textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1. A strong cold front passing through the region late tonight into early Friday morning will bring showers with beneficial rainfall and breezy conditions.

2. Mild and unsettled pattern takes hold as early as Monday night next week.

DISCUSSION

KEY MESSAGE 1...A strong cold front passing through the region late tonight into early Friday morning will bring showers with beneficial rainfall and breezy conditions.

Modest southwest flow ahead of tonight's cold front will yield warm temperatures into tonight. Temperatures will remain in the 60s overnight until frontal passage with southwest winds gusting 20-30 mph.

Showers will begin to spread into the area from north to south late this evening and into the overnight period. While a stray shower cannot be ruled out as far south as the Philly metro this evening, most areas will likely not experience rain until after midnight (prior to midnight near/north of I-78). Some rumbles of thunder and brief downpours will be possible overnight, however severe thunderstorms are not expected.

The frontal system will continue pushing south and clear our Delmarva zones by mid morning. The showers will also continue spreading south, where rainfall for our far southern NJ and Delmarva counties will be focused mainly during the daytime Friday. Periods of rain will continue off and on through the day for these areas. Farther north, especially near and northwest of I-95, conditions will dry out be midday under mostly cloudy skies.

Generally expecting around 0.25-0.50" of rainfall across the board through Friday, with localized amounts up to 1" possible. Long story short, a beneficial rainfall event for our area.

Winds will shift northerly behind the front and remain breezy, with gusts 20-30 mph gradually diminishing into the afternoon. Temperatures will fall to near 50 degrees behind the front, and remain steady during the daytime Friday. Temperatures then falling into the mid 20s to low 30s Friday night into Saturday morning.

KEY MESSAGE 2...Mild and unsettled pattern takes hold as early as Monday Night next week.

Cool high pressure that dominates this weekend resulting in dry and quiet weather will move offshore on Sunday. Return flow sets up, ushering in a warmer airmass after below normal temperatures on Saturday, and near normal temperatures on Sunday. Warm south/southwesterly flow for the beginning and middle part of next week will result in a stretch of above normal temperatures for the early and middle portion of next week.

While it will be on the more mild and warmer side next week, there will be multiple chances for rain as several frontal systems slide by. None of these systems look overly impactful at this point, but there could be some periods of rain, beginning late Monday and continuing off and on through the middle of the week.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

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

Tonight...VFR conditions will prevail for most of the night, however scattered showers may briefly result in MVFR conditions, especially after 06Z. LLWS ahead of a cold frontal passage between 07-12Z, then a period of MVFR conditions and steadier rainfall likely following FROPA. A low chance (10-20%) of brief thunder, but probability is too low to include a TAF mention. Southwest winds 10-15 kts prior to FROPA, with some occasional gusts up to 25 kts, then shifting northerly following FROPA. High confidence in general progression of conditions, but lower confidence on details of exact timing.

Friday...Some MVFR ceilings possible early (especially at MIV/ACY), then VFR conditions should prevail. Periods of light rain linger for MIV/ACY much of the day, but conditions should be mainly VFR after 15Z. Northerly winds 10-15 kts, gusting up to 25 kts early, then winds diminishing after 18Z. High confidence overall.

Outlook...

Friday night...VFR. North to northwest winds 5-10 kts, with some gusts up to 20 kts possible late.

Saturday...VFR. Northwest wind gusts between 20-25 kt.

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

MARINE

South to southwest winds 15-25 kts with gusts up to 30 kts will continue through tonight. Winds increase across Delaware Bay tonight. A cold front will pass offshore early Friday morning, and winds will shift northerly around 10-15 kts with gusts up to 20 kts on Friday. Seas 4-6 feet across the Atlantic waters through Friday morning.

A Small Craft Advisory is now in effect through noon Friday for the Atlantic waters. The Small Craft Advisory remains in effect for Delaware Bay for tonight.

Outlook...

Friday night through Saturday...Advisory conditions expected as wind gusts 25-30 kt pick up after a cold front moves through late Friday Night. Gusts continue through Saturday afternoon. Seas could near 5 feet at times.

Saturday night through Sunday night...No marine hazards expected.

Monday...Advisory conditions likely (60-70%) as winds pick up out of the south/southwest around 20-25 kts and seas 4 to 6 feet.

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 8 AM EDT Friday for ANZ430-431. Small Craft Advisory until noon EDT Friday for ANZ450>455.