Marine Weather and Tide Forecast for Frederick, MD

NEAR TERM /THROUGH SUNDAY/
Winds are gradually starting to turn out of the south as high pressure shifts offshore. This will push a warm front will move across our western zones later tonight and Sunday morning. Given the widespread temperatures in the 20s overnight, precipitation is expected to begin as a wintry mix of precipitation. As such, a Winter Weather Advisory is in effect for this threat, mainly for the higher elevations where freezing rain will be the primary threat. Valley locations, and perhaps even areas just east of the Blue Ridge, may see a mix of snow, sleet, and/or freezing rain at the onset. However, those locations will rise above freezing much quicker, transitioning more to a cold rain for most. The ridges will hang onto above freezing temperatures later into the morning and even until around noon. After that, any lingering precipitation will be in the form of a cold rain, but will quickly push off towards the east. When all is said and done, very minimal snow and sleet accumulations are forecast, while ice accumulations should be around a glaze if not a few hundredths of an inch. Gusty winds could also reach up to 35 mph at times during the Winter Weather Advisory.

SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/
The precipitation, outside of some lingering upslope showers, should be east of the area by sunset or so. A push of gusty NW winds will move through overnight Sunday into early Monday, though it doesn't look to necessitate any wind headlines at this time. The main impact would be some pretty cold wind chills Sunday night, with low temperatures forecast in the 20s (wind chills in the teens to low 20s).

Monday will be chilly and dry with a second dome of high pressure building into the region behind Sunday's cold front.
This high is expected to also move east and away from the region Monday evening and overnight. The next storm system will move toward us Monday night. Some wintry precipitation could arrive in the central Shenandoah Valley and southern Appalachians late Monday night, but much of the precipitation will be on Tuesday morning (see long term below).

LONG TERM /TUESDAY THROUGH FRIDAY/
A deepening low pressure system moving along the Eastern Seaboard on Tuesday is likely to bring a wintry mix to parts of the area.

A retreating surface high will be near Nova Scotia come early Tuesday morning, with a low pressure quickly moving across the Carolinas to offshore of Virginia. The low is forecast to deepen as it moves offshore of the Delmarva toward southern New England Tuesday night. There is increasing confidence for a wintry mix along and west of the Blue Ridge, with freezing rain likely being the primary p-type. This is due to a strengthening LLJ that quickly ushers in a warm nose aloft. Though, given the cold airmass in place and earlier precip onset, there could be a quick burst of snow and/or sleet before precip transitions to freezing rain or rain.

Perhaps in parts of western MD or the Alleghenies the cold air hangs on through the event, keeping snow as the primary p-type. Still, that will be dependent on where the low tracks, how strong the low is (whether it can surge warmer air farther northward faster), and how the retreating high to the north can keep the cold air wedged in. Latest model trends are for a faster onset of precipitation (seen in the GFS and Canadian), though virtually all of the guidance has precip starting west of the Blue Ridge by 4-5AM Tuesday morning.

For areas east of the Blue Ridge, it seems the most likely scenario is for a possible wintry mix of snow/sleet/rain at the onset, then quickly transitions to a cold rain. Those along/east of US-15 have the best chance of seeing non-rain p-type at the onset. Still, a lot to determine in the next few days so continue to monitor the weather for additional updates. Those areas that do get a wintry mix could experience travel disruptions during the Tuesday morning commute.

The low pulls away from the area quickly Tuesday night, with precip coming to an end from west to east. High pressure builds in Wednesday into Thursday, with dry and cold conditions expected. A cold front looks to cross the area Thursday afternoon, possibly bringing some mountain snow showers. Friday looks to be very cold with morning lows in the teens to low 20s, and highs in the 30s to around 40F.

AVIATION /18Z SATURDAY THROUGH THURSDAY/
VFR conditions today and tonight with dry weather and chilly temperatures. Winds northwest 5 to 10 knots for the remainder of the day, becoming southeast around 5 knots tonight.

Some light wintry precipitation could move into CHO and MRB later tonight into Sunday morning that could drop our ceilings to MVFR to IFR or perhaps our visibility to 2 or 3 miles.
Introduced a PROB30 for some ZR at CHO, and for snow showers at MRB in the latest TAF updates. Otherwise, the other terminals may see a brief rain/snow(or sleet) mix at the onset of precipitation early to mid morning. Some minor restrictions can be expected if this threat materializes. Emphasizing the PROB30s in the TAFs because this event has a lot of uncertainty.

Winds south becoming southwest around 10 knots Sunday and Sunday night behind a warm front and ahead of a cold front.

Dry with gusty NW winds on Monday in the wake of the aforementioned cold front. Expect gusts to around 20 to 25 knots during the first half of the day, before tapering off in the afternoon/evening.

Sub-VFR conditions are likely Tuesday morning and afternoon as a low pressure system tracks just east of the area. A wintry mix is possible at all terminals early Tuesday morning, though most quickly transition to a cold rain. MRB is the most likely to see freezing rain persist into the afternoon. VFR conditions return Tuesday night into Wednesday as high pressure builds into the region.

MARINE
Light southeast winds expected through tonight as high pressure shifts offshore. This shift in high pressure will push a warm front through the region on Sunday, and will result in a slight increase in winds Sunday morning, as well as a directional change out of the SW. Additionally, some light rain is expected over the waters during this time as well. No marine hazards are expected however, as winds stay AOB 15 knots at best.

A cold front will then push through later in the afternoon, which will bring a push of stronger winds through Sunday night and into the first half of Monday. SCAs will likely be needed during this timeframe.

A low pressure system will pass east of the area Tuesday into Tuesday night. This is likely to bring SCA conditions across all the waters, with near-gale force gusts possible in the open waters of the Chesapeake Bay. High pressure builds over the region on Wednesday, with sub-SCA winds likely.

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Winter Weather Advisory from 3 AM to noon EST Sunday for MDZ509-510.
VA...Winter Weather Advisory from 3 AM to noon EST Sunday for VAZ025-036-503-504-507-508.
WV...Winter Weather Advisory from 3 AM to noon EST Sunday for WVZ501-503-505.
MARINE...None.