Marine Weather and Tide Forecast for Fredericksburg, VA

KEY MESSAGES
- 1) Severe thunderstorms are possible on Sunday.

- 2) Seasonably warm conditions and daily chances for showers and thunderstorms are expected through Monday, with drier conditions for Tuesday and Wednesday.

DISCUSSION
KEY MESSAGE 1...Severe thunderstorms are possible on Sunday.

A potent shortwave by late-summer standards and an associated area of low pressure will track across Ontario toward Hudson Bay on Sunday, with a likely convectively induced disturbance and associated weak area of low pressure tracking into the Great Lakes. Low-level winds will turn out of the south in response to this disturbance, drawing a boundary that is currently stalled out to our south northeastward as a warm front. This front is expected to clear much of the area by Sunday evening, advecting in a very warm, humid, and highly unstable airmass into the region. However there are some uncertainties with regard to just how far north and east this highly unstable airmass will make it. Guidance is in good agreement that locations to the west of the Blue Ridge will destabilize, but there's greater spread in solutions further east.

An atypically strong low-level jet for late summer will accompany this system. Model soundings show large, clockwise turning hodographs, with ample streamwise vorticity and SRH at low-levels. When combined with 2000 J/kg of MLCAPE, this raises concerns for severe thunderstorms, with supercells possible.
Damaging winds should be the primary threat, but a tornado or two can't be ruled out given the high SRH environment in place.
As mentioned before, locations to the west of the Blue Ridge appear to have the greatest chance for severe thunderstorms, but there is plenty of time for things to change with two days of convection upstream of the event.

KEY MESSAGE 2...Seasonably warm conditions and daily chances for showers and thunderstorms are expected through Monday, with drier conditions for Tuesday and Wednesday.

A typical late summertime pattern will remain in place through early next week, with seasonable temperatures and daily chances for showers and thunderstorms. High temperatures will generally be in the mid 80s to around 90 each day, with overnight lows in the upper 60s to low 70s.

An early morning thunderstorm complex has begun to push out of the Ohio Valley toward the central Appalachians. While it has undergone a great deal of weakening in the last few hours, this system does have a decent amount of lightning while crossing central West Virginia. Further, the swirl on radar signifies a remnant mesoscale convective vortex (MCV) accompanying this cluster of storms. Based on the surface boundary being off to the south, this complex is largely elevated in nature. Expect much of this activity to gradually dissipate, but remnant mid-upper level disturbances associated with this activity will likely progress into the area later today, eventually sparking the development of showers and thunderstorms. Instability is mainly expected to be focused across southwestern portions of the forecast area, with locations to the south and west of the Potomac having the greatest chance for a thunderstorm this afternoon. A passing shower can't be ruled out anywhere, but northeastern Maryland will have the greatest chance to remain dry.

Thunderstorm activity is expected to be focused even further off toward the southwest on Saturday, with the Central Shenandoah Valley and Central Virginia having the greatest chance for a storm. The background environment both today and tomorrow has vertical profiles that are deeply saturated, with modest flow through the mid-levels (around 35 knots of 0-6 km shear). DCAPE values will be low given the saturated profiles, but a wet microburst or two can't be ruled out. SPC has southwestern portions of the forecast area outlooked in a Marginal Risk for severe thunderstorms today, with damaging winds being the primary risk. On Saturday the Marginal Risk only clips Highland an Augusta Counties.

Following a greater severe thunderstorm threat on Sunday, there may be additional thunderstorms across the forecast area on Monday, but details remain highly uncertain this far out. Most guidance suggests that a cold front will move through later Monday into Monday night as high pressure builds to our north.
Temperatures will change very little behind this front, but drier air will advect in from the north, with dewpoints likely dropping into the 50s on Tuesday. This drier air will suppress thunderstorm activity, most likely leading to dry conditions on both Tuesday and Wednesday.

AVIATION /13Z FRIDAY THROUGH TUESDAY/
Prevailing VFR conditions are expected at the terminals through early next week. Temporary drops to sub-VFR conditions may be possible at times during showers and thunderstorms. Today the greatest chance for storms will be at CHO, with chances decreasing off toward the north and east. For now, a PROB30 group for thunderstorms has been included at CHO, with mentions of showers further northeast. Additional showers and a thunderstorm or two may be possible near CHO on Saturday. More widespread chances for showers and thunderstorms are expected on Sunday, with the potential for all terminals to see impacts.
Showers and thunderstorms may be possible again on Monday, with drier conditions expected on Tuesday behind a cold front.

Winds will be light and variable today, light out of the east to northeast on Saturday, out of the south on Sunday, west to northwest on Monday, and north to northwest on Tuesday.

MARINE
Light and variable winds are expected over the waters today, before turning light out of the east tomorrow. Winds become southerly and increase in magnitude on Sunday, with Small Craft Advisory conditions likely. Sub-SCA level northwesterly winds are forecast for Monday and Tuesday. An SMW associated with thunderstorms can't be ruled out any day through Monday. As it looks now, the greatest chance for an afternoon or evening storm will be on Sunday, with the lowest chance on Saturday.

TIDES/COASTAL FLOODING
Water levels are largely expected to stay below Action Stage through Saturday. The potential exception could be Annapolis, which could reach Action Stage at the higher of the daily tides.
Water levels will start to increase in southerly flow on Sunday, with Annapolis potentially approaching Minor Flood Stage.

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.