textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

06Z TAF update.

No significant changes otherwise.

KEY MESSAGES

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

A weak surface trough will cross the region early this morning, touching off some showers and possibly a thunderstorm across portions of the southern Poconos, northern New Jersey, and the Lehigh Valley through the early morning hours. Conditions should clear out by daybreak.

Mostly sunny, warm and humid today with surface dewpoints rising into the upper 60s and low 70s. Highs will top off in the mid to upper 80s. As a result, max heat index values will be around 90 degrees, perhaps in the low 90s in Delmarva and extreme southern New Jersey.

Another cold front approaches later today. 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 this afternoon and tonight.

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 /06Z THURSDAY THROUGH MONDAY/

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

Early this morning...VFR. Some SHRA, possibly a TSRA at KRDG/KABE up until 12Z. Light SW winds. Moderate confidence.

Today...VFR. W winds 5 to 10 kt in the morning, turning W-NW 10 to 15 kt with gusts up to 20 kt after 18Z. There is the chance for some SHRA/TSRA, mainly at KMIV/KACY, and possibly at the I-95 corridor terminals. Will not include in the TAFs at this time. Moderate confidence.

Tonight...Mostly VFR, though sub-VFR possible at KMIV/ACY. Potential for SHRA/TSRA as well. Light NW winds. Low confidence.

Outlook...

Friday through Friday night...VFR. No significant weather.

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

Small Craft Advisories remain up for all waters for west to southwest winds 15 to 20 kt with gusts up to 25 kt. The SCA ends on Delaware Bay at 8 am, then comes down on the ocean waters from south to north through the late morning hours.

By this afternoon, west to southwest winds will range from 5 to 10 kt.

Tonight, west winds 5 to 10 kt will turn north late.

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...

Today, southwest winds will range from 15 to 20 mph with gusts up to 25 mph in the morning, diminishing to 5 to 10 mph late. Breaking waves will be 2 to 3 feet with an 8 to 9 second period. Given winds turn more offshore and will gradually be decreasing through the day, elected to go with a LOW risk for the development of dangerous and life threatening rip currents at the Jersey Shore and Delaware Beaches.

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

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 8 AM EDT this morning for ANZ430- 431. Small Craft Advisory until 2 PM EDT this afternoon for ANZ450>453. Small Craft Advisory until 10 AM EDT this morning for ANZ454- 455.