Marine Weather and Tide Forecast for Richmond, VA

NEAR TERM /THROUGH TODAY/
As of 800 PM EST Saturday...

Key Messages:

- Freezing fog is expected inland tonight, dry and a bit warmer Sunday.

A Freezing Fog Advisory has been issued for our western tier of counties as of 8 PM EST. Temperatures will continue to drop this evening, falling back into the 20s tonight. This combined with widespread visibilities of 1/4 SM (or less) will lead to the potential for slippery conditions tonight into Sunday morning, especially on bridges, elevated surfaces, or untreated roadways.
Expect the fog to continue to spread east over the next few hours and an expansion of the advisory to the east is likely.

Previous Discussion: The latest WX analysis shows a rather weak pressure gradient over the local area, with widespread low clouds hanging on east of the Blue Ridge. Temperatures have remained quite cold in the the piedmont, in the low-mid 30s which is about 10 degrees below NBM forecasted readings as of 3 PM. Somewhat warmer air is in place across SE VA/NE NC (temperatures in the 40s).

Challenging forecast tonight with respect to fog/freezing fog as the models continue to strongly suggest that it becomes widespread along and W of I-95 after midnight, while the latest conditions have been much slower to allow for any clearing over the CWA (which leads to lower confidence). For now, will still show some clearing this evening, with light winds conducive to radiational cooling later tonight. NAM and GFS BUFKIT soundings continue to depict boundary level saturation with the potential for more widespread and dense fog/freezing fog. Lows tonight fall into the 20s for most of the area with low 30s near the bay/coast. After morning fog/freezing fog, Sunday would eventually see partial sunshine. especially south, along with milder temperatures rising into the low-mid 40s north, with lower 50s SE.

SHORT TERM /TONIGHT THROUGH TUESDAY/
As of 310 PM EST Saturday...

Key Messages:

- Weak low pressure off the SE coast will bring a chance for rain/snow changing to snow Monday.

- Dry and cold Tuesday.

High pressure will be offshore Sunday night, allowing low level flow to become southerly ahead of an approaching cold front.
Meanwhile, weak low pressure lifts ENE off the coast of northern Florida, gradually strengthening off the SE coast on Monday. All of the models have trended farther north with the precip chances Monday, with a similar temperature profile to previous runs.

As a short wave aloft traverses the region on Monday, expect at least a chc for precip for most of the CWA (generally highest PoPs across the south). Deep layer moisture is still somewhat limited behind the surface cold front, but the trends are wetter so would not rule out the potential for QPF amounts to ~0.25" and think the NBM is behind on the trends. With ~1030 mb sfc high pressure sliding east from the Great Lakes into NY/PA during the day Monday, there will be a good feed of cold air into the mid-Atlantic, with very cold air aloft. Latest 12Z/06 GEFS/GEPS/ENS have trended significantly upward and now show 20-60% chances for at least 1" snowfall across central and south central VA (assuming a 10:1 SLR) which may actually end up being more like 15:1 later in the day. Will mention the winter WX potential Monday in the HWO for now and continue to monitor model trends over the next few cycles as this will bear watching.
High temps Monday top out in the mid 30s NW to the low 40s SE (but if moisture lingers Mon evening even SE zones have some snow potential).

Very cold air moves into the region Monday night with lows in the mid to upper teens inland, mainly low to mid 20s near the coast. High pressure over the region on Tuesday will become centered south of the area late in the day. Mostly sunny, but cold Tuesday with highs in the mid/upper 30s NW to the mid 40s SE.

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
As of 320 PM EST Saturday...

- Milder Wednesday and Thursday.

- Another front crosses the region late in the week with colder temps and precip potential.

