Friday, January22, 2021
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Marine Weather and Tides
Round Hill, VA

Version 3.4
NOTICE
8/26/2020 The 7 day forecast is taking about 5 seconds to load but it will eventually load. NOAA is still working on it.
8/18/2020 NOAA continues to have trouble. Wind guest will occasionally be left off graphs. I am working with NOAA to resolve the issue.
12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed.
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.

Sunrise 7:22AMSunset 5:21PM Friday January 22, 2021 8:54 PM EST (01:54 UTC) Moonrise 12:32PMMoonset 1:56AM Illumination 72% Phase: Waxing Gibbous; Moon at 10 days in cycle
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- 643 Pm Est Fri Jan 22 2021
.small craft advisory in effect through Saturday afternoon...
Tonight..NW winds 10 kt with gusts to 20 kt. Waves 1 ft.
Sat..NW winds 10 to 15 kt. Gusts up to 30 kt. Waves 1 ft.
Sat night..NW winds 5 to 10 kt with gusts to 20 kt. Waves 1 ft.
Sun..W winds 5 kt. Waves less than 1 ft.
Sun night..SE winds around 5 kt. Waves 1 ft.
Mon..E winds around 5 kt. Waves 1 ft. Rain with a chance of snow.
Mon night..E winds 5 kt. Waves less than 1 ft. Rain and snow.
Tue..N winds 5 to 10 kt. Waves 1 ft. Rain and snow in the morning.
Wed..N winds 5 kt. Waves less than 1 ft. A chance of snow through the night.
ANZ500 643 Pm Est Fri Jan 22 2021
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A cold front will push through our region this afternoon. High pressure over the midwest will build eastward through the weekend. Low pressure may impact the region early next week. Small craft advisories will likely be needed for portions of the waters through the weekend. Small craft advisories may be needed Monday into Tuesday.


7 Day Forecast for Marine Location Near Round Hill, VA
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location: 39.12, -77.77     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 221940 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 240 PM EST Fri Jan 22 2021

SYNOPSIS.

High pressure will gradually build over the region tonight through Sunday morning, then move offshore Sunday night. Low pressure will pass through the area Tuesday. High pressure will return for Wednesday and the second half of next week.

NEAR TERM /THROUGH SUNDAY/.

Main story through the weekend will be the return to much colder temperatures and blustery conditions Saturday and Sunday. Highs Sat will be about 10 degs colder than today and when you add a biting NW wind gusting up to 30 mph, it will feel like in the teens and twenties. Still chilly on Sunday, but with less wind as center of high pressure builds closer to the area. A few snow showers will be possible across the mountains, but these will be of little significance.

SHORT TERM /SUNDAY NIGHT/.

Thickening clouds Sun night as moisture increases ahead of low pressure over the central Plains. Forcing for ascent is expected to remain weak Sun night until deeper moisture and stronger forcing overspread the area Mon with the approach of low pressure over the Midwest. Any precip through 12Z Mon should remain well west of I-81 and in the form of snow with any accumulations less than an inch.

LONG TERM /MONDAY THROUGH FRIDAY/.

High pressure off to our southeast will continue to slide further offshore early Monday as low pressure emerges out of the south- central US. Guidance has come into better agreement over the last 24 hours in regards to the track of the system. Given a negative EPO, PNA, and NAO, the pattern is more inducive of a inside tracking system (northeastward along the Appalachians) which is now being modeled by all guidance members. The question now becomes the timing of the system which will help determine p-types. As of now, precip onset looks to occur Monday morning and continue into the evening/overnight hours.

Overall, guidance has been trending downward in terms of snow accumulations and continues to trend more towards a wintry mix type of event, especially at onset until a more southerly flow at the surface scours out any cold air trapped in the BL. With a good amount of uncertainty still remaining, it appears that (at this time) areas best suited for any winter weather will be along the Mason Dixon Line and into western Maryland and the eastern Panhandle of WV.

