Tuesday, May23, 2017 L-36.com


Marine Weather and Tides
Ashburn, VA

Version 3.4
What's New / NOTES
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.
3/12/2015 - Added section for Gulf current for users in the GMZ marine zones.
This was requested by a user. If you have requests, please let me know.

Sunrise 5:48AMSunset 8:25PM Tuesday May 23, 2017 1:01 AM EDT (05:01 UTC) Moonrise 3:33AMMoonset 4:52PM Illumination 7% Phase: Waning Crescent; Moon at 27 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- 1032 Pm Edt Mon May 22 2017
Rest of tonight..N winds 5 kt. Waves less than 1 ft. A slight chance of showers late this evening. Patchy fog with vsby 1 to 3 nm.
Tue..NE winds 5 kt. Waves less than 1 ft. Showers likely. Patchy fog. Vsby 1 to 3 nm.
Tue night..N winds 5 kt. Waves less than 1 ft. A chance of showers.
Wed..E winds 5 to 10 kt. Waves 1 ft.
Wed night..SE winds 5 to 10 kt. Waves 1 ft. Showers.
Thu..S winds 5 kt. Waves less than 1 ft. Showers likely with a chance of tstms.
Thu night..W winds 5 kt. Waves less than 1 ft. A chance of showers.
Fri..W winds 5 to 10 kt. Waves 1 ft. A chance of showers in the morning.
Sat..SE winds around 5 kt. Waves 1 ft. A chance of showers through the night. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 1032 Pm Edt Mon May 22 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A cold front will cross the area this evening. High pressure will briefly build in tonight into early Tuesday before a low pressure system moves up near the delmarva coast Tuesday night. Another area of low pressure will move through the area Wednesday night. Small craft advisories may be needed for portions of the waters Wednesday night into Thursday.

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 230145
afdlwx
area forecast discussion
national weather service baltimore md/washington dc
945 pm edt Mon may 22 2017

Synopsis
A cold front is crossing the region this evening. High pressure
will briefly return overnight before low pressure develops over
eastern carolina Tuesday and moves northeast off the delmarva
Tuesday night. Upper-level low pressure will move toward the
area Wednesday through Friday.

Near term /through Tuesday/
Cold front is currently near the blue ridge but only slowly
moving eastward. Have slight chance pops til late evening for
anything the front initiates, but at this points odds favor
nothing more tonight.

If the front makes it through the area overnight, it won't be
by much, but drier air should eventually filter in. Before it
does so, some patchy fog may develop, mainly in southeastern
areas. Lows will be in the 50s to lower 60s.

Short term /Tuesday night through Wednesday night/
Tuesday's forecast remains very tricky due to a gap between the
synoptic and mesoscale models handling low pressure development
along the front to our southeast. Previous shift chatted with
wpc, and they think the gfs/ecmwf could be suffering from
feedback, and think the nam/wrfs simulations may prove more
accurate unless an unmodeled MCV pulls the surface low farther
north. With better precipitable water values to our southeast,
think heavy rain threat is limited, but areas from
charlottesville to st. Marys could have a period of moderate
rain. It is more uncertain how much rain falls in the metros.

The low will be progressive though, with any rain ending for
most areas Tuesday evening.

A closed upper low will be moving south into the mid-west Wednesday
while a sfc low and associated cold front moves eastward across the
ohio valley. A brief period of subsidence is expected across the mid-
atlantic Wednesday leading to mostly dry conditions for most of the
day. Weak instability and lift increase across the southwest by
late afternoon. If current trends hold, widespread rainfall will
occur Wednesday night as a boundary lifts northward into the
area. There may be some weak instability, resulting in a few
rumbles of thunder.

Have not strayed too far from model consensus for temperatures.

Diurnal ranges will be muted due to clouds and precipitation,
with lows in the 50s to lower 60s and highs in the upper 60s to
mid 70s.

Long term /Thursday through Monday/
A slow-moving low pressure system will allow for the chance for rain
showers and a few thunderstorms to linger across the region Thursday
into Thursday evening.

The chance for rain showers shift to the mason-dixon line and
adjacent areas Friday as the storm system finally departs northeast
into new england.

By Friday night and Saturday, weak high pressure will move into the
region. Dry conditions and a gusty breeze should ensue.

Rain showers develop in the region again for Sunday as the next
storm system pivots into the region. Temperatures will be warmer.

Aviation /02z Tuesday through Saturday/
Vfr to high MVFR currently, with lower clouds lingering in spots.

Some patchy fog may develop overnight, most likely affecting mtn
and bwi. No additional precip expected through early Tuesday.

Tuesday forecast remains uncertain with guidance spread in
position of low pressure and moderate rainfall. Continued to
hedge toward a more optimistic solution of MVFR for now except
at cho, but ifr isn't out of the question. A break in
precipitation is expected Tuesday night through most of
Wednesday, although with continued uncertainty of how ceilings
will respond.

