Chesapeake Bay north of Pooles Island MD Marine Forecast
| Today...Ne Winds 5 To 10 Kt. Waves 1 Ft Or Less. |
| Tonight...Se Winds 5 To 10 Kt. Waves 1 Ft Or Less. |
| Sun...S Winds 10 To 15 Kt. Gusts Up To 20 Kt In The Late Morning And Afternoon. Waves 1 Ft. Showers With A Chance Of Tstms. |
| Sun Night...S Winds 10 To 15 Kt...Becoming W After Midnight. Gusts Up To 25 Kt. Waves 2 Ft. Showers With A Chance Of Tstms. |
| Mon...Nw Winds 5 To 10 Kt. Waves 1 Ft. |
| Mon Night...Nw Winds 5 To 10 Kt. Waves 1 Ft. |
| Tue...Nw Winds 5 To 10 Kt. Waves 1 Ft Or Less. |
| Wed...Sw Winds 5 To 10 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 953am EDT Sat August 15 2026 .WHAT HAS CHANGED... The earlier Dense Fog Advisory will be allowed to expire at 10 AM. .KEY MESSAGES... - 1) Severe thunderstorms and some instances of flash flooding are possible on Sunday. - 2) Seasonably warm conditions and daily shower and thunderstorm chances are expected through Monday, before another round of storms are possible on Thursday. KEY MESSAGE 1...Severe thunderstorms and some instances of flash flooding are possible on Sunday. Overnight model guidance has come into a broad consensus regarding the synoptic evolution for Sunday. In the upper levels, a belt of seasonably strong westerlies will persist from the upper Great Lakes across the Saint Lawrence Valley into the Northeast and Canadian Maritimes. Broad ascent on the equatorward side of this jet will persist much of the time from early Sunday morning through late Sunday night. Meanwhile, a pair of mid-level shortwaves, likely augmented by upstream convection over the Midwest and Ohio Valley, will track across the Mid-Atlantic on Sunday. Although timing remains a bit uncertain, most guidance now agrees on an initial wave and attendant enhanced lift/flow during the morning. This initial wave may slow on its exit during the afternoon, only to be followed by another stout wave during the late afternoon and evening. W/NW flow in the 700-500 hPa layer increases to 30-40 kts, possibly higher depending on how these waves are deepened by convection that occurs today/tonight upstream. In the low levels, flow will also increase. This will allow a sharp rise in theta-e, with PWs rising from around 1.75" at 03Z Sunday to near 2.25" by 09Z Sun. Further increases are forecast through Sunday evening. Low-level/steering flow will lie parallel to a slowly northward lifting warm front expected to bisect the area, so despite the increased flow, backbuilding/repeating convection seems plausible. Training plus the high PW airmass yields a threat for excessive rain and flooding, perhaps mitigated a bit by ongoing drought east of the Appalachians. Areas that have seen recent heavy rain, or typical poor drainage/urban areas would be rather susceptible to any such excessive rainfall amounts. Of note, the 00Z HREF 3-hr PMM has 50-70% chance of exceeding 1" in the vicinity of western MD early Sunday morning as a presumably weakening MCS (Mesoscale Convective System, a complex of thunderstorms which becomes organized on a scale larger than the individual thunderstorms) treks into the region. The probs for 3" are less than 10%, but recent heavy rain in this area could raise at least a conditional flood concern as early as the predawn hours on Sunday. Probs for 1" and 3" in 3 hours are notably higher east of the Blue Ridge during the afternoon hours. The latest HREF only goes out until early Sunday evening, but guidance such as the NAM and extended RAP suggest a further increase in PWs, low-level flow, and SBCAPE Sunday night suggesting a lingering heavy rain threat. In addition to any heavy rain threat is the potential for bands of strong to severe thunderstorms. Increased flow down into the low levels would be favorable for organized line segments capable of mixing down damaging wind gusts in any organizing cold pools. The saturated profiles could result in water loading downdrafts, though the lack of mid-level dry air may keep DCAPE low putting a ceiling on just how high damaging wind gusts can get (most likely in the 50-65 mph range). The increased low- level flow and SRH coupled with moist profiles could lend to the threat of a few tornadoes as well. Although the prospect of early morning clouds and precipitation may at first glance seem to preclude a higher potential for heating and severe weather later in the day, the high low-level moisture content coupled with steady height falls aloft means that heating will not need to be as robust to result in sufficient CAPE for strong to severe convection, especially given the shear that will be present. Some severe weather or flood threat may persist into the night given the above listed factors. KEY MESSAGE 2...Seasonably warm conditions and daily shower and thunderstorm chances are expected through Monday, before another round of storms are possible on Thursday. High pressure building across southern Quebec down into New England will favor a mostly quiet day for the area today. An onshore component to the winds should favor a mix of clouds and sun through the day. Highs will rise into the mid/upper 80s with any shower/thunderstorm chances confined to the Potomac Highlands across the central Shenandoah Valley toward I-64. Recent high-resolution models are showing an MCS racing across the Ohio Valley late today. Some of this could leak across the Alleghenies, but confidence remains low. As Sunday's cold front tracks offshore, upper-level zonal flow bringing drier air from the Great Lakes persists over the Mid- Atlantic through midweek, creating a break in the rain and thunderstorms. While temperatures and dewpoints drop a few degrees by Tuesday in the wake of the front, temperatures should gradually increase again in the latter half of the week as high pressure builds overhead. Prior to high pressure building, additional convection is possible Monday but with a likely lesser threat of severe weather or flooding. Meanwhile, an upper-level trough will begin to form over the Northern Plains and then track across the Great Lakes late in the week, with a strong cold front potentially moving through the Mid- Atlantic between Thursday and Friday. Medium-range algorithms are already highlighting a potential for severe thunderstorms with this system. However, severe probabilities currently vary widely across models, with CSU ML probabilities highlighting only a marginal 5%- 15% probability as of the 12Z model runs while the WxNext2 Mean AI outlook is already showing a 30%-45% probability. Deterministically, the GFS/ECMWF (European Centre for Medium-Range Weather Forecasts) also have not quite aligned on the timing and placement of the trough 7 days out. Should this setup materialize, storms capable of heavy downpours and damaging winds would be possible. As drought conditions continue to improve area-wide, localized flooding becomes more of a concern with any thunderstorms that form in the region. For now, this will be a feature to continue to monitor as the synoptic setup becomes more defined. Marine Background wind fields remain below advisory threshold through early Sunday. Ahead of a cold front, southerly winds increase in earnest which will carry gusts to around 20 to 25 knots. This likely requires Small Craft Advisories from Sunday afternoon into the overnight hours. Additionally, there will be an increasing risk of strong to severe thunderstorms, many of which may need Special Marine Warnings. Sunday likely presents itself as the most hazardous day to be on the waters, particularly from the afternoon onward. Convection may continue into Monday morning before the storm threat and winds drop off through the day. Winds stay below SCA (Small Craft Advisory) thresholds on Tuesday. Beginning Wednesday afternoon, wind gusts pick up to marginal SCA (Small Craft Advisory) thresholds before diminishing overnight. Northwest winds shift southeast by Wednesday morning. Tides / Coastal Flooding Water levels are largely expected to stay below Action Stage through Saturday. The potential exception could be Annapolis, which could reach Action Stage at the higher of the daily tides. Water levels will start to increase in southerly flow on Sunday, with Annapolis potentially approaching Minor Flood Stage. NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories DC...None. MD...None. VA...None. WV...None. Marine None. |
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