textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Light snow and freezing rain may impact the area during the Tuesday morning commute.

KEY MESSAGES

1. Low pressure riding along an arctic front will bring some wintry weather to portions of the area today.

2. Several waves of low pressure will impact the area starting Monday night with wintry precipitation possible during the Tuesday morning commute.

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

DISCUSSION

KEY MESSAGE 1...Low pressure riding along an arctic front will bring some wintry weather to portions of the area today.

An arctic front is tracking through the area this morning and should stall out over the Delmarva around daybreak. A wave of low pressure riding along this front will track east across the area later this morning before moving offshore this afternoon. This will allow a period of wintry precip to work its way into the area, mainly north of the PA Turnpike and I-195 in NJ. At the onset, there is a slight threat for some spotty freezing rain as surface temps will be around freezing and a warm nose aloft lingers with the stalled boundary nearby. As colder air slowly infiltrates south, precipitation should change over to a period of light snow before ending. Any ice accretion would be sporadic in nature and confidence in occurrence is low, so no headlines have been issued. Snow accumulations in these areas will mainly range from a coating to up to an inch. Elsewhere, mainly just some rain showers are expected through the morning, before ending by early afternoon. Perhaps a stray snowflake may mix in before precipitation ends.

Temperatures today will mainly range in the mid 30s to mid 40s from north to south under mostly cloudy skies. Skies will begin to clear by mid-afternoon with winds around 10-15 mph. Tonight, cold air will advect in with another blast of "winter-like" temps. Lows will range in the teens and 20s. Factoring in the wind, wind chills will mainly be in the teens, with single digits in the higher terrain.

KEY MESSAGE 2...Several waves of low pressure will impact the area starting Monday night with wintry precipitation possible during the Tuesday morning commute.

Arctic high pressure will be over the Gulf of Maine Monday night, but will still have an impact on the area with sub- freezing temperatures Monday night into Tuesday morning. A warm front will lift north through the region both behind the offshore high and low pressure moving through the Midwest. Precipitation develops after midnight Monday night, initially as some snow, but then as mid-level warm air lifts north and overrides cold air at the surface, snow should mix with and change to freezing rain from south to north during the early Tuesday morning hours. Snowfall will generally be less than an inch, and a light ice accretion is possible as well. Wintry precipitation will change to plain rain throughout by Tuesday afternoon, though the wintry mix may hold a bit longer in the southern Poconos. Rain then continues through Tuesday night as low pressure passes north of the area.

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

A spring-like warmup will develop over the area starting on Wednesday and continuing through at least Saturday. For some areas, highs will be some 15 to 20 degrees above normal, especially starting on Thursday.

Bermuda high pressure sets up off the Southeast and Mid-Atlantic coasts for the middle to the end of the week. While several impulses will pass through the region, bringing rain from time to time, strong warm air advection will be in place. Highs on Wednesday will generally be in the mid to upper 50s for southeast Pennsylvania and New Jersey, and in the low to mid 60s across Delmarva. Then it really gets warm.

The 01Z/01 NBM indicating a 20 to 40 percent probability of high temperatures over 65 across southeast Pennsylvania and New Jersey, generally south of I-78, and from 50 to 80 percent from north to south through Delmarva. A weak cold front knocks temperatures down by some 5 to 10 degrees on Friday, then the warmth returns for Saturday. The 01Z/01 NBM indicating a 20 to 40 percent probability of high temperatures over 65 north of I-78, and 40 to 60 percent across the rest of southeast Pennsylvania and southern New Jersey and 60 to 80 percent from north to south through Delmarva. Some spots, mainly inland, may exceed 70!

AVIATION /12Z SUNDAY THROUGH THURSDAY/

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

Today...Prevailing VFR conditions expected. There may be a brief period of MVFR ceilings between 12-16Z with precipitation. A rain/snow mix possible at RDG, ABE, TTN and PNE with light rain elsewhere. North winds around 8-13 kt may occasionally gust up to 20 kt. Moderate-high confidence, but lower confidence with regards to timing.

Tonight...VFR and SKC. North winds around 5-10 kt. High confidence.

Outlook...

Monday...VFR.

Monday night...Primarily VFR. Sub-VFR conditions could develop late in light SN.

Tuesday through Tuesday night...Sub-VFR conditions expected in RA/SN/FZRA Tuesday morning, then RA Tuesday afternoon into Tuesday night. Conds should improve late Tuesday night.

Wednesday through Thursday...Primarily VFR. Brief periods of sub-VFR conditions are possible with a chance of RA.

MARINE

No marine headlines are in effect through tonight. North- northeast winds around 10 kt this morning will increase to around 15-20 kt this afternoon and continue through tonight. Gusts up to 22-25 kt are possible at times, but due to sporadic nature, have opted to hold off on issuance of SCA headlines at this time. Seas around 2-4 feet.

A chance of rain/snow showers this morning. Spotty freezing spray possible tonight. Otherwise, fair weather expected.

Outlook...

Sunday night...Sub-SCA conditions.

Monday through Tuesday...Sub-SCA conditions expected with winds below 25 kt and seas below 5 feet.

Tuesday night through Wednesday...SCA conditions possible. South-southwesterly winds 10-15 kt and gusts 20-25 kt with seas 3-5 feet. Conditions are likely to improve through the day on Wednesday.

Wednesday night...Sub-SCA conditions expected with winds below 25 kt and seas below 5 feet.

Thursday...SCA conditions possible with southwesterly winds increasing to 10-15 kt and gusts 20-25 kt. Seas 3-5 feet.

PHI WATCHES/WARNINGS/ADVISORIES

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