Marine Weather and Tide Forecast for Williamsburg, VA

KEY MESSAGES
1) Hot and humid today, then strong to severe storm chances increase this evening. Showers and storm continue overnight and through much of tomorrow.

2) In light of the breezy and hot conditions, a late-season Increased Fire Danger Statement has been added for most of our NC counties for tomorrow.

DISCUSSION
As of 300 AM EDT Thursday...

KEY MESSAGE 1...Hot and humid today, then strong to severe storm chances increase this evening. Showers and storm continue overnight and through much of tomorrow.

Heating up today as SW flow increases ahead of a cold front.
Breezy conditions expected today with wind gusts around 30mph.
Highs will generally be in the upper 90s with the hottest temps in the southeast. Heat indices approaching 105F have prompted the issuance of a Heat Advisory for Hampton Roads and the interior southeast as far west as Greensville County. Outside of the advisory, heat indices will be 97-102.

Storm chances increase during the late afternoon and evening hours.
Based on the 00z suite of CAMs, storms during the daylight hours will likely be kept to the N/NW counties- primarily from Cumberland northeast to Dorchester MD. PoPs are less than 40% through 00z. Storms increase in coverage and spread to the remainder of the FA overnight. There is the potential for storms to be strong to severe during the evening hours. Hot and humid conditions will mean plenty of instability during the day (up to ~1800 J/kg mid afternoon). The later start time, however, will mean waning instability as storms get going. The HRRR depicts quickly dropping mean MLCAPE values with values around 1100 at 8pm, then down to 500 J/kg by 10. This means the window for severe will be roughly 5-9pm. Primary hazard is still damaging wind gusts as evidenced by DCAPE values of 800-1000 J/kg. The Slight Risk of severe weather from SPC still goes down to the NC border, but the best chance is probably north of US-460.

Starting to see some consensus in the global models with how this system evolves going into Friday. It appears all the models are on board with developing a sfc low from the remnant tropical wave from the gulf, though to varying degrees of strength. Therefore, there is higher confidence in lingering moisture for much of Friday. Showers and storms should continue through at least mid day, lingering the longest in the SE as the sfc low moves out to sea. If the low is a bit stronger like the ECMWF still suggests, this could mean moderate to heavy rain, at least across southern counties. Rain clears out from NW to SE later in the day Friday.

KEY MESSAGE 2...In light of the breezy and hot conditions, a late-season Increased Fire Danger Statement has been added for most of our NC counties for tomorrow.

A tightening pressure gradient and downslope W-SW flow will result in dry, breezy conditions on Thursday. After collaboration with neighboring offices and NCFS fire officials, concern for 20-30 mph gusts and hot temperatures, despite marginal RH values (~35-40%), justifies the IFD statement. This is especially true given the ongoing drought conditions and very dry fine fuels across the area.

AVIATION /06Z THURSDAY THROUGH MONDAY/
As of 145 AM EDT Thursday...

VFR conditions prevail during the 06z/18 TAF period. SW flow increases ahead of a cold front starting around 11-13z with elevated winds lasting through this evening. Gusts up to 30kt will be possible. Showers and storms ahead of the front move into the area late this evening into the overnight hours.
Impacts to terminals will likely not be until the end of the period (after 03z). Storms could be strong to severe with damaging wind gusts the main threat.

Outlook: Lingering showers and embedded storms continue into Fri afternoon, with best chances at PHF/ORF/ECG. Drier conditions/VFR conditions return late Fri through the upcoming weekend.

MARINE
As of 300 AM EDT Thursday...

Key Message:

- Elevated SW winds continue today into tonight, with Small Craft Advisories remaining in effect for all waters.

- A Gale Warning is in effect for the offshore 20-60nm zone south of the VA/NC border this afternoon into tonight.

Early this morning, a warm front is lifting north over the waters leading to winds become SW and increasing. Winds are currently averaging 10 to 15 knots with locally higher gusts. Seas are running 2 to 3 feet, whiles waves in the Chesapeake Bay are running around 1 to 2 feet.

Winds will rapidly increase as we approach sunrise as low pressure deepens over the Great Lakes, creating a strong gradient with high pressure located off the SE coast. In addition, forecast soundings also show very deep mixing across the region later this morning into the afternoon. Sustained winds will average 15 to 25 knots with gusts pf 25 to 30 knots. The highest gusts will likely occur near shore, including the lower James River and southern Ches Bay. Small Craft Advisories remain in effect for all waters and a Gale Warning remains in effect for the far southern 20-60nm offshore zone off the NC coast. Still thinking the highest gusts will be confined to the SE third of the zone. Waves in the bay increase to 2-3 ft with seas 4-6 ft nearshore and 5-8 ft well offshore. Will need to watch the potential for strong to severe storms, mainly this evening into the overnight hours. Locally gusty winds along with increased waves/seas can be expected in the vicinity of any thunderstorms. The surface front finally drops southward during the day on Friday with winds becoming N and NW 5-10 kt behind the boundary. Much improved marine conditions are expected this weekend as high pressure moves into the area. The next system approaches the region early next week with increasing SW winds.

CLIMATE
As of 145 PM EDT Wednesday...

Record Highs for tomorrow 6/18

Record High/Year Location 6/18 -------- ---- Richmond 100 (1970)
Norfolk 99 (1944)
Salisbury 98 (2014)
Eliz. City 100 (2011)

AKQ WATCHES/WARNINGS/ADVISORIES
MD...None.
NC...INCREASED FIRE DANGER from 10 AM EDT this morning through this evening for NCZ012>017-030>032.
Heat Advisory from 11 AM this morning to 8 PM EDT this evening for NCZ012>017-030>032.
VA...Heat Advisory from 11 AM this morning to 8 PM EDT this evening for VAZ087>090-092-097-098-523>525-528>531.
MARINE...Small Craft Advisory until 1 AM EDT Friday for ANZ630-631.
Small Craft Advisory until 10 AM EDT Friday for ANZ632-634.
Small Craft Advisory from 7 AM this morning to 7 AM EDT Friday for ANZ633-650-652-654-656-658.
Small Craft Advisory from 7 AM this morning to midnight EDT tonight for ANZ635>637.
Small Craft Advisory until 7 AM EDT Friday for ANZ639.
Gale Warning from 4 PM this afternoon to 1 AM EDT Friday for ANZ688.