textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Aviation section updated for the 12z TAFs.

KEY MESSAGES

1) Showers and thunderstorms return and increase along with increasingly more humid for the first half of next week. There is also the potential for areas of heavy rain and some strong to severe thunderstorms Tuesday.

DISCUSSION

KEY MESSAGE 1...Showers and thunderstorms return and increase along with increasingly more humid for the first half of next week. There is also the potential for areas of heavy rain and some strong to severe thunderstorms Tuesday.

As a strong upper-level ridge expands into the Plains early next week, northwesterly flow aloft will occur across much of the East. This ridge gets pushed back some as a potentially strong upper-level trough in eastern Canada sends spokes of energy southeastward across the Great Lakes and Northeast. This will initially allow for the upper-level trough to become more carved out across the Northeast by later this weekend. Some guidance maintains a vigorous shortwave riding over the ridge and sliding southeastward across the Great Lakes Monday and then across the Northeast during Tuesday. This results in some model solutions continuing to close off the trough across the Northeast Tuesday into Wednesday. Some other guidance is slower and weaker and thus does not close it off or briefly closes it off a day or two later. The upper-level system will drive surface low pressure and a cold front our way Tuesday into Wednesday. It will become much more humid during the first half of next week, with dew points looking to surge on Tuesday.

This will all result in an increase in convective chances Monday and especially Tuesday into Wednesday. While there remains some differences among the model guidance on the timing and strength of the features diving southeastward early next week, the setup would continue to favor upstream convective development given northwesterly flow aloft. This would be enhanced if the trough aloft closes off. Deeper moisture (dew points into the low 70s) advecting northward ahead of this feature with eventual cooling aloft and stronger forcing for ascent should result in widespread showers and some thunderstorms which maximizes on Tuesday. Depending on the evolution of this system, some areas of heavy rainfall (precipitable water values increase to 1.5-2.00 inches) and some severe thunderstorms are possible. The intensity and coverage of thunderstorms though may partially depend on the prior days convective development and then its evolution downstream.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

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

Today...VFR. Light and variable winds becoming northeast near 5 knots this morning, then becoming east to southeast 5-10 knots. Moderate confidence.

Tonight...VFR. East-southeast winds around 5 knots, becoming light and variable to calm. High confidence.

Outlook...

Sunday...VFR.

Monday...Some showers and thunderstorms in the afternoon and at night with some times of sub-VFR conditions.

Tuesday...Times of sub-VFR conditions with showers and thunderstorms. Southerly wind gusts up to 20 knots possible.

Wednesday...Some sub-VFR conditions possible with a few showers and thunderstorms.

MARINE

The conditions are expected to remain below Small Craft Advisory criteria through tonight.

Outlook...

Sunday and Monday...The conditions are anticipated to be below Small Craft Advisory criteria.

Tuesday...Small Craft Advisory conditions possible as southerly flow increases.

Wednesday...The conditions are anticipated to be below Small Craft Advisory criteria.

Rip Currents...

For today, east-northeast winds 10-15 mph with breaking waves of 2-3 feet in the surf zone with multiple swell groups and a period of around 7 seconds. For these reasons, a MODERATE risk for the development of dangerous rip currents continues at all beaches.

For Sunday, northeast winds of 10-15 mph become more easterly through the afternoon at 5-10 mph. Breaking waves of 2-3 feet in the surf zone remain with multiple swell groups and a period of 7-8 seconds. For these reasons, a MODERATE risk for the development of dangerous rip currents is maintained at all beaches.

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

PHI WATCHES/WARNINGS/ADVISORIES

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