textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1. A few showers possible through this afternoon across Delmarva and far southern NJ. Drier, but colder weather takes hold into tonight.

2. There is the potential for fire weather concerns on Saturday.

3. We trend warmer into next week with multiple chances for rain showers across the area.

DISCUSSION

KEY MESSAGE 1...A few showers possible through this afternoon across Delmarva and far southern NJ. Drier, but colder weather takes hold into tonight.

This morning's cold front is now south of our area, however a few showers will remain possible across Delmarva and far southern NJ through this afternoon. Temperatures will continue to fall into the 40s this evening and then 30s overnight.

A breezy north wind will diminish through this evening, however northwest wind will pick up again overnight and become gusty. By the daytime Saturday, Northwest winds 15-20 mph may gust up to 30 mph at times. Rather chilly and brisk for Saturday with highs only in the 40s in most areas.

KEY MESSAGE 2...There is the potential for fire weather concerns on Saturday.

With Canadian high pressure building in from the west, relatively cold, dry, and breezy conditions set up. MinRH values will range from 20 to 30 percent and northwest winds will range from 10 to 20 mph with 25 to 30 mph gusts. This may set up the potential for fire weather concerns. Mitigating factors will be rainfall today.

KEY MESSAGE 3...We trend warmer into next week with multiple chances for rain showers across the area.

Our high pressure system passes overhead Saturday night leading to tranquil conditions and the potential for radiational cooling. Lows Saturday night are in the 20s for most. This high pressure system then starts to move offshore Sunday into Sunday night which allows for return flow out of the southwest. Warm air advection then overspreads the region allowing our warming trend to begin. A gradual warming trend will then take us into midweek where high temperatures reach into the 70s for many with some locations getting close to 80 degrees.

As the high pressure system exits, the dry conditions Saturday night through Sunday night are followed by unsettled weather. We start off with the chance (20-40%) of some isolated rain showers Monday into Monday night for locations mainly near and NW of the urban corridor as a cold front approaches from the northwest and stalls near or just north of the area. This stalled boundary moves north into Tuesday night as a warm front. This warm front is attached to a low pressure system near the Midwest that moves into the Northeast on Wednesday. Tuesday into Tuesday night is drier for much of the area. Our better potential for rain showers is Wednesday into Wednesday night as a cold front attached to the low pressure system moves through the region. During this timeframe, an isolated thunderstorm is also possible.

This cold front looks to stall across the area into the end of the week leading to continued chances for precipitation. During the end of the week, there will be a high pressure system located to the north in Canada which may allow for cooler air to filter in. This cooler air can impact temperatures during this timeframe, but due to this being towards the end of the extended forecast period, there remains uncertainty.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

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

Through 00Z...VFR. Northerly winds around 10 kts, diminishing some late. A few showers possible at MIV/ACY, but no restrictions anticipated. High confidence overall.

Tonight...VFR. North winds 5-10 kts, shifting more northwest and becoming a bit gusty at times after 06Z. High confidence.

Saturday...VFR. Northwest winds 10-15 kts with gusts up to 25 kts. High confidence.

Outlook...

Saturday night through Monday...VFR. No significant weather.

Tuesday...Generally VFR, but sub-VFR conditions possible in SHRA.

Wednesday...Sub-VFR with rain showers moving through.

MARINE

No marine hazards expected through much of tonight. Winds out of the north around 10-15 kt with seas 2 to 4 feet.

Northwest winds will increase to 15-20 kts with gusts up to 30 kts across our southern waters around dawn Saturday. A new Small Craft Advisory was issued to highlight this threat.

Outlook...

Saturday night...Sub-SCA conditions.

Sunday through Monday...There is the potential for SCA conditions Sunday with wind gusts near 25 kt. Sunday night into Monday morning looks more probable for SCA conditions with wind gusts of 25 kt and seas near 5 feet. Sub-SCA conditions are then expected for Monday afternoon.

Tuesday through Wednesday...SCA conditions expected with wind gusts of 25-30 kts and seas of 6-8 feet.

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory from 5 AM to 4 PM EDT Saturday for ANZ430- 431-454-455. Small Craft Advisory from 5 AM to 2 PM EDT Saturday for ANZ451>453.