Marine Weather and Tide Forecast for Alexandria, VA

KEY MESSAGES
- 1) Frost and/or freezing temperatures this weekend.

- 2) Daily chances for showers next week as a Nor'easter develops off the Carolina coast.

DISCUSSION
KEY MESSAGE 1...Frost and/or freezing temperatures this weekend.

Mid level trough axis is crossing the Appalachians as of mid morning. Anafrontal rain continues in southern portions of the forecast area but should depart by this afternoon. Drier air in the wake of the upper jet streak is seen in water vapor imagery and is leading to cloud breaks west of the Blue Ridge. Gradual clearing should spread eastward through this afternoon.

Temperatures drop today in the wake of a strong cold front with highs expected to be in the 50s for most (40s mtns). Gusty winds of 25-35 mph continue through the day before decreasing tonight.
Tonight's cold air will be driven mainly by advection, although some decoupling may occur west of the Blue Ridge which will be closer to the surface high. Winds remain much more uncertain to the east, and while it will be chilly, this may maintain notable temperature/dew point spreads (the latter of which will be in the upper 20s) to prevent frost formation. Unless 12Z guidance shifts, further expansion of the Frost Advisory is unlikely.
While the Freeze Warning area still appears to be in good shape, it may not be a widespread freeze along/east of I-81.

Temperatures begin gradually warming on Sunday although additional Frost Advisories are possible Sunday night west of the Blue Ridge where low temperatures drop into the 30s (in any areas where the growing season does not end tonight). Beginning early next week, chances for Frost/freeze diminish as temperatures continue to warm.

KEY MESSAGE 2...Daily chances for showers next week as a Nor'easter develops off the Carolina coast.

As an upper trough advances through the Mid-Atlantic today, part of it cuts off along a stalled front south of our region this weekend.
Heading into next week, this cutoff upper-level low results in the development of a nor'easter off the Carolina coast. This system then meanders offshore and near the coast, but guidance is uncertain on its track and strength. Forecast models show considerable spread with respect to the location nor'easter next week. Some solutions keep the system offshore, while others have it retrograding further westward. If this system does track further westward, it could lead to local impacts. With this mid-level low being cut off from the main steering flow, it could linger through much of next week.
Northeast breezes and daily chances for showers are possible.
Regions along and east of I-95 have the best potential for showers next week.

AVIATION /13Z SATURDAY THROUGH WEDNESDAY/
Lingering rain should exit CHO shortly. VFR ceilings will gradually clear through the afternoon. Northwest winds gusty 20 to 30 knots today before diminishing overnight. Winds shift to north/northeasterly Sunday and Monday, gusting around 15 knots each afternoon.

For terminals in the eastern portions of the forecast area, sub-VFR conditions could develop next week from showers associated with a nor'easter lurking offshore. Northeast winds could become breezy at times depending on how close the system gets.

MARINE
Gusty northwest winds are expected today in the wake of a strong cold front, with Small Craft Advisories and Gale Warnings in effect. Small Craft Advisory conditions continue Sunday with northwest winds gusting around 20 knots. Elevated winds continue Monday as a Nor'easter develops off the Carolina coast with SCA criteria winds possible, mainly in the open portions of the Chesapeake Bay.

Next week, northeast winds around a nor'easter may remain gusty through much of next week. Small Craft Advisories and Gales are possible at times over the wider/southern waters.

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Freeze Warning from 1 AM to 9 AM EDT Sunday for MDZ003>006-501- 502-507-509-510.
Frost Advisory from 1 AM to 9 AM EDT Sunday for MDZ503-505.
VA...Freeze Warning from 1 AM to 9 AM EDT Sunday for VAZ025>031- 503>505-507-508.
Frost Advisory from 1 AM to 9 AM EDT Sunday for VAZ036>040-050- 051-501-502-506-526.
WV...Freeze Warning from 1 AM to 9 AM EDT Sunday for WVZ050>053-055- 501>506.
MARINE...Small Craft Advisory until 6 AM EDT Sunday for ANZ530-531-536- 538>542. Gale Warning until 6 AM EDT Sunday for ANZ532>534-537-543. Small Craft Advisory until 11 PM EDT this evening for ANZ535.