Medium range models and ensembles are in decent agreement that midweek should be milder as a deep upper trough amplifies across central Canada, with low pressure tracking through the Great Lakes. This allows for an increasing SW low level flow Wed, with highs into the 50s for most. Remaining relatively mild Wed night and Thursday, with increasing rain chances Thursday night/Friday as the next system impacts the region. Precip potentially changes over to a rain/snow mix before ending Friday night. Saturday looks dry and cold as high pressure builds in from the NW.

AVIATION /06Z SUNDAY THROUGH THURSDAY/
As of 125 AM EST Sunday...

Widespread LIFR/VLIFR conditions in place over much of the region early this morning. Freezing Fog Advisory includes the RIC, SBY, and PHF terminals until 14z. 1/4SM VSBY (or lower in a few spots). Satellite shows LIFR conditions spreading SE and will likely impact ORF over the next hour or so. Temperatures across the SE terminals are still above freezing so not expecting widespread FZFG at ORF. ECG may escape the fog but CIGs fall to IFR prior to sunrise. Light and variable winds overnight continue through the end of the period.

Outlook: Primarily VFR conditions return by Sunday night.
Another system Monday morning may bring degraded flight conditions, especially to the S terminals, behind a strong cold front.



MARINE
As of 300 PM EST Saturday...

- Benign marine conditions through Sunday.

- Another round of SCAs expected early Monday as a strong cold front moves across the local waters, with a brief period of gale force gusts possible.

- Another system may bring degraded marine conditions to the area Wednesday through the end of the week.

Weak high pressure is spread across the Southeast, with an area of low pressure well offshore this afternoon. This set-up has led to a weak gradient across the local waters. Marine observation sites are measuring winds of 5-10 kts and waves of around 1 ft in the Bay and seas ranging between 3-4 ft in the Ocean. The aforementioned high will slide northeastward across the area over the next 24 hours, leading to benign marine conditions through the end of the weekend.
Winds will become light and variable, with waves remaining around 1 ft and seas subsiding to 2-3 ft in the Ocean.

Marine conditions will rapidly deteriorate early Monday morning as a cold front drop through the area. Winds will reach high-end SCA conditions for a majority of the day and through the first part of Monday night. This will occur as high pressure builds southward across the region and an area of low pressure skirts northeast off the Carolina coast. With the tightened gradient in place, combined with strong CAA expected in the wake of this front, there will likely be a period of gale-force gusts accompanying at least the initial push of this drier, colder air. Guidance has trended upwards some in the southern waters, though our in-house wind probs remain >50% for gale force gusts. This upwards trend is the result of a slightly closer placement of the low to the Carolina coast as opposed to a low further offshore. There is still some uncertainty in the exact location of the low at this time, and we will continue to iron out the exact details over the next few forecast cycles.
With the lower confidence and the possible brief nature of this wind surge, have held of on a Gale Watch for now. High pressure is forecast to build across the area late Monday night through Tuesday, and winds will quickly diminish in response. This reprieve from winds will be fleeting as another system approaches the region on Wednesday. Winds will begin to increase Wednesday morning as a warm front lifts across the region, followed by another strong cold frontal passage by late week.

As winds increase on Monday, waves will rapidly build to 3-5 ft in the Bay (highest at the mouth of the Bay) and seas will build to 6-8 ft in the Ocean. Despite an expected downtrend in winds late Monday night through Tuesday, seas will be slower to subside and will likely remain near or just briefly drop below SCA criteria before building again with the second wind surge forecast for Wednesday.

AKQ WATCHES/WARNINGS/ADVISORIES
MD...Freezing Fog Advisory until 9 AM EST this morning for MDZ021>025.
NC...Freezing Fog Advisory until 9 AM EST this morning for NCZ012>014.
VA...Freezing Fog Advisory until 9 AM EST this morning for VAZ048- 060>062-064>069-075>090-092-093-096-097-099-509>524.
Dense Fog Advisory until 9 AM EST this morning for VAZ095-098- 100-525.
MARINE...Dense Fog Advisory until 9 AM EST this morning for ANZ630>632- 634>638.