textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Updated aviation section.

KEY MESSAGES

1. Additional rounds of showers and storms through Friday. Cooler and drier conditions for the weekend.

2. There is potential for minor tidal flooding during the evening high tides this week along the Atlantic coast, Delaware Bay, and tidal Delaware River, especially on Tuesday and Wednesday.

DISCUSSION

KEY MESSAGE 1...Additional rounds of showers and storms through Friday. Cooler and drier conditions for the weekend.

A quasi-stationary boundary will linger around Wednesday and Thursday before fully pushing through Friday. Chances for showers and thunderstorms will arrive as upper level shortwaves ride along the boundary over the next few days.

Latest forecast guidance in addition to radar trends have largely backed off on any aggressive convection this morning, with only a spotty shower or two around. Mostly dry conditions are now expected during the day Wednesday before another round of isolated showers and thunderstorms arrives Wednesday evening and into the overnight hours. Once again, the coverage and evolution of these storms will be reliant on upstream MCS/thunderstorm cluster propagation across the Ohio Valley, adding a frustrating level of uncertainty to the forecast. Overall, however, forcing will be rather weak with limited elevated instability to work with given that the timing of these storms will be largely after the diurnal heating cycle in the evening and into the overnight hours. Deep layer shear will be only modest, around 35 kts or so, but that overall weak forcing will likely limit the severe threat.

Additional rounds of upper level shortwaves look to ride along the quasi-stationary boundary as it gradually sinks south Thursday into Friday. North of the front, a drier and cooler airmass will filter in while isolated showers and thunderstorms will linger along and south of the front. The cold front looks to finally push through late Friday, finally bringing a more pronounced break in convective potential and more pleasant weather conditions for the weekend. Highs over the weekend will be in the low to mid 80s. Dewpoints Saturday will be comfortably in the mid 50s to low 60s before creeping back up Sunday into the mid to upper 60s. Another round of showers and thunderstorms arrive late Sunday into Monday.

KEY MESSAGE 2...There is potential for minor tidal flooding during the evening high tides this week along the Atlantic coast, Delaware Bay, and tidal Delaware River, especially on Tuesday and Wednesday.

As we approach the New Moon Wednesday, astronomical tides for the evening high tide cycles will increase to around a half foot below minor flood stage in many areas this week along the Atlantic coasts of New Jersey and Delware, Delaware Bay, and the tidal Delaware River. With tide departures running around a half foot above average, this will raise a threat of minor flood stage being reached for these areas.

We will continue to monitor the tide departures in the coming total water level forecasts. Coastal Flood Advisories remain in effect for Wednesday evening's high tide cycle. At least spotty minor tidal flooding should be anticipated around the times of the evening high tides this week with the potential for additional Advisories depending on the tidal departures. The highest astronomical tides will occur Wednesday. The threat of minor tidal flooding may linger through Thursday or Friday as well.

Tidal flooding is not currently forecast for the Eastern Shore of the Chesapeake Bay.

AVIATION /09Z WEDNESDAY THROUGH SUNDAY/

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

Wednesday...VFR. An isolated shower or TSRA possible N/W late afternoon may bring brief restrictions. N winds 5 to 10 kt, backing to the W in the afternoon. Moderate confidence.

Wednesday night...Prevailing VFR. Restrictions possible with evening/overnight isolated showers and thunderstorms. Low confidence.

Outlook...

Thursday thru Saturday...Mostly VFR. No significant weather expected.

Sunday...VFR early then scattered showers/tstms with restrictions possible.

MARINE

No prevailing marine hazards expected through Wednesday night.

Outlook...

Thursday through Friday...No prevailing marine hazards expected. Thunderstorms possible each afternoon and evening.

Saturday...No marine headlines are anticipated.

Sunday...Possible SCA conditions developing late.

Rip Currents...

For Wednesday...Light winds around 5 to 10 mph will gradually turn from northwesterly in the morning to southeasterly in the late afternoon. Breaking wave heights will remain around 2 feet or less with a southerly 1 foot swell around 5 to 7 seconds. With little changes in overall conditions, will continue with a LOW risk for dangerous rip currents at all beaches.

For Thursday...A southwesterly wind around 5 to 10 mph. Breaking wave heights will remain around 2 feet or less with a southeasterly 1 foot swell around 6 to 8 seconds. Due to these conditions there is a LOW risk for dangerous rip currents at all beaches.

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

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...Coastal Flood Advisory from 10 PM this evening to 2 AM EDT Thursday for NJZ016. Coastal Flood Advisory from 7 PM this evening to 1 AM EDT Thursday for NJZ021-023-024. DE...Coastal Flood Advisory from 10 PM this evening to 2 AM EDT Thursday for DEZ001. Coastal Flood Advisory from 7 PM this evening to 1 AM EDT Thursday for DEZ002>004. MD...None. MARINE...None.