textproduct: Philadelphia/Mt Holly

SYNOPSIS

The region will remain between low pressure over Quebec and an expanding high centered over the South Central US through mid- week. A weak area of low pressure will pass to the north with a trailing cold front moving through the area Wednesday night. High pressure looks to build in beginning late Thursday and continuing into Friday. A couple of weak disturbances could approach the region this weekend into early next week.

NEAR TERM /THROUGH TODAY/

Tonight, the tight pressure gradient between departing low over Quebec and high pressure over the Gulf Coast will continue to lessen allowing gusts to diminish to less than 30 mph overnight. Skies will be mainly clear early, however will see a thickening and lowering in cloud cover after midnight as a strong, quick- moving shortwave approaches. This wave will be lacking moisture in the low levels as it treks east but may remain strong enough in the mid levels to overcome the dry air in place over the Mid- Atlantic. So, while there may be a slight chance (~20%) of snow showers near the I-95 corridor, have opted to at least include the mention of flurries areawide during the 4 AM to 10 AM timeframe on Wednesday. Outside of a light dusting in isolated areas, no accumulation is expected. Lows will be in the low to mid 20s with wind chills in the teens for the majority of the area, with mid to upper teens and wind chills in the single digits in the higher terrain.

Any lingering snow showers or flurries will depart by late morning as the shortwave swings offshore. Despite mostly cloudy skies in the morning, skies should become partly to mostly sunny during the afternoon with broad high pressure located over the Southeast US. Temperatures will be a tad warmer than those on Tuesday, with highs in the mid 30s to low 40s (mid to upper 20s in higher terrain). Fortunately, winds will be far less noticeable compared to previous days where gusts top out around 20 mph in the afternoon.

SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/

Broad upper-troughing will be in place across the northeastern CONUS through the period as an upper-low meanders over Quebec. A couple of shortwaves will pass near or through the region. The first looks to move through Wednesday night, with a second passing just to the north of the area Thursday evening. Northwesterly flow aloft and rising heights appear likely Thursday night as the trough axis begins to slide eastward. At the surface, A weak low will pass to the north of the area Wednesday night, with a trailing cold front passing through. Weak high pressure will build into the area in its wake.

As the cold front approaches and moves through the region Wednesday night, snow showers appear increasingly likely across portions of the area, with the greater chances generally along and north of I-78. However, a few snow showers could extend southwestward along the I-95 corridor as far southwest as northern DE late Wednesday night into Thursday morning. With cold temperatures firmly in place, some light accumulations are possible, with a coating 0.5-1" possible north of I-78 and perhaps 1-2" across the Pocono Plateau. South of I-78, any snow amounts appear negligible, perhaps a true dusting to couple tenths of an inch at best. This activity could also end up just being some scattered flurries. Lows Wednesday night look to be in the teens across the Poconos and into far northern NJ, and low-mid 20s elsewhere.

Behind the cold front and any associated snow showers/flurries, skies should clear during the day Thursday, but the reinforcing shot of cold air will keep temperatures below freezing for most of the area, with only portions of the Delmarva and far southern NJ rising into the mid 30s. It will also likely be breezy, with northwest winds gusting 20-30 mph. This could lead to wind chill values 10-15 degrees below actual air temperatures. The shortwave passing to the north of the area Thursday evening is not expected to result in any precipitation as the area will be devoid of any moisture. Skies should start mostly clear, but increasing clouds are expected late. Temperatures look to bottom out in the teens areawide Thursday night, with some upper single digits possible across the Poconos and into far northern NJ.

LONG TERM /FRIDAY THROUGH TUESDAY/

At the moment, the extended range forecast looks fairly uneventful, with only a couple of chances for light precipitation. Temperatures should remain generally below normal through the weekend.

The upper-air pattern appears fairly benign, with troughing remaining in place over the much of the Northeast. There are some indications that a more progressive pattern could begin to take shape early next week. At the surface, a weak wave of low pressure looks to develop off the Eastern Seaboard Saturday and track eastward, with high pressure taking shape for Sunday. By Monday, the high should start to slide eastward with another area of low pressure potentially approaching from the Great Lakes region.

Depending on the placement of the wave of low pressure Saturday, some light rain could make its way into portions of the Delmarva, but amounts currently appear negligible. In fact, many deterministic models keep precipitation south of the area entirely. The next chance for meaningful precipitation appears to be on Monday. Some of it could be of the wintry variety, but for now amounts appear insignificant.

Temperatures through the entire extended range look to be cold, with highs generally in the 30s to near 40 and lows in the teens and 20s.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

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

Early this morning...VFR with 5000 ft CIGs. Some light SHSN or flurries possible, but not expecting restrictions so will not include in the TAF at this time. W-NW winds 10 to 15 kt with gusts up to 20 kt. Moderate confidence.

Today...VFR. CIGs 5000-8000 ft. W-SW winds 10 to 15 kt with 20 to 25 kt gusts.

Tonight...VFR initially. Sub-VFR possible in SHSN, especially at KRDG/KABE. For now, confidence is too low to warrant including in the TAF. SW winds 5 to 10 kt. Low confidence.

Outlook...

Wednesday night through Thursday...Primarily VFR. Brief restrictions can't be ruled out in snow showers, particularly overnight Wednesday into early Thursday morning at ABE/RDG/TTN.

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

MARINE

Winds have begun to decrease and as a result, the Gale Warning has been replaced with a Small Craft Advisory. The SCA continues for all coastal waters, including the Delaware Bay, through the overnight hours.

Westerly winds of 15-20 kt with gusts up to 30 kt possible tonight. Winds become southwesterly through the day on Wednesday with gusts decreasing to around 20-25 kts so marginal SCA conditions may continue throughout the day. Seas around 4-7 feet this evening will subside to 2-4 feet later tonight into Wednesday. Aside for a stray snow shower, fair weather is expected outside of marine headlines.

Outlook...

Wednesday night through Thursday night...SCA conditions are likely, with west winds 20-25 kt gusting up to 30 kt. Seas 3-5 feet.

Friday through Sunday...No marine hazards currently anticipated, with winds below 25 kt and seas below 5 feet.

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 6 AM EST early this morning for ANZ430-431-450>455.