textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1. There is a limited risk for fire weather conditions through Tuesday.

2. A few systems bring showers to the area Wednesday into Thursday. Another weak system could bring some showers on Saturday.

DISCUSSION

KEY MESSAGE 1...There is a limited risk for fire weather conditions today.

High pressure centered off the Mid-Atlantic coast continues to push offshore this afternoon leading to southerly flow across the region. With an upper-level trough over the Great Lakes advancing a cold front towards the region, we have seen substantial mixing across interior locations with southwesterly winds in the 10-20 mph range with gusts 20-30 mph. This PBL mixing has also mixed down some lower dewpoints and lead to relative humidities along the immediate coast in the 50-70% range and at as low as 25% for inland locations.

This will continue again Tuesday with winds still SW 10-20 mph gusting 25-35 mph. PBL mixing should again allow for minimum RH's to drop into the 22-27% range during the day Tuesday. These parameters do support the potential spread of fires if they ignite. Will continue to coordinate with the State Fire Partners on fuel conditions before any issuance of another Special Weather Statement for Tuesday as green up is in full effect.

KEY MESSAGE 2...A few systems bring showers to the area Wednesday into Thursday. Another weak system could bring some showers on Saturday.

The high pressure system is finally displaced on Tuesday, but the continued influence from the high will keep most of the area on the drier side. Also during this timeframe, there will be a low pressure system well to the north in Canada with a cold front sinking southeast from the Great Lakes region. Our NW areas have the potential to see an isolated shower (20%) late Tuesday into Tuesday night. The bulk of the showers will move in late Tuesday night and Wednesday morning and continue through the day Wednesday as the cold front sinks southeast into our area. This cold front then stalls across the region into Thursday with a wave of low pressure moving northward along the front leading to more showers on Thursday. The model trends today is for the front to shift farther east and offshore Thursday, with some guidance missing most if not all of our area with showers associated with low pressure along the front.

While some guidance still attempted to bring some convective elements to the region, the consensus is that we will see low instability and limited to zero severe/flooding threat. Overall, this will be more beneficial rain for the area with an isolated thunderstorm possible.

For Saturday, a weak area of low pressure will move into the region, potentially producing some showers. This appears to be nothing more than a potential weekend spoiler with no significant impacts expected at this time.

AVIATION /19Z MONDAY THROUGH SATURDAY/

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

Rest of this afternoon...VFR. Southwest to south winds 10-15 knots with gusts 20-25 knots. High confidence.

Tonight...VFR. South winds 10 knots or less. As the winds decouple at the surface tonight, a modest low-level jet will move in and lead to low-level wind shear during the overnight hours. High confidence.

Tuesday...VFR. South to southwest winds 10-20 knots with gusts 25-30 knots. Moderate confidence.

Outlook...

Tuesday Night...Primarily VFR. Some showers possible north and west of the I-95 terminals. Gusty south/southwest winds gradually diminishing.

Wednesday through Thursday...MVFR/IFR conditions expected with periods of rain, an isolated thunderstorm, and low clouds. Southerly wind gusts around 20-25 kt on Wednesday.

Thursday Night...Conditions improving but lingering restrictions possible (30-40%).

Friday...VFR. No significant weather.

Saturday...Sub-VFR conditions and showers possible.

MARINE

A Small Craft Advisory remains in effect through Tuesday. South to southwest wind gusts will increase up to 30 knots into Tuesday. Seas will also build.

Outlook...

Tuesday night and Wednesday...A Small Craft Advisory is in place for all marine zones. Wind gusts up to 30 knots out of the south/southwest and seas 4 to 7 feet.

Wednesday Night through Thursday...SCA conditions could linger as winds decline but seas could near 5 feet.

Thursday Night through Saturday...No marine headlines expected.

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory from 2 PM Tuesday to 2 AM EDT Wednesday for ANZ430-431. Small Craft Advisory until 6 PM EDT Wednesday for ANZ450>452. Small Craft Advisory until 6 PM EDT Wednesday for ANZ453>455.