Marine Weather Net

Chesapeake Bay From Pooles Island to Sandy Point MD Marine Forecast




5 - 10





The Marine Weather Forecast In Detail:
ANZ531 Forecast Issued: 439 PM EDT Thu Aug 06 2020

Rest Of This Afternoon...E Winds 10 Kt. Waves 1 Ft. Numerous Showers And Tstms.
Tonight...E Winds 5 To 10 Kt. Waves 1 Ft. Widespread Showers And Tstms.
Fri...E Winds 5 Kt. Waves Flat. Showers Likely With A Chance Of Tstms.
Fri Night...E Winds 5 Kt. Waves Flat. Showers Likely With A Chance Of Tstms.
Sat...N Winds 5 Kt. Waves Flat. A Chance Of Showers.
Sat Night...Se Winds 5 Kt. Waves Flat.
Sun...S Winds 5 To 10 Kt. Waves 1 Ft Or Less.
Mon...S Winds 5 To 10 Kt. Waves 1 Ft. Winds And Waves Higher And Visibilities Lower In And Near Tstms.
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Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
241pm EDT Thu August 6 2020

A frontal boundary will remain stalled near the region through Friday. High pressure builds over our region this weekend before shifting offshore early next week.

Near Term - Through Tonight
Looking at surface obs this afternoon the stalled boundary looks to be located near the I-95 corridor. This boundary is looks to shift westward this afternoon but should remain mostly stalled over our region. Mesoanalysis shows that an axis of higher PW's is located east of the Blue Ridge Mountains with values above 1.9 inches and above 1.7 east of the Allegany front. A few showers and thunderstorms are currently on the radar but the coverage is expected to increase through this evening. A combination of the stalled boundary coupled with a shortwave moving through along with with good placement of the upper level jet will lead to environment conducive for scattered thunderstorms that have the potential to become severe. The main threat this evening will be the threat for heavy rain storms that have the potential to cause flash flooding and longer fused flood warnings.

The 12Z HREF has come in with more widespread coverage with a signal that areas in central Virginia especially east of I-81 and south of the DC metro. There is significant signs that southern Maryland and central Virginia will get a decent punch of rain and storms, but there are hints of a threat for northern Virginia and possibly parts of northern Virginia. A Flash Flood Watch has been issued to cover this threat. Models have been showing that the threat for heavy rain could continue into the early morning periods of Friday.

Short Term - Friday Through Saturday Night
The stationary boundary remains stalled over our region through Friday. Multiple upper level shortwaves are expected to move through our region with the main trough axis approaching from our west late Friday through early Saturday. The continued presences of the stalled boundary overhead along with multiple shortwaves and upper level jet will lead to a continue threat for severe weather and flash flooding. Both global and mesoscale models are showing an axis of precipitation moving through areas along and east of the Blue Ridge mountains. This area has already received a lot of rain from the tropical storm and will received additional rainfall this evening. The current Flash Flood Watch may need to be extended through tomorrow afternoon but I will punt that off to evening shift to make that decision. I again think that flooding threat will be the bigger concern but I can't rule out a few severe storms on Friday. The coverage of storms and showers should lessen by Friday evening and into the overnight periods.

The trough axis shifts through and east of our region by Saturday morning. A few lingers showers will be possible into early Saturday but weak high pressure tries to start building over our region by Saturday afternoon. Clearing skies and a weak easterly flow should allow temps to rise up into the mid to upper 80s on Saturday with lows in the 60s and lower 70s.

Long Term - Sunday Through Thursday
Sunday through Wednesday will see a gradual warming, as upper level ridging very slowly builds into the region from the west. Our area will be right on the outer periphery of the upper ridge, so there will be a few week shortwave troughs through the middle of next week that pass nearby. Meanwhile, surface high pressure will be overhead Sunday, before moving offshore into the early portion of the week.

So, all that being said, think Sunday is the least active day in the long term period, with only a few diurnally driven showers/storms out over the higher elevations with the aid of the terrain circulation. As high pressure moves offshore, heat and humidity will gradually increase Monday through Wednesday, which will aid in thunderstorm development each day. This is a return to the pattern we saw for much of July, which favored thunderstorm formation off of the river/bay breezes and the terrain circulations over the higher elevations. While not anticipating any organized severe weather at this time, can't rule out a few stronger storms each day, aided by locally enhanced shear due to mesoscale boundaries.

In addition to showers and storms each day, heat and humidity will be on the increase, which will start to lead to some higher heat indices. Temperatures in the upper 80s to near 90 on Sunday will then climb into the mid 90s by Wednesday. This, paired with dew points rising into the mid 70s, could lead to some heat indices returning to the triple digits, particularly Tuesday/Wednesday.

A weak boundary will remain stalled near the region through Friday. Showers and thunderstorms will remain the main threat for the marine areas. After Friday no small craft issues are expected for Saturday.

High pressure overhead on Sunday will push offshore into Monday. Winds will generally be light both days, with a southerly flow developing into Monday. No long-fuse marine hazards expected during this time. However, showers and storms are possible each day, but especially on Monday afternoon and continuing into mid-week. These could produce wind gusts that necessitate SMWs.


Advancing warm front plus very moist and warm (unstable) air mass advecting north behind it plus shortwave energy aloft will likely result in periods of heavy rain with passing thunderstorms through this evening. Given antecedent conditions, a flash flood watch through early Friday is warranted for those locations which received significant rain earlier this week and areas where CAMS guidance is suggesting heavy rains are possible later today. As guidance is similarly wet for Friday, the watch may need to be extended.

NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...Flash Flood Watch through late tonight for DCZ001. MD...Flash Flood Watch through late tonight for MDZ003>006-011-013- 014-016>018-503>508. VA...Flash Flood Watch through late tonight for VAZ025>031-036>040- 050>057-501-502-505>508. WV...Flash Flood Watch through late tonight for WVZ051>053. MARINE...None.