Marine Weather Net

Tidal Potomac from Cobb Island MD to Smith Point VA Marine Forecast




10 - 15


5 - 10


5 - 10

The Marine Weather Forecast In Detail:
ANZ537 Forecast Issued: 256 PM EST Thu Dec 07 2023

This Afternoon...Sw Winds 15 Kt With Gusts To 20 Kt. Waves 1 To 2 Ft.
Tonight...Sw Winds 10 To 15 Kt...Becoming W 5 Kt Late. Gusts Up To 20 Kt Until Early Morning. Waves 1 To 2 Ft.
Fri...S Winds 5 To 10 Kt. Waves 1 Ft Or Less.
Fri Night...S Winds 5 To 10 Kt. Waves 1 Ft.
Sat...S Winds 5 To 10 Kt. Waves 1 Ft.
Sat Night...S Winds 5 To 10 Kt. Waves 1 Ft.
Sun...S Winds 15 To 20 Kt...Becoming Nw After Midnight. Waves 2 To 3 Ft...Building To 4 Ft After Midnight. Showers.
Mon...Nw Winds 15 To 20 Kt...Diminishing To 5 To 10 Kt After Midnight. Waves 3 Ft...Subsiding To 2 Ft After Midnight.
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Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
202pm EST Thu Dec 7 2023

High pressure will build across the Southeast states through Saturday. A strong frontal system will impact the region on Sunday. High pressure will return Monday.

Near Term - Through Tonight
As of 2pm, precipitation had cleared the area. Wave clouds were persisting near and east of I-81, but will continue to gradually clear heading into this evening.

Tonight won't be quite as cold with most of the area dropping into the low 30s (into the upper 20s at locations where winds go calm).

Short Term - Friday Through Saturday Night
High pressure will move offshore Friday into Saturday. This will allow for light southerly return flow and moderating temperatures.

Friday should be mainly sunny with ridging overhead, but high clouds likely start to increase as early as midday Saturday as a large and powerful trough/frontal system takes shape over the Midwest. This trough will be the next impactful weather maker for our area heading into the second half of the weekend (see more in the Long Term section below).

Long Term - Sunday Through Thursday
A potent weather system will track toward the area on Sunday. A highly amplified and positively-tilted upper trough will reside over the center of the country to start the day Sunday, with southwesterly flow downstream across the eastern US. This trough will take on more of a neutral tilt as it progresses eastward through the day, and then eventually a negative tilt as it passes overhead Sunday evening.

Rain will break out from west to east Sunday morning as large scale ascent ahead of the approaching upper trough gradually overspreads the area. A soaking rainfall is expected through much of the day Sunday as strong warm/moist advection ensues at low levels within an environment characterized by highly anomalous precipitable water values (around 1.5 inches, which is near 3-4 sigma for this time of year). Nearly all model solutions show a widespread 1-3 inch rainfall across the forecast area, with the highest totals to the east of the Blue Ridge. Normally this would raise flooding concerns, but with ongoing drought across the area, flooding concerns are expected to be rather isolated and confined to more sensitive urban locations.

Many model solutions also show limited surface-based instability developing Sunday afternoon into Sunday evening. As a result, thunderstorms will be possible. With a very strong wind field in place aloft (60+ kt low-level jet) providing ample shear, and the approaching trough and strong cold front providing focused forcing for ascent, some strong to severe thunderstorms may also be possible late Sunday afternoon into Sunday evening.

A strong cold front will move through the area Sunday evening into Sunday night, leading to an abrupt drop in temperatures from the 50s/60s to the 30s. With strong differential cyclonic vorticity advection driven ascent lagging a bit behind the surface cold front, some anafrontal precipitation may be possible. As a result, the precipitation may change over to snow for a brief time Sunday night before ending. The greatest chance for this to occur will be to the west of the Blue Ridge, but a fair amount of ensemble members even show it occurring further east. As with many other aspects of the forecast, the finer scale details of the snow forecast remain highly uncertain four days out.

Upslope snow showers will continue through the night and into Monday morning to the west of the Allegheny Front, where several inches of snow accumulation appears possible. Further east, precipitation should wind down late Sunday night, leading to drier conditions on Monday. Winds will remain gusty out of the west to northwest, and temperatures will be much cooler on Monday, with highs ranging from the upper 20s in the mountains, to the mid 40s to the south and east of I-95. High pressure will move overhead on Tuesday, leading to continued dry conditions and seasonable temperatures.

A period of 15-25 kt S/SW wind gusts is anticipated into this evening. Winds diminish over the waters tonight through most of Saturday with high pressure overhead and southerly flow continuing, though brief/marginal channeling is possible Friday evening/night. SCAs (Small Craft Advisories) may be necessary starting Saturday night as winds increase ahead of an approaching frontal system.

At least SCA (Small Craft Advisory) conditions appear likely Sunday through Monday evening, with gale conditions also possible at times. Winds will be out of the south through much of Sunday, before turning out of the west Sunday evening behind a strong cold front. Gusty west to northwesterly winds will continue on Monday.

Tides / Coastal Flooding
A snapback of tidal anomalies is expected through tonight as water that piled up near the mouth of the Chesapeake Bay returns north due to the easing offshore flow. Water levels will be near action stage later tonight and Friday.

A southerly flow is expected Saturday, but it should be light. Therefore, the most likely scenario is for action stages. However, the southerly flow will strengthen Sunday, increasing the chances for minor tidal flooding heading into Sunday night.

A strong offshore flow will return Sunday night into Monday.

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

Small Craft Advisory until 6pm EST this evening for ANZ530>532-535-536-538>540-542. Small Craft Advisory until 1am EST Friday for ANZ533-534-537- 541-543.