Tuesday appears to be more of a transition day, as showers are likely to continue throughout much of the day; albeit the bulk of the precip will have ended. Canadian high pressure returns for Wednesday, resulting in dry conditions. Another low pressure system may impact the region Thursday into Friday. However, the trend is for the system to remain more towards our south. However, confidence this far out remains low and will have to continue to monitor forecast trends over the next several days. General temperature trend in the long term period looks to remain slightly below normal for this time of year.

AVIATION /19Z FRIDAY THROUGH WEDNESDAY/.

Blustery conditions Sat with NW winds gusting up to 30 knots, diminishing Sunday. Increasing clouds Sun night with any precip likely to hold off until after 12Z Monday.

CIG/VSBY restrictions are likely, especially by Monday afternoon as low pressure spreads northward across the terminals. Restrictions are likely to continue through Tuesday as the low slowly exits the region. However there's a good chance that conditions improve late Tuesday into Wednesday.

MARINE.

Strong SCA conditions Saturday with winds diminishing Sun afternoon. Gale conditions Saturday do not appear likely anymore.

SCA will be possible Monday and Tuesday as low pressure spreads eastward across the waters. SubSCA conditions possible on Wednesday.

LWX WATCHES/WARNINGS/ADVISORIES. DC . None. MD . None. VA . None. WV . None. MARINE . Small Craft Advisory until 6 PM EST Saturday for ANZ530>543.

SYNOPSIS . LFR NEAR TERM . LFR SHORT TERM . LFR LONG TERM . MSS AVIATION . MSS/LFR MARINE . MSS/LFR


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 43 mi54 min NW 6 G 15 41°F 40°F1015.1 hPa (+2.7)
BSLM2 - Chesapeake Bay, MD 61 mi84 min WNW 2.9 40°F 1013 hPa20°F
BLTM2 - 8574680 - Baltimore, MD 64 mi54 min NW 5.1 G 8 41°F 42°F1013.6 hPa (+1.9)

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Leesburg / Godfrey, VA11 mi59 minWNW 610.00 miOvercast37°F21°F52%1015.2 hPa
Winchester Regional, VA20 mi59 minW 11 G 1810.00 miOvercast36°F19°F52%1013.9 hPa
Washington/Dulles International Airport, DC, VA20 mi62 minNW 810.00 miA Few Clouds37°F18°F46%1014.9 hPa
Eastern WV Regional Airport/Shepherd Field, WV23 mi61 minW 17 G 2710.00 miA Few Clouds37°F15°F41%1014.3 hPa

Link to 5 minute data for KJYO

Wind History from JYO (wind in knots)
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Last 24hrW6SW4SW3CalmW8NW7NW9NW9W14
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1 day agoCalmCalmE4CalmSW4CalmSW4CalmW5SW3S4S4SW4S3S4CalmW6W8W10
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2 days agoNW5SW4W4SW4CalmSW4NW4W3W9
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Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Fri -- 01:53 AM EST     Moonset
Fri -- 03:30 AM EST     2.27 feet High Tide
Fri -- 07:22 AM EST     Sunrise
Fri -- 09:22 AM EST     0.01 feet Low Tide
Fri -- 12:29 PM EST     Moonrise
Fri -- 03:47 PM EST     2.57 feet High Tide
Fri -- 05:18 PM EST     Sunset
Fri -- 10:32 PM EST     0.15 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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11.622.22.21.91.30.70.200.10.411.72.22.52.62.31.81.30.80.40.20.2

Tide / Current Tables for Chain Bridge, one mile below, D.C.
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Chain Bridge
Click for Map
Fri -- 01:52 AM EST     Moonset
Fri -- 03:25 AM EST     2.27 feet High Tide
Fri -- 07:21 AM EST     Sunrise
Fri -- 09:17 AM EST     0.01 feet Low Tide
Fri -- 12:29 PM EST     Moonrise
Fri -- 03:42 PM EST     2.57 feet High Tide
Fri -- 05:18 PM EST     Sunset
Fri -- 10:27 PM EST     0.15 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.11.622.22.21.81.20.60.200.10.411.72.22.52.62.31.81.20.70.40.20.2

Weather Map
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wmap_A
GEOS Local Image of    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East
Ground Weather Radar Station




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The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerous of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.