textproduct: Philadelphia/Mt Holly

SYNOPSIS

High pressure passes through our region today through Sunday afternoon. A strong low pressure will move into the Great Lakes region on Monday, dragging a strong cold front through our region. The next low pressure system could approach our region Thursday into Friday.

NEAR TERM /THROUGH TONIGHT/

All Winter Weather Advisories were allowed to expire as wintry precipitation tapers off and road conditions improve. Rest of today will be rather quiet. Lowered ceilings and cloud cover will lift though the day and trends in the hires guidance now suggest that the tiny amount of instability that was potentially going to be developing across the northern areas is now not going to exist. Thus the light flurries/isolated snow showers that guidance was showing a few nights ago is unlikely for today. Expect seasonable cold temps across the region with some gusty winds along the land/sea interface.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/

Flow turns more southerly as a warm front approaches during the day Sunday. This will allow almost all of the region to warm above freezing (the only potential exception is the ridge lines in the southern Poconos). Rain is expected to accompany the warm front late Sunday afternoon into Sunday night. As it lifts through Sunday night, lingering cold air is likely to result in freezing rain in the southern Poconos and far Northwest NJ. However, temperatures should continue to increase overnight Sunday night, and by daybreak Monday, all lingering precipitation should be all rain.

For Monday, the main story is the cold front blowing through. Southerly winds ahead of it should push temps up into the 50s and even lower 60s. At this point it appears as if the cold front will sweep through our region from west to east from mid day through the afternoon. With the cold front coming through, we'll have some more showers, maybe even a rumble of thunder, but the main story will be the wind, which will be gusty from the south ahead of the front then switching northwest and getting very strong behind it. Wind gusts of 40 to 50 mph are possible. Wind advisories may be needed for portions of our region if our confidence increases in the wind threat.

LONG TERM /TUESDAY THROUGH SATURDAY/

In the wake of the cold front on Monday, some guidance is pointing to a potential for snow squalls on Tuesday, primarily for the southern Poconos and Northwest NJ. At this point though, there remains quite a bit of uncertainty if the area of higher RH in the lower levels will line up with the area of low level instability. For now, have stayed close to a blend of guidance, which keeps our region mostly dry.

Beyond that, the other main story in the long term is a fast moving low pressure system and associated cold front which could move through our region in the Thursday/Friday time period. This system will likely have very limited moisture with it, but if there is any precipitation associated with it, the temperature profiles and pattern look very favorable for a quick window of light snow.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

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

Rest of Today (through 23Z)...MVFR CIGs to prevail with occasional brief periods of VFR CIGs possible. An occasional flurry at TTN/ACY/MIV. North winds around 6-12 kt. Moderate confidence overall.

Tonight...Lingering MVFR CIGs early are expected to scatter out and lift to VFR. SCT/BKN high clouds expected thereafter. Patchy fog/freezing fog may be possible. North winds 5 kt or less, becoming light and variable at times. Moderate-high confidence.

Sunday...Primarily VFR expected with sub-VFR conditions possible with periods of light rain in the afternoon. South- southwest winds around 4-8 kt. High confidence.

Outlook...

Sunday night through Monday night...Sub-VFR conditions probable with periods of rain expected for Sunday night and Monday. VFR conditions should return by Monday night. Winds may gust up 30-40 kt on Monday afternoon into Monday night.

Tuesday through Wednesday night...VFR expected. Winds may gust up to 30-35 kt on Tuesday, otherwise no significant weather expected.

Thursday (New Years Day)...Sub-VFR conditions possible with a chance of light snow.

MARINE

SCA will be going into effect as winds increase of of the northeast 15-20 with gusts up to 25kts. Seas will be building to 4-6 feet with the occasional 7 foot wave depending on the wave trains colliding for the Atlantic Ocean Waters. Winds on the DE bay will generally be 10-20 and will make for choppy conditions but just under SCA.

Outlook...

Sunday...winds and seas should stay below SCA criteria.

Sunday night into Monday morning...Southerly winds increase above 25 kt and seas subsequently increase.

Monday afternoon through Tuesday...Expect an abrupt shift to westerly winds and winds to increase above gale force. This wind shift should come with a cold front on Monday afternoon, but the gale force winds are likely to continue through much of the day time on Tuesday.

Tuesday night through Wednesday...Winds should diminish, but SCA conditions are still likely through this period.

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Gale Watch from Monday afternoon through Tuesday afternoon for ANZ430-431-450>455. Small Craft Advisory until 9 PM EST this evening for ANZ450. Small Craft Advisory until 4 AM EST Sunday for ANZ451. Small Craft Advisory until 6 AM EST Sunday for ANZ452>455.