Marine Weather and Tide Forecast for Mineral, VA

KEY MESSAGES
- 1) A meandering front will bring highly variable temperatures, occasional rain/storm chances, and nighttime fog through Saturday.

- 2) Well above normal temperatures are expected through much of next week.

DISCUSSION

KEY MESSAGE 1..A meandering front will bring highly variable temperatures, occasional rain/storm chances, and nighttime fog through Saturday.

The CAD wedge has eroded substantially east of the Blue Ridge, but some portion of it will remain in a broken to scattered layer of low level clouds. This has allowed a bit more sunshine to peak through and bring temperatures to the 50s everywhere under the CAD.
Temperatures likely rise to the 60s across central VA to southern MD, and maybe it reaches right around 60F up toward the southern suburbs of Baltimore. It is warmest in the central Shenandoah Valley and along the I-64 corridor where temps have reached the mid to upper 70s.

Based on surface wind obs and satellite, the wavy/stalled frontal boundary is draped across the Potomac Highlands down to around New Market, then east across the VA Piedmont toward Southern MD. The boundary could lift a bit further north as a warm front across central MD, but likely won't make too much northward progression. A surface high building over Quebec continues to reinforce the CAD across the northern Mid-Atlantic with noted steady ENE/E winds across PA/NJ into northern MD. Showers earlier this morning were moving along the MD/PA border, but have mostly dissipated now.

A shortwave trough aloft and its associated wave of surface low pressure track from the OH Valley through the northern Mid-Atlantic this evening/tonight. This brings widespread showers to the northern half of the area (generally along and north of a line from Franklin to Warrenton to Annapolis). SPC introduced a Marginal Risk for severe storms this morning across the Potomac Highlands to the northern Shenandoah Valley. This corridor broke out earlier from the clouds this morning, and satellite shows a decent cu field has developed. This is where SBCAPE values around 500-1000 J/kg and increased low-level helicity due to the nearby stalled front could support isolated stronger thunderstorms this evening. Damaging wind is the main threat, though any thunderstorm could produce small hail due to cold temps aloft (around -15C at 500mb). To the east of the Blue Ridge, some guidance has elevated instability into the night, which could support a few thunderstorms. Due to increasing low-level stability, not expecting any strong to severe storms east of the mountains.

Abundant fog and low clouds are likely once again tonight, though some of this could be counteracted by low-level dry advection behind the surface low passage. The most likely area for fog looks to be along/northeast of the stalled boundary - looking at north to northeast MD. Showers dwindle overnight, though some patchy drizzle could linger through sunrise.

A backdoor cold front makes its way into the area Friday morning, reinforcing the CAD wedge across the northeast part of the forecast area. There is going to be a sharp temp gradient, with temps in the 70s to around 80F to the south/west and in the 40s to low 50s to the north/east of the boundary. The latest guidance has the edge somewhere across the DC Metro toward the northern Shenandoah Valley.
This makes the temp forecast very difficult, with a possible range of upper 40s to upper 60s for the immediate DC area. Scattered showers and perhaps a thunderstorm may develop Friday afternoon, especially west of the Blue Ridge, as a subtle shortwave trough passes overhead during peak heating. Some dense fog could form again Friday night as higher dew points attempt to start advecting back northward.

Another low pressure system will be moving through the Great Lakes early Saturday, tightening the pressure gradient with high pressure off the southeast coast. The increased southerly flow will have the best chance of lifting the wedge front northward and bringing 60s and 70s (to near 80) to much of the area. However, there is still some guidance that keeps the wedge firmly in place across the eastern half of the forecast area. So, additional refinements to the temperature forecast (currently in the 60s to 70s) might be needed.
SPC is highlighting a Marginal/Slight risk for severe storms west of the Blue Ridge Saturday late afternoon to evening. Building instability, modest shear, and forcing for ascent ahead of the approaching cold front will allow for scattered thunderstorms to develop. The front slows substantially as it crosses the area Saturday night.

KEY MESSAGE 2...Well above normal temperatures are expected through much of next week.

A decaying cold front will pass to our south and east during the day on Sunday. Drier and slightly cooler air of mid-latitude, continental origin will filter into the area within west to northwesterly flow behind the front. Temperatures on Sunday are forecast to be a few degrees cooler than preceding days, but still well above normal, with highs in the upper 60s and lower 70s for most (50s mountains). Primarily dry conditions and well above normal temperatures will persist through much of next week as flow turns zonal aloft. Temperatures are forecast to reach into the upper 70s to lower 80s across much of the area by Tuesday and Wednesday, with 60s in the mountains.

There are signs that a strong cold front may approach from the northwest by later Wednesday into Wednesday night, but some guidance holds the front off to our north and west until Thursday. A chance for showers and/or thunderstorms may accompany the frontal passage, with temperatures turning sharply colder behind the front.

AVIATION /20Z THURSDAY THROUGH TUESDAY/
Low clouds have lifted over most of the area, with some patches of MVFR CIGs lingering. Could go VFR at all terminals for a few hours through this evening. Another round of showers and perhaps even an embedded thunderstorm will cross the northern terminals this evening. Chance for thunderstorms at the metro terminals continues to be too low to include in the TAFs (around 20 pct).

IFR to LIFR conditions in low ceilings and/or fog will spread back across the area tonight. CHO could be near the southern boundary, with impactful CIGs /fog limited to a few hours late in the night.
These low ceilings will have trouble lifting northward Friday, with perhaps only minimal diurnal increases to the cloud base and continued light east to northeast winds. Some scattered showers are possible Friday afternoon and evening but with minimal impact compared to the ceilings. Expect ceilings to lower again Friday night.

Greater chance for improving conditions Saturday but not guaranteed at BWI/MTN. Showers and thunderstorms will approach from the west late in the day, with MRB having the greatest chance of a thunderstorm.

Prevailing VFR conditions are expected on Sunday and Monday. Winds will generally be out of the west to northwest on Sunday, and then south to southwest on Monday.

MARINE

A quasi-stationary boundary remains across the region, with a reinforcing backdoor cold front dropping into the area Friday morning. The boundary lifts back north as warm front on Saturday. A cold front will try to cross the waters late Saturday into Sunday before washing out over the region early next week.

Dense fog is likely to be an issue again Friday and Saturday mornings as well as winds remain light. The northern Chesapeake Bay may largely keep east to northeast winds through Friday night, while areas south of Washington DC and the Bay Bridge could flip to southerly at times. Winds should remain below advisory criteria.

Increasing SSW/SW winds on Saturday could bring conditions to near SCA levels. However, the colder bay waters with warmer air temperatures could lead to a stable atmosphere and little mixing of winds to the surface.

Sub-SCA level northwesterly winds are expected on Sunday. Winds will turn out of the south on Monday, but remain sub-SCA level in magnitude.

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