Monday, December11, 2017 L-36.com


Marine Weather and Tides
Alexandria, VA

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 7:15AMSunset 4:48PM Monday December 11, 2017 4:13 AM EST (09:13 UTC) Moonrise 12:45AMMoonset 1:20PM Illumination 46% Phase: Third Quarter Moon; Moon at 23 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- 331 Am Est Mon Dec 11 2017
.small craft advisory in effect from Tuesday morning through Tuesday afternoon...
Rest of the overnight..SW winds 5 kt. Waves less than 1 ft. Scattered flurries.
Today..S winds around 5 kt. Waves 1 ft.
Tonight..S winds 5 kt. Waves less than 1 ft.
Tue..W winds 10 to 15 kt. Gusts up to 25 kt. Waves 1 ft.
Tue night..NW winds 10 to 15 kt with gusts to 25 kt. Waves 1 ft.
Wed..W winds 10 to 15 kt with gusts to 25 kt. Waves 1 ft.
Wed night..W winds 5 to 10 kt. Waves 1 ft.
Thu..NW winds around 5 kt. Waves 1 ft.
Fri..W winds around 5 kt. Waves 1 ft. A chance of rain or snow through the day.
ANZ500 331 Am Est Mon Dec 11 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure will over the waters today and then offshore tonight. An arctic cold front will pass through late Tuesday and high pressure will return for Wednesday. Weak low pressure will pass through the waters Thursday and another weak low will pass by to the east Friday. A gale warning may be needed for portions of the waters Tuesday night and Wednesday. A small craft advisory may be needed for portions of the waters Wednesday night and Thursday.

7 Day Forecast for Marine Location Near Alexandria, VA
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location: 38.83, -77.04     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 110843
afdlwx
area forecast discussion
national weather service baltimore md washington dc
343 am est Mon dec 11 2017

Synopsis
Weak high pressure will slide offshore through tonight. An
arctic cold front will pass through the area Tuesday and weak
high pressure will build overhead Wednesday. Weak low pressure
will pass through Thursday and another one will pass by to the
east Friday. High pressure will return for Saturday.

Near term through today
Upper level shortwave is passing across the region early this
morning with some clouds and perhaps a few scattered flurries.

Behind it, we're seeing a shift to westerly winds and some terrain-
driven cumulus. A ridge of surface high pressure will build in
over the region by this afternoon, which will lead to dry
conditions and relatively light winds. Aside from the departing
clouds associated with the shortwave and the cumulus over the
terrain this morning, mostly sunny skies are expected through
the first half of the day, before high clouds increase during
the afternoon hours, out ahead of the next fast-approaching
shortwave trough.

Temperatures will nudge back up towards climatological normals,
with highs in the 40s.

Short term tonight through Wednesday night
A clipper low will dive through the great lakes region later
today, before tracking up the saint lawrence valley tonight
and Tuesday. Warm air advection will overspread the area
tonight, followed by a cold frontal passage from west to east
beginning along the allegheny front early Tuesday morning, and
pushing eastward towards the chesapeake bay by Tuesday
afternoon. A potent upper level shortwave trough will also move
eastward into the region by Tuesday afternoon.

While much of the forcing and therefore precipitation is
expected to remain north of the region tonight into early
Tuesday morning, a few areas of light precip are possible late
tonight and early Tuesday morning, mainly north towards the pa
border. With marginally cold temperature profiles, there is the
potential for some very light mixed precip, but coverage and
intensity will be limited. Precip chances then increase along
the allegheny front along and behind the cold front as northwest
flow begins. Lows tonight in the 30s.

On Tuesday, there may be a few light showers along and ahead of
the front, but as temperature profiles crash behind the front
and forcing increases as the strong upper level trough moves
towards the region, chances for convective snow (and possibly
rain to start) showers increase. Along and near the allegheny
front, with strong northwest flow and favorable froude numbers
and moisture profiles, upslope snow showers and squalls are
expected. Some of these may spill east of the allegheny front
with the deep mixing, strong northwesterly flow, and strength of
the trough. Highs Tuesday will be met prior to frontal passage,
generally in the 30s 40s, but near 50f across parts of central
va and southern md.

