Ashburn, VA Marine Weather and Tide Forecast
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Marine Weather and Tide Forecast for Ashburn, VA

June 21, 2024 12:27 PM EDT (16:27 UTC) Change Location
Sunrise 5:42 AM   Sunset 8:40 PM
Moonrise 7:56 PM   Moonset 3:51 AM 
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NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.

Marine Forecasts
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ANZ535 Tidal Potomac From Key Bridge To Indian Head- 1034 Am Edt Fri Jun 21 2024

Rest of today - S winds 5 kt. Waves less than 1 ft.

Tonight - S winds 5 kt. Waves less than 1 ft.

Sat - S winds 5 kt. Waves less than 1 ft.

Sat night - S winds 5 kt. Waves less than 1 ft.

Sun - SW winds 5 to 10 kt. Waves 1 ft. A chance of showers and tstms.

Sun night - SW winds 5 to 10 kt. Waves 1 ft. A chance of showers and tstms.

Mon - W winds 5 to 10 kt. Waves 1 ft. A chance of showers and tstms.

Tue - SW winds around 5 kt. Waves 1 ft.
winds and waves higher and visibilities lower in and near tstms.

ANZ500 1034 Am Edt Fri Jun 21 2024

Synopsis for the tidal potomac and md portion of the chesapeake bay -
high pressure will remain anchored offshore through the weekend. A front will stall near the great lakes this weekend before passing through the area Monday. High pressure briefly returns to the waters Tuesday before another series of fronts cross midweek. Periodic small craft advisories are possible Saturday through Monday, especially during the afternoon and evening hours.


7 Day Forecast for Marine Location Near Ashburn, VA
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Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 211426 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1026 AM EDT Fri Jun 21 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. Another cold front will approach from the northwest on Wednesday.

NEAR TERM /THROUGH TONIGHT/
Current surface and upper air analyses show high pressure centered offshore at the surface, with broad upper level ridging in place aloft. High pressure will remain in place offshore today, as the upper level ridge slowly starts to break down. With temperatures cooling off slightly aloft, terrain driven circulations in response to daytime heating over the Allegheny Front and Potomac Highlands may be enough to spark the development of a few isolated thunderstorms this afternoon.
As noted by the 12Z KIAD sounding, vertical winds are pretty weak with generally up to 10 knots observed through the entire cloud-bearing layer. As such, any thunderstorms should remain near the higher terrain to the west of I-81, with dry conditions further east. It will be yet another hot day, with high temperatures in the mid 90s for most (mid-upper 80s in the mountains). Combining this heat with modest humidity will yield heat indices into the upper 90s.

Any leftover storms over the higher terrain should quickly dissipate this evening with loss of daytime heating, leading to dry conditions for all overnight. Overnight low temperatures will be noticeably warmer than preceding nights, with low to mid 70s for most (upper 60s in the mountains).

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
High pressure will remain in place offshore on Saturday as heights continue to slowly fall aloft. A shortwave trough will track into the Western Great Lakes, causing 850 hPa flow to turn southwesterly in response. This will draw the hottest air of the year into the region, with 850 hPa temps soaring to around 21-23 C. When fully mixed out, that will yield high temperatures in the upper 90s to near 100. Dewpoints will also increase into the upper 60s to lower 70s. When combined, this will result in peak heat index values of 100-110 across lower elevations. An Excessive Heat Watch remains in effect for much of the area Saturday afternoon.

A southwest to northeast oriented surface trough is expected to develop through the center of the forecast area Saturday afternoon. Most model guidance has showers and thunderstorms developing within that surface trough in response to daytime heating Saturday afternoon. Ample instability will be present within the hot and humid airmass, but CAMs show thunderstorms struggling to intensify within an environment characterized by relatively dry air aloft and negligible large scale forcing for ascent. If any stronger storms were to become established, high levels of DCAPE will be present, making localized downbursts a conditional possibility. Any thunderstorms should quickly dissipate with loss of daytime heating after dark, leading to dry conditions once again overnight. Very warm temperatures are expected overnight, providing very little relief from the heat.
Record high minimum temperatures may be threatened Sunday, with overnight lows only dropping into the mid-upper 70s to the east of the Blue Ridge Saturday night. Lows in the lower 80s may even be possible in DC and Baltimore.

