Friday, August14, 2020
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Marine Weather and Tides
National Harbor, MD

Version 3.4
NOTICE
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 6:20AMSunset 8:05PM Friday August 14, 2020 12:36 PM EDT (16:36 UTC) Moonrise 12:37AMMoonset 3:48PM Illumination 18% Phase: Waning Crescent; Moon at 25 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- 1037 Am Edt Fri Aug 14 2020
Rest of today..NE winds 5 to 10 kt. Waves 1 ft. Scattered showers late this morning, then showers likely with scattered tstms this afternoon.
Tonight..NE winds 5 kt. Waves less than 1 ft. Showers likely with scattered tstms.
Sat..NE winds 5 kt. Waves less than 1 ft. Scattered showers.
Sat night..E winds 5 to 10 kt. Waves 1 ft. Showers likely.
Sun..NE winds 5 to 10 kt. Waves 1 ft. Showers.
Sun night..N winds 5 kt. Waves less than 1 ft. Scattered showers.
Mon..NW winds around 5 kt. Waves 1 ft.
Tue..SW winds around 5 kt. Waves 1 ft or less. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 1037 Am Edt Fri Aug 14 2020
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A stationary front will remain near the mid atlantic through Saturday before gradually moving to the south late in the weekend. A cold front will approach early next week. A small craft advisory may be needed for portions of the waters Saturday through Saturday night and again Sunday night through Monday morning.


7 Day Forecast for Marine Location Near National Harbor, MD
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location: 38.8, -77.03     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 141408 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1008 AM EDT Fri Aug 14 2020

SYNOPSIS. A surface front will meander over the region through the weekend, bringing showers and thunderstorms each day. Low pressure will develop on this front and move across the region Saturday night into Sunday. High pressure will then briefly return early next week before an unsettled pattern likely returns by the middle of the week.

NEAR TERM /THROUGH TONIGHT/. Clouds are hanging tough as expected with onshore flow, but there are some signs of at least a few breaks. For the rest of today, a frontal boundary to our north will drop south through the area today. Meanwhile, a slow moving upper low will be approaching from the west. This will lead to more showers and storms today, especially into the afternoon hours. Hi-res guidance doesn't paint an ominous picture today, with QPF amounts much lighter than in previous days on the 00z HREF. Additionally, any showers/storms should be relatively progressive (as we are seeing this morning). Of course, given the antecedent conditions across a majority of the area, will have to watch for any heavier elements that may try to train along the front itself. However, with the front actually moving today, think this will be harder to do.

A brief lull in activity is possible overnight tonight for much of the area, though do expect lingering showers overnight in central VA and eastern WV. Overnight lows into the upper 60s/low 70s (upper 50s to low 60s in the higher elevations).

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/. On Saturday, the slow-moving upper trough over the Ohio Valley will finally swing through the region. Additionally, at the surface, the aforementioned frontal boundary will remain over central VA. Meanwhile, a surface low will develop east of the upper trough and latch onto this front. This will result in low pressure moving just to the south of the region later Saturday into early Sunday. The track may move right over some of our southern zones. Onshore flow associated with this system could lead to locally enhanced rainfall along the ridges and in the Potomac Highlands. Guidance then takes the low across southern MD into the Delmarva overnight, while also gradually strengthening it. Rainfall amounts could also be locally be enhanced from central Virginia to southern Maryland, where they'll stand the best chance of destabilizing and developing some convective elements. With the continued clouds and storms, highs will continue to be in the 80s. Lows will be in the 60s to 70s.

All this being said, looking at a potential for flooding Saturday/Saturday night. Current forecast shows 2-3 inches of rain with this system across central VA and into southern MD. Some locally higher amounts are likely with convective elements and upslope flow. Given the recent heavy rains, it isn't going to take much to cause more flooding issues.

By Sunday morning, the low should be pushing off to the east, taking the rain with it. Some guidance is a little slower however, so leaving some POPs in through the early afternoon. Though, do think there is a good shot we are dry by early afternoon. Sunday will be much cooler than normal, with highs in the mid to upper 70s (low 80s closer to the water). Just hope we can get the rain out of here early enough to enjoy it. Sunday night will be dry, with lows ranging from the mid 50s in the higher elevations to upper 60s in the typical normal areas along the waters.

LONG TERM /MONDAY THROUGH THURSDAY/. Troughiness will dominate the East Coast states the first half of next week keeping temps aob normal. There will be drying for the first part of the week as NW flow develops in the wake of low pressure organizing offshore. By the middle of the week, moisture begins to increase as sfc high moves offshore and srly flow develops. However, moisture supply is not expected to be anywhere close to the past few days, so the risk of excessive rainfall appears low at this time. Ridging tries to build along the East Coast for the second half of next week likely limiting areal coverage of showers and t-storms.