Showers and perhaps a storm are possible Wed night-thu night as
a warm front moves across the terminals. Sub-vfr conditions
possible during this time.

Ifr conditions Thursday. Winds southwest around 5 knots Thursday.

MVFR conditions Thursday night. Winds becoming west 5 to 10 knots
Thursday night.VFR conditions Friday into Friday night. Winds
increasing northwest 10 to 15 knots gusts 20 knots Friday,
diminishing to 5 to 10 knots Friday night.

Marine
Winds remain less than 10 kt. Southerly flow will become
west/northwest overnight with a cold frontal passage. No further
showers expected overnight.

The pressure gradient will tighten Tuesday as low pressure
moves up the coast. Have kept small craft advisory for the mid
bay and lower potomac, where the gradient will be the best. The
winds should subside Tuesday night as the low moves away.

Low pressure will be moving west of the area Wednesday night
into Thursday, lifting a warm front into the area. Southerly
flow may reach SCA criteria.

No marine hazards Thursday night. Small craft advisories
possible Friday. No marine hazards Friday night.

Tides/coastal flooding
Anomalies have continued to fall to around 1/2 ft except on the
potomac. Flooding looks unlikely for the next couple cycles at
least. However, a coastal low Tuesday provides some
uncertainty. Guidance ensembles then diverge substantially
through midweek, although increasing water levels look more
likely by Wednesday night.

Lwx watches/warnings/advisories
Dc... None.

Md... None.

Va... None.

Wv... None.

Marine... Small craft advisory from 2 pm Tuesday to midnight edt Tuesday
night for anz533-534-537-543.

Synopsis... Ads/rcm
near term... Ads/rcm
short term... Ads/rcm
long term... Klw
aviation... Ads/klw/rcm
marine... Ads/klw/rcm
tides/coastal flooding... Ads


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 26 mi44 min NNE 2.9 G 2.9 65°F 71°F1014.5 hPa
44061 - Upper Potomac, MD 28 mi44 min SE 1.9 G 1.9 64°F 69°F1014.7 hPa
BSLM2 - Chesapeake Bay, MD 44 mi152 min Calm 59°F 1015 hPa58°F
BLTM2 - 8574680 - Baltimore, MD 50 mi44 min N 2.9 G 4.1 64°F 70°F1014.8 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Washington/Dulles International Airport, DC, VA5 mi70 minN 610.00 miMostly Cloudy64°F62°F93%1015.3 hPa
Leesburg / Godfrey, VA6 mi67 minN 910.00 miFair64°F59°F83%1016.3 hPa
Gaithersburg - Montgomery County Airport, MD19 mi66 minN 00.50 miFog58°F57°F97%1018.7 hPa
Manassas, Manassas Regional Airport/Harry P. Davis Field, VA22 mi66 minN 010.00 mi63°F61°F93%1016.4 hPa

Wind History from IAD (wind in knots)
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Last 24hrSE3SE3CalmCalmSE4CalmSE4SE3SE5S5SW4S4CalmSW4CalmCalmCalmCalmNW4CalmSW4SW3N6NW5
1 day agoE5S5SE4CalmE4SE3S3E8SE6E6E7E8SE5SE8S9SE10SE7S5SE8S6SE7SE7SE6S4
2 days agoCalmW3S3N4N7N6N7NE10E11NE9E7E9E9E7E6E6NE8E7E7E10E6SE7SE7SE8

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Tue -- 01:03 AM EDT     0.27 feet Low Tide
Tue -- 04:31 AM EDT     Moonrise
Tue -- 05:49 AM EDT     Sunrise
Tue -- 06:56 AM EDT     3.63 feet High Tide
Tue -- 02:01 PM EDT     0.23 feet Low Tide
Tue -- 05:50 PM EDT     Moonset
Tue -- 07:29 PM EDT     3.21 feet High Tide
Tue -- 08:21 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.40.30.4122.93.53.63.42.821.40.80.40.20.41.22.12.83.23.22.721.3

Tide / Current Tables for Chain Bridge, Washington, D.C.
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Chain Bridge
Click for Map
Tue -- 01:00 AM EDT     0.29 feet Low Tide
Tue -- 04:31 AM EDT     Moonrise
Tue -- 05:49 AM EDT     Sunrise
Tue -- 06:53 AM EDT     3.60 feet High Tide
Tue -- 02:00 PM EDT     0.25 feet Low Tide
Tue -- 05:50 PM EDT     Moonset
Tue -- 07:27 PM EDT     3.17 feet High Tide
Tue -- 08:21 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.40.30.4122.93.43.63.32.721.30.80.40.30.51.22.12.83.13.12.61.91.3

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 (1,6,7,8)
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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.