Eastern Bay, MD Marine Forecast (2024)

Synopsis
High pressure will remain in place offshore through this weekend. A cold front will progress through on Monday, with high pressure building back in by Tuesday.

Near Term - Through Tonight
A strong upper-level ridge remains overhead this afternoon, but there is enough moisture around to Probability of Precipitation off a few clouds in the mid-upper levels. This hasn't affected temperatures much overall with coverage being fairly limited. Temperatures right now are generally in the mid-upper 80s. We should add a few to that before the end of the day, with most sites getting to 90 or so. Meanwhile, dew points are only in the mid 60s, so heat indices are pretty tolerable in comparison to what is to come into the weekend.

High pressure will remain in control tonight, leading to continued dry conditions. Overnight lows will be in the mid- upper 60s for most, with lower 70s in DC and Baltimore.

Short Term - Friday Through Saturday Night
Upper level ridging does begin to break down a bit by Friday. As this occurs, the 850 hPa high will shift a bit further south, lessening the easterly component of the wind and resultant oceanic influence. Temperatures will be a few degrees warmer as a result, with highs in the mid 90s for most. As the upper ridge starts to weaken, a few afternoon thunderstorms may form over the higher terrain of the Potomac Highlands and Allegheny Front in response to daytime heating and resultant terrain-induced circulations. These thunderstorms could potentially drift as far east as the Shenandoah Valley before dissipating in the evening hours. While not likely, if one of these were to get enough juice behind it, low-level thermodynamics would be supportive of some isolated strong wind gusts. Any storms that do develop should be pretty short-lived.

Dry conditions are expected further east. Friday night will feature warmer temperatures compared to preceding nights, with overnight lows generally in the low-mid 70s. This will mark the big change that will lead into the heat for the remainder of the weekend.

Upper-level riding aloft continues to break down further on Saturday. While this occurs, we will see flow shift out of the west at 850 mb. This will result in even hotter temperatures Saturday afternoon, with highs in the mid-upper 90s. It will also turn more humid as southerly flow increases in intensity. Dewpoints are expected to reach the lower 70s. Peak heat indices of 100-105 appear likely across much of the forecast area, with some even potentially exceeding 105 in the metro areas. Heat Advisories seem increasingly likely for this time period and will be carefully considered on the evening shift.

With the ridge breaking down, there will be less subsidence aloft to suppress thunderstorm activity. With such a warm airmass, we are likely to see a northeast oriented surface trough across the center of the forecast area in response to differential heating over the higher elevations. Mid-level flow (and as a result, shear) will be relatively weak, at around 15 knots, but instability will be plentiful (MLCAPE values over 2000 J/kg) within the hot and humid airmass. While the activity should be somewhat disorganized, storms may be capable of producing localized downbursts given high levels of CAPE and DCAPE in place. It isn't entirely impossible for storms to get all the way to the Chesapeake Bay if development continues along outflow boundaries from previous storms. So have increased POPs further east as well. Have also added some enhanced wording to the thunderstorm forecast Saturday afternoon as a results.

Saturday night will be warmer still, with overnight lows in the mid-upper 70s to the east of the Blue Ridge, with lower 80s even possible in DC and Baltimore. This level of heat overnight, when the daytime temperatures are near 100, is especially dangerous because there will be very little relief. Current forecast would only have heat indices below 90 between midnight and 8am Sunday.

Long Term - Sunday Through Wednesday
The conclusion of this weekend will mark a temporary end to the lengthy period of above average temperatures. On Sunday, 850-mb temperatures rise to around 21-23C which dry adiabatically mixed to the surface would support some century degree readings. Consequently, the forecast does call for some spots reaching 100 degrees. This is accompanied increasing humidity levels as dew points rise into the upper 60s to low 70s. The resultant heat indices range from 100 to 107 degrees across the forecast area. If this were to be maintained, Heat Advisories may be needed for much of the region. An additional threat will be some strong to severe thunderstorms, particularly during the afternoon to evening hours. After over a week of continued heating of the surface, instability levels should be maximized as mixed-layer CAPE values reach 2,500 to 3,000 J/kg. The guidance vary in convective coverage which suggests there could be some capping issues.

After around 9 to 10 days without a cold frontal passage, the guidance does bring a boundary through during the second half of Monday. This would bring an additional threat for some severe convection, especially for those east of the Blue Ridge Mountains. The added clouds and thunderstorm activity does carry Monday's high temperatures back down into the upper 80s to mid 90s. Through Tuesday, this boundary eventually settles off to the south across the coastal Carolinas. Another round of hot temperatures ensue toward mid-week as highs rise into the mid/upper 90s again. Heat indices begin to approach advisory levels again. Another cold front races across the local area by Thursday which helps usher temperatures down. This would again come with another risk of severe thunderstorms.

Marine
Light southerly flow will continue over the waters through Friday morning. As high pressure strengthens offshore, winds pick up out of the south, and could reach SCA (Small Craft Advisory) criteria as early as tomorrow afternoon. Confidence was too low for an SCA (Small Craft Advisory) at this time however.

On Saturday though, winds will be picking up substantially, with SCA (Small Craft Advisory) winds likely by the afternoon into Saturday night. Some evening thunderstorms can't be ruled out on Saturday either, and if those do make it to the waters, SMWs may be necessary.

A period of southerly channeling may unfold from Sunday afternoon through Monday afternoon. These channeling effects may warrant Small Craft Advisories, especially for the wider waters of the Chesapeake Bay. A cold front races through the waters by late Monday evening. Given the threat for convection each day, Special Marine Warnings may be needed each afternoon and evening.

Climate
Very hot temperatures are expected Friday through Sunday. Several records could be in jeopardy, as seen below. Below is a list of record high temperatures for Jun 21st, 22nd, and the 23rd and the year the record was set, and the current forecast high temperatures for those days. RERs are only issued for DCA, IAD, BWI, and MRB, but other sites are shown for reference.

Friday Jun 21st Climate Site Record High Forecast High Washington-National (DCA) 99F (2012) 96F Washington-Dulles (IAD) 98F (1988) 95F Baltimore (BWI) 100F (2012+) 93F Martinsburg (MRB) 102F (1931) 94F Charlottesville (CHO) 99F (1933) 94F Annapolis (NAK) 100F (1988) 89F Hagerstown (HGR) 97F (1923) 94F

Saturday Jun 22nd Climate Site Record High Forecast High Washington-National (DCA) 101F (1988) 100F Washington-Dulles (IAD) 99F (1988) 99F Baltimore (BWI) 100F (1988) 97F Martinsburg (MRB) 102F (1933) 95F Charlottesville (CHO) 101F (1933) 97F Annapolis (NAK) 101F (1988) 94F Hagerstown (HGR) 100F (1988) 97F

Sunday Jun 23nd Climate Site Record High Forecast High Washington-National (DCA) 98F (1988) 101F Washington-Dulles (IAD) 96F (1988) 99F Baltimore (BWI) 97F (2010) 99F Martinsburg (MRB) 100F (1934) 96F Charlottesville (CHO) 100F (1894) 98F Annapolis (NAK) 98F (1988) 96F Hagerstown (HGR) 98F (1988) 97F

NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...None. MD...None. VA...None. WV...None.

Marine
None.