textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

A Coastal Flood Advisory is now in effect for Saturday evening and Saturday night.

Cooler temperatures expected on Saturday with a coastal influence.

KEY MESSAGES

1. Isolated showers and thunder for parts of the area into early this evening.

2. Cooler temperatures expected on Saturday with an onshore flow.

3. A strong cold front will bring rain showers to the area Saturday night into Sunday.

4. Widespread minor tidal flooding is forecast to occur along the Atlantic coasts of NJ and DE, Delaware Bay, and the tidal Delaware River with the Saturday evening/night high tide.

5. Cooler temperatures into early next week, followed by a return to above normal later in the week.

DISCUSSION

KEY MESSAGE 1...Isolated showers and thunder for parts of the area into early this evening.

An upper-level trough is sliding through the region this afternoon. As a result, isolated/scattered showers have developed north and west of the I95 corridor. Can't rule out some thunder with some skinny CAPE in play. This convection will sink south and east into the early evening hours.

KEY MESSAGE 2...Cooler temperatures expected on Saturday with an onshore flow.

While this morning's NBM picked up the coastal influence right along the coast, it didn't pick it up further west across the interior. Both the MET and MAV stat guidance look more reasonable tomorrow. As a result, I shaved NBM afternoon highs by about 5 to 9 degrees. This includes the city of Philadelphia.

KEY MESSAGE 3...A strong cold front will bring rain showers to the area Saturday night into Sunday.

A cold front will move into the area Saturday night and across the area on Sunday. An area of low pressure will develop along the front and move northeast along the boundary as it moves eastward across the area. Rainfall amounts will range from around a tenth of an inch closer to the coast, to as much as a half an inch for the Poconos. As the low moves across the area, it could lead to some locally heavier amounts. There is little to no instability, so overall thunder chances will be low. However, it would not be surprising to have a few rumbles of thunder.

KEY MESSAGE 4...Widespread minor tidal flooding is forecast to occur along the Atlantic coasts of NJ and DE, Delaware Bay, and the tidal Delaware River with the Saturday evening/night high tide.

A Coastal Flood Advisory is now in effect for the Atlantic coasts of New Jersey, as well as along Delaware Bay and up Delaware River Saturday with the high tide cycles Saturday evening and Saturday night.

High astronomical tides associated with the new moon occurring today and persistent onshore flow developing tonight and especially Saturday is forecast to result in widespread minor tidal flooding with the Saturday evening/night high tide along the Atlantic coasts of NJ and DE, Delaware Bay, and the tidal Delaware River. Some spotty minor tidal flooding may occur in some areas with the high tide this evening/tonight, though any impacts will be limited enough to preclude and advisory. As southeast winds persist on Saturday, surge values will increase to near 1 foot above normal, which will put most tidal areas into minor flood stage during high tide Saturday evening/night.

A modest offshore wind will develop in the wake of a cold front on Sunday, which should limit the threat of any additional flooding for Sunday night's high tide.

No tidal flood is forecast for the Eastern Shore of Chesapeake Bay.

KEY MESSAGE 5...Cooler temperatures into early next week, followed by a return to above normal later in the week.

Behind the cold front, below normal temperatures will return for Sunday through Tuesday. Some areas of frost may develop for northern areas Sunday night/Monday morning, but more widespread frost and freeze conditions will occur Monday night/Tuesday morning. A return of above normal conditions is expected for Wednesday through Friday of next week.

AVIATION /19Z FRIDAY THROUGH WEDNESDAY/

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

Tonight...VFR with increasing clouds. MVFR or IFR ceilings develop overnight from east to west. North-northwest winds 5-10 knots, becoming northeast near 5 knots. Higher confidence terminals will see MVFR conditions vs. IFR. Can't rule of some fog.

Saturday...MVFR/IFR ceilings to start, then VFR. High confidence the terminals will return to VFR tomorrow afternoon.

Outlook...

Saturday night-Sunday...An extended period of MVFR or IFR conditions are expected with a chance of rain. An isolated thunderstorm cannot be ruled out. Southeast winds Saturday night, shift to the northwest during the day Sunday with gusts 20-30 knots possible Sunday.

Sunday night-Tuesday night...VFR conditions expected. Winds may gust 20-25 knots Monday and Tuesday.

Wednesday...Generally VFR conditions are expected, but may briefly lower to MVFR at times.

MARINE

Tonight...Sub-SCA conditions expected. A wind shift to the northeast is expected.

Saturday...Sub-SCA conditions expected.

Outlook...

Saturday night...Conditions remain below Small Craft Advisory levels.

Sunday-Monday...Small Craft Advisory conditions likely, especially Sunday.

Monday night-Wednesday...Conditions expected to remain below advisory levels.

PHI WATCHES/WARNINGS/ADVISORIES

PA...Coastal Flood Advisory from 1 AM to 6 AM EDT Sunday for PAZ070- 071-104-106. NJ...Coastal Flood Advisory from 11 PM Saturday to 3 AM EDT Sunday for NJZ016. Coastal Flood Advisory from 8 PM Saturday to 2 AM EDT Sunday for NJZ012>014-020>027. Coastal Flood Advisory from 1 AM to 6 AM EDT Sunday for NJZ017>019. DE...Coastal Flood Advisory from 11 PM Saturday to 3 AM EDT Sunday for DEZ001. Coastal Flood Advisory from 8 PM Saturday to 2 AM EDT Sunday for DEZ002>004. MD...None. MARINE...None.