Marine Weather Net

Tidal Potomac from Indian Head to Cobb Island MD Marine Forecast


REST OF TODAY

N
WINDS
5 - 10
KNOTS

TONIGHT

N
WINDS
5 - 10
KNOTS

THU

NW
WINDS
15 - 20
KNOTS

THU NIGHT

NW
WINDS
15 - 20
KNOTS

The Marine Weather Forecast In Detail:
ANZ536 Forecast Issued: 958 AM EST Wed Feb 19 2025

SMALL CRAFT ADVISORY IN EFFECT FROM THURSDAY MORNING THROUGH THURSDAY AFTERNOON ...GALE WARNING IN EFFECT FROM THURSDAY AFTERNOON THROUGH LATE THURSDAY NIGHT...
Rest Of Today...N Winds 5 To 10 Kt. Waves 1 Ft. Snow. Vsby 1 To 3 Nm.
Tonight...N Winds 5 To 10 Kt. Waves 1 Ft. Snow Likely. Vsby 1 To 3 Nm.
Thu...Nw Winds 15 To 20 Kt With Gusts To 35 Kt. Waves 1 Ft... Building To 3 Ft In The Afternoon. Snow Showers. Vsby 1 To 3 Nm.
Thu Night...Nw Winds 15 To 20 Kt. Gusts Up To 35 Kt...Diminishing To 25 Kt After Midnight. Waves 2 To 3 Ft.
Fri...Nw Winds 15 To 20 Kt With Gusts To 30 Kt. Waves 2 Ft.
Fri Night...Nw Winds 10 To 15 Kt...Diminishing To 5 Kt After Midnight. Waves 1 Ft.
Sat...Sw Winds Around 5 Kt. Waves 1 Ft.
Sun...Sw Winds Around 5 Kt. Waves 1 Ft.
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Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
401am EST Wednesday Feb 19 2025

Synopsis
An area of low pressure will track to the Carolinas and off the East Coast through Thursday. High pressure will take over late in the week. A frontal system may approach the area by early next week.

Near Term - Through Thursday
Radar/satellite composite shows low pressure taking shape over the northern Gulf Coast. Main surface low pressure is being drive by a southern stream wave, which will move swiftly to and then offshore of the Carolinas through Thursday.

Low-level fgen was resulting in snow (at least aloft) along and south of the I-64 corridor early this morning. Snow should begin reaching the ground from west to east rather readily through daybreak (a bit earlier in the Alleghenies).

Overnight guidance has come into much better agreement, and also appears to line up with upstream obs at this point. This bolsters confidence in the overall forecast, though there will be a tight gradient on the north end of the snow which leads to somewhat lower confidence across north-central VA into interior southern MD including the southern DC suburbs.

Snow associated with the southern stream low should pivot along the I-64 corridor to southern MD from this morning through this evening before shifting offshore. A pronounced lull is likely in between, before snow showers associated with a trailing northern stream upper low move into the Appalachians late overnight.

Snow showers are expected to press east with the upper low Thursday morning through early afternoon. Light accumulations are likely across the area, even with the higher late February sun angle and time of day given the cold antecedent temps. There is an outside chance this light snow could impinge on the western DC/Batlimore suburbs during the second half of the Thursdayam commute, which will need to be monitored closely.

As the upper low departs Thursday afternoon, winds will increase substantially. Gusts of 30 to as high as 50 mph are possible, especially over the higher elevations.

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/... Temperatures will plummet on a blustery northwest wind Thursday night. This likely results in wind chills well below zero over the Appalachians.

Blustery and cold but dry conditions will continue Friday, though upslope snow showers may very well persist Thursday night through Friday. Overall, accumulations look to be somewhat on the lighter side and drawn over a longer period (24 to 36 hours), however will need to monitor any steadier periods of upslope, particularly with and immediately in the wake of the upper low.

