Area Forecast Discussion

WHAT HAS CHANGED

Aviation section updated for 0z TAFs.

The Tornado Watch has been cancelled for our eastern PA and northern NJ zones.

KEY MESSAGES

1. There continues to be an elevated risk for severe thunderstorms and flash flooding this evening and Wednesday, with the greater risk through this evening.

DISCUSSION

KEY MESSAGE 1...There continues to be an elevated risk for severe thunderstorms and flash flooding this evening and Wednesday, with the greater risk through this evening.

As of early this evening, there are still strong to severe storms ongoing across portions of Delmarva and southern NJ. Farther north and northwest over eastern PA northern NJ storms have exited and the threat for additional severe weather has diminished. For this reason, we cancelled the Tornado Watch for these areas while farther south the watches remain in effect.

Storm evolution will remain chaotic this evening with additional storms likely over Delmarva and southern NJ. There will continue to be a threat for severe weather, including tornados, along with flash flooding. The threat of severe weather should start to diminish by the second half of the evening while the threat for flash flooding could linger into the overnight before the cold front arrives from the west and pushes all the convection towards the coast by around 2 AM or so. During the rest of the overnight hours, convection may persist mainly across the southern Delmarva as the frontal boundary stalls across the region. The flash flood guidance for this region is not as sensitive to excessive rainfall, but will still bear monitoring through the early morning hours.

On Wednesday, the cold front will sag farther south and east and depending on how quickly this clears our area there will be some showers and thunderstorms, especially as additional shortwaves move through the flow within the upper-level trough overhead. This looks to be more concentrated across southern New Jersey to Delmarva but could extend into the I-95 corridor for a time. There is some severe weather risk mainly near and south/east of the I-95 corridor with locally damaging wind gusts the main threat. The greater instability and shear looks to reside across Delmarva on southward, where a little higher severe thunderstorm risk is indicated. Some locally excessive rainfall is possible with some local flash flood risk, however this looks to be less compared to today given the shift farther south and more into the coastal plain. Once the front moves away by later Wednesday, it turns drier for Thursday/Friday and right into the weekend.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

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

Tonight...Still some showers and thunderstorms around this evening mainly from around Philly southward. In any of these showers conditions may still drop to MVFR or even IFR...best chances for this at MIV and ACY. Otherwise, widespread showers diminish by the overnight period with MVFR cigs likely affecting most sites by around the 04-07z time frame. Winds generally southwest 10 to 15 knots but locally strong and variable winds possible in any storms.

Wednesday...Once morning clouds clear by around 14Z, should have prevailing VFR conditions. However, temporary MVFR or even IFR conditions will be possible with showers and storms. The highest risk of showers and storms is at KACY, but it is possible the storms will be south of all TAF sites. Southwest winds around 10 KT with some gusts of 15-20 knots possible. Moderate confidence.

Outlook...

Thursday through Saturday...VFR.

MARINE

Small Craft Advisory conditions for all coastal waters through Wednesday evening. SCA conditions do subside though overnight on Delaware Bay. Gusty thunderstorms probable mainly this evening and into tonight.

Outlook...

Wednesday...Small Craft Advisory remains in effect for the ocean zones.

Thursday through Saturday...The conditions are anticipated to be below Small Craft Advisory criteria.

Rip Currents...

For the rest of today, southerly winds of 15-25 mph with either a shore parallel or slight onshore flow expected depending on location. Breaking waves of 2-4 feet will result in more energy within the surf zone. As a result, maintained a MODERATE risk for the development of dangerous rip currents at all beaches.

For Wednesday, winds turn more southwesterly but still 10-20 mph. However, breaking wave heights are expected to increase, with breaking waves in the surf zone as high as 5 feet possible. Still a 7 second period though which will mitigate the rip current threat some. However, will continue with a MODERATE risk for the development of dangerous rip currents at all beaches.

For Thursday, winds come around to the northeast and will generally be 15 to 20 mph. Breaking waves are expected to be around 2-4 feet with a 7 second period. With the onshore component of the wind and multiple swell groups expected, expecting a MODERATE risk for the development of dangerous rip currents at all beaches.

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

PHI WATCHES / WARNINGS / ADVISORIES

PA...Flood Watch until 2 AM EDT Wednesday for PAZ070-071-101>106. NJ...Flood Watch until 2 AM EDT Wednesday for NJZ008>010-012>015- 017>019. DE...Flood Watch until 2 AM EDT Wednesday for DEZ001. MD...None. MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ430-431. Small Craft Advisory until 2 AM EDT Thursday for ANZ450>455.