textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Added a key message for tidal flooding this weekend.

Updated Aviation Discussion for 12z TAFs.

KEY MESSAGES

1. Unsettled weather will continue for today and Saturday as a cold front slowly moves through. A Marginal Risk (1/5) for Severe Weather is in place for today with a Marginal Risk for Excessive Rainfall (1/4) in place both days.

2. Drier and warmer conditions return by the end of the weekend into next week.

3. Minor tidal flooding possible this weekend for coastal communities and areas around Delaware Bay.

DISCUSSION

KEY MESSAGE 1...Unsettled weather will continue for today and Saturday as a cold front slowly moves through. A Marginal Risk (1/5) for Severe Weather is in place for today with a Marginal Risk for Excessive Rainfall (1/4) in place both days.

A cold front slowly sags down from the north, which will result in some showers and thunderstorms developing this afternoon and evening. Coverage will be less compared to yesterday, and it should be an overall less impactful day as well. Cannot rule out some stronger to severe thunderstorms today with a modest instability profile, though shear is on the weaker side. Most of the area remains in a MARGINAL (1/5) Risk for severe weather which is about right as the threat for widespread severe thunderstorms is limited.

In terms of the flash flood threat today, PWATs won't be as high compared to yesterday and there is less of a signal for training of storms compared to yesterday. Storm motion should be high enough to also limit flooding concerns. However, if some thunderstorms were to move over urban areas or areas that have seen significant rainfall in the last week, some flooding cannot be ruled out. Overall though, the threat is much lower compared to yesterday.

Some showers/isolated thunderstorms could linger for some of the night as the front takes its time to drop through the region. However, things should have stabilized by that point with little to no risk of impactful weather.

By Saturday morning, the cold front is progged to bisect our area and continuing to slowly move south, continuing a trend of a slower frontal passage. This will result in one final day of unsettled weather, with showers and thunderstorms focused along and south of the front as the day goes on. Thinking most of the activity will be along and south of I-76 and I-195. Currently outlooked in general thunder which is about right given things should be more stable and shear remaining week. Similar to today though, there is a low risk for flash flooding, mainly over areas that have seen significant rainfall over the last 7 days and for urban areas. A Marginal (1/4) Risk for excessive rainfall is in place from Philly on south. Not anticipating too many issues, though if the development of storms is focused over certain areas, there could be some isolated flash flooding.

The cold front should finally clear the area by Saturday Night, ushering in a period of dry weather beginning on Sunday.

KEY MESSAGE 2...Drier and warmer conditions return by the end of the weekend into next week.

By Sunday and into early next week, guidance is showing an expansive upper level ridge setting up over the northern High Plains. This will yield dry weather and mainly sunny/clear skies across the majority of the Mid-Atlantic region. Temperatures will be around normal for Sunday, Monday and Tuesday, but will swing back above normal for Wednesday and Thursday. Medium to longer range guidance shows a potential hot day on Wednesday with highs potentially getting well into the 90s. Does not look like anything we experienced to start July, but still noteworthy nonetheless.

KEY MESSAGE 3...Minor tidal flooding possible this weekend for coastal communities and areas around Delaware Bay.

A light onshore flow sets up for this weekend, resulting in a minor push of water towards the coastline. Astronomical tides also begin to increase with the upcoming New Moon on Tuesday. This will result in elevated tides with minor tidal flooding possible beginning with the high tide Saturday evening. Guidance hints at tidal flooding continuing with the evening/nighttime high tide cycles into early next week before flow turns more southerly. However, there will be a stronger influence of astronomical tides as we get towards the New Moon which could keep elevated tides through the middle of next week. The areas most at risk of seeing minor tidal flooding are along the Atlantic Ocean coastline and within Delaware Bay. The severity looks to remain within minor levels but will monitor how things trend over the coming days. No plans for Advisories yet but it would not be a surprise for some Coastal Flood Advisories being needed for the weekend.

Cannot rule out some spotty minor tidal for communities along the Delaware River with the upcoming elevated tides. No tidal flooding is expected in our Eastern Shore zones along the Chesapeake Bay.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

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

Today...Primarily VFR after 12z with fog dissipating. Scattered showers and thunderstorms are expected to develop this afternoon and evening, though coverage will be more limited compared to Thursday. Model guidance this morning has even trended down a bit in terms of coverage. As a result, ended up going with VCSH with PROB30 groups this afternoon for the I-95 and Lehigh Valley terminals. Chance of showers and thunderstorms at each terminal between 18z-00z is around 30-40%. Any showers/thunderstorms should hold off around KMIV/KACY until tonight. Winds out of the west/northwest around 10 kt. Moderate confidence.

Tonight...Primarily VFR. Some showers and isolated thunderstorms possible (30-40%) through the night at KACY/KMIV. With a stalled frontal boundary nearby and light winds, some patchy fog is likely to develop after 06z. Have included MVFR conditions after 06z at all sites, but cannot rule out conditions dropping down to IFR (10-20% chance). Winds generally light/variable under 5 kt though a northerly direction may be favored at times. Low confidence.

Outlook...

Saturday...Primarily VFR, though another day of unsettled weather with showers/thunderstorms may result in some restrictions, mainly for the I-95 and South Jersey terminals.

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

MARINE

Sub-SCA conditions expected through tonight. West/southwest winds around 10-15 kt and seas 2 to 3 feet

Outlook...

Saturday through Tuesday...No marine headlines expected.

Rip Currents...

For today, while we have multiple swell groups, low wave heights around 2 feet or less and offshore winds will result in a LOW risk for rip currents at the Jersey Shore and Delaware Beaches.

For Saturday, flow turns more onshore, but winds will be light around 10 MPH or less. Multiple swell groups will also remain but with relatively calm conditions (1 to 2 foot breakers), thinking the rip current risk remains LOW at all shore points.

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

PHI WATCHES/WARNINGS/ADVISORIES

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