Marine Weather Net

Baltimore Harbor & Patapsco River Marine Forecast


5 - 10


10 - 15


5 - 10



The Marine Weather Forecast In Detail:
ANZ538 Forecast Issued: 937 PM EST Thu Nov 21 2019

Rest Of Tonight...Sw Winds 5 To 10 Kt. Waves 1 Ft.
Fri...W Winds 10 To 15 Kt. Gusts Up To 20 Kt. Waves 1 Ft. Showers Likely.
Fri Night...Nw Winds 5 To 10 Kt. Gusts Up To 20 Kt In The Evening. Waves 1 Ft.
Sat...S Winds Around 5 Kt. Waves Flat. Rain Likely.
Sat Night...N Winds Around 5 Kt. Waves 1 Ft Or Less. Rain.
Sun...Nw Winds 10 To 15 Kt With Gusts To 20 Kt. Waves 1 Ft.
Sun Night...W Winds 5 To 10 Kt. Waves 1 Ft.
Mon...Sw Winds 5 Kt. Waves Less Than 1 Ft.
Tue...S Winds 5 To 10 Kt. Waves 1 Ft. A Chance Of Rain Through The Night.
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Area Forecast Discussion
...UPDATED National Weather Service Baltimore MD/Washington DC
1031pm EST Thu Nov 21 2019

High pressure will move offshore tonight as a cold front approaches from the Ohio Valley. The cold front will cross the region on Friday. Low pressure will develop over the Mid Mississippi Valley Friday night and track northeastward across the Mid- Atlantic through early Sunday. High pressure is expected to return later Sunday into early next week. Another area of low pressure and its associated cold front may approach from the west during the middle of next week.

Near Term - Until 6am Friday Morning
Clouds will continue to stream into the area from the west ahead of an approaching trough and attendant surface cold front. Radar is picking up a few returns but doubt if many or any of these will reach the ground much of tonight east of the mountains given residual drier low-level air in place.

Clouds and light southerly flow will keep temperatures in the lower to middle 40s tonight, several degrees above normal.

Short Term - 6am Friday Morning Through Saturday Night
A cold front will be moving across our area on Friday morning into the early afternoon with high temperatures occurring before that. Rain showers associated with this front will start in the morning hours west of the Blue Ridge and overspread east into the afternoon. Quantitative Precipitation Forecast maxima are expected along and west of the Allegheny Front, and near central Virginia into southern Maryland. Highest values seems to be between two tenth and half an inch of rain, but most areas likely see a tenth to quarter of an inch on average.

Sounding profiles suggests a brief period of snow is possible for the highest peaks of the Allegheny Front, but with marginal temperatures and brief duration, not expecting appreciable accumulation, though as moisture becomes shallow there's a small chance there could be freezing drizzle on the ridgetops primarily along the Allegheny Front Friday evening.

High pressure will build behind the front Friday night into early Saturday bringing dry and cool air into our region. Low temperatures Friday night will be in the mid 20s to mid 30s.

A low pressure system with plenty of moisture will move from the southwest into our region on Saturday as mid-level low pushes east into our region from the Midwest. This system will be over or near our area on Saturday night. Precipitation will overspread the region from the southwest into the northeast, with plain rain expected over most of our region. However, BUFKIT soundings from pretty much all available guidance showers a sub-freezing layer between 1000 and 3000 feet, which would result in freezing rain over the ridges of the Allegheny Front, Blue Ridge and Catoctins Saturday into Saturday night. Given the small sub-freezing layer and relatively small geographic area, uncertainty is moderate, but higher resolution model runs beginning late tonight should begin to be able to better resolve this potential.

Long Term - Sunday Through Thursday
Wave of low pressure will be exiting stage right early Sunday, with dry weather likely to prevail. Temperatures will remain a bit below normal, but not by a large margin. High pressure will slide by to the south Monday into Tuesday. While temperatures likely stay fairly steady Monday, southerly flow as the high heads off the coast Tuesday should allow temps to rise back to near or even a bit above normal. Rain may infringe on the area by Tuesday night as another wave of low pressure lifts northeastward to our west, followed by a cold frontal passage during early Wednesday. Downslope flow with a Pacific air mass may help Wednesday turn out on the mild side, even warmer than Tuesday, but temps will cool as Canadian high pressure slides south for Thursday.

A Small Craft Advisory is in place for tonight for most waters, though there's a 5-8 kt speed spread in latest guidance even 6-12 hours out, accentuating an uncertain wind forecast overnight.

SCA (Small Craft Advisory) winds likely linger over middle Bay waters south of North Beach MD and the lower tidal Potomac in stronger SW gradient Friday, with northwest push of SCA (Small Craft Advisory) expected for a few hours during the late afternoon into the evening behind a cold front. This front will also be accompanied by a period of showers. Winds should diminish Friday night into Saturday before a low pressure system impacts us on Saturday night.

SCA (Small Craft Advisory) can't be ruled out immediately behind the departing low pressure Sunday, but by Monday sub-SCA (Small Craft Advisory) conditions are expected.

Tides / Coastal Flooding
Southerly to southwesterly flow will increase a bit over the next 12 to 24 hours, resulting in increasing water levels. This may result in near minor flooding at Annapolis tonight and tomorrow, though ETSS and ESTOFS are notably lower than CBOFS and SNAP-ex mean. Split the difference since southwesterly flow doesn't usually result in quite as high water levels, thus with current forecast no headlines are needed, but will require close monitoring the next day or so.

NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...None. MD...None. VA...None. WV...None.
Small Craft Advisory until 6am EST Friday for ANZ530>532-536- 539-540. Small Craft Advisory from 4pm to 10pm EST Friday for ANZ530>532-535-536-538>540-542. Small Craft Advisory until 4am EST Saturday for ANZ533-534- 537-543. Small Craft Advisory until 10pm EST Friday for ANZ541.