Marine Weather Net

Tidal Potomac from Key Bridge to Indian Head MD Marine Forecast


10 - 20


5 - 10


10 - 15


10 - 15

The Marine Weather Forecast In Detail:
ANZ535 Forecast Issued: 1100 AM EDT Wed Apr 08 2020

Rest Of Today...Nw Winds 10 Kt With Gusts To 20 Kt. Waves 1 Ft. Scattered Showers With Isolated Tstms This Afternoon.
Tonight...N Winds 5 To 10 Kt...Becoming Se Late. Waves 1 Ft.
Thu...S Winds 10 To 15 Kt With Gusts To 20 Kt... Becoming W 15 To 20 Kt With Gusts To 30 Kt In The Afternoon. Waves 1 To 2 Ft. Showers Likely.
Thu Night...W Winds 10 To 15 Kt With Gusts To 25 Kt. Waves 1 Ft.
Fri...W Winds 10 To 15 Kt With Gusts To 30 Kt. Waves 1 Ft.
Fri Night...Nw Winds 10 To 15 Kt. Gusts Up To 25 Kt In The Evening. Waves 1 Ft.
Sat...W Winds 5 To 10 Kt...Becoming Se After Midnight. Waves 1 Ft.
Sun...Se Winds 5 To 10 Kt. Waves 1 Ft. Rain. 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
1022am EDT Wednesday April 8 2020

A front will drop southward through our region this morning. A strong cold front moves through our area on Thursday. A Canadian high pressure builds over our area Friday through Saturday before low pressure possibly impacts the area early next week.

.NEAR TERM Through Tonight
Earlier convection has pushed south/dissipated, with some clearing in its wake. A weak boundary remains to our north and will settle southward through the day. Additional showers and storms will be possible by early afternoon, mainly across the southern half of the forecast area. As temperatures are expected to warm up into the mid 70s to low 80s, less than 1000 J/kg of CAPE will develop. Stronger updrafts will have the potential to tap into 40+ kt of shear and could pose an isolated severe weather threat with marginally severe hail or localized damaging winds. Weak forcing and instability will likely keep the threat marginal. The threat for showers and thunderstorms should continue to wane by early evening as the front moves further south of our region and we become positioned on the cold side of the front. Dry conditions are expected this evening. Remnant convection from the Ohio Valley may approach from the west late tonight.

Short Term - Thursday Through Friday Night
A strong cold front will move through our region early Thursday morning and continue through our area into the afternoon. A strong upper level jet will shift northward and help to enhance lift along the frontal boundary as it moves through our forecast area. HiRes guidance is hinted at the formation of squall line feature that forms during the early morning periods Thursday and progresses eastward through our area by the early Thursday afternoon. This line has the potential to develop thunderstorms capable of producing strong to damaging winds but there remains uncertainty whether this line will hold together through our area.

Behind the frontal passage, a strong pressure gradient will lead to gusty winds of 25 to 35 knots with locally higher gusts possible. High pressure will build into our region through Friday but strong winds could linger into Friday. A cooler air mass will move into our region on Friday with temperatures running much cooler in the upper 40s and 50s with overnight lows in the 30s Friday night. As temps drop near freezing along with winds becoming light, there is potential that frost/freeze advisory may need to be issued for Friday night but there remains a lot of uncertainty at this time.

Long Term - Saturday Through Tuesday
The aforementioned area of high pressure will push offshore on Sunday, with southerly flow returning, bringing warmer and more moist air into the region. Initial thougheights are that the first half of the day stays dry. However, a potent cutoff upper low, previously sitting over the desert southwest, will be moving out over the southeast. Surface low pressure will form over the Arklatex and move off generally towards our region. Guidance is spread about how exactly this will evolve. Maintaining thougheights from yesterday that this has the potential to be an impactful event for the region in one of two ways. The first option is that the system tracks to our south, but we are solidly within the heavy rain threat, so flooding concerns could arise. The other possibility is for the system to track into the Ohio Valley, and bring a cold front through late Sunday or Monday (timing is still very much in flux), which would result in the potential for some severe weather. This is out near the end of the forecast period, so not locking onto any particular solution at this time, but at this point, these are the two scenarios that the guidance is coming up with.

West winds will increase through the midday hours. A Small Craft Advisory is in effect for this afternoon. An isolated thunderstorm could require a Special Marine Warning this afternoon, mainly near southern Maryland. A strong cold front will move through the waters on Thursday. Strong and gusty winds are expected along and behind the front. Gusts of 25 to 35 knots are expected. Small Craft Advisories are likely Thursday and Friday with Gale Warnings possible Thursday afternoon into Friday.

SCA (Small Craft Advisory) conditions will be possible both Saturday and Sunday.

Tides / Coastal Flooding
DC Southwest Waterfront briefly reached minor stage this morning. The next high tide is lower and should be below flood, but sensitive site may be close with the high tide occurring tonight/Thursday morning.

NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...None. MD...None. VA...None. WV...None.
Small Craft Advisory until 8pm EDT this evening for ANZ530>543.