Sunday, September24, 2017 L-36.com


Marine Weather and Tides
Washington, DC

Version 3.4
What's New / NOTES
6/25/2017 - NOAA is having a major issue that impact the 7 day forecast load times. Many users are reporting problems. The issue has been reported.
5/23/2017 - Worked with NOAA again to speed up the 7 day forecast load times. Thanks to them for being responsive.
5/19/2016 - There were issues with the 3 day airport observation history. I switched to another data source. Let me know if you see any issues with the data feeds.

Sunrise 6:57AMSunset 7:02PM Sunday September 24, 2017 8:25 AM EDT (12:25 UTC) Moonrise 10:09AMMoonset 8:53PM Illumination 15% Phase: Waxing Crescent; Moon at 4 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- 732 Am Edt Sun Sep 24 2017
Today..NE winds 5 kt. Waves less than 1 ft.
Tonight..N winds around 5 kt. Waves 1 ft.
Mon..E winds around 5 kt. Waves 1 ft. Patchy fog. Vsby 1 to 3 nm.
Mon night..NE winds 5 to 10 kt. Waves 1 ft.
Tue..NE winds 5 kt. Waves less than 1 ft.
Tue night..NE winds 5 kt. Waves less than 1 ft.
Wed..NE winds 5 kt. Waves less than 1 ft. A chance of showers.
Thu..N winds 5 to 10 kt. Waves 1 ft.
ANZ500 732 Am Edt Sun Sep 24 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A ridge of high pressure will remain over the eastern united states through the first part of the week. Small craft advisories may be needed Tuesday through Thursday as hurricane maria approaches north carolina. Refer to the latest statements from the national hurricane center for up-to-date information on hurricane maria.

7 Day Forecast for Marine Location Near Washington, DC
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location: 38.89, -77.03     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 240757
afdlwx
area forecast discussion
national weather service baltimore md washington dc
357 am edt Sun sep 24 2017

Synopsis
High pressure will remain in place through the first part of
the week, then slowly weaken its grip over the area by the
midweek as hurricane maria moves northward through the western
atlantic. A cold front will move through late in the week,
bringing more seasonable temperatures.

Near term through tonight
The final glimpse of summer continues, as high pressure remains
anchored across the eastern great lakes region. Guidance picked
up on fog being less prevalent than yesterday morning, and in
fact that has been the case. Once the fog burns off, it will be
another toasty day. 925 mb temps and low-level thickness values
are both forecast to be higher than yesterday, so I anticipate
it to be just a touch warmer.

Tonight, low-level moisture will start to creep up as winds turn
from northerly to northeast easterly. This should keep lows in
the 60s in most areas, with the urban areas staying above 70.

Short term Monday through Tuesday night
High pressure remains in control Monday, but weakens slightly,
along with a continued increase in low-level moisture. This
should hold high temps down a degree or two lower than today.

Still remaining dry.

By Monday night, hurricane maria will be somewhere southeast of
the north carolina outer banks. Right now it appears the storm
will be well southeast of us, with little if any impacts. But
it's still a few days away, so consult the latest advisories
from the national hurricane center regarding maria's expected
track. Depending on the storm's proximity to us, and ability to
generate a large rain shield, a stray shower or thunderstorm is
possible east of the blue ridge late Monday night through
Tuesday or Tuesday night. Otherwise, it remains unseasonably
warm and humid.

Long term Wednesday through Saturday
The start of the long term period will continue to be dominated
by attention to hurricane maria. At the start of the period,
many models plot the hurricane as hovering just off the outer
banks of north carolina. This would likely bring some increased
(but not particularly strong) winds to our southernmost zones,
perhaps some gusts in the 30 mph range in southern md and along
the bay shore, along with a few showers. Impacts further north
and west would likely be less. As we will remain in a warm air
mass, temperatures will remain above normal, with 80s appearing
likely, unless there is more cloud cover and precip that
currently anticipated.

Maria appears to stall due to the erosion of the ridge to its
north, which would allow westerlies in association with an
approaching shortwave to influence the storm. The timing of this
will be critical, as a late arrival could allow the storm to
continue northwestward. While most guidance does not support
this occurring, everyone should continue to monitor the progress
of the storm over the next few days. Refer to the latest
statements from the national hurricane center for up-to-date
information and forecasts on maria.

