Sunday, December10, 2017 L-36.com


Marine Weather and Tides
Ashburn, 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 7:17AMSunset 4:49PM Sunday December 10, 2017 7:17 PM EST (00:17 UTC) Moonrise 12:00AMMoonset 12:50PM Illumination 50% Phase: Third Quarter Moon; Moon at 22 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- 631 Pm Est Sun Dec 10 2017
Tonight..SW winds 5 kt. Waves less than 1 ft.
Mon..S winds around 5 kt. Waves 1 ft.
Mon night..S winds 5 kt. Waves less than 1 ft.
Tue..W winds 10 to 15 kt with gusts 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..SW winds around 5 kt. Waves 1 ft.
Fri..W winds around 5 kt. Waves 1 ft.
ANZ500 631 Pm Est Sun Dec 10 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure will build toward the waters through Monday. A frontal system will cross Monday night into Tuesday. Another low pressure system will move through the area Thursday. Small craft advisories may be required Monday night, and gale warnings are likely Tuesday into Wednesday.

7 Day Forecast for Marine Location Near Ashburn, VA
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location: 39.03, -77.47     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 102009
afdlwx
area forecast discussion
national weather service baltimore md washington dc
309 pm est Sun dec 10 2017

Synopsis
Weak high pressure will slide by south of the area through
Monday. A low pressure system will cross the lower great lakes
on Tuesday, bringing a cold front through the region. High
pressure will build overhead Wednesday with another low
pressure area approaching from the west on Thursday.

Near term through tonight
Clouds have been on the decrease this afternoon with sunshine
making an appearance this afternoon. As clouds eroded, winds
began to increase out of the west as expected, gusting 20 to 25
mph at times. Temperatures this afternoon are in the low to mid
30s in our western zones, upper 30s to near 40 degrees
elsewhere.

A weak shortwave will pass just to our north tonight bringing an
increase in clouds, but not much precipitation with it. Some
areas in the favored upslope locations could see snow showers
overnight, but only minor accumulations likely. Low temperatures
will be a bit tricky as how low they go will be dependent on
the amount of cloud cover and how quickly those clouds move out
by morning. Those locations with snow remaining on the ground,
and are able to clear, could see temperatures drop well in to
the 20s. All that being said, feel most everyone will dip in to
the mid to upper 20s, except near the city centers where
temperatures near the freezing mark are expected.

Short term Monday through Tuesday night
The shortwave will exit to our east Monday morning, with
clearing skies in its wake. Weak high pressure will move in from
the west, keeping winds light, and bringing mostly sunny skies.

This ridge will quickly move through our area, turning winds out
of the south by Monday afternoon. This will allow temperatures
to moderate a bit, topping out in the low to mid 40s. High
clouds will start to stream overhead during the afternoon hours
ahead of the next approaching shortwave over the lower great
lakes.

A stronger shortwave (compared to tonight) will near our area
late Monday night in to Tuesday morning. The associated surface
low pressure will pass to our north, dragging a cold front
through the area during the day on Tuesday. Dynamics appear
somewhat favorable with strong mid-level vorticity advection
and an upper jet nearby. Add to that low-level isentropic
upglide looks possible. Model guidance continues to keep the
bulk of the moisture north of the mason dixon line, with
upslope snow looking very likely Tuesday morning.

Temperature profiles hint at the possibility of light mixed
wintry precipitation along the northern portions of our cwa,
particularly near the md pa border. That being said, most of
the moisture and lift will remain to the north, so do not expect
much in the way of accumulation. The best chance for
accumulating snowfall will be along and west of the allegheny
front through early Tuesday afternoon, where advisory criteria
snow looks possible.

On the heels of this shortwave is another stronger mid-level
trough which will help push a cold front through the region,
bringing strong cold air advection in its wake and strong gusty
northwesterly winds. Wind direction will be favorable for
continued upslope snow and snow squall potential. Temperatures
at the surface and aloft do not seem too supportive of snow
squalls making much impact east of the mountains. The
combination of strong gusty winds and the cold air filtering in,
wind chills may drop below zero over the western ridges of
allegheny front. Tuesday night, temperatures will fall in to the
teens across our western zones, lower 20s elsewhere, and the middle
20s in the metro areas.

Long term Wednesday through Saturday
A highly amplified upper level flow pattern with east coast
troughing will result in a wintry pattern through Friday. Wednesday
will be blustery and cold, with strong winds possible as low
pressure pulls away from maine. High temperatures may fail to crack
the freezing mark across a large part of the area. With a slightly
faster exit to the upper trough, flurries are looking less likely on
Wednesday. Weak surface ridging will relax the winds by Wednesday
night, but lows will be in the teens and 20s.

There's some model spread in timing on the next clipper system which
will arrive sometime between late Wednesday night and Thursday
evening. While the best chance for snow will be along the upslope
areas, it's not out of the question some light snow could spread
east of the mountains as well, particularly near the pennsylvania
border. The next, sharper shortwave trough will arrive on Friday,
prolonging chances for upslope snow. Instability through the snow
growth zone could allow snow showers to move east of the mountains
as well, although surface temperatures will likely rise above
freezing at lower elevations.

