Monday, December18, 2017 L-36.com


Marine Weather and Tides
Mantua, 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 7:21AMSunset 4:50PM Monday December 18, 2017 4:10 AM EST (09:10 UTC) Moonrise 7:26AMMoonset 5:28PM Illumination 0% Phase: New Moon; Moon at 0 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 18 2017
Rest of the overnight..Light winds. Waves flat.
Today..SW winds around 5 kt. Waves 1 ft.
Tonight..SW winds 5 kt. Waves less than 1 ft.
Tue..SW winds 5 to 10 kt. Waves 1 ft.
Tue night..W winds 5 to 10 kt. Waves 1 ft.
Wed..NW winds 5 kt. Waves less than 1 ft.
Wed night..N winds 5 kt. Waves less than 1 ft.
Thu..SE winds around 5 kt. Waves 1 ft.
Fri..S winds 5 to 10 kt. Waves 1 ft. A chance of rain through the night.
ANZ500 331 Am Est Mon Dec 18 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure will control the weather pattern through Tuesday before a cold front crosses the area Tuesday night. High pressure will build to the north Wednesday into Thursday as a front stalls to the south. A small craft advisory may be needed Tuesday night into Wednesday for portions of the waters.

7 Day Forecast for Marine Location Near Mantua, VA
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location: 38.84, -77.25     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 180854
afdlwx
area forecast discussion
national weather service baltimore md washington dc
354 am est Mon dec 18 2017

Synopsis
Warm front will lift northward away from the region today, but a
pressure trough will linger over the appalachians. High
pressure will return Tuesday before a cold front crosses the
region Tuesday night. A storm system will pass to the south
Wednesday. High pressure will return Thursday before a storm
system approaches from the west at the end of the week.

Near term through tonight
A surface warm front presently resides north of the forecast
area, and it will continue north today. There will be a pressure
trough along the spine of the appalachians that will be
responsible for clouds, light rain, drizzle, and fog in the
mountains. Otherwise, broad ridging will be affecting the
southeastern united states today.

Present cloudiness will break apart somewhat, especially across
virginia southern maryland where low-mid level moisture a bit
more sparse. Aside from that, its tough to pinpoint any forcing
features. As 850 mb temperatures rise to +2 to +4c, anticipate
high temperatures to be able to exceed 50f just about
everywhere. Since insolation will be best in virginia, matched
maxt accordingly.

A similar setup exists tonight, with zonal flow and subtle warm
advection. There is a shallow layer of moisture around 925 mb,
so i'm not sure how clear it will be. Am keeping temps above
freezing areawide. Winds don't fully decouple either, so even if
there were clearing, radiational cooling may not be that ideal.

Short term Tuesday through Wednesday night
Broad ridging and zonal flow will be the key features for
Tuesday and Wednesday as well. A northern stream system will
drag a cold front through Tuesday night. Expect enough moisture
for a period of clouds but no precipitation. An impulse in the
southern stream will then ride along this boundary Wednesday
afternoon-evening. However, the consensus solution is to keep
most of the associated precip south of the forecast area. Will
entertain chance pops south of harrisonburg- fredericksburg.

Given the Sun and shot of warm advection, highs near 60f
reasonable on Tuesday. The frontal passage will carve 10 to
maybe 15 degrees off that for Wednesday. Although Wednesday
night lows likely to be subfreezing, any precip would exit
before temps drop, so p-type issues not anticipated. Will be
maintaining just rain as precipitation type for Wed pm.

Long term Thursday through Sunday
While the long term starts out tranquil, the general theme is
"un"... "un"settled and "un"certain.

On Thursday, we start out with a broad flat ridge over the
eastern half of the country, while a closed low is sitting near
the four corners. By Friday, this closed low opens up into a
short-wave trough extending from minnesota to western texas,
while the ridge over the east strengthens ahead of it. On
Saturday, the shortwave weakens and moves northeast across our
region, beating the ridge back, while another shortwave digs
over the west, such by this time a broad trough dominates much
of the country. By Sunday, the new shortwave digging out west
starts to push east towards the plains, while the ridge regains
a bit of strength over the southeast.

The details are where the trouble lies. To start, high pressure
at the surface will dominate on Thursday, with temps fairly
close to normal and mostly sunny skies. Things change Friday as
warm advection isentropic lift gets underway ahead of the
approaching trough and surface front, with increasing clouds and
a growing chance of rain, though still slight during the day
Friday. We will need to keep an eye on potential for a little
freezing rain if precip arrives early enough, particularly west
of the blue ridge catoctins, but expect all areas to end up
above freezing by afternoon.

Saturday and Sunday are where the real uncertainty lies. The ec
and ggem keep the southeast ridge just strong enough such that
the approaching cold front stalls out just to our southeast. The
gfs, on the other hand, pushes the front off the southeast coast
before stalling it. With the front stalling fairly close by on
all models, the chance of precipitation is elevated through the
weekend. However, the GFS would suggest enough cold air moves in
behind the front such that we could have some mixed
precipitation or snow issues, particularly christmas eve into
christmas day. Meanwhile, the ECMWF and ggem keep the area mild
with just plain rain expected. In fact, by Monday, ec guidance
is over 20 degrees warmer than the gfs. Model blending has
suggested that a solution closer to the ec is more likely than
the gfs, and this is also suggested by the digging trough out
west which would likely cause the southeast ridge to bring the
front to a halt faster than the GFS would suggest. That said,
there remains a fair amount of run to run inconsistency.

