textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

1. High pressure will remain in control through tonight, bringing cooler and less humid conditions.

2. Warmer and more humid conditions return Sunday, along with daily chances for showers and thunderstorms into the middle of the week.

DISCUSSION

KEY MESSAGE 1...High pressure will remain in control through tonight, bringing cooler and less humid conditions.

High pressure will remain in place through tonight, with a cooler and much drier airmass in place. After a nice day with temperatures only in the mid 70s to around 80, a cool night is in store with lows mainly in the mid 50s to low 60s. Some patchy fog cannot be ruled out in sheltered areas as winds will be very light to calm overnight allowing temperatures to radiate down to near-saturation, especially in areas that have received substantial rainfall recently and have residual ground moisture. Increasing clouds late should temper this potential enough that widespread or dense fog appears unlikely.

KEY MESSAGE 2...Warmer and more humid conditions return Sunday, along with daily chances for showers and thunderstorms into the middle of the week.

Broad upper level ridging returns to the eastern US early next week, bringing in surface high pressure across the eastern US. Afternoon highs will creep back into the mid 80s to low 90s, about 5 degrees above average for early September. Dewpoints will also creep back into the upper 60s to low 70s.

Convection potential will return starting Sunday, although any showers and storms should remain fairly isolated to widely scattered in nature and focused mainly along and NW of the I-95 corridor. Instability will be the limiting factor. Severe storms are unlikely, though gusty winds, small hail, and brief heavy downpours are possible with any stronger storms.

One other aspect to watch with this ridging pattern is the potential for thunderstorms to rotate around the periphery of the ridge and the position of a warm front next week. The exact location, timing, and intensity of the thunderstorms remains a bit uncertain at this range. Currently, the main days to monitor are Tuesday and Wednesday regarding heavy rain and severe weather potential.

AVIATION /19Z SATURDAY THROUGH THURSDAY/

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

Rest of today...VFR. Winds generally north to northeast around 5 kts, gradually shifting more southwesterly after 20Z. Sea and river breezes could lead to winds being more southerly for PHL, MIV, and ACY. High confidence overall, with lower confidence in wind direction.

Tonight...Prevailing VFR, though there is a low chance (less than 20%) of some patchy fog, particularly for MIV and ACY. Winds favoring a south-southwesterly direction at less than 5 kts, with calm periods likely. Moderate confidence overall.

Sunday...Primarily VFR. Isolated to scattered showers and storms will be possible in the afternoon and evening, which could lead to restrictions after 18Z. RDG and ABE have the highest chance for restrictions, but they cannot be ruled out as far southeast as the I-95 terminals. South winds 5-10 kts. Moderate confidence.

Outlook...

Sunday night through Thursday...Restrictions possible in showers and thunderstorms each day, mainly during the afternoon to evening hours.

MARINE

No prevailing marine hazards expected. Northeast winds 10-15 kts should shift southeasterly at around 5-10 kts by this evening. Winds will shift south-southwesterly at 10-15 kts on Sunday. Seas 2-3 feet. Showers and storms are possible beginning Sunday evening, particularly for the northern NJ coastal waters.

Outlook...

Sunday night and through Thursday...No prevailing marine hazards expected. Chances for thunderstorms each day, mainly in the afternoon and evening hours.

Rip Currents...

On Sunday, south to south-southwest winds of 5-10 mph increase to 10-15 mph in the afternoon. Breaking waves of 1 to 2 feet. A light southeasterly swell with a period around 8 seconds will remain. As a result, there is a LOW risk for the development of dangerous and life threatening rip currents at the Jersey Shore and Delaware Beaches.

On Monday, north to northwest winds in the morning will shift to east in the afternoon around 5 mph. Breaking wave heights around 1 foot. A light southeasterly swell with a period around 8 seconds will remain. This will continue to lead to a LOW risk for the development of dangerous and life threatening rip currents at the Jersey Shore and Delaware Beaches.

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

PHI WATCHES/WARNINGS/ADVISORIES

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