Marine Weather Net

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




5 - 10


5 - 10


5 - 10

The Marine Weather Forecast In Detail:
ANZ537 Forecast Issued: 1038 AM EDT Mon May 20 2024

Rest Of Today...E Winds 5 Kt. Waves Less Than 1 Ft.
Tonight...Se Winds 5 To 10 Kt. Waves 1 Ft. Areas Of Fog. Vsby 1 To 3 Nm.
Tue...Se Winds 5 To 10 Kt. Waves 1 Ft Or Less. Areas Of Fog. Vsby 1 To 3 Nm.
Tue Night...S Winds 5 To 10 Kt. Waves 1 Ft.
Wed...S Winds 5 To 10 Kt. Waves 1 Ft.
Wed Night...S Winds 5 To 10 Kt. Waves 1 Ft.
Thu...Sw Winds 5 To 10 Kt. Waves 1 Ft. A Chance Of Showers And Tstms.
Fri...Se Winds 5 Kt. Waves Less Than 1 Ft. A Chance Of Showers. A Chance Of Tstms Through The Night. Winds And Waves Higher And Visibilities Lower In And Near Tstms.
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Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
956am EDT Monday May 20 2024

Warmer temperatures and mostly dry conditions are expected through Wednesday as high pressure meanders overhead. A cold front will approach from the Ohio River Valley Wednesday night into Thursday bringing renewed chances for showers and thunderstorms. Additional shower and thunderstorm chances are likely Friday into the weekend as the front stalls nearby. Drier conditions return by the middle of next week.

Near Term - Through Tonight
Dense Fog Advisories will be allowed to expire at 10am although some fog may still hang on for another hour or two especially in areas east of US-15. Outside of the fog, low and mid level stratus continues to hang on in these same locations with mostly sunny skies further west into western MD, eastern WV, and the Shenandoah Valley.

Any residual fog and and low stratus should lift out before midday with mostly sunny to partly cloudy skies this afternoon. A large area of subsidence beneath surface high pressure overhead should keep the region dry with just an outside chances of a spotty shower over the higher ridges west of the Appalachians

High temperatures are expected to reach the upper 70s to lower 80s across most of the area today once the sun comes out. Low temperatures tonight are expected to fall into the 50s with some patchy fog or low clouds possible once again overnight.

Short Term - Tuesday Through Wednesday Night
High pressure will move offshore Tuesday into Wednesday. Ridging aloft will still be present Tuesday, and this may act to cap convection. However, just enough lift from added terrain circulations could Probability of Precipitation a shower or thunderstorm later in the afternoon on Tuesday mainly west of I-81 in eastern WV.

The ridge will begin to break down a bit on Wednesday, but with the main forcing from the incoming trough/cold front still well to the west, convection should remain isolated and generally confined to west of the Blue Ridge late Wednesday afternoon.

Long Term - Thursday Through Sunday
To the south of a deep upper trough tracking across Quebec will be a series of lower amplitude waves that race toward the Mid- Atlantic region on Thursday. As this occurs, a slow moving cold front is expected to push through the local area by midday into the evening hours. There is fairly strong mid/upper support with a belt of 500-mb west-southwesterlies around 40 to 50 knots. This is accompanied by ample right entrance region jet dynamics within a jet streak running between 100 to 110 knots. The key parameter that will dictate the degree of severe weather threat is the instability. At this point, even global ensembles are showing around 1,000 to 1,500 J/kg of surface-based CAPE on Thursday. This would be more than adequate to support severe convection given the extent of vertical shear in the profile. However, as usual, the near to short term trends of cloud cover which inhibits convective potential will need to be monitored ahead of the event. Besides the threat for showers and strong/severe thunderstorms, it should be a very warm day with decent humidity owing to persistent south-southwesterlies. Forecast highs are in the mid/upper 80s, with heat indices approaching the low 90s. The frontal boundary eventually slides off to the south by Friday morning.

In the wake of this frontal system, temperatures and dew points drop off some to finish out the work week. Shower and thunderstorm chances do return later in the day on Friday as this boundary re-approaches the area from the south. This leads to a period of unsettled conditions heading into the weekend. The position of this frontal zone and amplitude/strength of disturbances aloft will dictate the degree of threats to the local area. General low-amplitude troughiness persists upstream which would tend to support this semi-active convective pattern. Daily chances of showers and thunderstorms are shown in the forecast package for this weekend. Temperatures remain fairly close to average for late May standards.

Generally light south to southeast winds are expected through Wednesday, though some channeling/river or bay breeze enhancement is possible during the afternoon and evening each day. This should stay entirely sub SCA (Small Craft Advisory) through tonight given high pressure moving overhead, with some marginal/sporadic SCA gusts possible late Tuesday afternoon into early evening. By Wednesday afternoon, the gradient tightens a bit with high pressure more firmly offshore, raising the prospects for channeling and SCAs.

Background winds should stay below Small Craft Advisory levels on Thursday on Friday. However, this comes with a caveat as strong to severe thunderstorms may impact the local waters on Thursday, possibly into Thursday night. There is certainly a risk of Special Marine Warnings along with a threat of frequent lightning with any of the convection. As the cold front responsible for this activity settles to the south on Friday morning, winds will be out of the west-northwest. This boundary does return northward as a warm front which may bring additional showers and thunderstorms on Friday.

Tides / Coastal Flooding
Elevated water levels are expected to persist through the middle of the week with persistent light onshore (S/SE) flow. Minor flooding is likely along vulnerable shoreline particularly during the overnight/early morning high tide cycles (the higher of the two astronomically). The higher end of the guidance envelope approaches moderate flooding at Straits Point and Annapolis, but this seems unlikely given the light flow.

Winds turn offshore behind a cold front Thursday, which will cause a subsequent decrease in water levels.

NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...Coastal Flood Advisory until 9am EDT Tuesday for DCZ001. MD...Coastal Flood Advisory from midnight tonight to 9am EDT Tuesday for MDZ014. Coastal Flood Advisory until 3am EDT Tuesday for MDZ017. VA...None. WV...None.