textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Increasing risk of low clouds and fog overnight into tomorrow morning.

Aviation section updated.

KEY MESSAGES

1. Milder tonight with some patchy fog and frost possible.

2. Elevated risk of rapid fire spread expected Saturday behind a mostly dry cold front. A mainly dry weather pattern continues through the weekend.

3. A significant warm up is expected for the early and middle part of next week.

DISCUSSION

KEY MESSAGE 1...Milder tonight with some patchy fog and frost possible.

A southerly flow tonight will result in some moderation to the airmass and slightly warmer temperatures. Lows for the most part will remain just above freezing and in the mid 30s, though some more sheltered and rural areas could fall below freezing. A large majority of any freezing temperatures will be in areas where the growing season has not started yet.

However, low dewpoint depressions tonight could result in some frost developing where the growing season is active. With temperatures in the mid 30s, patchy frost is likely to develop within more rural areas away from the I-95 corridor and away from the coast (where temperatures could be warm enough to preclude frost development). In addition, with RHs expected to be between 95-100% tonight, some low clouds and patchy fog cannot be ruled out either. Given uncertainty about coverage of fog vs frost, will hold off on any frost advisories and just have included patchy frost and patchy fog in the forecast.

KEY MESSAGE 2...Elevated risk of rapid fire spread expected Saturday behind a mostly dry cold front. A mainly dry weather pattern continues through the weekend.

A cold front will move through the region Friday night. A few light showers may accompany the frontal passage, mainly up in the Poconos, though as of right now the potential for a wetting rainfall remains low (15% chance or less). Widespread RHs around 25-35% are expected to follow on Saturday with northwest wind gusts potentially increasing to around 25-35 mph. Saturday continues to bear watching for fire weather concerns, as a result. Otherwise, dry conditions should prevail through the weekend.

KEY MESSAGE 3...A significant warm up is expected for the early and middle part of next week.

After a seasonable weekend, a significant warming trend will likely take place across the area early next week. High pressure will initially build back in across the region in the wake of the cold front this weekend, before shifting east and allowing for a prolonged period of return flow. By mid-week, high temperatures could surge well into the 80s across much of the area, with overnight lows only falling into the 60s. 90 is not out of the question in the typical hot spots.

A few weak disturbances could bring a slight chance for a few showers to northern parts of the area Monday night. Otherwise, conditions are expected to remain dry until at least Wednesday, when a cold front may begin to approach the area from the northwest.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

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

Through this morning (16z)...Another round of stratus has developed and satellite does show that it has gotten to the I-95 corridor. Unlike yesterday though, stratus appears to be struggling to move much further inland towards KRDG/KABE. Kept those terminals VFR through the night though cannot rule out some MVFR/IFR condiitons developing towards daybreak.

For the I-95 and South Jersey terminals...MVFR CIGs likely drop to IFR as the morning goes on. Patchy fog is expected towards the coast, potentially impacting KMIV/KACY with VSBYs under 1SM. Areas of fog likely develop right up to the I-95 terminals but kept fog out of the I-95 TAFs except for KTTN. Conditions should quickly improve to VFR between 12z-13z.

Confidence is low overall in timing and extent of restrictions.

This Afternoon...VFR. Southerly winds around 10 kt with gusts up to 20 kt. High confidence.

Tonight...VFR. Winds start out around 5-10 kt out of the southwest with some low-level wind shear ahead of a cold front. Winds shift quickly and become northwesterly sometime after 04z, around 10 kt. Slight chance of showers (20%) at KRDG/KABE but not expecting any restrictions at this time. Moderate confidence.

Outlook...

Saturday through Tuesday...VFR. No significant weather.

MARINE

Tranquil conditions on the waters expected through tonight. Winds out of the east/southeast around 10 kt or less with 2 to 4 foot seas. Marginal Small Craft Advisory possible later Friday with waves possibly reaching 5 feet, but holding off on headline for the time being.

Outlook...

Friday night through Saturday...SCA conditions possible. Winds may gust to 25 kt and seas may reach 4-6 feet Friday night and continue through Saturday.

Saturday night through Sunday night...No marine hazards anticipated. Winds under 25 kt. Seas under 5 feet.

Monday...SCA conditions possible. Southerly winds gusting near 25 kt. Seas increase to 4-6 feet.

Monday night through Tuesday...No marine hazards anticipated. Winds under 25 kt. Seas under 5 feet.

PHI WATCHES/WARNINGS/ADVISORIES

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