textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Increased precipitation chances late this evening into tonight, mainly in east/northeast Pennsylvania and far northern New Jersey.

KEY MESSAGES

1. A cold front will slowly move through the region late Friday into Saturday. This will bring showers and thunderstorms to the region as early as this evening, continuing at times into Saturday. Sunday dries out.

2. Heat will build into the region toward the middle of next week. Maximum heat index values in the 90s to around 100 degrees will be possible for the second half of the week.

DISCUSSION

KEY MESSAGE 1...A cold front will slowly move through the region late Friday into Saturday. This will bring showers and thunderstorms to the region as early as this evening, continuing at times into Saturday. Sunday dries out.

Slightly warmer and more humid air will build into the region through Friday ahead of a slow-moving front. Scattered showers and storms are expected to develop as a S/W disturbance progresses through the region late this evening into early Friday. The showers/storms should develop upstream of the local area by this evening well ahead of the front. This activity will progress into northern parts of the local area, especially near/north of I-78, toward midnight through the early overnight hours.

Although deep-layer moisture will be increasing locally this evening into Friday morning, the activity should be progressive enough as to not cause an widespread flooding concerns. This being said, downpours are certainly possible as this activity slowly weakens with eastward extent late into the night. Instability should be meager, suggesting the potential for any strong/severe storms is also quite low. But certainly some rumbles of thunder will be possible in central/ern PA and far northern NJ late this evening into tonight before activity withers into the predawn hours Friday.

As we progress into the daytime Friday, the front will still be north/west of the local area. Coverage of activity is somewhat uncertain during the day on Friday, especially on the backside of the departing S/W and in an environment with only very marginal instability. Cannot completely rule out some ISO activity, but most of the daytime may end up being mainly dry for much of the local area. However, coverage of showers, with perhaps a few storms, should increase late Friday evening into Friday night with the approach of another S/W as the sfc front slowly sags to the southeast. This activity should linger into the daytime Saturday, especially south of I-78, as the front slowly shifts S and clears the region into late Saturday night.

Precipitation chances diminish by Sunday and into early next week.

KEY MESSAGE 2...Heat will build into the region toward the middle of next week. Maximum heat index values in the 90s to around 100 degrees will be possible for the second half of the week.

Although still at least several days away, there continues to be a steady signal for pronounced midlevel ridging developing from the Great Lakes into the mid-Atlantic and northeast CONUS by Wednesday of next week. Certainly there are still some details to be worked out, but confidence continues to increase in the potential for heat index values in the 90s to near 100 degrees across the region at times from mid week through the end of next week.

AVIATION /06Z THURSDAY THROUGH MONDAY/

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

Through 12z this morning...VFR with increasing high clouds. A FEW mid clouds are possible at KABE. Light/VRB winds will persist through daybreak. High confidence.

Today...VFR with increasing mid/high clouds during the afternoon alongside from diurnally-driven VFR Cu. South- southwest winds generally around 10 kt with gusts up to 20 kt possible, primarily after 18Z. ISO/SCT SHRA will drift into the region late evening, potentially impacting KRDG/KABE late in the period. Suppose a brief TS cannot be ruled out with this activity. High confidence.

Tonight... ISO/SCT SHRA will be possible, particularly at KRDG, KABE, and KTTN in the several hours around 06z. Spotty TS cannot be ruled out at these sites. Brief sub-VFR conditions are possible in the heaviest activity. Otherwise, VFR conditions expected with south wind 5-10kts becoming light at less than 5kts. Medium confidence on coverage and maintenance of SHRA/TSRA.

Outlook...

Friday through Saturday...With a cold front moving through the region and showers and thunderstorms expected, sub-VFR conditions can be anticipated with precipitation.

Sunday and Monday...VFR conditions expected. No significant weather.

MARINE

Sub-Small Craft Advisory conditions through tonight. Southwest winds around 5kts through daybreak. South winds 10 to 15 kt with gusts around 20 kt during the daytime. Occasional gusts up to 25 kt possible north of Barnegat Light late this afternoon. Seas 2 to 3 feet. Fair weather.

Outlook...

Thursday night through Monday...Sub-SCA conditions expected.

Rip Currents...

For Thursday, breaking waves will be 1 to 2 feet with a low to medium period southeast swell. Southerly winds increasing to near 10-15 mph. Therefore, there is a LOW risk for the development of rip currents for the Jersey Shore and Delaware Beaches.

On Friday, similar surf conditions are expected. Southerly winds will be a bit lighter, mainly near 10 mph. This will continue the LOW risk for the development of rip currents for the Jersey Shore and 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.