Baltimore Harbor & Patapsco River Marine Forecast
| Rest Of Tonight...W Winds 5 Kt. Waves Flat. A Chance Of Showers With A Slight Chance Of Tstms. |
| Fri...Nw Winds 5 Kt. Waves Less Than 1 Ft. A Chance Of Showers And Tstms. |
| Fri Night...Nw Winds 5 Kt. Waves Less Than 1 Ft. A Chance Of Showers And Tstms. |
| Sat...N Winds 5 Kt. Waves Less Than 1 Ft. |
| Sat Night...N Winds 5 To 10 Kt. Waves 1 Ft. |
| Sun...Ne Winds 5 To 10 Kt. Waves 1 Ft. |
| Sun Night...E Winds 5 To 10 Kt. Waves 1 Ft. |
| Mon...Se Winds Around 5 Kt. Waves Flat. |
| Tue...S Winds Around 5 Kt. Waves 1 Ft Or Less. Winds And Waves Higher And Visibilities Lower In And Near Tstms. |
| Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 928pm EDT Thu September 3 2026 .WHAT HAS CHANGED... A new Severe T-storm Watch has been issued for most of the area outside of locations along and south of US-33 until 2ma Friday. A Severe T-Storm Watch remains for portions of western MD and the eastern WV until midnight. Monitoring a a large cluster of storms dropping south and east along the PA/MD border from Hagerstown, MD west to Morgantown/Wheeling, WV. .KEY MESSAGES... - 1) Hot temperatures, high humidity, and severe thunderstorm chances look to continue through Friday. - 2) Mostly dry conditions and lowering humidity for the Labor Day holiday weekend ahead. KEY MESSAGE 1...Heat, humidity, and severe thunderstorm chances look to continue through Friday. The Severe T-Storm Watch has been expanded further east of the Alleghenies and north of US-33 through 2am Friday. For western MD and the eastern WV Panhandle the Severe T-Storm Watch remains until midnight. Damaging winds, large hail, and locally heavy rainfall will be the primary threat with these storms as they push south from the PA/MD border and north-central WV between 10PM-2am. Further watch expansion may be needed on the southern end if storms survive. Overall monitoring a clusters of storms (MCS) dropping souyth from Morgantown/Wheeling, wv to Cumberland/Hagerstown, MD. This storm complex will have plenty of instability to work with given pooling CAPE values of 3000-5000 j/kg. Locally, mid- level lapse rates of 6.5-7 C/km (per latest mesoanalysis and the KIAD 00Z RAOB) atop a very moist boundary layer with surface dew points well into the 70s F will lead to increasing CAPE despite the late start at surface heating. The question then becomes just how organized upstream storms become, and how stable the boundary layer is heading further into the evening. A more organized and potent line of storms a bit earlier in the evening would result in a notably higher risk for more numerous damaging wind gusts, especially focused along the residual baroclinic zone/theta-e gradient which should lie near the Potomac River/US- 50/I-66 this evening. A somewhat slower and/or more disorganized line would result in a lower risk for severe surface gusts, though some isolated damaging winds would still be possible given high CAPE/DCAPE and the shallow nature of the stable layer near the surface. Areas of western Maryland and perhaps into the eastern West Virginia panhandle are most likely to see the storms prior to the onset of appreciable nocturnal boundary layer stability. The area remains in a Slight Risk (level 2 out of 5) for severe weather from Storm Prediction Center as of the 20z/4pm outlook update, driven mostly by the threat of damaging wind gusts. There is a threat for large hail in stronger cores, though mid-level lapse rates will gradually become less steep tonight. A linear storm mode would tend to be less favorable for large hail production (as opposed to discrete/individual cells), as well. A few discrete cells are possible this evening in weak low-level WAA, however, independent of any linear system that may affect the region. These storms would be most likely to develop over northern and central Virginia into central Maryland along a weak surface trough and the aforementioned moisture/instability gradient. Current timing has this initial round of storms into western MD and eastern WV between 7-9pm gradually advancing east toward northern and central MD and northern VA between 9pm-midnight. The secondary complex of storms will push south and east mostly likely after 10pm- 2am. Pending how much energy the first complex of storms zaps away combined with the nocturnal stable layer will determine how of the secondary complex survives. The severity may drop off although gusty winds, frequent lightning, and locally heavy rainfall will remain the primary concerns. Additional showers and thunderstorms, possibly strong to severe, are anticipated again on Friday. Timing is a bit uncertain given the subtle waves aloft, but increasing low-level convergence paired with another upper impulse may very well result in another round or two of storms with a damaging wind risk. The latest guidance has nudged the threat a bit further north, encompassing areas as far north as I- 70 or the Mason-Dixon line (as opposed to I-66/US-50). This will depend on any residual early day clouds or convection, of course. Lows tonight will fall into the upper 60s and mid 70s with heat index values in the mid 70s and low 80s. Highs Friday will range from the upper 80s to lower 90s with dew points in the lower to middle 70s resulting in heat indices in the upper 90s to lower 100s. This will be just shy of heat headline criteria (except in Charlottesville and surrounding Albemarle/Nelson Counties). The potential for early day clouds to offset heating precludes enough confidence to issue any further heat headlines at this time, though it will be unusually hot and humid for early September regardless. KEY MESSAGE 3...Drier conditions expected for the Labor Day weekend through early next week. A high pressure system over the Great Lakes continues to track southeastward towards our forecast region through Tuesday. Over this time period, condtions remain predominantly dry, apart from an isolated shower in the Appalachian mountains. Temperatures remain seasonable for early September this weekend, with temperatures rising above normal by Tuesday. Moist and warmer conditions return as we head into the middle of next week. Warm, moist air at the surface could lead to unstable conditions, with chances for showers and thunderstorms returning by late Wednesday. Marine Special Marine Warnings may be needed this evening as storms develop and track towards the waters. Additional storms are anticipated on Friday, most likely late afternoon and evening. Otherwise, generally light flow is expected into the upcoming weekend, though NW gusts could approach SCA (Small Craft Advisory) levels Friday night into Saturday. On Sunday and Monday, wind gusts remain below SCA-criteria with highest chances for approaching SCA (Small Craft Advisory) thresholds Sunday afternoon or evening. Light northeasterly winds on Sunday shift easterly by Monday. NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories DC...None. MD...None. VA...None. WV...None. Marine None. |
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