textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Aviation discussion updated.

High confidence in records potentially being set, mainly on Wednesday and Thursday, where the I-95 corridor and Delmarva could see their first 90 degree days of the year.

KEY MESSAGES

1. Fire weather concerns persist through today.

2. Potentially record breaking warmth is possible this week with very warm and above normal temperatures continuing through the upcoming weekend.

DISCUSSION

KEY MESSAGE 1...Fire weather concerns persist through today.

An elevated risk for fire spread continues through today.

After a dry Sunday, moisture begins to sneak back in today, but the winds will increase as well. Southwest winds are forecast to gust up to 25-35 mph by the afternoon, which are highly concerning for fire spread. That said, minimum RH values are only expected to fall into the 35-50% range, noticeably higher than the last few dry days. A weak disturbance will graze the region during the day as well, bringing high clouds and a slight chance for a light shower, mainly north and west of the I-95 corridor, though a stray shower can't be ruled out further south and east.

KEY MESSAGE 2....Potentially record breaking warmth is possible this week with very warm and above normal temperatures continuing through the upcoming weekend.

A significant warm up is expected to continue through the upcoming weekend with the potential for record breaking temperatures.

With high pressure situated over the Atlantic Ocean and the warm front well north of the Mid-Atlantic region by Tuesday, continued warmth is expected to continue. Very warm air aloft coupled with warm air at surface levels will allow temperatures to be as much as 15 to 30 degrees above average this week. As of now, expecting highs in the low to mid 80s on Tuesday, with upper 80s to low 90s on Wednesday and possibly into Thursday (see Climate Section below regarding potential record breaking temperatures).

If temperatures touch 90F, it would be the first 90 degree day of the year and first since early September. As is typical in spring though, temperatures along and near the coast will be significantly cooler due to the colder sea surface temperatures and diurnal sea breeze. While a weak surface front passes through late Thursday night into Friday morning, temperatures will stay well above normal through the weekend with temps mainly in the upper 70s to mid 80s.

Not only will it be very warm over the course of the week, but it will also remain mainly dry. This is of elevated concern for ongoing drought/abnormally dry conditions over much of the area, which will likely only get worse after this week. A few weak disturbances will pass by to the north during the Tuesday through Thursday timeframe, but other than a stray shower or thunderstorm each afternoon north of the I-78 corridor, no significant rainfall is expected. Flow will generally be out of the southwest, which is more favorable in terms of moisture, which likely will limit fire weather concerns through this week. Winds will generally be light after today as well, also another limiting factor. So, even though it will be warm and dry, fire weather concerns are minimal.

AVIATION /12Z MONDAY THROUGH FRIDAY/

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

Today...Lingering MVFR prior to 13-14Z due to low stratus then primarily VFR. Chance of light showers at KRDG/KABE (25%-35%) in the afternoon, though any impacts will be brief and limited. Southwest winds 10-15 kts with gusts of 20-25 kts anticipated. Moderate-high confidence.

Tonight...Primarily VFR. Southwesterly winds around 5-10 kts decreasing to around 5 knots or less late in the overnight hours. Moderate-high confidence.

Outlook...

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

Wednesday through Wednesday Night...Primarily VFR. Chance of showers and isolated thunderstorms (20-30%) in the afternoon and evening for the I-95 and Lehigh Valley terminals.

Thursday through Friday...VFR. No significant weather.

MARINE

SCA conditions develop this morning with southerly winds around 15 knots with gusts of 20-25 knots and seas building to 4-6 feet, peaking this afternoon. Winds and seas then begin to decrease later this evening into tonight. A Small Craft Advisory remains in effect for Atlantic Ocean coastal waters through tonight as a result.

Sub-SCA conditions expected for the Delaware Bay, but gusts around 20 kts are expected this afternoon.

Outlook...

Tuesday through Friday...No marine headlines expected.

CLIMATE

Warm temperatures well above normal are expected for the upcoming week. Wednesday is currently projected to be the warmest day, though Tuesday through Thursday could see some records broken depending on the site. Below are record highs and record high minimum temperatures for April 14th through April 16th.

Record High Temperatures April 14 Site Record/Year Allentown (ABE) 88/2023 AC Airport (ACY) 86/1945 AC Marina (55N) 90/1941 Georgetown (GED) 87/1977 Mount Pocono (MPO) 84/2023 Philadelphia (PHL) 91/1941 Reading (RDG) 90/1941 Trenton (TTN) 89/1941 Wilmington (ILG) 87/1941

Record Warmest Low Temperatures April 14 Site Record/Year Allentown (ABE) 61/2014 AC Airport (ACY) 63/2023 AC Marina (55N) 60/2023 Georgetown (GED) 65/2019 Mount Pocono (MPO) 56/2014 Philadelphia (PHL) 62/2014 Reading (RDG) 64/2014 Trenton (TTN) 62/2014 Wilmington (ILG) 60/2014

Record High Temperatures April 15 Site Record/Year Allentown (ABE) 86/1941 & 1994 AC Airport (ACY) 90/1967 AC Marina (55N) 86/1941 Georgetown (GED) 86/1960 & 2024 Mount Pocono (MPO) 82/1941 Philadelphia (PHL) 88/1941 Reading (RDG) 86/1941 & 1994 Trenton (TTN) 87/1994 Wilmington (ILG) 86/1896

Record Warmest Low Temperatures April 15 Site Record/Year Allentown (ABE) 59/2002 AC Airport (ACY) 61/2002 AC Marina (55N) 59/2006 Georgetown (GED) 65/2002 Mount Pocono (MPO) 58/2002 Philadelphia (PHL) 64/2002 Reading (RDG) 64/1938 Trenton (TTN) 63/2002 Wilmington (ILG) 62/2002

Record High Temperatures April 16 Site Record/Year Allentown (ABE) 90/2012 AC Airport (ACY) 89/2002 AC Marina (55N) 88/2002 Georgetown (GED) 89/2002 Mount Pocono (MPO) 85/2002 Philadelphia (PHL) 90/2002 Reading (RDG) 90/2012 Trenton (TTN) 91/2012 Wilmington (ILG) 92/1896

Record Warmest Low Temperatures April 16 Site Record/Year Allentown (ABE) 60/1941 AC Airport (ACY) 62/2002 AC Marina (55N) 64/2002 Georgetown (GED) 65/2012 Mount Pocono (MPO) 56/2002 Philadelphia (PHL) 62/2002 Reading (RDG) 65/1941 Trenton (TTN) 62/2002 Wilmington (ILG) 63/2002

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 1 AM EDT Tuesday for ANZ450. Small Craft Advisory until 1 AM EDT Tuesday for ANZ451>455.