textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Aviation section updated for the 12z TAFs.

KEY MESSAGES

1. Significantly cooler temperatures and several rounds of showers for the end of this week and the holiday weekend.

DISCUSSION

KEY MESSAGE 1...Significantly cooler temperatures and several rounds of showers for the end of this week and the holiday weekend.

A cold front will settle and stall to our south as we get into the holiday weekend. Some ripples of energy ride along and north of it and this looks to bring some rounds of showers to our region. A more organized surface low well to our west may provide an increase in showers or a period of rain later Friday and Saturday. The precipitation may become enhanced some as surface high pressure to our northeast wedges southwestward into our area creating some cool air damming. Furthermore, with PWAT values around 1.50-1.90 inches over the weekend, which is around the climatological maximum for this time of the year, there is at least a marginal chance for excessive rainfall on Saturday. We will be keeping an eye on how strong the baroclinic forcing gets along the stalled boundary wedged between the high to the northeast and the low to the west. Northeast flow along with several rounds of showers will all result in much cooler temperatures Thursday through Saturday, then some warming should take place Sunday and into Memorial Day. The pattern looks active though and therefore some additional showers are quite possible right into Memorial Day. While not great timing for the holiday weekend and unofficial start of summer, our region needs rain as a long-term drought continues.

Overall rainfall totals Thursday through Saturday Night are forecast to range around 0.50 to 1.00 inches with locally higher amounts possible.

AVIATION /12Z THURSDAY THROUGH MONDAY/

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

Today...VFR ceilings (MVFR at KMIV and KACY) lower to MVFR. Showers or a period of rain overspreads the area from northwest to the southeast through the day. Northeasterly winds increasing to 10-15 knots, with gusts 20-25 knots especially at KMIV and KACY. Low confidence.

Tonight...MVFR ceilings, however VFR possible further north and west with higher ceilings. East-northeast winds 5-8 knots. Low confidence.

Friday...Ceilings varying between MVFR and VFR. Some showers start to arrive from the south later in the day. East-northeast winds 10-15 knots. Low confidence.

Outlook...

Friday night through Monday...An unsettled pattern takes over with periods of MVFR/IFR conditions expected with several rounds of rain showers. Most widespread restrictions look to come Saturday and Saturday Night though the entire period likely will feature showers and low clouds with perhaps sporadic stretches of VFR if ceilings lift a bit.

MARINE

A northeast flow increases during today and with a much cooler air mass moving in the mixing should become more efficient over the chilly ocean water with gusts around 25 knots. Seas will also build during today. Small Craft Advisory in effect for this afternoon for all waters except for the waters off Monmouth County and the upper Delaware Bay through tonight.

ENE winds will diminish briefly to around 20 knots tonight, but ramp back up early Friday morning with seas beginning to build to 4-5 feet.

Outlook...

Friday...A Small Craft Advisory is in effect for ocean zones south of Manasquan Inlet as periods of 25-30 kt winds and seas nearing 5 feet are expected. Sub-SCA conditions expected on the coastal waters north of Manasquan Inlet. An SCA was hoisted for the upper Delaware Bay beginning early Friday morning.

Friday Night through Monday... SCA conditions expected with seas of 4 to 7 feet and periods of 25-30 kt winds, mainly on Saturday.

Rip Currents...

Today, east to northeast winds will ramp up to 15 to 20 mph with gusts up to 25 mph. There will be a southeast swell with a period around 6 seconds and breaking waves of 1 to 3 feet. As a result, there is a MODERATE risk for the development of dangerous rip currents for the Jersey Shore and for Delaware Beaches.

On Friday, east to northeast winds will range from 15 to 20 mph with 25 to 30 mph gusts. There will be a southeast swell with a period of 10 to 13 seconds and breaking waves of 2 to 4 feet. This should result in a HIGH risk for the development of dangerous rip currents.

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

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory from 6 AM Friday to 6 AM EDT Saturday for ANZ430. Small Craft Advisory from 2 PM this afternoon to 6 AM EDT Saturday for ANZ431. Small Craft Advisory from noon today to 6 AM EDT Saturday for ANZ451>455.