The upper level pattern will break down to more progressive flow
next weekend. Surface high pressure will arrive on Saturday and
temperatures will rise closer to normal. There's still a large
amount of uncertainty regarding the next frontal system which may
arrive late in the weekend.

Aviation 19z Sunday through Friday
Vfr conditions are expected at all the terminals through Monday
as weak high pressure traverses the area. Gusty winds this
afternoon will subside by this evening, remaining light and
westerly through Monday. An clipper system will pass to the
north Monday night in to Tuesday, bringing the possibility of
brief flight restrictions along and to the north of mrb bwi mtn.

Behind a cold frontal passage on Tuesday, gusty northwesterly
winds will overtake the terminals in to Tuesday afternoon and
Tuesday night, gusting 25 to 30 knots.

OverallVFR conditions are expected Wednesday through
Friday. W NW winds could gust over 30 kt on Wednesday. There are
a couple disturbances which could bring snow showers Thursday
and Friday, but impacts are uncertain at this time.

Marine
Gusty winds over much of our waters today will subside this
evening, with the exception of the open waters to the south
where an SCA will remain in effect overnight. Weak high pressure
move through on Monday will bring light winds. Ahead of an
approaching cold front Monday night and Tuesday, winds may reach
sca level, with SCA likely behind the front Tuesday afternoon
and night with strong gusty northwesterly flow. Gale conditions
look possible behind the front, and through Tuesday night.

Strong winds will continue into Wednesday behind departing low
pressure. Small craft advisory conditions are likely, and gales are
possible early in the day. High pressure will bring lighter winds by
late Wednesday night. Low pressure will cross near the area on
Thursday, but winds may not increase appreciably at the surface
until a second disturbance moves through on Friday.

Lwx watches warnings advisories
Dc... None.

Md... None.

Va... None.

Wv... None.

Marine... Small craft advisory until 6 pm est this evening for
anz530>533-535-536-538>542.

Small craft advisory until 5 am est Monday for anz534-537-543.

Synopsis... Bkf
near term... Bkf
short term... Bkf dhof
long term... Ads
aviation... Ads bkf
marine... Ads bkf


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 26 mi48 min SSW 2.9 G 5.1 39°F 45°F1018.2 hPa
BSLM2 - Chesapeake Bay, MD 44 mi48 min SSE 1 33°F 1018 hPa28°F
BLTM2 - 8574680 - Baltimore, MD 50 mi48 min W 2.9 G 5.1 38°F 51°F1017.4 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/Dulles International Airport, DC, VA5 mi26 minSSE 410.00 miPartly Cloudy30°F25°F82%1017.7 hPa
Leesburg / Godfrey, VA6 mi43 minN 010.00 miPartly Cloudy34°F26°F75%1017.3 hPa
Gaithersburg - Montgomery County Airport, MD19 mi22 minS 310.00 miFair33°F21°F61%1020.3 hPa
Manassas, Manassas Regional Airport/Harry P. Davis Field, VA22 mi22 minS 310.00 miPartly Cloudy31°F27°F85%1019 hPa

Wind History from IAD (wind in knots)
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Last 24hrCalmCalmCalmS3S6S3S4SW4CalmW9SW3NW14W5W5W5W3W6W12
G17
W7W10SW4SW3S4SE4
1 day agoS3S3CalmS5S4S3SW3S3CalmCalmCalmCalmNW5NE7NE6NE8NE9N5N9N6N4CalmCalmW4
2 days agoCalmCalmCalmN5CalmNW5NW6NW5N5N4N7N5N5N5CalmCalmCalmCalmCalmCalmCalmCalmCalmCalm

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Sun -- 01:35 AM EST     2.86 feet High Tide
Sun -- 02:53 AM EST     Last Quarter
Sun -- 07:16 AM EST     Sunrise
Sun -- 08:32 AM EST     -0.24 feet Low Tide
Sun -- 12:48 PM EST     Moonset
Sun -- 02:13 PM EST     2.75 feet High Tide
Sun -- 04:46 PM EST     Sunset
Sun -- 08:56 PM EST     -0.14 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
2.42.82.82.51.91.30.70.2-0.2-0.20.31.222.52.72.62.21.610.50.1-0.10.10.9

Tide / Current Tables for Chain Bridge, Washington, D.C.
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Chain Bridge
Click for Map
Sun -- 01:39 AM EST     2.83 feet High Tide
Sun -- 02:53 AM EST     Last Quarter
Sun -- 07:16 AM EST     Sunrise
Sun -- 08:34 AM EST     -0.26 feet Low Tide
Sun -- 12:48 PM EST     Moonset
Sun -- 02:17 PM EST     2.73 feet High Tide
Sun -- 04:46 PM EST     Sunset
Sun -- 08:59 PM EST     -0.16 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
2.42.82.82.51.91.30.70.2-0.2-0.20.31.11.92.52.72.62.21.610.50.1-0.20.10.8

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 (19,4,5,8)
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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.