to 25 kt. Seas around 2-4 feet.

Monday through Tuesday...No marine headlines expected. Winds generally less than 15 kt and seas around 2-3 feet.

PHI WATCHES/WARNINGS/ADVISORIES

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