Upslope snow showers will continue into Tuesday night with
continued northwest flow. Will currently show total snowfall
accumulations in the 3-7" range along the allegheny front, and
winter weather advisories will likely be needed. In addition, a
very cold air mass is expected to move overhead, with 850mb
temps from -15c to -18c by Wednesday morning. This will allow
for lows to bottom out in the teens to around 20f. That coupled
with a strong wind field will likely lead to wind chills in the
single digits for most locations and near -10f for the higher
elevations.

A brief window of calm weather will move overhead by Wednesday
afternoon, but this will be short-lived, as another weak clipper
system will approach the region Wednesday night, with additional
chances for some light snow by Thursday morning. Highs Wednesday
may not break freezing area-wide, with lows Wednesday night
15-25f.

Long term Thursday through Sunday
A weak clipper low will pass through the area Thursday. Guidance
has diverged on the track with solutions ranging from this
system tracking well to our north vs. To our south. The ecmwf
has been consistent on keeping the low farther south with other
guidance having it pass farther to the north. However... The 00z
gfs has trended a bit farther south with the track of the low.

Should the low track to the north... Dry conditions would most
likely occur but should the low track to our south... Then a
period of light snow could affect the morning rush Thursday.

Temperatures would be cold enough for light snow to stick as
well. This will have to be closely monitored over the next
couple days. Will carry a chance for snow during this time.

High pressure will briefly build into the area late Thursday
into Thursday night... But another northern stream system will
dig through the great lakes Thursday night and then through our
area Friday. A southern stream system will also pass through the
southeastern CONUS and then offshore during this time. It is
unlikely that these systems will phase in time for strong
coastal low pressure to develop... But some of the southern
stream moisture could get drawn into our area bringing the
chance for rain or snow.

High pressure will briefly build into the area for
Saturday... Bringing dry and seasonably chilly conditions. The
high will move offshore Saturday night and cold front will
approach Sunday. A southwest flow in between these systems will
allow for milder conditions Sunday... But showers cannot be ruled
out ahead of the cold front.

Aviation 07z Monday through Friday
Vfr is expected area-wide today and tonight with some high
clouds and relatively light winds. A patchy area of light
precipitation is possible towards Tuesday morning, but
coverage impact low. A cold front will then cross the region on
Tuesday, which will lead to an increase in winds by Tuesday
afternoon. Winds may gust near 30 knots out of the northwest by
Tuesday afternoon. A few rain snow showers are also possible,
especially at mrb. Gusty northwest winds will continue Tuesday
night into Wednesday morning, but conditions expected to beVFR.

The next chance of sub-vfr conditions will then come late
Wednesday night into Thursday morning with potential for light
snow.

A clipper low will pass through the area Thursday. A period of
light snow is possible Thursday morning and light accumulations
are possible. Confidence in this occurring is low at this time.

Subvfr conditions are expected in any snow that does develop.

Another area of low pressure will pass by to the southeast
Friday. There may be enough moisture for a period of rain or
snow.

Marine
Sca in effect until 7 am this morning, with winds diminishing
for the rest of the morning and afternoon. Tonight, winds will
increase out of the south ahead of an approaching frontal
system, and SCA is in effect for portions of the waters. Sca
then GOES into effect for all waters on Tuesday for southerly
winds ahead of a cold front Tuesday morning, as well as
northwest winds behind the front. Gale conditions are then
possible late Tuesday through Wednesday morning. SCA conditions
may continue into Wednesday night.

A clipper low will pass through the area Thursday and another
low will pass by to our southeast Friday. Winds may approach sca
levels during this time.

Tides coastal flooding
Elevated water levels are occurring this morning due to a
southwest flow. Anomalies should drop some today as the flow
goes west to northwest... But anomalies will likely increase as a
southerly flow picks up for tonight into Tuesday. At this
time... It does not appear that there will be minor flooding but
it will have to be monitored closely for sensitive areas.

Strong northwest winds are expected later Tuesday and Tuesday
night. Tidal blowout conditions are possible Tuesday night into
Wednesday.

Lwx watches warnings advisories
Dc... None.

Md... None.

Va... None.

Wv... None.

Marine... Small craft advisory from midnight tonight to 6 pm est Tuesday
for anz531-532-538>543.

Small craft advisory until 7 am est this morning for
anz531>534-536-537-540-541-543.

Small craft advisory from 7 am to 6 pm est Tuesday for anz530-
535-536.

Small craft advisory from 9 pm this evening to 6 pm est
Tuesday for anz533-534-537.