Therefore, anyone with travel plans during the holiday weekend,
particularly christmas eve and christmas day, should keep
abreast of the latest forecast, in case a colder and perhaps
snowier icier outcome starts to look more likely. This is
especially true if those travel plans are north and west of
i-95.

Aviation 07z Monday through Friday
Vfr conditions expected today. Believe the layer of moisture
around 040-050 will be rather stagnant, although some thinning
will be possible. If there were any flight restrictions in the
next three days, it would come late tonight as this layer of
clouds lower. There is a chance at CIGS dropping to or just
below 030. Have that in tafs at this time, but not completely
confident in it.

Clouds will mix out Tuesday, with a dry frontal passage Tuesday
night and increased wind Wednesday. Cloud bases tue-wed will be
scattered stratocumulus, although brief periods of bkn clouds
possible.

GenerallyVFR Thursday under high pressure with light winds.

Friday clouds thickening and lowering as next system approaches,
but chance of sub-vfr is still fairly low.

Marine
Light winds across the waters at this hour (3am) will continue
through the daylight hours. Southwest winds will pick up Tuesday
ahead of a cold front. However, warm air over relatively cool
waters should impede good mixing. Am capping daytime wind gusts
near the sustained speeds-- near 15 kt. Thus, small craft
advisory not anticipated at this time for tue. Not sure the same
can be said Tue night near frontal passage, and especially
Wednesday in the wake of the front with favorable mixing.

Likely sub-sca Thursday under high pressure. Southerly flow
increases the risk of SCA gusts Friday as the next system
approaches, but cold air damming probably going to keep gusts
below threshold.

Lwx watches warnings advisories
Dc... None.

Md... None.

Va... None.

Wv... None.

Marine... None.

Synopsis... Rcm
near term... Hts
short term... Hts
long term... Rcm
aviation... Rcm hts
marine... Rcm hts


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 12 mi41 min Calm G 0 42°F 40°F1019.9 hPa
BSLM2 - Chesapeake Bay, MD 29 mi101 min Calm 36°F 1020 hPa35°F
NCDV2 38 mi41 min Calm G 1 40°F 41°F1019 hPa
APAM2 - 8575512 - Annapolis, MD 42 mi41 min 40°F 1019.3 hPa
TPLM2 - Thomas Point, MD 43 mi71 min SSE 1.9 G 1.9 42°F 44°F
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 46 mi41 min NNE 1.9 G 2.9 39°F 1019.9 hPa
BLTM2 - 8574680 - Baltimore, MD 46 mi41 min ENE 4.1 G 5.1 40°F 45°F1019.5 hPa
CPVM2 47 mi41 min 41°F 37°F
FSNM2 47 mi53 min NE 4.1 G 4.1 39°F 1019.2 hPa
44062 - Gooses Reef, MD 48 mi31 min SSW 1.9 G 3.9 44°F 1020.2 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Fort Belvoir, VA8 mi15 minN 010.00 miOvercast39°F35°F86%1020 hPa
Washington/Reagan National Airport, DC, VA12 mi19 minSSW 310.00 miOvercast43°F35°F74%1019.9 hPa
Washington/Dulles International Airport, DC, VA13 mi19 minN 010.00 miMostly Cloudy38°F35°F89%1019.6 hPa
Manassas, Manassas Regional Airport/Harry P. Davis Field, VA17 mi15 minN 010.00 miMostly Cloudy35°F34°F96%1020.9 hPa
College Park Airport, MD20 mi25 minN 010.00 miOvercast39°F33°F80%1020 hPa
Camp Springs / Andrews Air Force Base, MD20 mi15 minN 010.00 miOvercast40°F34°F82%1020.1 hPa
Quantico Marine Corps Airfield - Turner Field, VA23 mi75 minWNW 310.00 miOvercast40°F36°F86%1020.6 hPa
Gaithersburg - Montgomery County Airport, MD23 mi15 minN 010.00 miMostly Cloudy38°F34°F86%1022.6 hPa
Leesburg / Godfrey, VA24 mi16 minNE 310.00 miOvercast41°F35°F81%1019.6 hPa

Wind History from DAA (wind in knots)
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Last 24hrCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalm
1 day agoCalmCalmS3S3S4S4SW7SW5S9
G18
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S8S5S5CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalm
2 days agoCalmCalmCalmE4NE3CalmCalmCalmN3CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalm

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Mon -- 01:31 AM EST     New Moon
Mon -- 03:07 AM EST     -0.16 feet Low Tide
Mon -- 07:22 AM EST     Sunrise
Mon -- 07:24 AM EST     Moonrise
Mon -- 08:40 AM EST     2.51 feet High Tide
Mon -- 02:59 PM EST     -0.09 feet Low Tide
Mon -- 04:48 PM EST     Sunset
Mon -- 05:27 PM EST     Moonset
Mon -- 08:49 PM EST     2.83 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.10.60.1-0.200.71.422.42.52.11.50.90.40.1-0.10.10.81.62.32.72.82.62

Tide / Current Tables for Chain Bridge, Washington, D.C.
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Chain Bridge
Click for Map
Mon -- 01:31 AM EST     New Moon
Mon -- 03:06 AM EST     -0.21 feet Low Tide
Mon -- 07:22 AM EST     Sunrise
Mon -- 07:24 AM EST     Moonrise
Mon -- 08:41 AM EST     2.55 feet High Tide
Mon -- 02:59 PM EST     -0.14 feet Low Tide
Mon -- 04:48 PM EST     Sunset
Mon -- 05:27 PM EST     Moonset
Mon -- 08:50 PM EST     2.86 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
10.50.1-0.2-00.61.42.12.52.52.21.50.90.40-0.10.10.81.62.32.72.92.62

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.