Marine Weather and Tide Forecast for Charles, MD

KEY MESSAGES
1. Trending warmer today after a cold night. Some rain showers also move in for tonight.

2. A return to above average temperatures briefly later this week before cooling down again over the weekend. Widespread rainfall possible over the weekend.

DISCUSSION
KEY MESSAGE 1...Trending warmer today after a cold night. Some rain showers also move in for tonight into Wednesday.

After a cold night across the area, we start to warm up today.
Freeze warnings remain unchanged through mid-morning before we see temperatures climb through the day. This will be due to our high pressure system moving offshore today and allowing for return flow to develop with a south to southwest wind. Warm air advection takes place today into tonight allowing for this warm up. High temperatures reach into the 50s for many.

In the wake of our high pressure system, a weak low pressure system approaches the area from the Great Lakes region tonight resulting in rain showers developing across the area. This system slowly clears the region later in the day Wednesday. Lows tonight are in the mid 30s to mid 40s with highs Wednesday in the upper 50s to upper 60s.

KEY MESSAGE 2...A return to above average temperatures briefly later this week before cooling down again over the weekend.
Widespread rainfall possible over the weekend.

In the wake of Wednesday's system, warm air advection and rising heights will result in temperatures climbing back above average Thursday through Friday. Highs for most of the area are forecast to be in the 70s for Thursday. By Friday, a backdoor cold front may arrive which pushes temps back down a few degrees, though uncertainty here is high and if the front is potent, it could be more than just a few degrees. A low pressure may then arrive Friday night into Saturday with some showers, and with the air mass behind the backdoor front becoming more firmly established, Saturday now looks 10-15 degrees cooler than Friday, possibly even more.

In terms of rainfall, the next low pressure over the weekend has the potential for widespread showers or a period of rain.
The strength and timing of the involved features for the weekend however is lower confidence. The pattern that is currently indicated among the model guidance however would result in perhaps up to a half inch of very beneficial rainfall.
Uncertainty remains high, however.

AVIATION /18Z TUESDAY THROUGH SUNDAY/
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.

Today...VFR with mostly clear skies. Lingering northerly winds will transition to south-southwest around 5-10 kt this afternoon. High confidence.

Tonight...Prevailing VFR. Increasing clouds in the evening will give way to BKN/OVC skies overnight. A slight chance of rain showers early in the evening (between 00-03Z), before increasing again after 06-10Z. A slight chance of MVFR ceilings with showers, but expect VFR conditions to remain. South-southeast winds around 10 kt, locally higher near KMIV/KACY. Moderate confidence overall.

Wednesday...Prevailing VFR for most terminals, with MVFR ceilings likely at KABE and possibly KRDG/KTTN. Rain showers continue through the morning and end from northwest to southeast between 15-18Z. Skies should begin to scatter out after 18Z.
South-southeast winds will gradually become north-northwest in the afternoon around 5-10 kt. Low-moderate confidence.

Outlook...

VFR likely returns by Wednesday night and continues through Friday. Sub-VFR then likely returns Friday night and especially Saturday.

MARINE
A north wind in the morning gradually shifts to be out of the south- southeast this afternoon at around 10 knots with gusts up to 15 knots. Winds increase out of the south tonight at 15-20 knots with gusts to 25 knots. A Small Craft Advisory has been issued for the Delaware Bay from 2AM to 8AM Wednesday. For a portion of the Atlantic coastal waters, a Small Craft Advisory has been issued from 2AM to 11AM Wednesday. Seas through the period are 2-4 feet.

Outlook...

Sub-SCA expected Wednesday night through Friday night. Marginal SCA conditions possible Saturday with gusts up to 25 kts and seas up to 5 feet.

CLIMATE
Record low temperatures are possible at some climate sites for this morning, April 21st. Below are the daily low temperature records for 4/21:

Daily Record Low Temperatures April 21 Site Record/Year Allentown (ABE) 28/1925 & 1956 & 2018 AC Airport (ACY) 25/1981 AC Marina (55N) 26/1875 Georgetown (GED) 27/1961 Mount Pocono (MPO) 11/1908 Philadelphia (PHL) 27/1875 Reading (RDG) 26/1982 Trenton (TTN) 30/1907 & 1925 Wilmington (ILG) 28/1925

PHI WATCHES/WARNINGS/ADVISORIES
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 2 AM to 8 AM EDT Wednesday for ANZ430-431.
Small Craft Advisory from 2 AM to 11 AM EDT Wednesday for ANZ450>455.