textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1. Breaks of sun and clouds this afternoon will give way to unsettled weather tonight through Wednesday.

2. Drier and more seasonable conditions return for the end of the week into the weekend.

DISCUSSION

KEY MESSAGE 1...Breaks of sun and clouds this afternoon will give way to unsettled weather tonight through Wednesday.

A mostly dry and partly sunny afternoon will continue with mild temperatures.

The stationary front will set up over Delmarva for tonight and tomorrow, with a wave of low pressure moving along it. This will result in a few more rounds of showers for the Tuesday Night and Wednesday period, mainly for areas south of I-78. A cold front will sweep in on Wednesday from the northwest, which will put an end to the unsettled pattern. Rainfall amounts around a half inch or more are expected south of Philadelphia with anywhere from a few hundredths to a quarter of an inch expected north of the Philadelphia metro. Latest high res guidance suggests at least modest instability, favorable low level lapse rates, and around 20-30 kts of shear will be in place to support at least some strong to marginally severe thunderstorms across the Delmarva. Locally damaging wind gusts are possible in the strongest storms. Temperatures Wednesday should be similar to today, hovering around 80.

Once the cold front comes through on Wednesday Night, a transition to more tranquil and nicer weather is expected.

KEY MESSAGE 2...Drier and more seasonable conditions return for the end of the week into the weekend.

Behind the cold front from Wednesday, we trend slightly cooler for Thursday which continues into the weekend. High temperatures for most locations will be in the 70s during this timeframe and lows generally in the 50s. A high pressure system is forecast to gradually build into the region Thursday and remain in place into the weekend. A low pressure system is also forecast to move into New England Friday into Saturday, but model guidance trends continue to show the high pressure system having more of an influence across our area. Due to this high pressure system in control, it looks to be a drier end of the week, continuing into the weekend.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

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

Rest of today...Prevailing VFR. Winds variable around 5 kts or less. High confidence.

Tonight...VFR conditions drop to MVFR between 05z-09z and then down to IFR or even LIFR with fog and stratus developing with rain moving through late in the night. Isolated thunderstorms possible, warranting the addition of VCTS for terminals PHL and south/east. Have added a period of LIFR conditions at KACY/KMIV around 10z-11z due to low CIGs and potentially low VSBY. Winds out of the south/southwest 5 kt or less. Low confidence.

Wednesday...MVFR/IFR conditions expected with scattered showers and possibly a thunderstorm and low clouds. Low confidence.

Outlook...

Thursday through Sunday...VFR. No significant weather.

MARINE

Sub- SCA conditions expected through Wednesday night. Seas of 2 to 4 feet.

Outlook...

Wednesday Night...Conditions are expected to be below Small Craft Advisory criteria. Some showers with a few thunderstorms are expected Wednesday evening.

Thursday through Sunday...Mainly sub-SCA conditions expected though seas may briefly approach 5 feet Saturday night. Fair weather.

Rip Currents...

For today, winds will shift to the east-southeast and will be light, around 5 to 10 MPH. Wave heights continue to lower as well. A medium period swell will continue. Given less energy in the surf zone with lower wave heights and very light winds through today, have elected for a LOW risk for the development of rip currents for today.

On Wednesday, winds turn more offshore with breaking waves only around 1 to 2 feet. A medium period 7 second well will persist. With offshore winds and low wave heights, a LOW risk for the development of dangerous rip currents is in place.

Ocean temperatures are mainly in the 50s to low 60s. These cold water temperatures can quickly cause hypothermia and physical incapacitation to anyone suddenly immersed in the water.

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

PHI WATCHES/WARNINGS/ADVISORIES

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