textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

All sections refreshed but no major changes to the forecast.

KEY MESSAGES

1. A cold front will continue moving through the area this afternoon and be offshore by early this evening resulting in dry but breezy conditions.

2. Tranquil weather will prevail this week continuing into the weekend with no significant weather hazards anticipated.

DISCUSSION

KEY MESSAGE 1...A cold front will continue moving through the area this afternoon and be offshore by early this evening resulting in dry but breezy conditions.

A modest northwest pressure gradient is setting up as high pressure currently centered to our west builds towards the area in the wake of a cold front. Generally expect a clearing trend in skies this afternoon with NW winds 10-15 gusting 20 to 30 mph. Afternoon highs should mainly be in the upper 60s to low 70s.

Tonight will be by far the coolest so far this season, as temperatures fall into the 40s in many areas by dawn Tuesday. Coastal areas and the Philly urban core will likely stay closer to 50 degrees, and areas north of I-78 will drop into the mid to upper 30s in some spots. There could be some patchy frost in the sheltered valleys of NW NJ and the southern Poconos, but confidence on this is somewhat low give the gradient wind that will still be in place. This should help prevent strong radiational cooling and thus temperatures from bottoming out too much.

KEY MESSAGE 2...Tranquil weather will prevail this week continuing into the weekend with no significant weather hazards anticipated.

High pressure will be in control through much of the week resulting in mostly clear/sunny skies and seasonably cool to mild temperatures. The first notably cool Canadian airmass of the season will settle into the area by Tuesday. Highs on Tuesday will only get into the low to mid 60s, with overnight lows Tuesday night/Wednesday morning dropping into the upper 30s and low to mid 40s.

Forecast temperatures are high enough to not need any frost headlines just yet. The radiational cooling setup Tuesday night is not the most ideal. While surface winds will be light to calm, winds not far above the surface will be modest and beginning to advect higher moisture air that is closer to saturation aloft into the area. This combined with rebounding dewpoints should work to suppress strong radiational cooling despite mostly clear skies and light surface winds.Nevertheless, there could certainly be at least some patchy frost in the sheltered valleys of northwest New Jersey and the southern Poconos, where temperatures could locally drop into the mid 30s.

As high pressure shifts offshore by Wednesday, airmass modification will commence. Temperatures return to more seasonable values on Wednesday, and likely go above normal on Thursday with highs in the mid to upper 70s. Temperatures look to return to near normal again for Friday and into the weekend. It should be an extended stretch of pleasant weather days with the next chance for rain not arriving until Sunday at the earliest.

AVIATION /18Z MONDAY THROUGH SATURDAY/

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

Today...MVFR CIGs have mostly lifted to VFR though a few sites still have a BKN025/BKN030 ceiling. This should lift over the next hour with all sites returning back to VFR and remain that way through the afternoon. Winds out of the northwest around 10-15 kt and gusts around 20 to 25 kt, diminishing between 22z-00z. Moderate confidence.

Tonight...VFR/SKC. Northwest winds around 5 to 10 kt. High confidence.

Tuesday...VFR. Northwest winds around 5 to 10 kt. High confidence.

Outlook...

Tuesday Night through Saturday...VFR. No significant weather expected.

MARINE

NW winds increase this afternoon into early this evening over the waters and a Small Craft Advisory remains in effect for all waters through midnight tonight. Generally expect NW winds of 15 to 20 gusting up to 25 knots. As the winds begin to subside later this evening the Advisory expires at midnight for all zones except the coastal waters off Ocean and Monmouth Counties. Expect seas mainly 3 to 4 feet this afternoon and tonight diminishing to 2 to 3 feet for Tuesday.

Outlook...

Tuesday night through Friday...No marine hazards expected.

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until midnight EDT tonight for ANZ430-431- 452>455. Small Craft Advisory until 6 AM EDT Tuesday for ANZ450-451.