Baltimore Harbor & Patapsco River Marine Forecast
| Today...W Winds 5 Kt. Waves Flat. |
| Tonight...W Winds Around 5 Kt. Waves Flat. |
| Thu...Ne Winds Around 5 Kt. Waves 1 Ft Or Less. Showers With A Chance Of Tstms. |
| Thu Night...N Winds 5 Kt. Waves Flat. Showers Likely With A Chance Of Tstms. |
| Fri...Ne Winds 5 To 10 Kt. Waves 1 Ft. |
| Fri Night...Se Winds 5 Kt. Waves Less Than 1 Ft. A Chance Of Showers And Tstms. |
| Sat...Se Winds Around 5 Kt. Waves 1 Ft Or Less. A Chance Of Tstms In The Morning. A Chance Of Showers. |
| Sun...W Winds Around 5 Kt. Waves 1 Ft Or Less. A Chance Of Showers And Tstms Through The Night. Winds And Waves Higher And Visibilities Lower In And Near Tstms. |
| Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1029am EDT Wednesday August 19 2026 .WHAT HAS CHANGED... We continue to monitor the severe weather threat on Thursday for those along and east of I-95. No significant changes were made to the forecast. .KEY MESSAGES... - 1) Departing high pressure gives way to a cold front and increasing shower and thunderstorm chances by Thursday. - 2) Chances for showers and thunderstorms continue through at least Saturday, before cooler and drier air moves in early next week. KEY MESSAGE 1...Departing high pressure gives way to a cold front and increasing shower and thunderstorm chances by Thursday. High pressure moving overhead will maintain dry conditions with partly to mostly sunny skies today. The high will move offshore tonight as a cold front approaches from the Great Lakes. Clouds will increase this evening, with shower chances ticking up near and west of I-81 after midnight. Shower activity is possible across much of the area by daybreak Thursday, depending on the evolution of showers and storms over the OH Valley today. Latest guidance is a bit slower and further west/northwest with the position of a cold front on Thursday. SLP progs hint at two subtle warm front type features that will lift northeast during the day on Thursday ahead of a pair of weak surface lows (one near PA/NJ, and the other near central VA). Where this front ends up just prior to peak heating will be crucial in determining the severe weather threat locally on Thursday. Forecast soundings show strong mid-level capping west of the front Thursday afternoon, with no capping and notably stronger CAPE approaching or exceeding 2000 J/kg east of it. The consensus is for this front to be more or less over I-95 Thursday afternoon during peak heating, though there is some variance anywhere from near the Blue Ridge to the Chesapeake Bay. Mid-level lapse rates start the day unimpressive, around 5 C/km likely due to saturation aloft associated with a weak wave of showers, but steepen slightly closer to 6 C/km by afternoon due to some cooling aloft. The extent of any clouds and showers cast some uncertainty on the extent of heating and instability later in the day. The background environment is favorable for strong to severe updrafts and even supercells. An 80-90+ kt upper jet will pivot over the area, with its right entrance ascent positioned over the surface frontal zone in the afternoon. Mid-level heigheights stay relatively steady, but PVA (strongest north) will be prevalent ahead of the aforementioned mid/upper wave and jet. Flow will increase through the column, with 25-40 kts in the 2-5 km AGL layer and effective deep layer bulk shear around 40 kts. SRH also increases to 100-200 m2/s2. Initial discrete cells in this environment may quickly grow upscale into a line capable of surges of strong to severe straight-line wind and a few embedded spin ups. Some hail can't be ruled out in the strongest storms due to cooling temps aloft. Finally, although Corfidi vectors are not too low (10-15 kts), on the mesoscale some backbuilding or training potential may exist on the tail (southwest) end of any developing line heading into the evening. Again, the highest potential will be along and east of the front which currently appears to be near I-95 during the afternoon into the early evening hours. Although somewhat conditional based on (1) the placement of the front, and (2) the degree of instability, Thursday's severe weather and excessive rainfall risk bears monitoring. For now, given the uncertainties listed above, the risk is more in the Marginal (level 1 out of 5) bin for severe weather (i.e. any damaging winds, large hail, tornadoes), but with a conditionally much higher ceiling than most typical late summer days. The excessive rainfall/flood risk may be even more conditional due to uncertain mesoscale factors and lingering drought. KEY MESSAGE 2...Chances for showers and thunderstorms continue through at least Saturday, before cooler and drier air moves in early next week. The longwave pattern across the CONUS will amplify moving into the weekend, with a shortwave disturbance and an even more potent upper-level low digging into the Ohio Valley and Great Lakes on Saturday. Downstream of the trough axis, we'll be in a favorable location for large scale ascent, with showers and thunderstorms possible Saturday afternoon. The upper trough axis will shift eastward to near our longitude by Sunday as an upper low continues to deepen to the north of Lake Ontario. Most solutions favor a cold front moving through either late Saturday night or early Sunday. Drier low-level air will filter into the region behind the front, with dewpoints dropping through the 60s on Sunday. That combined with the trough axis being located overhead (leading to less large scale ascent), leads to most solutions showing dry conditions locally. However, there still are a few solutions that produce a passing shower or storm on Sunday. Even drier air will advect into the area for Monday and Tuesday, with dewpoints forecast to drop into the 50s. This will lead to dry conditions, and also make it feel considerably less humid. High temperatures each day Saturday through Tuesday will generally be in the low to mid 80s at lower elevations, with 70s in the mountains. Marine Light winds are expected through Friday. Northwest winds become southerly by tonight. A brief enhancement is possible along the Chesapeake Bay this evening due to channeling, but prospects of advisory conditions are marginal at best. Winds then shift back to the northwest and north Thursday and Friday as a cold front pushes southward. This cold front may bring some thunderstorms to the waters on Thursday into Friday. The chance of thunderstorms has increased particularly for Thursday afternoon, during which time gusty winds or a few waterspouts are possible. Sub-SCA (Small Craft Advisory) level winds are expected this weekend, with winds generally out of the southeast on Saturday, and then northwest on Sunday. A shower or thunderstorm can't be ruled out either afternoon. NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories DC...None. MD...None. VA...None. WV...None. Marine None. |
Baltimore/Washington Radar
Northeast Radar
East Coast Satellite