By Thursday, the approaching shortwave and attendant surface
cold front should turn the hurricane eastward and it should
begin to increase speed away from the coast. This same system
will put an end to our late september warm spell, with a much
more seasonable air mass arriving behind it for Friday. While
the front will bring a fairly noticeable air mass change,
limited dynamics and moisture mean that any rain with this
system will likely be spotty and light.

By Saturday, uncertainty increases. While some models show high
pressure overhead, the ec has continued to bring a sharp
shortwave southeast from canada, which then tries to induce
cyclogenesis in our vicinity. Each subsequent run has had
varying locations and strengths with this, so confidence on it
occurring is low and confidence on it affecting our weather
significantly is lower.

Aviation 06z Sunday through Thursday
Vfr with light winds expected through the valid TAF period. Only
potential exception would be MVFR vsby due to fog primarily at
cho (perhaps at mrb also?) this morning. Repeat performance
tonight.

Clouds increase Monday night and Tuesday out ahead of hurricane
maria, with a potential isolated shower or thunderstorm at
bwi iad dca, but exact details and extent are track-dependent
and will become clearer in the days ahead.

Attention will be on hurricane maria Wednesday into Thursday.

While subVFR conditions are not likely, a gusty northwest
breeze of 20-25 knots is possible, as are a few showers. A
further deviation northwest in the track of maria, though not
likely, could bring worse conditions. Refer to latest nhc
statements for up-to-date information on maria.

Marine
Light winds continue over the waters through Monday night.

Perhaps a stray shower or thunderstorm on Tuesday as winds begin
to increase due to enhanced gradient between high pressure and
hurricane maria. How strong those wind gusts get depends on the
ultimate track of the storm, but the most likely outcome yields
small craft advisory level gusts starting Tuesday afternoon.

Sca winds looking likely across the waters on Wednesday and
Thursday as hurricane maria approaches and we get enveloped by
its expanding wind field. A few showers will also be possible.

If the storm's track deviates further northwest, more
significant impacts are possible (though not likely). Refer to
latest NHC statements for up-to-date information on maria.

Tides coastal flooding
Tidal anomalies have been dropping since evening, and there's
actually a bit of negative surge pushing water levels below the
long-term average for the first time in a while. The current
tide cycle is the lower of the two diurnal tides. With
virtually no surge on the waters and the anomaly at the mouth of
the bay also close to that long-term average... We might avoid
reaching minor flood everywhere except on the lower tidal
potomac where higher water remains trapped, without the benefit
of the bay current. Will have to watch annapolis and dc though
for possibly approaching the threshold this morning.

The afternoon evening cycle is the higher of the two, and minor
flooding looks likely again in st. Mary's, annapolis, dc, and
perhaps calvert. I already extended st. Mary's through that tide
cycle. Confidence is lower in the rest, but only 0.8 foot
anomaly is necessary to reach minor at annapolis, and less than
a foot also at dc. It will be close.

Given light winds, things should remain status quo through
Monday. As hurricane maria moves northward in the atlantic, the
increasing winds should start piling water up in the lower bay,
which will gradually seep northward, similar to what happened
when jose passed last week. Tidal anomalies could approach two
feet by midweek; ironically though, the astronomical tide
becomes less favorable, so it could be a net result of status
quo even then.

Lwx watches warnings advisories
Dc... Coastal flood advisory until 2 pm edt this afternoon for
dcz001.

Md... Coastal flood advisory until 10 pm edt this evening for
mdz017.

Va... None.

Wv... None.

Marine... None.

