Marine Weather and Tide Forecast for Williamsburg, VA

KEY MESSAGES
1) A weak front and surface low lift slowly back to the north today, bringing greater coverage of showers and storms to the region.
Locally heavy rainfall is the primary hazard.

2) Convective coverage is expected to decrease Wednesday and especially during the late week period with warmer temperatures returning to the area.

DISCUSSION
As of 315 AM EDT Tuesday...

KEY MESSAGE 1...A weak front and surface low lift slowly back to the north today, bringing greater coverage of showers and storms to the region. Locally heavy rainfall is the primary hazard.

Morning analysis shows a weak stationary front draped across the region from near South Hill northeastward into the MD Eastern Shore.
Aloft, a closed low is noted to the SW of the area in central GA.
Deep southerly flow on the eastern flank of the upper low continues to funnel moisture northward into the Carolinas and along the stalled frontal boundary. PW values are 2.2-2.4" across eastern NC but taper to around 1.75" along the boundary. Some showers with occasional thunder have been persistent along and west of the I-85 corridor this morning. These showers should linger for a few more hours before dissipating.

A subtle shortwave trough embedded in the upper level southerly flow will spawn a weak surface low in central NC early this morning. The low and attendant front are forecast to lift slowly northward through the day with increasing chances for showers and storms expected, mainly along and south of the boundary.
Increasing deep layer moisture spreads back to the north as well with the 00z HRRR showing fairly impressive 30-50% probs for 3"/3 hours, mainly centered along and east of I-95 and south of I-64 this afternoon. Contemplated issuing a small Flood Watch for these areas but recent rainfall has largely spared this region with 3 hour flash flood guidance generally in the 3-4" range. However, given the deep moisture, weak flow aloft, and tall/skinny instability profiles noted on forecast soundings, the potential for localized areas of flash flooding is apparent, especially in urban/poor drainage areas. WPC has maintained Marginal ERO for the entire area today. The weak winds aloft combined with widespread clouds will limit shear/instability and the chance for severe weather across the region today and tonight. Temperatures will mainly be in the low to mid 80s with cloud cover and showers/storms lingering into tonight. Warm and very muggy overnight with lows in the upper 60s to low 70s.

KEY MESSAGE 2...Convective coverage is expected to decrease Wednesday and especially late week into the weekend with warmer temperatures returning to the area.

00z guidance has trended downward with respect to convective coverage on Wednesday. Isolated showers/storms are possible but not expecting widespread severe or flooding issues. With fewer clouds and showers around, temperatures will rebound into the mid and upper 80s on Wednesday. Precip coverage is expected to further decrease late week into the weekend as the upper trough to the west lifts northward and away from the area. Slight chance PoPs each day are mostly confined to western portions of the region in the afternoon and early evening hours. With lower shower and storm coverage, temperatures return into the upper 80s and low 90s Thursday through Sunday. Afternoon heat index values climb back into the upper 90s and low 100s late week into the weekend. While apparent temps may briefly creep into Heat Advisory range (105+) in the afternoon, am not expecting the need for heat headlines at this time.

AVIATION /12Z TUESDAY THROUGH SATURDAY/
As of 705 AM EDT Tuesday...

A mix of flying conditions is in place this morning with a weak stationary front across the region. A few showers and storms have persisted overnight, mainly across SW portions of the area but may impact RIC over the next hour or two. Guidance shows increasing coverage of MVFR CIGs spreading northward as weak low pressure develops across central NC and lifts northward with the front. Increasing coverage of showers and storms will lift northward along and ahead of the front/low this afternoon.
Confidence is low with respect to coverage and exact timing of convection at any one terminal so have limited afternoon MVFR/-TSRA to PROB30 groups for now. Generally light winds this morning will become NE 5-10 kt north of the front and SE 5-10 kt in the wake of the boundary. Precip lingers into the overnight period with localized flight restrictions likely to accompany the heavier showers/storms.

Outlook: Shower/storm chances continue through mid- week, with periodic flight restrictions lingering, mainly from early morning stratus, and brief visibility restrictions in heavy rain. A more typical Summer pattern returns for the latter half of the week, with a somewhat lower coverage of late afternoon and evening isolated to scattered showers and storms Thu-Fri.

MARINE
As of 240 AM EDT Wednesday...

Key Messages:

- Benign marine conditions are expected to prevail from late tonight through late week, outside of local thunderstorm influences.

Expansive high pressure is currently centered east of Bermuda and extends across the western North Atlantic. Another high has built down across the Eastern U.S. behind a stationary front draped across our area. The gradient between these two features is weak and marine observation sites are measuring winds of generally 5 kts or less from the S-SW. There are some showers and isolated thunderstorms to the south, but the local waters are not currently seeing any convective development this morning. Seas have been a little slower to come down, but are currently around 3-4 ft in the nearshore coastal waters and 1-3 ft (highest at the mouth of the Bay), so all SCAs have been allowed to expire.

The aforementioned front will sag a little farther south over the next few hours and the northern coastal waters and Middle Bay will likely see winds increase to 5-10 kts and shift to the NE briefly.
Through the afternoon, the front will lift slowly back to the north and winds will shift back to the SE-S by tonight. As the front lifts across the local waters, scattered to widespread showers and storms will develop. The front will linger across the area through Wednesday before starting to wash out. Locally degraded marine conditions are likely to accompany the stronger storms through mid- week, mainly in the form of VSBY restrictions in heavy rain and frequent lightning, but some localized gusty winds and confused seas will also be possible. As the front washes out, weak high pressure will rebuild over the area, then slide offshore for late week. A more typical summer setup resumes, with Sub-SCA S-SW winds ~10-15 kt developing, turning S-SE nearshore with seabreeze circulations each afternoon. Daily afternoon and evening shower and storm chances persist into the weekend, though chances gradually diminish beyond Wednesday.

Rip Currents: There is a Moderate Rip risk for the northern beaches today with a Low Rip Risk for southern beaches.

AKQ WATCHES/WARNINGS/ADVISORIES
MD...None.
NC...None.
VA...None.
MARINE...None.