textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Added a slight chance for showers to the forecast for later today.

KEY MESSAGES

1. A weak cold front passes through the region early this morning, followed by a weak back door cold front later today.

2. Monitoring a far offshore low mid-week, but high pressure keeps it dry through the end of the week.

DISCUSSION

KEY MESSAGE 1...A weak cold front passes through the region early this morning, followed by a weak back door cold front later today.

Weak low pressure will pass through the region during the late night/pre-dawn hours, and as it does, it will drag a cold front through the region shortly after sunrise. Not expecting any precipitation with its passage, but there will be a shift in winds from south to southwest to northwest, and then north.

Thereafter, a weak back door cold front will slide south through the region this afternoon. With onshore flow ahead of it, as well as some mid-level shortwave energy over the area, this may be enough to spark off some light, isolated showers. Will go ahead add slight chance/isolated PoPs for most of the area. Not expecting much more than a trace to a hundredth of an inch of QPF or so. East winds will increase to 10 to 15 mph with some gusts up to 20 mph. Seasonable highs topping off in the mid to upper 70s, though cooler in the higher elevations of the southern Poconos and at the Jersey Shore and Delaware Beaches.

Clearing skies tonight with seasonably chilly temperatures with lows in the 40s to low 50s.

KEY MESSAGE 2...Monitoring a far offshore low mid-week, but high pressure keeps it dry through the end of the week.

By mid-week, the upper-level trough across the Northeast continues to move away and become more amplified. The base of the trough is expected to close off into an upper low. Some guidance has this occurring near the North Carolina coast while others have it more off to the northeast in the Atlantic Ocean as the progression of the upper-level trough is faster. Either way, an upper low is forecast to develop and move off to the northeast. At the surface, a low pressure system will likely form in association with the closed upper low.

Guidance continues to show the surface low pressure system being well off the coast. There will be an expansive area of high pressure that will remain in control across the Great Lakes region and into the rest of the Northeast. As a result, it is increasingly likely that the vast majority of land areas will stay dry with this system. Should the surface low drift closer to the eastern seaboard, we could see a northeasterly flow that could help cool temperatures down slightly mid-week, especially along the coast, but even so, dry conditions will likely still prevail.

Otherwise, we are expecting seasonable temperatures Tuesday with gradual warming through the end of the week. Friday and Saturday could see temperatures in the afternoon creep back into the low 90s as surface high pressure slips to the southeast and ushers in a much warmer airmass across the Northeast. Some precipitation could be possible by the weekend, but confidence remains low at this time.

AVIATION /06Z MONDAY THROUGH FRIDAY/

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

Early this morning...VFR. Winds becoming LGT/VRB. High confidence.

Today...VFR. N-NE winds 10 to 15 kt, becoming E 10 to 15 kt with 20 to 25 kt gusts with the strongest winds at KACY. A few light SHRA possible after 18Z, but restrictions not expected. Moderate confidence.

Tonight...VFR. E winds 5 to 10 kt, becoming LGT/VRB late. High confidence.

Outlook...

Tuesday through Friday...VFR. No significant weather.

MARINE

A weak cold front passes through the waters early this morning, and winds will turn to the north-northeast at 10 to 15 kt. Another cold front slides south across the waters later this afternoon, and winds become east 15 to 20 kt. Seas will build to around 4 feet. Cannot rule out a few 25 kt gusts, but will hold off on issuing a Small Craft Advisory, as widespread 25+ kt gusts not expected.

A few light showers are possible with the passage of that second cold front, but not expecting visibility restrictions.

East winds will generally remain 15 to 20 kt tonight.

Outlook...

Tuesday through Friday...Sub-SCA conditions probable. Continuing to monitor the far offshore low mid-week for potential changes to the forecast for elevated seas.

Rip Currents...

Today, north to northeast winds this morning at 10 to 15 mph will turn east with 20 to 25 mph gusts this afternoon. Breaking waves will be 2 to 3 feet with a southerly swell at 9 to 10 seconds. As a result, there is a MODERATE risk for the development of dangerous and life threatening rip currents at the Jersey Shore and at Delaware Beaches.

For Tuesday, northeast winds 10 to 15 mph in the morning will become southeast 5 to 10 mph in the afternoon. Breaking waves will be 2 to 4 feet with an easterly swell at 7 to 9 seconds. As a result, there is a HIGH risk for the development of dangerous and life threatening rip currents at Delaware Beaches and a MODERATE risk at the Jersey Shore. Will hold off on a Rip Current Statement for Delaware Beaches for now.

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

PHI WATCHES/WARNINGS/ADVISORIES

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