Synopsis... Bjl
near term... Mm
short term... Mm
long term... Bjl
aviation... Bjl mm
marine... Bjl mm
tides coastal flooding... Bjl


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 3 mi56 min SSW 2.9 G 2.9 38°F 45°F1017.4 hPa
BSLM2 - Chesapeake Bay, MD 18 mi44 min S 1.9 35°F 1017 hPa29°F
APAM2 - 8575512 - Annapolis, MD 32 mi44 min 38°F 1016.3 hPa
TPLM2 - Thomas Point, MD 32 mi74 min S 6 G 8 39°F 47°F
NCDV2 35 mi44 min NW 1 G 2.9 35°F 45°F1016.7 hPa
CPVM2 36 mi44 min 40°F 26°F
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 38 mi44 min WSW 5.1 G 6 38°F 1016.9 hPa
44062 - Gooses Reef, MD 38 mi34 min W 3.9 G 5.8 38°F 1017.7 hPa
FSNM2 38 mi44 min WSW 5.1 G 7 38°F 1016.3 hPa
BLTM2 - 8574680 - Baltimore, MD 39 mi44 min NW 1.9 G 5.1 37°F 51°F1016.6 hPa
COVM2 - 8577018 - Cove Point LNG Pier, MD 46 mi44 min WNW 7 G 9.9 37°F 1018 hPa
SLIM2 - 8577330 - Solomons Island, MD 47 mi44 min WNW 5.1 G 7 38°F 48°F1017.2 hPa

Wind History for Washington, DC
(wind in knots)    EDIT      (on/off)   Help
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Washington/Reagan National Airport, DC, VA2 mi22 minSSW 410.00 miMostly Cloudy36°F28°F73%1017.2 hPa
Camp Springs / Andrews Air Force Base, MD9 mi18 minN 010.00 miOvercast34°F26°F72%1017.5 hPa
Fort Belvoir, VA10 mi18 minN 010.00 miMostly Cloudy34°F27°F76%1017.6 hPa
College Park Airport, MD12 mi28 minN 010.00 miPartly Cloudy34°F25°F72%1016.9 hPa
Fort Meade / Tipton, MD23 mi29 minN 010.00 miMostly Cloudy32°F28°F87%1017.9 hPa
Washington/Dulles International Airport, DC, VA24 mi22 minN 010.00 miOvercast31°F27°F85%1017.1 hPa
Gaithersburg - Montgomery County Airport, MD24 mi18 minN 010.00 miOvercast33°F24°F70%1019.8 hPa

Wind History from DCA (wind in knots)
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Last 24hrSW5SW5S66S7S6SW7W5W8W8
G16
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1 day agoCalmCalmN6NW8N7NE9NE12NE8N9N10N10NW5NW8NW9NW73W6W6SW7SW6SW5S4S5SW4
2 days agoN7N7N8N4N5NE3NE4N3E3CalmCalmCalmS3S8S6S6S4S4SW4SW5S7SW5SW3Calm

Tide / Current Tables for Bellevue, Potomac River, Washington, D.C.
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Bellevue
Click for Map
Mon -- 12:45 AM EST     Moonrise
Mon -- 02:24 AM EST     2.73 feet High Tide
Mon -- 07:16 AM EST     Sunrise
Mon -- 09:08 AM EST     -0.24 feet Low Tide
Mon -- 01:20 PM EST     Moonset
Mon -- 02:59 PM EST     2.76 feet High Tide
Mon -- 04:46 PM EST     Sunset
Mon -- 09:40 PM EST     -0.15 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.92.42.72.72.31.71.10.50.1-0.2-00.61.42.12.62.82.52.11.50.90.4-0-0.10.3

Tide / Current Tables for Benning Bridge, D.C.
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Benning Bridge
Click for Map
Mon -- 12:45 AM EST     Moonrise
Mon -- 02:35 AM EST     2.85 feet High Tide
Mon -- 07:16 AM EST     Sunrise
Mon -- 09:20 AM EST     -0.22 feet Low Tide
Mon -- 01:19 PM EST     Moonset
Mon -- 03:10 PM EST     2.87 feet High Tide
Mon -- 04:45 PM EST     Sunset
Mon -- 09:51 PM EST     -0.13 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.82.42.82.82.51.91.20.60.2-0.2-0.10.51.42.12.62.92.72.21.610.50.1-0.10.2

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 (4,6,7,8)
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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.