AVIATION /15Z FRIDAY THROUGH TUESDAY/. Low clouds continue but are slowly lifting with a few breaks developing. Scattered showers are likely this afternoon, with a few thunderstorms possible mainly east of the Blue Ridge. Patchy fog is possible tonight (along with lower ceilings, which will probably offer a higher risk of restrictions).

More significant chance for rainfall will move into the region Saturday afternoon and continue through early Sunday, as low pressure tracks along a stationary front to our south. Locally heavy rain is possible with this system, and potentially some embedded thunderstorms (primarily towards KCHO). VSBY/CIG restrictions likely during this time.

Conditions begin to clear later in the day on Sunday, as low pressure pushes off to the east, with high pressure building in behind it and VFR conditions returning.

No sig wx expected the first half of next week.

MARINE. Generally sub-SCA conditions expected on the waters through Saturday, though a few NE wind gusts to around 20 knots are possible this morning (SCA until 1pm for the Chesapeake Bay between North Beach MD and Smith Point VA where it's most persistent). Main concern each day will be thunderstorms, primarily during the afternoon hours, though some may develop during the mornings. Gusty winds and even a few waterspouts will be possible with stronger storms.

Onshore flow is expected to persist Sunday, and may be near Small Craft Advisory (SCA) levels.

SCA conditions possible Monday morning. Otherwise, winds should diminish through time next week.

TIDES/COASTAL FLOODING. Minor coastal flooding is possible late Sat night and Sun as onshore flow strengthens as low pressure passes to the south. Near moderate coastal flooding can't be ruled out, especially near Straits Point and Annapolis MD.

LWX WATCHES/WARNINGS/ADVISORIES. DC . None. MD . None. VA . None. WV . None. MARINE . Small Craft Advisory until 1 PM EDT this afternoon for ANZ533- 534.

SYNOPSIS . CJL NEAR TERM . DHOF/CJL SHORT TERM . CJL/KJP LONG TERM . LFR AVIATION . LFR/DHOF/CJL MARINE . LFR/DHOF/CJL TIDES/COASTAL FLOODING . LFR/DHOF


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BSLM2 - Chesapeake Bay, MD 17 mi126 min NNE 4.1 1015 hPa
TPLM2 - Thomas Point, MD 32 mi36 min NNW 13 G 15 79°F 83°F1015.7 hPa (-0.4)74°F
44062 - Gooses Reef, MD 37 mi36 min 80°F 83°F1 ft

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Washington/Reagan National Airport, DC, VA4 mi44 minNNE 710.00 miMostly Cloudy82°F72°F72%1015.4 hPa
Camp Springs / Andrews Air Force Base, MD9 mi1.7 hrsN 1110.00 miPartly Cloudy79°F72°F81%1016 hPa
Fort Belvoir, VA9 mi1.7 hrsN 010.00 miPartly Cloudy82°F72°F75%1015.8 hPa
College Park Airport, MD14 mi61 minNE 610.00 miMostly Cloudy79°F68°F71%1015.6 hPa
Fort Meade / Tipton, MD24 mi61 minN 010.00 miMostly Cloudy81°F71°F74%1016.6 hPa

Link to 5 minute data for KDCA

Wind History from DCA (wind in knots)
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Last 24hrN5E5NE5NE8E7E8E8E7E8NE8NE7NE7NE7NE8NE8NE10
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1 day agoCalmS6S5S6SE9S4NE13N7CalmE3E6NE5NE4NE5NE6E4NE4E4NE5N4NE8E7E4N5
2 days agoS8S10S10S10S10S8S11S6S6S7S6S5S7S7S4S5W6W10
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Tide / Current Tables for Alexandria, Virginia
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Alexandria
Click for Map
Fri -- 01:37 AM EDT     Moonrise
Fri -- 04:38 AM EDT     3.06 feet High Tide
Fri -- 06:21 AM EDT     Sunrise
Fri -- 11:40 AM EDT     0.65 feet Low Tide
Fri -- 04:47 PM EDT     Moonset
Fri -- 05:27 PM EDT     2.62 feet High Tide
Fri -- 08:03 PM EDT     Sunset
Fri -- 11:12 PM EDT     0.56 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.91.52.22.8332.82.31.81.30.90.70.70.91.522.42.62.62.21.71.10.70.6

Tide / Current Tables for Fort Washington, Maryland
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Fort Washington
Click for Map
Fri -- 01:37 AM EDT     Moonrise
Fri -- 04:23 AM EDT     2.69 feet High Tide
Fri -- 06:21 AM EDT     Sunrise
Fri -- 11:25 AM EDT     0.57 feet Low Tide
Fri -- 04:47 PM EDT     Moonset
Fri -- 05:12 PM EDT     2.30 feet High Tide
Fri -- 08:03 PM EDT     Sunset
Fri -- 10:57 PM EDT     0.49 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.91.52.12.52.72.62.41.91.510.80.60.60.91.41.92.22.32.21.91.40.90.60.5

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.
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Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Baltimore, MD/Washington (12,3,4,5)
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Ground Weather Radar Station Sterling, VA
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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.