textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Refreshed Key Messages and mentioned new Day3 SPC Outlook changes.

Updated rip current forecast.

KEY MESSAGES

1. High pressure keeps the area dry through into much of Saturday.

2. Late this weekend into early next week, a trough will bring cooler weather and a chance for rain.

DISCUSSION

KEY MESSAGE 1...High pressure keeps the area dry through into much of Saturday.

High pressure over the Appalachians will slowly edge eastward overnight and into Saturday. This will lead to clear skies and mild tonight with lows in the low 60s and some upper 50s for the NW most areas.

High pressure is expected to remain in control across the region through the end of the week leading to dry conditions. The pleasant weather will continue through most of Saturday with a slight chance for a shower or thunderstorm Saturday afternoon and evening mainly for the Poconos. A Marginal risk for Severe weather is in the latest Day3 outlook from SPC for our northern and western counties.

A gradual warming trend will also take place into Saturday with high temperatures reaching near or into the low 90s for both Friday and Saturday. Shore areas and the southern Poconos are expected to be cooler with highs in the 80s.

KEY MESSAGE 2...Late this weekend into early next week, a trough will bring cooler weather and a chance for rain.

After the period of dry and tranquil conditions, a positively tilted upper-level trough digs in from the northwest Sunday into the beginning of next week. Our surface high pressure system weakens and moves offshore over the weekend. When the trough moves in, a surface low pressure system should develop in response. There are differences between the deterministic guidance as to if this will be a closed surface low or a trough, but regardless, the net effect appears to be a cooling trend, especially going into Monday as a cold front sinks southward.

On the precipitation side of things, showers become possible Saturday evening/night with perhaps a thunderstorm. The bulk of the precipitation is slated for Sunday with scattered showers developing along with some thunderstorms as our cold front moves south. Depending on the timing and how the atmospheric conditions evolve, the potential for an isolated stronger to severe thunderstorm may be possible. The latest SPC outlook has a Marginal risk for severe weather for the western and northern parts of our region. This would be the southern Poconos. The exact extent of the precipitation and timing is a bit more uncertain given the variations among deterministic guidance on how the surface pattern takes shape. Beyond Sunday, a few showers may linger into Monday with the cold front remaining close to the area.

AVIATION /20Z THURSDAY THROUGH TUESDAY/

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

Rest of Today...VFR with just some high clouds at times. Winds under 10 knots. The tricky issue is wind direction with W or SW directions favored inland and S or SE locally close to the shore. Better chance for SE/E winds at KACY/KMIV. A couple gusts 15 kts during any sea breeze. High confid except with regards to winds directions.

Tonight...VFR/SKC. S to SW winds 5 kt or less. High confidence.

Friday... VFR expected. High clouds at times. SW winds 5 to 10 knots expected.

Outlook...

Friday night and Saturday...Mainly VFR. A slight chance (20%) for a shower or thunderstorm at KABE/KRDG later Saturday.

Saturday night through Sunday...Sub-VFR possible due to showers and thunderstorms.

Monday and Tuesday...VFR. No significant weather.

MARINE

sub-SCA conditions and fair weather through Friday. Winds will become onshore S to SE most areas 10 to 15 kts with a few gusts 20 kts into the early evening.

Outlook...

Friday night...Sub-SCA conditions probable.

Saturday...SCA conditions possible Saturday night with a southwest wind 15-20 kt with gusts to 25 kt and seas of 4-5 feet. Showers and tstms for Saturday evening/night.

Sunday through Monday...Another period of SCA conditions possible Sunday night into Monday with winds potentially gusting up to 25 kts and seas around 4-6 feet. Showers and tstms for Sunday.

Rip Currents...

For both Friday and Saturday, winds will be out of the south/southwest around 10-15 MPH, a general offshore direction. With an 8 second period and breaking waves around 2 feet, opted for a LOW risk for the development of rip currents for the Jersey Shore and Delaware Beaches.

Ocean water temperatures are in the upper 50s to low 60s. These chilly water temperatures can quickly cause hypothermia and physical incapacitation to anyone suddenly immersed in the water.

For specific beach forecasts, visit weather.gov/beach/phi

PHI WATCHES/WARNINGS/ADVISORIES

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