textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

No major changes were made to the forecast.

KEY MESSAGES

- 1) A slow moving cold front approaches and moves through the area on Friday, bringing the potential for heavy rain to portions of the area beginning on Thursday.

DISCUSSION

KEY MESSAGE 1...A slow moving cold front approaches and moves through the area on Friday, bringing the potential for heavy rain to portions of the area beginning on Thursday.

Upper level troughing pivoting over the Great Lakes region slowly tracks eastward through Friday, before the upper low tracks overhead on Saturday. At the surface, this translates a slow moving cold front approaching the region on Thursday, before slowly moving overhead and stalling nearby through Friday.

As the front approaches from the west, precipitation chances increase for those in the western portions of the forecast area throughout the day on Thursday. Those along and east of the metros will stay primarily dry with 30% chance of precipitation or less. Precipitation chances increase Thursday night into Friday as the cold front approaches and moisture increases. Beneficial rainfall is expected with REFS ensembles showing a 24 hour precipitation total swath stretching from southern Delaware across the New Jersey coast of 1 to 1.5 inches. Further west, precipitation totals range from a trace to an inch. Exactly where the heaviest precipitation totals line up remains uncertain and will be dependent on where the front stalls. Overall, expected precipitation, heavy for some, to return to the forecast this weekend.

The cold front departs offshore on Saturday, with dry conditions returning to the forecast. High temperatures will be noticeably cooler with highs in the upper 50s to mid 60s. Overnight low temperatures will be in the 40s for most. Temperatures continue cooling Sunday into early next week with highs in the upper 50s to low 60s and overnight lows in the 30s for most (40s metro areas).

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

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

Wednesday afternoon...South/southwest winds 5 to 10 knots. Terminals near the coast gust 15 to 20 knots.

Wednesday night...VFR conditions continue. Slight chance of showers at KRDG and then KABE. Winds light and variable. MVFR ceilings move in around 9Z.

Outlook...

Thursday through Saturday....Precipitation brings periods of sub-VFR conditions through Friday. Terminals near the coast will maintain VFR conditions. Wind gusts 15 to 20 knots are expected across the terminals Thursday morning and into the afternoon, before diminishing after sunset. Dry conditions are expected on Saturday as high pressure builds in over the terminals.

Saturday night through Sunday...VFR and dry conditions are expected. West winds blowing 5 to 10 knots with gusts between 15 and 20 knots possible on Sunday.

MARINE

Quiescent conditions expected on the waters through the overnight with southerly winds blowing around 10 knots. Seas 1 to 2 feet tonight.

Outlook...

Thursday...Winds are expected to remain below Advisory criteria, blowing less than 20 knots with seas of 2 to 4 feet.

Thursday night through Sunday... Winds near SCA criteria blowing around 20 knots over the open waters. Seas 3 to 5 feet are expected. Advisories are possible, mainly Thursday night. Winds shift from southerly to west/northwesterly on Saturday.

PHI WATCHES/WARNINGS/ADVISORIES

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