Marine Weather and Tide Forecast for York, VA

NEAR TERM /THROUGH TONIGHT/
As of 1031 AM EDT Wednesday...

Key Messages:

- Very warm, breezy and moderately humid today. Highs in the upper 80s to low 90s, with maximum heat indices around 100 degrees.

- Isolated to widely scattered late day and evening convection possible over the northwestern third of the area, from north of Richmond to the northern neck and MD Eastern Shore.

Today is already off to a warm start, with heat indices already in the upper 80s into the lower 90s across the forecast area. The fog across the MD Eastern Shore counties dissipated as the warm front lifted and GOES Visible is depicting mostly clear skies.

An expansive mid/upper-level ridge off the Southeast coast will remain in place today, building a little farther north. This will help temperatures climb into the lower 90s today, despite the incoming weak shortwave and associated cloud cover expected to move toward the area later today. With dew points in the lower to mid 70s, heat indices will likely peak just below low end Heat Advisory criteria, but if some areas do manage to reach it, it will be very brief. Due to most areas likely only reaching a heat index around 95-102 degrees, we have decided not to issue any heat products today. With that being said, it is still important take precautions if any outdoor activities are on tap for today. Luckily, with a tightening gradient between a surface high in the western North Atlantic and a developing low to the west combined with southwesterly flow (typically allows for good mixing), there will be a breeze to try and help mitigate some of the heat this afternoon. Later this afternoon, the aforementioned weak shortwave will head towards our area, which will help with the development of widely scattered showers and isolated thunderstorms. The best chance for convection will be mainly NW of Richmond through the Northern Neck and Eastern Shore counties. A Marginal Risk is in place across our NE counties and a majority of our Eastern Shore counties, with main threat from any developing convection being isolated damaging wind gusts. Storms will likely wane after the loss of daytime heating, with clearing skies expected after midnight.
Temperatures will drop into the lower to mid 70s overnight.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
As of 310 AM EDT Wednesday...

Key Messages:

- Severe Tstms possible late Thursday afternoon into Thursday night. A Slight Risk is in place for our area for Thursday.
Large hail and damaging winds are the main threats.

Thicknesses rise a bit more tomorrow, portending an even warmer day tomorrow. Given the pattern, and with the recent wet spell, have kept high temperatures Thu on the "cooler" edge of guidance, but with dew pts at or slightly higher than MOS numbers (but a bit lower than NBM). Heat indices Thursday will be a degree or two warmer, especially across the SE where dewpoints are less likely to mix out (albeit slightly) in the afternoon. Heat Advisories are a possibility tomorrow over Hampton Roads and the N OBX. Highs in the low to mid 90s, with heat indices 100-105.

The previously referenced cold front slides across the region from the west Thursday afternoon into Thursday night. This will bring a better chance of showers and thunderstorms to the local area by later Thursday afternoon into Thursday evening. Ahead of the front, highs in the low to mid 90s and similar dewpoint values will result in considerable instability. Additionally, ahead of the mid-level trough, H5-7 lapse rates steepen to ~6-6.5 C/Km by 00z/Thu, along with bulk shear values of 30-40kt. This should result in a decent damaging wind threat, as evidenced by inverted-v soundings across the mid-Atlantic region. But large hail is also a consideration, especially given the previously referenced steepening mid-level lapse rates. SPC has outlooked the entire area in a Day 2 Slight Risk. Add all this up and the expectation at this time remains for a more organized linear/multi- cellular, outflow- driven storm mode with damaging winds and large hail as the primary threats. Flooding threat is worth monitoring given recent rains (Marginal Outlook for most of the area from WPC for Day 2), but storm motions do look to be high enough to mitigate the threat to a good degree. Best guess timing for storms remains Thu ~4 pm through about midnight through the area, but timing is still subject to some adjustment later in time given the progress of the frontal passage as we get closer.

Drying out behind the front on Friday, with a short-lived and modest reprieve from the heat as the upper trough slides across the area. Highs fall back toward seasonal climo, into the upper 80s to near 90. With NW flow and drier air pushing into the region, heat indices won't be too dissimilar from air temperatures. A few morning and early afternoon showers possible across E NC. Otherwise, partly to mostly sunny and dry. Lows Friday night in the 60s to near 70 SE.

LONG TERM /SATURDAY THROUGH TUESDAY/
As of 310 AM EDT Wednesday...

Key Message:

- Temperatures ramp back up over the weekend into early next week. Summer heat and moderate humidity levels expected Sunday through the middle of next week. Heat headlines are likely to be needed for (at least) portions of the area.

Not too much change to report on the long term side of things, for better or worse. Friday night into Saturday, an expansive 500 mb ridge will gradually move from the southern Plains towards the Mid- Atlantic region. Rapid height rises are expected through Sunday as this almost 600 dm high plants itself over the East Coast through mid-next week. While some of us have been looking forward to a few rain-free days, it will certainly come with a cost; temperatures will soar into the mid-upper 90s Sunday through Tuesday. The I95 corridor looks to climb well into the 90s to near 100 degrees for highs by Tuesday, with dew points in the low to mid 70s. This would result in heat indices ~100-105 degrees Sun-Mon and ~105-109 on Tuesday. If the forecast holds, Advisories are likely to be needed early next week, with Excessive Heat Warnings possible.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/
As of 137 PM EDT Wednesday...

VFR conditions will prevail at all terminals through the TAF period.
There is a chance that a few showers and possibly an isolated thunderstorm will move over RIC and SBY later this evening, but confidence was too low to include mention of thunder at either site.
Have inserted VCSH into SBY due to the higher chance for showers near the terminal, and we will continue to monitor and storm development in that area and amend as necessary. Southwesterly wind gusts of 20 to 25 kts will continue through the evening before diminishing after sunset. Winds will once again pick up tomorrow morning after sunrise, so have included another line at all sites to capture the increasing winds.

Outlook: Late day and evening convection is looking increasingly likely Thursday, as a cold front crosses the region. Very warm and dry, with VFR conditions to prevail for Friday into the weekend.

MARINE
As of 1031 AM EDT Wednesday...

- A Small Craft Advisory has been issued for the James River and Lower Chesapeake Bay for increasing SW winds.

- SW winds increase tonight potentially bringing another round of SCA conditions across the Bay.

Early morning weather analysis shows predominately weak SW flow aloft across the area as a trough out west continues to push east. At the surface, a 1020mb+ high pressure is currently located over the SE coast. While across the area a warm front continues to push north. Winds across the northern waters and bay are out of the SE between 5 to 10 kt. While across the southern waters winds are out of the S between 5 to 10 kt. Buoy observations this morning are showing waves across the bay ~1ft and 2 to 3 ft across the Ocean.

Marine conditions are expected to remain benign through this afternoon. Winds are expected to shift to the SSW by late this morning and into the afternoon as the warm front continues to lift northward. Winds will increase as the pressure gradient tightens due to a developing low to the west. Winds this afternoon are expected to be between 10 to 15 kt across all water. The potential for SCA comes tonight and lasting through Thursday night. The local wind probs for wind gusts of 18kt have decreased slightly for tonight and are now between 70 to 80%. While for late thursday morning and afternoon have increased to 80 to 90%. Waves will reach 2-3 ft in the Bay and seas will build to 3-4 ft in the coastal waters.
Once the cold front moves through late Thursday high pressure will sit over the area bringing benign marine conditions back to the area. Winds are expected to remain ~10 kt and waves between 1 to 2 ft across the ocean and ~1 ft across the bay.

AKQ WATCHES/WARNINGS/ADVISORIES
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory until 7 PM EDT this evening for ANZ632- 634-636>638.