Long Term - Friday Night Through Tuesday
A fairly progressive split flow regime is expected to finish the week, and continuing into the weekend and early next week. On Friday morning, the trailing vorticity from a powerful longwave trough offshore is expected to push off the Delmarva Peninsula. In the wake, the guidance shows a brief period of shortwave ridging dipping down from the Great Lakes. Heading into the upcoming weekend, an upstream southern stream feature generally becomes absorbed while progressing toward the Ohio Valley. This overall lends itself to more northern stream dominance as a series of weak perturbations track through the area. By early next week, the next system of interest begins to take shape over the Upper Midwest. Eventually the associated height falls reach the local area by late Monday into Tuesday morning.

Friday's surface pattern maintains residual tight gradients given a deep low center across the Canadian Maritimes and sprawling high pressure over the Missouri Valley. A brisk northwesterly wind persists before gradients weaken into the weekend. The mentioned ridge of high pressure gradually advances eastward in time before weakening and settling off toward the Mid-South by Sunday. Gradual northern stream amplification draws the next frontal system through the Mid-Atlantic region by early next week. It appears somewhat moisture-starved at this point. Otherwise, the main precipitation threats during this period would be the first half of Friday along the Allegheny Front. This is where continued upslope snow showers are expected before tapering off as heigheights begin to rise.

The temperature forecast features a chilly start to the work week before numbers creep back up during subsequent days. The northwesterly flow regime largely abates by Saturday with return flow ensuing. Looking into Monday, forecast highs rise back into the low 50s while mid/upper 50s are possible on Tuesday. Given ensemble box-and-whisker plots show relatively low spread, there is reasonable confidence on this expected warm up.

Marine
Light northerly flow is expected later today into this evening. Winds increase late tonight into Thursday and remain elevated through Friday. Gales have been issued for the highest period of winds late Thursday through early Friday. Meanwhile, snow is expected in the vicinity of southern Maryland later today, reducing visibility at times.

Gale conditions may persist into Friday morning, especially over the more southern waters. Although northwesterly winds diminish in strength through the day, Small Craft Advisories will likely be needed through early Friday evening. Sub-advisory caliber winds are anticipated into the weekend as high pressure approaches from the southwest.

Tides / Coastal Flooding
Persistent northwesterly flow has kept water levels lower than normal across the tidal Potomac and western shores of the Chesapeake Bay. As of this morning's low tide, a number of locations are reporting water levels around 1 to 1.5 feet below mean lower low water. Some rebound is expected into the afternoon as locations push toward high tide. Owing to another round of blustery northwesterly winds, tidal anomalies remain rather low the next couple of days. However, at this point, the forecast does keep water levels just above those requiring another Marine Weather Statement for blowout tides.

NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...None. MD...Winter Weather Advisory from 1pm this afternoon to 10pm EST this evening for MDZ016-018. Winter Weather Advisory from 1pm this afternoon to 1am EST Thursday for MDZ017. VA...Winter Weather Advisory from 1pm this afternoon to 10pm EST this evening for VAZ055. Winter Weather Advisory from 1pm this afternoon to 1am EST Thursday for VAZ057. Winter Weather Advisory from 7am this morning to 7pm EST this evening for VAZ025-036-037-504-508. Winter Weather Advisory from 10am this morning to 10pm EST this evening for VAZ038-050-056-507. Winter Weather Advisory until 6pm EST this evening for VAZ503. WV...Winter Weather Advisory until 6pm EST this evening for WVZ505.

Marine
Small Craft Advisory until 7am EST this morning for ANZ530>543. Small Craft Advisory from 10pm this evening to 1pm EST Thursday for ANZ530>534-537-539>541-543. Gale Warning from 1pm Thursday to 10am EST Friday for ANZ530>534-537-539>541-543. Small Craft Advisory from 7am to 1pm EST Thursday for ANZ535- 536-538-542. Gale Warning from 1pm Thursday to 1am EST Friday for ANZ535- 536-538-542.