Marine Weather and Tide Forecast for Severna Park, MD

NEAR TERM /THROUGH TONIGHT/
Current water vapor imagery shows a large, positively tilted trough, which extends northeastward from the Four Corners region across the Central Rockies, Northern Plains, and eventually toward Hudson Bay. Downstream of this trough, a strong upper ridge is in place across the Southeast, with an associated ridge axis extending northward into the Mid-Atlantic.
At the surface, a cold front (becoming stationary with southward extent), resides just downstream of the trough, extending from southwest to northeast from the Southern Plains through the Mid-Mississippi Valley, and into the Great Lakes.

Over the course of the day, the northern half of the aforementioned trough will become progressive, tracking across the northern Great Lakes and eventually reaching Northern New England by late tonight. Meanwhile, the southern end of the trough will lag behind and close off into an upper low over the Southern High Plains. At the surface, the northern half of the cold front will start to make more rapid southeastward progress, eventually reaching the local area overnight tonight.

Current radar imagery shows lots of convection ongoing in the vicinity of the front from Oklahoma northeastward into Illinois.
It's expected that the remnants of any ongoing storms should pass off to our north across PA later this morning. Locally, much of the day should feature high clouds and dry conditions, as the 00z IAD sounding and forecast soundings both show a prominent cap around 700 mb, associated with a remnant elevated mixed layer. This cap should help to prevent the development of storms, despite what will be a very warm day, with temperatures expected to reach well into the 80s.

There are some hints that mid-level capping may start to erode across far northwestern portions of the forecast area later this afternoon into this evening. As a result, a storm can't be ruled out along the MD/PA border from the Catoctins westward, with Garrett and Allegany counties having the greatest chance.
If storms were to occur, they'd likely form upstream over the Ohio Valley along the cold front, and then track east- northeastward into the area. While the overall chance for a storm in those areas appears to be very low, any storms that do occur could produce very strong winds, given 60-70 knots of flow present at 700 hPa and deep, well-mixed boundary layers with steep low-level lapse rates.

The frontal boundary will drop southward into our area tonight, causing winds to shift to out of the north during the second half of the night. Other than a stray shower or storm in far northwestern portions of the forecast area, dry conditions are expected overnight. Lows should be in the 60s for most, with 50s in the mountains and across northern MD.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
High pressure will build to our north tomorrow, causing winds to shift from northerly to easterly over the course of the day. The aforementioned frontal boundary should clear the bulk of the area, but may get caught up across southwestern portions of the forecast area. Daytime heating and residual low-level moisture/convergence in the vicinity of the boundary may be enough for some showers and thunderstorms to form tomorrow afternoon across southwestern portions of the forecast area (Central Shenandoah Valley and southern Potomac Highlands, roughly south of US-48 and west of the Blue Ridge). While instability looks to be limited, some small hail can't be ruled out with any that thunderstorms that form, given weak low-level shear, ample shear in the mid-levels, minimal CAPE below the freezing level, and low freezing levels. Elsewhere, conditions should remain dry with mostly cloudy skies. High temperatures tomorrow will range from the upper 60s in northeast MD to near 80 in the Central Shenandoah Valley.

An upper trough will lift northeastward from the Mid-Mississippi Valley toward the Great Lakes on Monday. Much of the day should remain dry, but a shower can't be ruled out during the late afternoon or overnight hours as the system's cold front moves through.

LONG TERM /TUESDAY THROUGH FRIDAY/
By Tuesday, the aforementioned cold front will continue to slowly settle toward the south as low pressure tracks through the St. Lawrence and upper troughing lifts off to our north and east. Weak zonal flow will move in aloft, which will likely cause the front to slow its southward progress. Guidance differs with respect to the positioning of the front on Tuesday, with some models having it clear the entire area prior to daybreak, and some others stalling the front from central Virginia to southern Maryland. Depending on the positioning of the front, a shower could be possible, especially to the south of I-66, but most solutions point toward dry conditions locally. High temperatures are expected to be in the upper 70s and lower 80s for most.

Weak high pressure at the surface and zonal flow aloft should lead to mostly sunny skies on both Wednesday and Thursday.
Temperatures will continue to run above normal, with highs in the upper 70s/lower 80s, and lows in the 50s.

Spread in guidance begins to increase by Friday, but there are some signs that by then we may begin to see an uptick in low- level moisture as high pressure shifts offshore and return flow starts to develop. Some solutions also have a shortwave disturbance tracking to our northwest across the Great Lakes.
This increase in low-level moisture and large scale forcing for ascent could potentially lead to a chance for showers or thunderstorms.

AVIATION /07Z SATURDAY THROUGH WEDNESDAY/
VFR conditions and southwesterly winds are expected today. Winds may gust to around 25-30 knots this afternoon. A weak cold frontal boundary will move through the area tonight, with winds turning north to northwesterly during the second half of the night behind the front. While no precipitation is anticipated with this front, some brief MVFR ceilings may be possible later tonight into early tomorrow morning while the front is in the vicinity. VFR conditions are expected for much of the day Sunday. Winds will be northerly around daybreak, and gradually shift around to out of the east over the course of the day. MVFR ceilings may be possible within onshore flow Sunday night, and potentially even into the day Monday as winds turn southeasterly.

Prevailing VFR conditions are forecast for both Tuesday and Wednesday, although a brief shower can't be ruled out on Tuesday.
Winds will be out of the west on Tuesday, and then light and variable on Wednesday.

MARINE
Low-end SCA conditions are ongoing in channeled southerly flow early this morning. SCA conditions are expected to continue through the day today as winds gradually turn southwesterly. A cold front will move over the waters later tonight, with winds abruptly turning north to northwesterly behind the front. Low-end SCA conditions may be possible for a few hours in the front late tonight. Winds will decrease to sub-SCA levels on Sunday and gradually shift from northerly to easterly over the course of the day. Winds will turn southeasterly and then eventually southerly on Monday. Winds may near low-end SCA levels in channeled southerly flow Monday afternoon into Monday evening.

Sub-SCA level winds are expected on both Tuesday and Wednesday.
Winds will be out of the west on Tuesday, and then light and variable on Wednesday.

TIDES/COASTAL FLOODING
Tidal levels are expected to increase a bit today within southwesterly flow. Annapolis and Havre de Grace may potentially reach Action stage with the tide cycle this afternoon, but no flooding is anticipated. Tidal anomalies will rapidly decrease later tonight as wind turn northerly behind a cold front, with no tidal flooding concerns evident over the next several days.

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Small Craft Advisory until midnight EDT tonight for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory until midnight EDT tonight for ANZ530>543.