textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Small Craft Advisories for the Lower Delaware Bay and Atlantic Coastal Waters from Manasquan Inlet to Great Egg Inlet have been cancelled/allowed to expire.

KEY MESSAGES

1. Freeze/frost conditions expected this morning and again tonight into Thursday morning.

2. A dry weather pattern continues for the remainder of the week and potentially most of this upcoming weekend.

DISCUSSION

KEY MESSAGE 1...Freeze/frost conditions expected this morning and again tonight into Thursday morning.

The center of strong Canadian high pressure is currently located over New York State and is expected to shift off the coast of New England tonight. A very dry and seasonably cold airmass will persist through tonight as a result. Temperatures this morning have mainly fallen into the low to mid 20s to low to mid 30s, with teens in the Poconos. No changes have been made to ongoing Freeze Warnings for this morning.

With the surface high moving offshore tonight, surface flow should gradually become more onshore, allowing dew points to recover some as low-level moisture slowly penetrates inland. As this occurs, frost formation is expected from east to west during the evening and overnight hours as low temperatures are expected to fall into the mid/upper 20s to low/mid 30s. Efficient radiational cooling conditions should develop with continued clear skies and light winds expected for most of the night. The exception is over the Delmarva and far southern New Jersey where some clouds may develop late, potentially precluding frost coverage. Upon discussion with all neighboring offices, where the growing season is active, have opted to keep current Freeze Watches in effect for tonight and convert to Freeze Warnings/Frost Advisories later this morning once the current headlines run their course.

KEY MESSAGE 2...A dry weather pattern continues for the remainder of the week and potentially most of this upcoming weekend.

Our expansive area of high pressure remains in control across the region through the remainder of this week. As a result, it is a dry week precipitation wise. This high pressure system is moving overhead today. At the surface, a very dry air mass will be in place tomorrow with min RH values in the 20-30% range. One difference from Tuesday's fire weather concerns is that the wind will be much lighter as the pressure gradient has lessened from the high pressure system moving overhead. Towards the end of the week, RH values do increase as winds are out of the southeast Thursday and southwest Friday from our high pressure system departing offshore. However, there will continue to be a lack of precipitation due to the region still feeling the influences of the high pressure system.

A cold front sinking southeast Friday night into Saturday morning is the next potential at some precipitation, but this potential currently looks pretty limited. Behind this cold front, another high pressure system looks to build in leading to dry conditions for the remainder of the weekend with temperatures remaining mild to warm. Temperatures warming well above normal again early next week, with highs well into the 70s Monday and 80s likely by Tuesday.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

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

Today...VFR/SKC. Northeast winds around 5-10 kt in the morning, will gradually become east-southeast in the afternoon. High confidence.

Tonight...VFR/SKC. A few clouds late. East winds around 5 kt or less, becoming light and variable at times. High confidence.

Outlook...

Thursday through Sunday...VFR.

MARINE

The Small Craft Advisory for the Atlantic Coastal Waters from Great Egg Inlet to Fenwick Island are now in effect until 11 AM this morning. All other Small Craft Advisories have been allowed to expire or cancelled.

North-northeast winds around 15-20 kt with gusts up to 25 kt will continue through this morning before diminishing and settling out of the east this afternoon. East-northeast winds will then continue through tonight around 10-15 kt. Seas around 3-5 feet early this morning will lower to around 2-4 feet this afternoon into tonight. Fair weather expected outside of SCA conditions.

Outlook...

Thursday...No marine hazards anticipated.

Friday and Saturday...A period of Small Craft Advisory conditions possible mainly due to seas building to 4-6 feet within an easterly swell.

Sunday...No marine hazards anticipated.

PHI WATCHES/WARNINGS/ADVISORIES

PA...Freeze Warning until 9 AM EDT this morning for PAZ060-070-071- 101>104-106. Freeze Watch from late tonight through Thursday morning for PAZ060-070-071-101>104-106. NJ...Freeze Warning until 9 AM EDT this morning for NJZ012>027. Freeze Watch from this evening through Thursday morning for NJZ012>023-027. DE...Freeze Warning until 9 AM EDT this morning for DEZ001>003. Freeze Watch from this evening through Thursday morning for DEZ001>003. MD...Freeze Warning until 9 AM EDT this morning for MDZ012-015-019- 020. Freeze Watch from this evening through Thursday morning for MDZ012-015-019-020. MARINE...Small Craft Advisory until 11 AM EDT this morning for ANZ453>455.