Marine Weather Net

Tidal Potomac from Indian Head to Cobb Island MD Marine Forecast


REST OF TONIGHT

SE
WINDS
10
KNOTS

MON

SW
WINDS
10 - 15
KNOTS

MON NIGHT

NW
WINDS
10 - 15
KNOTS

TUE

N
WINDS
5 KNOTS

The Marine Weather Forecast In Detail:
ANZ536 Forecast Issued: 935 PM EST Sun Dec 05 2021

SMALL CRAFT ADVISORY IN EFFECT FROM 6 AM EST MONDAY THROUGH MONDAY AFTERNOON ...GALE WARNING IN EFFECT FROM MONDAY EVENING THROUGH LATE MONDAY NIGHT...
Rest Of Tonight...Se Winds 10 Kt...Becoming Sw. Waves 1 Ft. Scattered Showers Late This Evening, Then Isolated Showers.
Mon...Sw Winds 10 To 15 Kt. Gusts Up To 30 Kt In The Late Morning And Afternoon. Waves 2 Ft. A Chance Of Showers.
Mon Night...Nw Winds 10 To 15 Kt With Gusts To 35 Kt...Diminishing To 5 To 10 Kt With Gusts To 20 Kt Late. Waves 1 To 2 Ft.
Tue...N Winds 5 Kt. Waves Less Than 1 Ft.
Tue Night...E Winds Around 5 Kt. Waves 1 Ft.
Wed...Ne Winds 5 Kt. Waves Less Than 1 Ft. Rain And Snow Likely.
Wed Night...N Winds 5 Kt. Waves Less Than 1 Ft. A Chance Of Rain.
Thu...E Winds 5 Kt. Waves Less Than 1 Ft.
Fri...S Winds 5 Kt. Waves Less Than 1 Ft.
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Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
832pm EST Sunday Dec 5 2021

Synopsis
High pressure resides over the area through tonight. A weak low pressure system will move up the east coast tonight, bringing some showers east of the Blue Ridge. A strong cold front will push through late Monday. After another brief return of high pressure, another storm system may impact the region Tuesday night into Wednesday, which may bring wintry precipitation to portions of the area. High pressure builds over the Eastern Seaboard by Thursday.

Near Term - Until 6am Monday Morning
Weak low pressure will track up the Mid-Atlantic coast tonight, and isolated/scattered showers will be associated with this system, especially near/east of Interstate 95 into north-central Maryland (closer to the low). The low will move off to the northeast toward morning, and there may be enough breaks in the clouds for low clouds and areas of fog to develop, especially across northeastern MD where the flow will be weaker and dewpoints may be a bit higher from previous showers. Some fog may be dense into early Monday morning.

A cold front will move into the Ohio Valley tonight, and a few showers associated with this system will approach the Allegheny and Potomac Highlands toward morning. Elsewhere, it should be dry with subsidence between the low to the east and the approaching cold front from the west. With the clouds returning and flow becoming southeasterly, expect lows to be milder compared to recent nigheights (upper 30s to lower 40s for most areas).

Short Term - 6am Monday Morning Through Wednesday
Dry and mostly warm to start the day Monday as a fairly strong southerly flow develops out ahead of a strong cold front approaching from the west. The primary exceptions will be some upslope showers/snow showers along the Allegheny Front early, and the lingering showers close to the Bay as the low departs the region. Wind gusts may approach 40 mph at times during the day, mainly over land as water temperatures are cooler than expected land temps. Front itself passes from west to east later in the day into the early evening. Could see some brief gusts to 50 mph or more with the front itself, especially if there is a convective line with the front, but don't feel the duration will warrant wind advisories.

High pressure will build across the region Monday night and Tuesday. This will provide gusty winds Monday night, with some of the coldest wind chills that we've had so far this season. Winds abate as the high builds briefly overhead Tuesday, but temps remain below normal.