A mid-level shortwave and associated area of low pressure will track through the Eastern Great Lakes into the St. Lawrence Valley on Sunday. Very hot conditions are expected across the area once again, with high temperatures climbing into the mid- high 90s for most (80s in the mountains). When combined with dewpoints near 70, this will once again result in max heat index values of 100-110 to the east of the Blue Ridge. Additional heat headlines will likely be needed across portions of the area for Sunday. Thunderstorms will be possible once again Sunday afternoon into Sunday night as forcing for ascent associated with the shortwave overspreads the area. Forecast soundings show around 1000-2000 J/kg of MLCAPE, around 30 knots of 0-6 km shear, and DCAPE values well in excess of 1000 J/kg. As a result, severe thunderstorms capable of producing damaging winds may be possible. SPC currently has much of the area in a Marginal risk for severe thunderstorms on Sunday.

LONG TERM /MONDAY THROUGH THURSDAY/
The cold front will either be nearing or already over the forecast area by Monday morning. There may be an ongoing risk of a few showers and storms along the boundary. By peak heating, the front may already be along or east of I-95. The greatest convective signal is across southern Maryland, with activity clearing by evening.
Temperatures will be lower Monday owing to the clouds and falling heights, but most areas along and east of I-81 will still reach the lower to mid 90s.

Surface high pressure will briefly build over the area Tuesday. Post- frontal relief will mainly be in the form of lower dew points (upper 50s to lower 60s), as high temperatures will once again reach the lower to mid 90s in the lower elevations.

The low level ridge moves offshore Wednesday, and southwesterly flow will rapidly bring back a hot air mass. Highs will be in the mid to upper 90s, with heat index values above 100 east of the Blue Ridge.
There is some uncertainty with the progression of the next trough.
For Wednesday afternoon, it appears any convection will be tied to mesoscale processes, with more widespread thunderstorms developing across the Ohio Valley. As long as the atmosphere isn't overturned, some of that convection could move into the area Wednesday night given the hot and humid airmass remaining in place. If the cold front is slower, Thursday could also be an active thunderstorm day.
However, the current consensus would place the front to the southeast, with only some lingering showers and a few storms associated with the upper trough. Temperatures would also be cooler with this scenario, in the mid to upper 80s.

AVIATION /14Z FRIDAY THROUGH TUESDAY/
Prevailing VFR conditions and light southerly winds are expected at the terminals through this weekend. Thunderstorms may be possible both Saturday and Sunday afternoon.

Thunderstorms are possible Monday as a cold front passes through, especially near the metro terminals. High pressure will provide VFR conditions Tuesday.

MARINE
Persistent southerly flow is expected over the waters through this weekend. SCAs are in effect late this afternoon into this evening on the Bay and Lower Tidal Potomac in channeled southerly flow. Similar low-end SCA conditions may be possible both Saturday and Sunday afternoon/evening. SMWs may also be possible in association with any thunderstorms that move over the waters during the afternoon or evening hours this weekend.

Small Craft Advisories may be needed for portions of the waters Monday in southwesterly flow ahead of a cold front, then with northwesterly winds behind the front Monday night. Thunderstorms may develop along the front Monday afternoon with a threat for strong winds. High pressure will support lighter winds on Tuesday.

