textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Updated the aviation section for the OOZ TAFs.

KEY MESSAGES

1. A warm front on Thursday will bring the next chance for widespread rain.

2. A cold front is expected to follow close behind on Friday.

DISCUSSION

KEY MESSAGE 1...A warm front on Thursday will bring the next chance for widespread rain.

By Thursday, high pressure moves offshore with southerly return flow behind a warm front will bring dew points into the low 70s. Showers will start moving into western areas before daybreak and continue through the day.

As for the hazards, there is a marginal (1 out of 4) risk for excessive rainfall. Precipitable water values increase to perhaps as high as 150% of normal for this time of year. Guidance suggests that the heaviest precipitation will be generally north and west of the I-95 corridor and much of the heavy recent rains have been further south. At this point the threat for widespread flooding appears to be limited.

For severe hazards, will have to continue to monitor, but instability and shear appear to be limited with this event, therefore minimizing the severe potential.

KEY MESSAGE 2...A cold front will cross the area Friday.

The timing of this cold front will be critical in the risk for thunderstorm hazards. There are differences between models in both the timing, and if this will be a single cold front, or an initial cold front with a reinforcing shot of cold air advection coming in behind it. Saturday and Sunday appear to be dry across most of the area with the exception of southern areas Saturday where low probabilities of showers and storms will exist.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

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

Tonight...VFR. Northwesterly winds initially become light and variable through the night. Some patchy fog is possible overnight but was too low confidence to include in the TAFs at this time.

Wednesday...VFR. Light and variable winds in the morning become more out of the southwest at around 5 knots during the afternoon.

Outlook...

Wednesday Night and Thursday...Prevailing VFR, but showers and storms after 06Z Thursday continuing at times through the day could lead to temporary flight restrictions.

Friday...Periods of MVFR or lower are possible in showers and storms.

Saturday and Sunday...Prevailing VFR conditions.

MARINE

No marine hazards expected. Light winds and no restrictions to visibility expected Wednesday.

Outlook...

Thursday and Friday...Gusts near 20 kt are possible, particularly on Thursday with southerly winds behind a warm front.

Saturday and Sunday...No marine hazards expected.

Rip Currents...

On Wednesday, winds will shift southerly and increase to near 10 to 15 mph in the afternoon. A medium period swell will persist with breaking waves around 2 feet during much of the daytime. As a result, there is a LOW risk for the development of dangerous and life threatening rip currents at the Jersey Shore and at Delaware Beaches.

For Thursday, winds remain southerly at 10 to 15 mph with gusts to 20 mph. An east-southeasterly swell remains with a period of 8-9 seconds with breaking waves around 2-3 feet. As a result, there is a MODERATE risk for the development of dangerous and life threatening rip currents at the Jersey Shore and a LOW risk at Delaware Beaches.

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

PHI WATCHES/WARNINGS/ADVISORIES

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