Tuesday, April24, 2018 L-36.com


Marine Weather and Tides
Ashburn, VA

Version 3.4
What's New / NOTES
3/3/2018 - There is a new GOES Satellite for the east coast that required rewriting that part of the code. Please report any issues.
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.

Sunrise 6:18AMSunset 7:57PM Tuesday April 24, 2018 8:26 PM EDT (00:26 UTC) Moonrise 1:21PMMoonset 2:30AM Illumination 72% Phase: Waxing Gibbous; Moon at 10 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- 751 Pm Edt Tue Apr 24 2018
Tonight..NE winds 10 kt with gusts to 20 kt. Waves 1 ft. Rain. Patchy fog. Vsby 1 to 3 nm.
Wed..NW winds 5 to 10 kt. Waves 1 ft. A chance of showers. Patchy fog. Vsby 1 to 3 nm.
Wed night..NW winds 10 kt. Waves 1 ft.
Thu..NW winds 5 to 10 kt. Waves 1 ft.
Thu night..S winds 5 kt. Waves less than 1 ft. Showers likely.
Fri..SE winds 5 kt. Waves less than 1 ft. Showers likely.
Fri night..SW winds around 5 kt. Waves 1 ft. A chance of showers.
Sat..NW winds around 5 kt. Waves 1 ft. A chance of showers in the morning.
Sun..NW winds 5 to 10 kt. Waves 1 ft.
ANZ500 751 Pm Edt Tue Apr 24 2018
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Low pressure will move northward from the carolinas tonight before passing overhead Wednesday. High pressure will then move near the area Thursday. Another low pressure system may affect the waters by overnight Thursday into Friday. A cold front will pass through the waters Saturday and high pressure will return for Sunday. Small craft advisories may be needed 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 241853
afdlwx
area forecast discussion
national weather service baltimore md washington dc
253 pm edt Tue apr 24 2018

Synopsis Low pressure over south carolina will slowly move
up the mid-atlantic coast tonight before passing by to our east
Wednesday. A cold front will pass through Wednesday evening and
high pressure will return for Thursday. Low pressure may impact
the area overnight Thursday into Friday before a cold front
passes through Saturday. High pressure will return by the end of
the weekend.

Near term through tonight
Rain has been very slow to move into northern va today, but it's
finally moving in. Strengthening onshore flow rest of today
into this evening will lead to a period of rain tonight ending
by midnight in the south but lingering into the early morning
hours in northeast md. Model QPF has trended lower this cycle
with amounts likely to remain below an inch in most places
except in the south and on the eastern slopes of the blue ridge
mountains where amounts greater than an inch have been reported
in highland county and approaching an inch in augusta county.

Mid-level dry slot will start working into southern areas by
09z as low pressure moves over southern md.

Short term Wednesday through Thursday night
Steady rain will end by 12z everywhere as onshore flow
weakens and low pressure passes just to the east. Not much in
the way of forcing available to generate precip, but can't
completely ruled out a few showers as weak instability develops
with passage of upper level trof axis. Otherwise, most cloudy
skies with some breaks in the clouds possible over the va
piedmont in the afternoon.

Very weak high pressure builds Wed night and thu. A second area
of low pressure will move across the area Thu night with
increasing chances of showers.

Long term Friday through Tuesday
On Friday, a upper level 500mb trough will be situated over the
midwestern us. A 500mb shortwave will move through the system and be
over our region on Friday. The associated sfc low pressure
system will shift into the region from the southwest. The exact
location of this sfc low is still uncertain as the 12z GFS keeps
the low further north and west in northern maryland and pa. The
00z euro has the low approaching and moving east north east
just to our south. The difference between solutions is that the
gfs tries to keep the majority of the precipitation to the north
and west of our forecast area while the euro tries to take the
low further southward. The 12z euro run may bring the low
further north like the GFS increasing the the chances for higher
precip amounts. As of now, this seems like a fairly weak
frontal passage that will bring light precipitation. The front
associated with this sfc low will likely move out of our
forecast area by early Saturday morning. Temperatures will rise
Friday up into 60s with some areas reaching the 70s due to warm
air advection from the south to southwest. A isolated
thunderstorm wouldn't be out of the question on Friday.

Behind the weak frontal passage, a strong high pressure will build
into the area from the upper midwest and the great lakes
region. The high will remain over the region through early next
week leading to clear skies and temperatures close to average
for this time of the year with temperatures in the upper 60s to
low 70s.