CLIMATE
Very hot temperatures are expected 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+) 95F Martinsburg (MRB) 102F (1931) 94F Charlottesville (CHO) 99F (1933) 94F Annapolis (NAK) 100F (1988) 90F 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) 98F Martinsburg (MRB) 102F (1933) 96F 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) 99F Washington-Dulles (IAD) 96F (1988) 98F Baltimore (BWI) 97F (2010) 99F Martinsburg (MRB) 100F (1934) 94F Charlottesville (CHO) 100F (1894) 96F Annapolis (NAK) 98F (1988) 95F Hagerstown (HGR) 98F (1988) 96F

LWX WATCHES/WARNINGS/ADVISORIES
DC...Excessive Heat Watch from Saturday afternoon through Saturday evening for DCZ001.
MD...Excessive Heat Watch from Saturday afternoon through Saturday evening for MDZ003>006-008-011-013-014-016-502>508.
VA...Excessive Heat Watch from Saturday afternoon through Saturday evening for VAZ026>031-037>040-050-051-053>057-501-502- 505-506-526-527.
WV...Excessive Heat Watch from Saturday afternoon through Saturday evening for WVZ050>053-055-502-504.
MARINE...Small Craft Advisory from 4 PM this afternoon to 2 AM EDT Saturday for ANZ530>534-537>543.




Weather Reporting Stations
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Stations Dist Age Wind AirWater WavesinHgDewPt
WASD2 - 8594900 - Washington, DC 26 mi58 minS 7G8 84°F 83°F30.21
BSLM2 - Chesapeake Bay, MD 44 mi58 minSE 4.1 86°F 30.2172°F


Wind History for Washington, DC
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Airport Reports
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Link to 1 hour of 5 minute data for KIAD
   
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Wind History graph: IAD
(wind in knots)
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Tide / Current for Chain Bridge, D.C.
   
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Chain Bridge
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Fri -- 02:38 AM EDT     0.50 feet Low Tide
Fri -- 04:49 AM EDT     Moonset
Fri -- 05:43 AM EDT     Sunrise
Fri -- 08:34 AM EDT     3.42 feet High Tide
Fri -- 03:52 PM EDT     0.32 feet Low Tide
Fri -- 08:37 PM EDT     Sunset
Fri -- 08:54 PM EDT     Moonrise
Fri -- 09:10 PM EDT     Full Moon
Fri -- 09:20 PM EDT     2.79 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Chain Bridge, D.C., Tide feet
12
am
1.3
1
am
0.8
2
am
0.6
3
am
0.5
4
am
0.8
5
am
1.4
6
am
2.3
7
am
3
8
am
3.4
9
am
3.4
10
am
3.1
11
am
2.5
12
pm
1.9
1
pm
1.3
2
pm
0.8
3
pm
0.5
4
pm
0.3
5
pm
0.6
6
pm
1.3
7
pm
2
8
pm
2.5
9
pm
2.8
10
pm
2.7
11
pm
2.3


Tide / Current for Chain Bridge, one mile below, D.C.
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Chain Bridge
Click for Map
Fri -- 02:33 AM EDT     0.50 feet Low Tide
Fri -- 04:49 AM EDT     Moonset
Fri -- 05:43 AM EDT     Sunrise
Fri -- 08:29 AM EDT     3.42 feet High Tide
Fri -- 03:47 PM EDT     0.32 feet Low Tide
Fri -- 08:37 PM EDT     Sunset
Fri -- 08:54 PM EDT     Moonrise
Fri -- 09:10 PM EDT     Full Moon
Fri -- 09:15 PM EDT     2.79 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Chain Bridge, one mile below, D.C., Tide feet
12
am
1.2
1
am
0.8
2
am
0.5
3
am
0.5
4
am
0.8
5
am
1.5
6
am
2.4
7
am
3
8
am
3.4
9
am
3.4
10
am
3
11
am
2.4
12
pm
1.8
1
pm
1.3
2
pm
0.8
3
pm
0.4
4
pm
0.3
5
pm
0.6
6
pm
1.3
7
pm
2
8
pm
2.6
9
pm
2.8
10
pm
2.7
11
pm
2.3


Weather Map
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GEOS Local Image of east us   
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Sterling, VA,




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