Baltimore Harbor & Patapsco River Marine Forecast
|Today...Nw Winds 5 Kt. Waves Flat. Scattered Sprinkles.|
|Tonight...Nw Winds 5 Kt. Waves Flat. Scattered Sprinkles.|
|Sat...Nw Winds 5 To 10 Kt. Waves 1 Ft.|
|Sat Night...Nw Winds 5 To 10 Kt. Waves 1 Ft Or Less.|
|Sun...Sw Winds 5 Kt. Waves Less Than 1 Ft.|
|Sun Night...Se Winds 5 To 10 Kt. Waves 1 Ft. Rain.|
|Mon...Se Winds 10 To 15 Kt...Becoming Sw 5 To 10 Kt. Waves 1 To 2 Ft. Showers Through The Day. A Chance Of Showers Through The Night.|
|Tue...Sw Winds 5 To 10 Kt. Waves 1 Ft.|
| Area Forecast Discussion|
National Weather Service Baltimore MD/Washington DC
424am EST Fri Nov 27 2020
Surface high pressure will build overhead today. A weak cold front will pass through early Saturday, followed by high pressure for Saturday night and Sunday. A strong storm system moving up from the Deep South is expected to move northeast through the Mid Atlantic on Monday. That storm will stall over Ontario and remain there to our north through midweek.
Near Term - Through Saturday
Latest analysis depicts yesterday's frontal system well off the coast, with high pressure centered over the upper Ohio Valley. A weak cold front is crossing the upper Great Lakes. Weak low pressure is starting to develop over Texas. Aloft, two weak upper level disturbances are nearby, one near the VA/NC border and another in the mid Mississippi Valley. A stronger shortwave is crossing the northern Plains while a closed low is in the Four Corners region.
For today, while high pressure will dominate, the two weak disturbances promise to keep clouds around. There could even be a few sprinkles, but nothing significant is expected. The clouds and slightly cooler air mass behind yesterday's system should keep highs closer to normal, but still on the plus side of where we should be this time of year.
The weak cold front will cross the region later tonight into early Saturday. This front looks rather diffuse on guidance, but we will definitely see an increase in northwest winds and cold advection behind the boundary. Some upslope showers are also possible along the Allegheny Front - likely dry elsewhere, though a sprinkle couldn't be ruled out further east. Downslope flow will keep temps still a bit on the plus side of normal Saturday for most of the region.
Short Term - Saturday Night Through Sunday Night
Cold advection behind Saturday's weak front will be noticed Saturday night, with considerably colder temps are expected behind it - lows will be in the upper 20s to mid 30s on Saturday night under high pressure, clear skies and light winds.
High pressure and sunshine dominates on Sunday, with temps knocked back a couple more degrees from Saturday's readings, but still not bad at all for the end of November, with high 50s common. Clouds start to increase late as the developing low, currently in Texas as of this writing, heads northeastward, gathers strength and moisture, and starts to affect our region. Most areas start out dry Sunday evening, but rain likely will be falling across the entire region by dawn Monday. Milder southerly flow will keep temps elevated, with 40s common.
Long Term - Monday Through Thursday
At the start of Monday morning, a complicated synoptic setup will be underway across the eastern U.S. The key players are a slow moving closed low currently over the Four Corners and a progressive shortwave approaching Vancouver Island. Much will depend on the timing of these features and if/when they are able to phase over the Mid-Atlantic to Ohio Valley region.
Based on the latest guidance packages, solutions have become further consolidated favoring a deep area of low pressure traversing the Central Appalachians early Monday. Wind fields accompanying this southern stream system are quite impressive with 850-mb winds likely in the 50 to 60 knot range. Some of these stronger wind fields could impinge on the surface so cannot rule out 25 to 35 mph gusts. Ample vertical shear will be in place, but the late November thermodynamic environment can often be lacking in terms of buoyancy. Given this is an 84 hour forecast, much can change, but the thunderstorm potential will need further attention. On the hydrology side of the equation, precipitable water values likely exceed an inch which is roughly 200% of normal. The heavy rainfall potential exists, but the precipitation elements should be quick movers. At this juncture, ensemble means favor around an inch of rainfall which seems reasonable. Conditions should clear out by late Monday as a pronounced dry slot crosses the I-95 corridor.
While a myriad of solutions are possible, the other aspect of this system will be wintery in nature. As the northern stream system interacts with the aforementioned upper low, the entire trough becomes more expansive and closed off. Broad cyclonic flow around this feature will usher in modified continental Arctic air on its back side. A steady period of westerly upslope snow is possible in this scenario. The ingredients are in place for such a setup, but a number of details still need to be worked out. Higher elevations of western Maryland, east-central West Virginia, and northwestern Virginia will need to monitor the upslope snow threat for Monday and Tuesday.
As this extensive upper low exits into Quebec, the trailing flow is a bit uncertain. Ensemble means favor a broad positively-tilted trough across the eastern third of the country. Dry conditions are currently expected beyond Tuesday, but confidence is below average in the details. Regarding temperatures, a mild start to the work week will be quickly replaced with a shot of cold air for Tuesday and Wednesday. Highs each of those days may only top out in the mid/upper 40s at lower elevations with sub-freezing overnigheights everywhere aside from near the bay waters. Such numbers sit a few degrees below climatology in most spots. Some chilly nighttime temperatures are likely in the mountains, especially given any accumulating snows. Wind chills could drop into the upper single digits on Tuesday night/Wednesday morning.
Light winds on the waters today into tonight. Weak cold front dropping southeast across the waters Saturday may bring marginal SCA (Small Craft Advisory) conditions, but not yet confident enough to issue an advisory. Winds slack off Saturday night into Sunday before starting to pick up again Sunday night as a much stronger system approaches.
Moderate to strong southeasterly winds overspreading the waters could lead to gale conditions on Monday. A pronounced wind shift takes place late Monday taking winds from southeasterly to westerly. Small Craft Advisories are likely on Tuesday with the system still lingering over the region.
Tides / Coastal Flooding
Water levels will remain below action stage over the next few days. However, a strong storm system approaching from the south threatens at least minor tidal flooding as we head into Monday.
NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...None. MD...None. VA...None. WV...None. MARINE...None.