Marine Weather and Tide Forecast for Philadelphia, PA

KEY MESSAGES
1. A cold front will cross through the area into tonight, bringing the potential for a round of showers and thunderstorms.

2. Another disturbance will approach the area Saturday into Sunday and produce a round of showers and thunderstorms.

DISCUSSION
KEY MESSAGE 1...A cold front will cross through the area into tonight, bringing the potential for a round of showers and thunderstorms.

Another cold front approaches into tonight. Highest instability will be across Delmarva and southern New Jersey where SBCAPE values will be as high as 500 to 750 J/kg, and MUCAPE values will be slightly higher. PWATs will be 1.5 to 1.75 inches in Delmarva where locally heavy rain is possible. In these areas will be the highest chances for convection, mainly after midnight through around daybreak Friday.

Following any morning showers, Friday will shape up to be a nice day with clouds breaking later in the day and humidity falling into the afternoon. Highs in the upper 70s to low 80s in most areas.

KEY MESSAGE 2...Another disturbance will approach the area Saturday into Sunday and produce a round of showers and thunderstorms.

In the wake of Thursday's cold frontal passage, high pressure will briefly build into the region for Friday. Dry conditions are expected with temperatures generally in the 70s to near 80.
However, guidance continues to indicate that the front will stall somewhere over the Carolinas before lifting slowly back north towards the area for the weekend. A mid-level shortwave looks to pass through the area Saturday night and an area of surface low pressure is likely to ride along the boundary as it shifts slowly northward into the area.

Confidence is increasing in scattered shower and storm activity across the region Saturday through Saturday night. As of right now, instability looks to be meager, limiting any severe storm threat. However, forecast soundings across the area indicate deeply saturated vertical profiles, especially across the southern half or so of the area. PWATs look to exceed 2 inches.
Given this, any storms across the area could be efficient rainfall producers. As such, there does appear to be some potential for isolated instances of flash flooding. The WPC has highlighted the entire area with a Marginal Risk (1 of 4) in their latest Excessive Rainfall Outlook to account for this potential.

Some time late Saturday night or Sunday, the front and low pressure will track offshore, bringing an end to the shower and storm chances and a return of tranquil conditions to start the next work week. With that said, timing discrepancies limit confidence on Sunday, as a slower progressing system could lead to rain chances lingering at least into Sunday afternoon.

In terms of temperatures, they look to hold fairly steady in the mid 70s to mid 80s through the weekend and into early next week, with perhaps a slow warming trend.

AVIATION /00Z FRIDAY THROUGH TUESDAY/
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.

Tonight...Primarily VFR. Some scattered showers move through KACY/KMIV but rainfall should be light. Cannot rule out brief VSBY restrictions but did not include any in the TAF at this time due to low probability (10-20% chance). Winds start out of the west/northwest then become more northerly between 04z-06z, around 5 kt or less. Moderate confidence.

Friday...VFR. Winds start north/northeasterly around 5 to 10 kt, eventually become more northwesterly by the afternoon. A sea- breeze may develop resulting in more east/southeast winds at KACY/KMIV but winds should be rather light. Moderate confidence.

Friday Night...VFR. Winds light and variable. High confidence.

Outlook...

Saturday through Sunday...Periods of sub-VFR conditions will be possible with scattered showers and storms.

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

MARINE
Tonight, west winds 5 to 10 kt will turn north to northeast late. Showers and a rumble of thunder possible overnight through around dawn on Friday.

Outlook...

Friday through Monday...No prevailing marine hazards anticipated with winds below 25 kt and seas below 5 feet.
Scattered showers and storms will be possible Saturday and into parts of Sunday.

Rip Currents...

On Friday, winds turn more northerly and will be around 5 to 10 mph. Breaking waves decrease to 2 feet or less. Dominant swell will be around 1-2 feet with a period of 6 to 8 seconds from the southeast. With more tranquil conditions expected to close out the week, there will be a LOW risk for rip currents at all beaches.

On Saturday, winds turn more onshore, from the ESE to SE, around 10-15 mph. Breaking waves remain around 1-2 feet. The dominant swell will be around 1 foot with a period of 9 seconds from the southeast. Given the more robust onshore flow, there will be a MODERATE risk for rip currents at New Jersey beaches and a LOW risk for rip currents at Delaware beaches.

PHI WATCHES/WARNINGS/ADVISORIES
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.