Thursday, October18, 2018 L-36.com


Marine Weather and Tides
Round Hill, VA

Version 3.4
What's New / NOTES
10/6/2018 Colors of tide XTide graphs changed to emphasize that they were upgraded. See next note. Comments welcome.
10/4/2018 I have fixed XTide and updated the harmonic files. There were some name changes so you might have to click EDIT to find the new station name.

Sunrise 7:22AMSunset 6:28PM Thursday October 18, 2018 4:20 PM EDT (20:20 UTC) Moonrise 2:42PMMoonset 12:14AM Illumination 69% Phase: Waxing Gibbous; Moon at 9 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- 308 Pm Edt Thu Oct 18 2018
.small craft advisory in effect until 6 pm edt this evening...
Rest of this afternoon..NW winds 10 kt with gusts to 20 kt. Waves 1 ft.
Tonight..W winds around 5 kt. Waves 1 ft.
Fri..S winds 5 to 10 kt. Waves 1 ft.
Fri night..SW winds 5 to 10 kt. Waves 1 ft. Showers likely.
Sat..W winds 5 to 10 kt. Waves 1 ft. A chance of showers.
Sat night..NW winds 10 kt with gusts to 20 kt. Waves 1 ft.
Sun..NW winds 10 to 15 kt...diminishing to 5 kt after midnight. Waves 1 ft.
Mon..SW winds 5 kt. Waves less than 1 ft.
ANZ500 308 Pm Edt Thu Oct 18 2018
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure will build overhead through tonight before moving offshore Friday. A cold front will cross the waters Saturday with high pressure returning early next week. Small craft advisories will likely be needed for portions of the waters Saturday through Sunday. Gale conditions are possible Saturday night into early Sunday.


7 Day Forecast for Marine Location Near Round Hill, VA
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location: 39.12, -77.77     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 181910
afdlwx
area forecast discussion
national weather service baltimore md washington dc
310 pm edt Thu oct 18 2018

Synopsis
High pressure will build overhead through tonight before moving
offshore Friday. A cold front will pass through Saturday into
Saturday night and high pressure will return for Sunday through
Sunday night. High pressure will move offshore Monday and a re-
enforcing cold front will pass through Tuesday into Wednesday.

Low pressure may approach the area late next week.

Near term through tonight
Canadian high pressure will continue to build overhead through
tonight. A northwest flow ahead of the high will cause chilly
conditions relative to climo this afternoon, despite sunshine.

Max temps will be in the mid to upper 50s for most locations.

Mainly clear skies, light winds and dry air will provide a good
setup for radiational cooling tonight as the high settles
overhead. Areas of frost are likely. Some sheltered valleys or
rural areas may drop below freezing as well, especially west of
the blue ridge mountains. Freeze warnings are in effect for
these areas with frost advisories elsewhere. Frost is likely
overnight for most areas with exceptions being in downtown
washington baltimore, along open ridge tops and along the shore
of the bay. Did lean toward the colder guidance for min temp
forecasts tonight given the good setup for radiational cooling.

Min temps will range from the lower 30s in the colder valleys
and rural areas, to the middle 30s across most other locations,
but 40s in downtown washington and baltimore.

Short term Friday through Saturday night
High pressure will move offshore Friday and a return southerly
flow will develop. The southerly flow will allow for a milder
afternoon with MAX temps in the lower to middle 60s for most
areas. High and mid-level clouds will increase late in the day
ahead of the next of an approaching upper-level disturbance in
the westerly flow aloft.

The upper-level disturbance will pass through Friday night,
likely triggering showers across the area. Precipitation amounts
should be light since most of the forcing will be from the mid-
levels, and there is little forcing in the lower levels due to a
strong westerly component to the low-level flow.

The disturbance will move off to the east Saturday, but a potent
cold front will approach Saturday before passing through late
Saturday afternoon into Saturday evening. A couple showers are
possible with the frontal passage. Would not be surprised to
see an isolated thunderstorm later Saturday afternoon and
evening, but did not reflect this in the forecast at this time.

This is because of a potent upper-level disturbance that will be
swinging through with the cold frontal passage. Our area will
be within left exit region of the mid-level jet, and height
falls will be potent. Strong cold advection will cause blustery
and chilly conditions overnight Saturday. Snow showers are
likely along and west of the allegheny front as colder air
filters in, and the first snowfall accumulation of the season is
possible across these areas. Low Saturday night will be in the
40s for most locations, but upper 20s to lower 30s along the
ridge tops.

Long term Sunday through Thursday
Cool and dry conditions will be the theme across the area late this
weekend through the middle of next week.

An upper level trough will be located overhead Sunday morning, then
progress off to the east throughout the day. Subsidence in the wake
of the trough, coupled with a weakening low-level wind field will
cause any leftover upslope rain or snow showers along the allegheny
front to dissipate by midday. Otherwise, mostly sunny skies are
forecast across the area. With the core of the cold air located
overhead, temperatures will be well below normal. High temperatures
will range from the low 40s in the mountains, to the low to mid 50s
east of the blue ridge.