Meanwhile, late Tuesday, two upper-level disturbances start to make their way towards the region. The first will dive out of the Northern Plains, and the second will slide out of the Central Plains. With a few different moving pieces at play, as usual there is a decent amount of spread amongst the guidance as to how exactly this storm system may evolve. One thing that seems relatively certain at this point is the cold air mass overhead. Most guidance is coming to a consensus that we will have cold air locked in over much of the area at least for the duration of the event, which should promote a mostly wintry precipitation event. The GFS had been the main straggler, but even the most recent 12z run favors a colder solution, falling in line with most other guidance. Timing also is coming pretty well into focus, and it appears the system will move in overnight Tuesday into Wednesday morning. Snow may overspread the region from SW to NE, with snow into the DC/Baltimore metros potentially near the morning rush hour Wednesday morning. Lastly, the amount of snow is the main thing in question at this point, and this will be directly proportional to the track this system takes. The Euro and Canadian deterministic runs are pretty sparse in terms of precip, owing to a track further south and east and a weaker system overall. Meanwhile the GFS and NAM like a stronger band of snow over the region due to closer proximity as the storm tracks slightly further north. The 12z run of the GEFS depicted a 30-40% chance of at least an inch of snowfall for much of the area, meanwhile the 12z EPS followed suite with the deterministic run, giving very little in terms of precip. Of note though is the fact that many members do still bring some light measurable snow to much of the area.

So, overall there is still some uncertainty, but looking like a decent shot for some of the area to see the first snowfall of the winter (east of the mountains of course). Preliminary forecast gives a broad T-1". There is the potential for higher amounts with this storm in areas of mesoscale banding. These are notoriously difficult to predict the exact location of, so at this point, uncertainty is too high to speculate where those higher amounts may be. Stay tuned to the latest forecast for this potential winter storm at weather.gov/lwx/winter.

Long Term - Wednesday Night Through Sunday
Dry conditions should follow Wednesday night into Thursday as the system moves out and high pressure builds into the region. The general pattern for the remainder of the extended will have a series of shortwave disturbances swing through over the weekend, bringing some precipitation chances to the region Friday into Saturday.

High temperatures behind the front Wednesday will be in the mid-30s to lower-40s, but should warm to above average temperatures by Saturday.

Marine
Strong cold front will result in increased southwest winds on Monday, with SCA (Small Craft Advisory) gusts expected on all waters. Winds around 35 knots will be toward the top of the mixing layer Monday afternoon, so gale force winds cannot be ruled out, especially over the inlets and northern Tidal Potomac where there will be less of an influence from colder water. However, it appears that this will be a brief window (about 2 hours or so from 18-20z), so confidence is too low for a Gale Warning during this time.

However, another pressure surge behind a cold front is expected Monday evening, and winds will be stronger and the mixing layer will be deeper. Therefore, a Gale Warning was issued for Monday night. The best chance for gale force winds will be during the evening hours for most areas, but gale force winds could hang around into the overnight over the open waters. A Gale Warning is in effect from 23z until 06z for the waters.

A line of showers may also produce gusty winds with the cold frontal passage, and this may trigger Special Marine Warnings. SCA (Small Craft Advisory) gusts likely continue on the waters behind the front late Monday night before gradually waning Tuesday.

Winds over the waters may approach SCA (Small Craft Advisory) criteria late Wednesday night, but should quickly diminish and remain light through Thursday.

Tides / Coastal Flooding
Tidal anomalies have gradually risen a little due to a light southerly flow. The flow will strengthen Monday, but winds will likely turn west of south during this time. Therefore, water levels are more likely to approach caution stages for sensitive areas instead of minor flood stage. Eventually a shift to northwesterly flow behind the front leads to a rapid drop in water levels into Monday night and Tuesday.

NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...None. MD...None. VA...None. WV...None.

Marine
Small Craft Advisory from 6am to 6pm EST Monday for ANZ530>543.