Synopsis... Je
near term... Je
short term... Je
long term... Rcm
aviation... Je rcm
marine... Je rcm
tides coastal flooding... Je


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 1 mi37 min WNW 2.9 G 4.1 68°F 76°F1019.4 hPa
BSLM2 - Chesapeake Bay, MD 19 mi115 min NNW 1 53°F 1018 hPa
APAM2 - 8575512 - Annapolis, MD 30 mi37 min 75°F 1018.3 hPa
44063 - Annapolis 31 mi25 min NNW 5.8 G 5.8 73°F 76°F1018.6 hPa (+1.1)
TPLM2 - Thomas Point, MD 31 mi25 min N 8 G 8.9 73°F 76°F
CPVM2 35 mi37 min 76°F 69°F
BLTM2 - 8574680 - Baltimore, MD 35 mi37 min N 2.9 G 5.1 74°F 78°F1018.5 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 35 mi37 min NNW 4.1 G 5.1 74°F 1018.8 hPa
44043 - Patapsco, MD 38 mi25 min NNE 7.8 G 9.7 74°F 76°F1019.4 hPa (+1.5)
NCDV2 39 mi37 min NW 2.9 G 4.1 68°F 76°F1018 hPa
44062 - Gooses Reef, MD 40 mi25 min N 7.8 G 9.7 75°F 75°F1019.1 hPa (+1.1)
TCBM2 - 8573364 - Tolchester Beach, MD 47 mi37 min NE 1.9 G 5.1 72°F 76°F1019 hPa
COVM2 - 8577018 - Cove Point LNG Pier, MD 48 mi37 min N 8.9 G 11 74°F 1019.1 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Washington/Reagan National Airport, DC, VA2 mi33 minNNW 410.00 miPartly Cloudy70°F62°F76%1019.5 hPa
College Park Airport, MD9 mi40 minN 010.00 miFair61°F59°F95%1019.3 hPa
Camp Springs / Andrews Air Force Base, MD9 mi27 minNW 410.00 miFair69°F59°F72%1019.5 hPa
Fort Belvoir, VA14 mi29 minN 010.00 miFair61°F60°F97%1019.6 hPa
Fort Meade / Tipton, MD20 mi40 minN 010.00 miFair59°F57°F94%1020 hPa
Gaithersburg - Montgomery County Airport, MD21 mi29 minWNW 38.00 miFair63°F59°F87%1022.8 hPa
Washington/Dulles International Airport, DC, VA23 mi33 minNW 510.00 miA Few Clouds64°F60°F87%1019.9 hPa

Wind History from DCA (wind in knots)
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Last 24hrN6N4N6NE6N9N11
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1 day agoN5N43E4CalmNW9NW9N9W9NW9N5N3CalmCalmCalmCalmN6N6N6N6N6N6N4N6
2 days agoN6N4N4CalmN7N9N6NW7N4NW7N6N7N6N5CalmCalmCalmCalmN6N7NW6N6N6N6

Tide / Current Tables for Washington, Potomac River, D.C.
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Washington
Click for Map
Sun -- 06:28 AM EDT     0.35 feet Low Tide
Sun -- 06:57 AM EDT     Sunrise
Sun -- 11:08 AM EDT     Moonrise
Sun -- 11:41 AM EDT     3.03 feet High Tide
Sun -- 06:21 PM EDT     0.35 feet Low Tide
Sun -- 07:01 PM EDT     Sunset
Sun -- 09:53 PM EDT     Moonset
Sun -- 11:54 PM EDT     3.25 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
3.22.82.11.510.70.40.411.82.52.932.72.11.50.90.50.40.40.91.82.63.1

Tide / Current Tables for Bladensburg, Anacostia River, Maryland
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Bladensburg
Click for Map
Sun -- 06:53 AM EDT     0.40 feet Low Tide
Sun -- 06:57 AM EDT     Sunrise
Sun -- 11:08 AM EDT     Moonrise
Sun -- 12:12 PM EDT     3.21 feet High Tide
Sun -- 06:46 PM EDT     0.40 feet Low Tide
Sun -- 07:01 PM EDT     Sunset
Sun -- 09:52 PM EDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
3.53.22.61.91.30.90.50.40.71.52.42.93.23.12.61.91.20.80.50.40.71.52.43.1

Weather Map and Satellite Images
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Weather Map
wmap_A
IR Satellite Image from GEOS
east_satellite

GOES Local Image of Mid-Atlantic    EDIT
Geos

Wind Forecast for Baltimore, MD/Washington (8,2,3,4)
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Ground Weather Radar Station Sterling, VA
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weather_mapweather_map weather_map

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Disclaimer:
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 numerious 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.