Aviation 19z Tuesday through Sunday
Developing MVFR ifr conditions tonight in rain if they haven't
already as low pres over sc lifts NE and onshore continues to
strengthen. Winds will remain gusty through 00z-03z, then start
to diminish after 06z. Gradual improvement in CIGS expected wed,
but still plenty of clouds.

Clouds will increase on Friday as a low pressures system moves in
from our south. Brief lowering of cloud bases and visibility will be
possible if showers and isolated thunderstorms move through the
region. Sub-vfr conditions will be possible on Friday. Clearing skies
along with light winds are expected over the weekend leading toVFR
conditions.

Marine
Sca conditions expected through 03z-06z tonight, then winds
diminishing rapidly as sfc low moves overhead. Light winds
expected on wed, then strengthening somewhat Wed night behind
departing low. Marginal SCA conditions possible, but confidence
low ATTM for any sca.

A low pressure approaching from out south on Friday will lead to a
southerly flow and increasing clouds. The southerly flow will
likely warrant the need for small craft advisory on Friday as winds
flow up the chesapeake bay. Over the weekend, a strong high pressure
will be present leading to clear skies and lighter winds. Sca
unlikely Saturday and Sunday as of now.

Lwx watches warnings advisories
Dc... None.

Md... None.

Va... None.

Wv... None.

Marine... Small craft advisory until 4 am edt Wednesday for anz530>534-
537>543.

Small craft advisory until 10 pm edt this evening for anz535-
536.

Synopsis... Lfr
near term... Lfr
short term... Lfr
long term... Jmg
aviation... Lfr jmg
marine... Lfr jmg


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 26 mi39 min ENE 2.9 G 7 56°F 56°F1017.8 hPa
BSLM2 - Chesapeake Bay, MD 44 mi117 min ESE 5.1 57°F 1018 hPa52°F
BLTM2 - 8574680 - Baltimore, MD 50 mi39 min ESE 12 G 16 55°F 56°F1018.3 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 mi35 minENE 122.50 miLight Rain Fog/Mist54°F54°F100%1017 hPa
Leesburg / Godfrey, VA6 mi32 minE 10 G 144.00 miLight Rain52°F51°F100%1017.6 hPa
Gaithersburg - Montgomery County Airport, MD19 mi31 minVar 52.00 miLight Rain Fog/Mist53°F52°F96%1021.2 hPa
Manassas, Manassas Regional Airport/Harry P. Davis Field, VA22 mi31 minE 63.00 miLight Rain Fog/Mist55°F53°F93%1017.8 hPa

Wind History from IAD (wind in knots)
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1 day agoSE5SE5SE5SE4SE4SE4SE5SE3CalmCalmCalmCalm4SE6SE7SE7
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2 days agoNE5E3SE3SW3CalmCalmS4S6S3SE4SE3E5E45E9E7SE1265E9SE8E10E11SE7

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Tue -- 03:28 AM EDT     Moonset
Tue -- 04:25 AM EDT     3.10 feet High Tide
Tue -- 06:19 AM EDT     Sunrise
Tue -- 11:06 AM EDT     0.41 feet Low Tide
Tue -- 02:19 PM EDT     Moonrise
Tue -- 04:45 PM EDT     3.20 feet High Tide
Tue -- 07:54 PM EDT     Sunset
Tue -- 11:47 PM EDT     0.29 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.71.42.22.83.132.62.11.510.60.40.61.22.12.73.13.22.92.41.81.30.80.4

Tide / Current Tables for Chain Bridge, Washington, D.C.
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Chain Bridge
Click for Map
Tue -- 03:28 AM EDT     Moonset
Tue -- 04:26 AM EDT     3.13 feet High Tide
Tue -- 06:19 AM EDT     Sunrise
Tue -- 11:06 AM EDT     0.35 feet Low Tide
Tue -- 02:19 PM EDT     Moonrise
Tue -- 04:46 PM EDT     3.23 feet High Tide
Tue -- 07:54 PM EDT     Sunset
Tue -- 11:47 PM EDT     0.24 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.61.42.22.83.13.12.72.11.50.90.60.40.51.22.12.73.13.22.92.41.81.30.80.4

Weather Map and Satellite Images
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wmap_A
GOES Local Image of Mid-Atlantic    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.
target = "new">Link to Loop



Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Baltimore, MD/Washington (20,4,5,8)
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Ground Weather Radar Station Sterling, VA
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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.