textproduct: Philadelphia/Mt Holly

SYNOPSIS

A weak clipper system will pass by to the north on Sunday. High pressure moves in Sunday night through Tuesday morning, with a frontal system moving in for the mid-week period. High pressure takes over in the wake of the frontal system for the Thanksgiving holiday through the end of the week, resulting in dry but cold weather.

NEAR TERM /THROUGH SUNDAY/

Low pressure off the southeast New Jersey coast continues to track east as a cold front works its way through the region. Surface high pressure briefly builds into the Northeast tonight before sliding offshore Sunday morning. A clipper system, an H5 trough with strong shortwave energy currently over central Canada just north of the Northern Plains, will approach on Sunday and will move into eastern Canada and northern New England Sunday afternoon.

Any lingering rain tapers off early this afternoon, and skies will clear out going into this evening.

Some weak shortwave energy may result in some high clouds late tonight, mainly over the southern Poconos, Lehigh Valley, and far northwest New Jersey. For the rest of the area, skies will be mostly clear to partly cloudy. One thing to watch out for late tonight and into Sunday morning is the development of fog. The ground will not get a chance to sufficiently dry out from rainfall last night into this morning given that sunset is so early and there may not be enough sunshine to dry the ground out. With a cooler and drier airmass building into the region due to that area of high pressure, that ground moisture should result in the development of fog, especially where skies are clear and winds are nearly calm. For now, not expecting dense fog, but cannot rule out some locally dense fog, especially in the Pine Barrens of New Jersey and away from the coasts in Delmarva. 12Z HREF showing probability of visibility less than 1 mile generally 10 to 20 percent across portions of New Jersey and southeast Pennsylvania. Also cannot rule out the potential for some patchy freezing fog with temperatures dropping below freezing. Lows tonight will be in the upper 20s to low 30s.

With the clipper system passing north of the area on Sunday, some rain and/or snow showers are possible, mainly for areas north of I-78, and those snow showers would be limited to the higher elevations of the southern Poconos. PoPs will generally be slight chance to low end chance. QPF will be minimal. For the rest of the area, skies will generally be partly cloudy. Highs will be in the upper 40s to low 50s, though in the mid and upper 50s in Delmarva.

SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/

Our clipper system exits Sunday night which allows for colder air to filter in which continues into Monday. Lows Sunday night are in the 30s. Highs on Monday reach the mid 40s to mid 50s. Behind this cold front there is an expansive area of high pressure. On Sunday night, there are some hints at some lingering light showers in the Poconos but these look to end through sunday night. The winds will also increase Sunday night with cold air advection and a tighter pressure gradient taking place. Generally wind gusts will be 15-25 mph with gusts in the Poconos upwards of 35 mph. Winds do start to diminish through the day Monday. For Monday and Monday night, we look completely dry with a mostly clear sky during the day Monday. Clouds do start to increase Monday night ahead of our next system that arrives Tuesday.

On Tuesday, a warm front will be lifting northward through the area which is attached to a deepening low pressure system near the Great Lakes region. This warm front along with the high pressure system moving offshore will set the stage for warmer air to filter in Tuesday into Tuesday night. We are cloudy Tuesday with rain starting to move in by midday and becoming more widespread Tuesday evening. Highs on Tuesday are in the low 50s to low 60s.

LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/

Periods of rain continue Tuesday night into Wednesday. The first cold front with the deepening low now moving into Canada will move through Wednesday night. This will result in more periods of rain into Wednesday night. In the temperature department, we see lows Tuesday night in the mid 40s to mid 50s. Highs on Wednesday are in the 60s for most. By Wednesday night, lows are in the 30s for many.

After the cold front departs into Thanksgiving morning, the trend continues to be drier for Thanksgiving day at this point. There is the signal for things to turn on the windier side and the colder air filtering in has highs in the mid 40s to low 50s. Another reinforcing cold front moves through Thanksgiving night which results in more cold air moving in. An expansive surface high builds in from the west on Friday, but with the westerly flow, it keeps the cold air advection going. Highs on Friday will be in the mid 30s to mid 40s with the potential for some windy conditions. The potential for windy conditions for the end of the week looks to be a combination of the strong cold air advection allowing for stronger winds aloft to mix down along with a tight pressure gradient from the deepening low to the north and the expansive high building in from the west.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

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

Rest of today...Lingering MVFR CIGs will become VFR by 21Z. N-NW winds 5 to 10 kt. High confidence.

Tonight...Overall, VFR. However, there is the potential for VSBY restrictions in mist/fog developing by 04Z. Confidence is too low to include BR in the 18Z TAF, but the potential cannot be ruled out. Best chances will be at KRDG/KABE/KTTN/KMIV/KACY. NW winds less than 10 kt, becoming LGT/VRB. Low confidence.

Sunday...VFR. Cannot rule out a brief, light SHRA at KABE in the afternoon. SW winds less than 10 kt. Moderate confidence overall.

Outlook...

Sunday night through Monday night...VFR. No significant weather.

Tuesday through Wednesday night...Sub-VFR conditions expected with periods of showers and low clouds.

Thursday...Sub-VFR conditions possible early and then becoming VFR.

MARINE

Sub-Small Craft Advisory conditions through Sunday. North to northwest winds 10 to 15 kt with gusts up to 20 kt, becoming less than 10 kt late tonight. Winds become southwest 10 to 15 kt by Sunday afternoon. Seas 2 to 3 feet. Fair weather.

Outlook...

Sunday night through Monday..A Small Craft Advisory has been issued for all marine zones from Sunday night through early Monday afternoon for wind gusts of 25 knots.

Monday Night through Tuesday...No marine headlines expected.

Tuesday night...SCA conditions possible with wind gusts near 25 kt.

Wednesday and Wednesday night...No marine headlines expected.

Thursday...SCA conditions possible with wind gusts near 25 knots.

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory from 7 PM Sunday to 1 PM EST Monday for ANZ430-431-450>455.