Marine Weather and Tide Forecast for Dahlgren, VA

NEAR TERM /THROUGH TONIGHT/
Latest satellite imagery depicts some mid/upper-level moisture moving south towards the region out of the Great Lakes region.
This is on located on the back side of an upper trough that is slowly drifting east off the New England coastline.

While today has started out cool and sunny for most, clouds will readily increase from northwest to southeast during the rest of the morning into this afternoon, and then especially tonight as the moisture plume moves overhead. High pressure building closer to the region from the south and west will result in lighter wind then recent days, though a few gusts of 15-20 mph are possible especially at higher elevations. Dry air in the low levels should prevent most if not all precip through tonight, though a couple of sprinkles can't be ruled out especially further north and west/over the Appalachians.

Temperatures will be rather seasonable through the period with highs in the 50s and 60s, and lows in the 30s and 40s.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
An upper-level low currently over northeastern British Columbia will eject southeastward across the Canadian Prairies and the Great Lakes this weekend, eventually merging with a cutoff low over the Canadian Maritimes. An associated surface low will develop over the upper Great Lakes Saturday before tracking across the Saint Lawrence Valley into northern New England on Sunday. A warm front is expected to lift across the Mid-Atlantic late tonight through Saturday afternoon, followed by a strong cold front late Saturday night into Sunday morning. High pressure will then build toward the region from the Ohio Valley Sunday night.

In terms of sensible weather, some shower activity is possible with the warm front over the Appalachians and northern Maryland during the day on Saturday, with the highest relative precip potential during the afternoon. By Saturday evening, the approaching cold front may spark an organized low-topped line of convection given strong forcing and low-level winds, despite meager CAPE. Any such line would cross the Mid-Atlantic in some form just ahead of the cold front Saturday night. The best chance for boundary layer based convection would seem to be over western Maryland where surface based instability will be relatively higher (though still meager). Further east, a few rumbles of thunder are possible with any stronger cells that evolve, though instability should be rooted above the surface.
Additionally, downsloping low-level winds could weaken the line's organization. Either way, at least a few showers along with some gusty winds could be on the docket overnight.

Strong winds behind the departing cold front and ahead of high pressure building in from the Midwest will result in a gusty day on Sunday. Despite the passage of the cold front the night before, downsloping winds gusting 30 to 40 mph will likely boost temperatures well into the 50s and 60s on Sunday east of the mountains. Lighter breezes linger into Sunday night with lows dropping into the 30s.

LONG TERM /MONDAY THROUGH THURSDAY/
A deep, vertically stacked area of low pressure will circulate off to our northeast during the day on Monday, with the center of the system located near the mouth of the St. Lawrence River. Post- frontal northwesterly flow will advect cooler and drier air into the area. Sunny skies are forecast for all, and temperatures are expected to reach into the 50s at lower elevations and 40s in the mountains. Northwest winds will gust to around 30 mph, making it feel a bit chillier.

A fast moving, low amplitude disturbance embedded in zonal flow will rapidly approach from the west on Tuesday. While there are some timing differences amongst models, nearly all show an uptick in cloud cover, and most ensemble solutions produce some light precip at some point Tuesday into Tuesday night. Winds will be lighter on Tuesday, but the increasing clouds and chance for rain will keep temperatures cooler, with highs in the upper 40s and lower 50s.

High pressure will build to our northwest over the Great Lakes on Wednesday. Dry conditions are expected as a result, with a mix of sun and clouds. Temperatures will be near seasonal normals, with highs in the 50s for most (40s mountains).

Guidance begins to diverge with respect to the finer details by Thursday, but most solutions show the longwave pattern beginning to amplify across the CONUS, with deep troughing becoming established across the center of the country. Most solutions also show an area of low pressure developing just downstream of that trough. Some ensemble members produce a bit of warm advection driven precipitation downstream of that trough and associated surface low over our forecast area, but spread is large this far out.
Regardless, odds seem to favor increasing cloud cover. Spread with respect to high temperatures on Thursday is also large, and will ultimately be dependent on how the system develops upstream.

AVIATION /14Z FRIDAY THROUGH TUESDAY/
VFR conditions are forecast to prevail through tonight, though mid and high level clouds will increase later today. There is an outside chance of low-end VFR or high-end MVFR CIGs (stratocu)
early Saturday morning ahead of an approaching warm front. Some spotty LLWS can't be ruled out as well during this time. Surface winds will be westerly today at about 6-10 kts with occasional gusts of 15-18 kts possible this afternoon. Winds shift to southerly tonight at very light speeds.

The warm front should lift away from the region by later Saturday morning with a spotty shower possible. A few showers/some low-topped convection could bring brief restrictions as a cold front crosses Saturday night. South winds Saturday could gust 15-20 kts during the afternoon, before shifting to west/northwest Saturday night. Winds increase in the wake of the cold front Sunday with gusts of 25-35 kts likely.
Winds diminish a bit but a few occasional gusts of 15-20 kts remain possible Sunday night.

VFR conditions and northwesterly winds are expected on Monday. Sub- VFR conditions and rain may be possible at times on Tuesday, along with light winds.

MARINE
Generally lighter westerly winds are expected today, though deeper mixing and a marginal wind field could result in sporadic 15-20 knot gusts this afternoon over the northern waters. A warm front will lift across the waters Saturday, and winds will shift to the south by then. Channeling likely pushes gust into the 20-25 knot range by Saturday evening ahead of an approaching cold front, then winds shift to the west/northwest and gust up to 30 knots through Sunday. Brief/sporadic gale conditions can't be ruled out both with the immediate frontal passage overnight Saturday night, then again during the day on Sunday in the wake of the front. Somewhat lighter winds are forecast Sunday night, though SCA conditions likely persist for most of the waters.

Small Craft Advisory conditions appear likely within northwesterly flow on Monday. Sub-SCA level winds are expected on Tuesday.

FIRE WEATHER
High pressure will build closer today which will lead to lighter winds. However, daytime relative humidities will drop into the 25 to 35 percent range again. The mountains can expect slightly higher values in the 35 to 50 percent range. Good overnight recoveries are expected into the weekend.

A brief reprieve from the low humidities is expected Saturday as a warm front lifts through the region. This will be followed by a cold front Saturday night, which could bring some light rain along with it. However, the chances for a wetting rain (a tenth of an inch or more) seem pretty low at this time.

Gusty westerly winds are expected Sunday in the wake of this cold front passage. Additionally, humidities will once again drop significantly as drier air move in. Even drier conditions are expected Monday, with a bit less in terms of wind. However, both days will pose a threat for adverse fire weather conditions, assuming the rain event Saturday night doesn't overperform.

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