Marine Weather and Tide Forecast for Oakton, VA

NEAR TERM /THROUGH TONIGHT/
High pressure will progress offshore overnight as upper ridging builds in aloft. Mostly clear skies and light southerly winds are expected overnight.
The southerly winds will act to keep temperatures up relative to preceding nights, with low temperatures in the 50s across the entire forecast area.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
Mid-level ridging peaks over the area Tuesday morning, then that ridge slides east as an upper trough approaches from the west. This along with another day of abundant sunshine should let temperatures reach well into the 80s Tuesday afternoon. Dew points also reach the 50s to low 60s by early evening. Breezy conditions are expected Tuesday, especially during the late afternoon to evening where winds gust around 25-30 mph for several hours before sunset.

Showers and thunderstorms develop along the approaching upper trough and its associated cold front in the OH Valley Tuesday afternoon.
Our area should remain dry until just before sunset (5-7PM) when a broken line of thunderstorms reaches western Maryland. The strongest corridor of jet energy is confined north of our area, with deep westerly flow overhead at only around 30-40 knots Tuesday evening.
Modest instability likely develops ahead of the front in the Potomac Highlands and Alleghenies with around 1000-1500 J/kg of MLCAPE.
However, weak shear (20-30 knots), lack of strong lift, and lingering dry air aloft will work to limit the extent of potential severe thunderstorms.

Most high-resolution models continue to favor an eastward propagating mesoscale-convective system (MCS) tracking toward western Maryland by the early evening hours. Damaging wind gusts are the primary threat. SPC has maintained a Slight Risk in the northwestern tip of Garrett County, with a Marginal Risk east over the Potomac Highlands and most of the Alleghenies. There are a couple of high res models showing much better organized, severe thunderstorms moving into our area, so will to continue monitoring and assessing the environment as we head into tomorrow.

As these thunderstorms move into the I-81 corridor they likely weaken below severe levels as nighttime low-level stability takes hold. A few showers and thunderstorms likely make it over the Blue Ridge toward the I-95 corridor late in the evening. As Tuesday night progresses the cold front sags south into the area, then stalls.
This could keep some shower activity around for much of the night, especially west of I-81. Very mild night as lows settle in the 60s.

The meandering front's exact location will play a key role in where scattered showers and thunderstorms develop Wednesday afternoon to evening. North of the boundary, expect cooler and mostly dry conditions, while locations to the south in the unstable warm sector see temps in the 80s with afternoon convection. The boundary gradually sags south of the area Wednesday night, causing winds to shift northeast to easterly. Wednesday night lows are forecast to be in the mid 50s to low 60s.

LONG TERM /THURSDAY THROUGH MONDAY/
Upper level ridge will begin to be pushed to the east Thursday as a trough approaches from the mid Mississippi Valley. A front will remain stalled nearby at the surface. Moisture advection will lead to increasing instability through the day, especially southwest of the front, although the amount of cloud cover and morning showers could have an effect. Wind fields are on the lower end of the spectrum, but could be enough to support a few stronger storms.
Lower to mid 80s are expected southwest of the front, with mid to upper 70s to the northeast. Low pressure will pass to the northwest Thursday night and toward the St. Lawrence Valley on Friday. The warm front will lift north, but be quickly followed by the trailing cold front from the west. While showers and thunderstorms will remain possible through this period, the evolution will be dependent in part due to the timing of the front and possibly a preceding trough. Should enough instability be able to build, wind fields would remain supportive of some organized, stronger storms. Another day with highs in the 80s is probable.

While the surface cold front should push to the east by Saturday morning, the sharp mid/upper level trough axis will be lagging and likely cross the area during the daytime of Saturday. This could lead to some isolated to scattered showers. Cooler air will filter into the area behind the front, supported by large Canadian high pressure. Highs over the weekend will be in the 60s and lower 70s with overnight lows in the 40s to near 50. There could be some frost/freeze concerns in the colder western valleys if radiational cooling is maximized. A warming trend will begin Monday as the high slides offshore.

AVIATION /01Z TUESDAY THROUGH SATURDAY/
High pressure will move offshore tonight, then a cold front approaches from the west Tuesday. The front stalls over the area on Wednesday. VFR conditions are expected to prevail through Tuesday night as dry conditions continue. A few showers or thunderstorms could approach the terminals Tuesday evening, though chances are too low to include in TAFs at this time.

As the front sags south into the area Wednesday morning, some lower clouds are possible though again confidence is low. Also, scattered showers and thunderstorms develop Wednesday afternoon/evening, with the best chance for impacts likely being at CHO. Some showers could linger through late Wednesday evening.

Sub-VFR ceilings are possible Thursday and Thursday night, especially north of a warm front that will be draped across the area. Showers and thunderstorms will remain possible at times Thursday and Friday as the warm front gradually lifts north, followed by a cold front crossing Friday night. Southwest winds may gust to around 20 kt Friday, then northwest winds may gust to around 20 kt Saturday.

MARINE
Southerly channeling is expected to pick up late this evening into tonight, with winds gusting around 15-20 knots over the open waters of the Chesapeake Bay. The start time of the SCA has been pushed up to 1 AM for the Bay and Lower Tidal Potomac to account for this southerly channeling overnight.

SCA conditions are expected for all of the waters Tuesday into Tuesday night ahead of a cold front that moves into the area Tuesday night. Winds diminish and turn west, north, then east quickly through the day on Wednesday as the front stalls over the area.
However, the forecast keeps winds at or below 10 knots across all the waters.

There is a chance for thunderstorms over portions of the waters Tuesday evening, and again Wednesday afternoon/evening. These storms could pose a threat to mariners if they move over the waters, with wind gusts over 30-35 knots being the main threat.

Southeast to southwest winds may remain sub-advisory on Thursday before increasing Thursday night into Friday as a warm front lifts north. Advisories may be needed for that time frame. There will also be a chance of thunderstorms each afternoon and evening. A cold front will push through Friday night, and advisories may be needed for northwest flow on Saturday.

TIDES/COASTAL FLOODING
Given a modest uptick in southerly flow, some of the typically higher guidance (SFAS, CBOFS) approaches minor flood stage at vulnerable sites like Annapolis during the astronomically higher morning tides Tuesday and Wednesday. However, given the brevity of the southerly flow and its relatively low magnitude, feel that flooding seems unlikely at this time.

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Small Craft Advisory from 1 AM Tuesday to midnight EDT Tuesday night for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 1 AM Tuesday to midnight EDT Tuesday night for ANZ530>532-538>540-542.
Small Craft Advisory from 1 AM Tuesday to 6 AM EDT Wednesday for ANZ533-534-537-541-543.
Small Craft Advisory from 9 AM Tuesday to midnight EDT Tuesday night for ANZ535-536.