High pressure will crest overhead Sunday night, leading to light
winds and cool overnight temperatures. Lows should dip below 40
degrees at most locations, with some 20s even possible in the higher
elevation valleys to the west of the blue ridge. High pressure will
move to our east on Monday, as a shortwave trough tracks southeast
from the canadian prairies toward the great lakes. Weak warm
advection in advance of this trough will allow temperatures to
moderate slightly for Monday, and then again on Tuesday. However,
temperatures will still be below normal with highs in the mid-upper
50s on Monday, and low 60s on Tuesday. Another strong area of high
pressure will build over the great lakes on Wednesday, helping to
prolong our stretch of dry weather.

Aviation 17z Thursday through Monday
Vfr conditions will persist through Friday. A few showers are
likely Friday night into Saturday.VFR conditions are still most
likely during this time, but brief MVFR conditions cannot be
ruled out. Gusty west to northwest winds are expected behind a
cold front late Saturday or Saturday night, depending on the
timing of the frontal passage. A few showers are possible during
this time as well.

Vfr conditions are expected at the terminals Sunday through
Wednesday. No precipitation is expected during the Sunday through
Wednesday time period, but gusty northwesterly winds will be
possible during the day on Sunday.

Marine
High pressure will build over the waters through tonight. Winds
will diminish during this time. The SCA continues through this
afternoon. High pressure will move offshore Friday and a
southerly flow will develop. The flow will strengthen ahead of a
cold front late Friday into Saturday. An SCA is in effect for
the bay and lower tidal potomac river Friday afternoon and
Friday night. SCA wind gusts are possible across the upper and
middle tidal potomac during this time, but confidence is not
high enough for an advisory during this time.

An SCA will likely be needed for Saturday through Saturday night
both ahead of and behind the front. The strongest winds will be
behind the front Saturday night and a gale warning may be needed
for portions of the waters during this time. A gale warning may
also be needed Sunday ahead of building high pressure.

Sca levels winds appear possible on Monday as high pressure moves
offshore.

Lwx watches warnings advisories
Dc... Frost advisory from 1 am to 9 am edt Friday for dcz001.

Md... Freeze warning from 1 am to 9 am edt Friday for mdz501-502.

Frost advisory from 1 am to 9 am edt Friday for mdz003>006-011-
013-014-016>018-503>508.

Va... Freeze warning from 1 am to 9 am edt Friday for vaz025>031-503-
504.

Frost advisory from 1 am to 9 am edt Friday for vaz036>040-
050>057-501-502-505>508.

Wv... Freeze warning from 1 am to 9 am edt Friday for wvz050>053-055-
501>506.

Marine... Small craft advisory until 6 pm edt this evening for
anz530>543.

Small craft advisory from 2 pm Friday to 6 am edt Saturday for
anz530>534-537>543.

Synopsis... Bjl
near term... Bjl
short term... Bjl
long term... Kjp
aviation... Bjl kjp
marine... Bjl kjp


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 43 mi32 min WNW 5.1 G 11 57°F 63°F1029.3 hPa
BSLM2 - Chesapeake Bay, MD 61 mi110 min WNW 6 56°F 1029 hPa30°F
BLTM2 - 8574680 - Baltimore, MD 64 mi32 min 71°F

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Leesburg / Godfrey, VA11 mi25 minN 6 G 1710.00 miFair55°F33°F44%1029.5 hPa
Washington/Dulles International Airport, DC, VA20 mi28 minNW 1210.00 miFair57°F30°F37%1029 hPa
Winchester Regional, VA20 mi45 minNW 12 G 1510.00 miFair54°F32°F44%1029.5 hPa
Eastern WV Regional Airport/Shepherd Field, WV23 mi27 minWNW 710.00 miFair56°F28°F36%1028.7 hPa

Wind History from JYO (wind in knots)
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1 day agoW3SW3S3S3CalmS4SW5SW3CalmCalmCalmCalmCalmN4N6CalmCalmW6NW12
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2 days agoS5W4SW4SW4SW4S3NW14
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Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Thu -- 01:12 AM EDT     Moonset
Thu -- 04:21 AM EDT     2.93 feet High Tide
Thu -- 07:21 AM EDT     Sunrise
Thu -- 11:06 AM EDT     0.55 feet Low Tide
Thu -- 03:38 PM EDT     Moonrise
Thu -- 05:01 PM EDT     2.77 feet High Tide
Thu -- 06:25 PM EDT     Sunset
Thu -- 11:07 PM EDT     0.55 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.11.82.42.72.92.92.521.410.70.60.71.21.82.32.62.82.62.11.510.70.6

Tide / Current Tables for Chain Bridge, one mile below, D.C.
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Chain Bridge
Click for Map
Thu -- 01:12 AM EDT     Moonset
Thu -- 04:16 AM EDT     2.93 feet High Tide
Thu -- 07:20 AM EDT     Sunrise
Thu -- 11:01 AM EDT     0.55 feet Low Tide
Thu -- 03:38 PM EDT     Moonrise
Thu -- 04:56 PM EDT     2.77 feet High Tide
Thu -- 06:25 PM EDT     Sunset
Thu -- 11:02 PM EDT     0.55 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.11.82.42.82.92.82.51.91.410.70.60.71.31.92.32.62.82.62.11.510.70.6

Weather Map and Satellite Images
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GOES Local Image of    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.
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Wind Forecast for Baltimore, MD/Washington (16,3,4,5)
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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.