Baltimore Harbor & Patapsco River Marine Forecast
|Today...N Winds 5 Kt. Waves Flat.|
|Tonight...N Winds Around 5 Kt. Waves Flat.|
|Wed...E Winds 5 Kt. Waves Flat.|
|Wed Night...Se Winds 5 To 10 Kt. Waves 1 Ft.|
|Thu...Se Winds 10 Kt. Waves 1 Ft.|
|Thu Night...S Winds 10 Kt. Waves 1 Ft. A Chance Of Showers.|
|Fri...Sw Winds 5 To 10 Kt. Waves 1 Ft Or Less. A Chance Of Showers And Tstms.|
|Sat...Sw Winds Around 5 Kt. Waves Flat. A Chance Of Showers And Tstms. Winds And Waves Higher And Visibilities Lower In And Near Tstms.|
Area Forecast Discussion|
...Corrected National Weather Service Baltimore MD/Washington DC
401am EDT Tuesday July 14 2020
A weak front along the Atlantic seaboard will push offshore this morning. High pressure will then build across the area through Wednesday before moving offshore. A front may approach from the north late in the week, before returning back north over the weekend.
Near Term - Until 6pm This Evening
A weak front remains analyzed across the Delmarva this morning while an upper low crosses northern New York. The combination of this subtle forcing along with higher instability near the warm waters of the bay is continuing to result in shower and thunderstorm development across far southern Maryland. Thinking any remaining activity should dwindle or exit within the next couple hours. The troughing is also resulting in some mid level clouds, which should generally hamper fog development.
A second, subtle boundary will push south today, marked primarily by lower dew points (mid 50s currently in PA). High pressure will also expand east from the Great Lakes/Ohio Valley. While some CAMs try to produce a few showers over the southern Shenandoah Valley where a smidge of instability will remain, am thinking the moisture will be too shallow under a subsidence inversion and am thus carrying a dry forecast. Slight cool advection may result in a degree or two lower than yesterday's highs, though still looking at mid 80s to around 90. Humidity will be pleasant for this time of year with dew points in the mid 50s to lower 60s.
Short Term - 6pm This Evening Through Thursday Night
The high will be positioned to the north tonight with dry, pleasant weather continuing. Some patchy fog could develop in the mountain valleys. Lows will be in the 60s to around 70.
The surface high will move toward New England on Wednesday while a ridge axis moves overhead. Return flow will begin, resulting in high temperatures inching up into the upper 80s and lower 90s. It's possible enough moisture may return to the southwestern part of the CWA that a shower could spark over the mountains; however, the subsidence inversion looks stout, so will keep a dry forecast for now. With onshore surface flow, clouds may try to develop Wednesday night, especially for the DC/Balt metro. Otherwise, expecting milder lows in the upper 60s to lower 70s.
The aforementioned clouds could persist into Thursday, and if they do, could have an effect on high temperatures -- keeping some areas in the 80s. However, more sun is expected west of the Blue Ridge where the wind should have more of a southerly component. Deeper moisture will begin to advect in, and there may be some height falls by afternoon. Thus expecting the highest chance of thunderstorms near and west of I-81. Shear may approach 30 kt, especially northwestern areas, so a few strong storms could be possible. Some showers could linger into the night depending on upstream coverage and if there is enough synoptic/shortwave forcing to support them.
Long Term - Friday Through Monday
A cold front will move southeastward Friday and Friday night. Showers and thunderstorm could develop along this front, mainly across our southern zones. Temperatures ahead of and along the front will reach the lower 90s, while temperatures reach the middle to upper 80s behind the front and across the northern half of our region.
Weak high pressure should nose in from the northwest Saturday and Saturday night. As light to moderate northerly winds becoming more southeasterly Saturday afternoon, showers and a thunderstorm could form in the Potomac Highlands or along the Blue Ridge Mountains. Temperatures will be in the lower 90s.
Weak high pressure should remain in control Sunday and Sunday night. Most areas could be rain-free. A pop-up thunderstorm in the Potomac Highlands Sunday afternoon could venture eastward into northern and central Virginia. Also, a bay breeze or sea breeze thunderstorm could develop over eastern and southern Maryland. Temperatures should be in the lower to middle 90s.
A cold front across the lower Great Lakes should sag southward into our region by Monday afternoon. Showers and thunderstorms, once again, could ignite ahead of and along this front. Temperatures could be in the 90s, as well.
The front could stall across the region Tuesday into Tuesday night; thus, allowing for showers and thunderstorms to remain a possibility. Temperatures should remain in the 90s.
Light NW winds/sub-SCA (Small Craft Advisory) conditions will continue today. High pressure will be in control through Wednesday allowing for sub- SCA (Small Craft Advisory) conditions with flow becoming more E/SE. Stronger S/SE flow will develop by Thursday, with potential SCA (Small Craft Advisory) conditions by late in the day/Thursday night. Most storms should stay west of the waters on Thursday.
No marine hazards expected Friday through Saturday night except for a chance of thunderstorms each day. Winds south 10 knots Friday and Friday night. Winds shifting northwest 10 knots Saturday, then veering around to the southeast 5 to 10 knots Saturday night.
Tides / Coastal Flooding
No coastal flooding issues are expected through Wednesday. Stronger south/southeast flow will return by late Thursday and could push some locations to near minor flooding thresholds by the evening high tide.
NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...None. MD...None. VA...None. WV...None. MARINE...None.