Wednesday, August21, 2019 L-36.com


Marine Weather and Tides
Round Hill, VA

Version 3.4
NOTICE
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.
6/2/2019. Many thanks to a user for reporting an error on one of the Edit pages. The switch to PHP 7.2 caused many pages that previously worked to quit working. I fixed many but I still depend on users to report ones I missed. Please report errors HERE or send an email to me at L-36.com. Allen

Sunrise 6:27AMSunset 7:59PM Wednesday August 21, 2019 12:15 PM EDT (16:15 UTC) Moonrise 10:18PMMoonset 11:01AM Illumination 65% Phase: Waning Gibbous; Moon at 21 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- 1035 Am Edt Wed Aug 21 2019
.small craft advisory in effect until 7 pm edt this evening...
Rest of today..S winds 10 kt with gusts to 20 kt. Waves 1 ft. Isolated showers and tstms this afternoon.
Tonight..SW winds 5 to 10 kt. Waves 1 ft. A chance of showers and tstms.
Thu..SW winds 5 kt. Waves less than 1 ft. A chance of showers and tstms.
Thu night..NW winds around 5 kt. Waves 1 ft. A chance of showers.
Fri..N winds 5 kt. Waves less than 1 ft. A chance of showers and tstms.
Fri night..N winds 5 kt. Waves less than 1 ft. A chance of showers.
Sat..NE winds around 5 kt. Waves 1 ft. A chance of showers in the morning.
Sun..E winds 5 kt. Waves less than 1 ft. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 1035 Am Edt Wed Aug 21 2019
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure in the atlantic will promote a light southerly flow over the region today. A cold front will approach the waters late tonight into Thursday, before stalling near or south of the area into Friday. High pressure will then settle over the area Saturday into 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 211423
afdlwx
area forecast discussion
national weather service baltimore md washington dc
1023 am edt Wed aug 21 2019

Synopsis
An upper level disturbance will cross the region this afternoon
and evening. A cold front will approach the ohio valley
Wednesday, sinking into our area Wednesday night into Thursday,
possibly stalling into Friday. Behind the front, high pressure
will build over the region for the weekend.

Near term through tonight
An upper level trough is crossing the appalachians this morning
and will move through the region during the mid to late
afternoon hours, followed by a second weaker shortwave this
evening. At the surface, a weak pressure trough is present in
the lee of the mountains this morning and this will gradually
push eastward through the day and be east of the region by
tonight. More cloud cover is present this morning but breaks of
sunshine are expected and this will allow temperatures to rise
into the upper 80s to low 90s. Instability will not be as
impressive as what we saw on Tuesday, given the additional
cloud cover and slightly cooler temperatures, and the synoptic
lift will be coming through piecemeal and focused further north.

That being said, 1000-2000 j kg of SBCAPE should develop by
this afternoon, along with modest low level lapse rates and
0-6km shear around 20-25 knots. These ingredients will support
at least an isolated threat for severe thunderstorms today, with
damaging winds and large hail continuing to be the primary
threats. Initial development is likely to occur in the surface
trough near or just east of the appalachians in the mid
afternoon as the primary upper trough moves through. These
showers thunderstorms should then progress eastward across the
metros during the remainder of the afternoon hours and into the
evening. A second round of activity is possible, but is less
certain during the mid to late evening as the second weaker
shortwave moves across.

Shower and thunderstorm activity will then dwindle heading into
the overnight, with partly cloudy skies and mainly dry
conditions persisting overnight. Patchy fog will be possible
towards morning as temperatures bottom out in the middle 60s to
middle 70s.

Short term Thursday through Friday night
The cold front will slowly drift into our area Thursday
morning, helping spark scattered showers and thunderstorms
during the afternoon and evening hours once again. Given the
front will be gracing us with its presence, while coinciding
with shortwave energy tracking overhead, do expect better
coverage of showers storms compared to today. Again, instability
may be limited given cloud cover and lower temperatures,
however we will remain moist and the flow will be parallel to
the front. So in addition to isolated strong to severe storms,
heavy rain resulting in isolated incidents of flooding will be a
concern.

The front shifts southward Thursday night into Friday, but
likely lingers close enough nearby to bring additional
scattered showers and storms on Friday afternoon and evening,
favoring our southern zones. Temperatures noticeably cooler on
Friday, likely holding in the 80s area wide. A drying trend
should commence Friday night as the front sinks further south
into southern virginia.

Long term Saturday through Tuesday
High pressure will build into the region from the north Saturday
and Sunday. Temperatures will be about 5 to 7 degrees below
average. Dry conditions and lower humidity is expected through the
period.

The high will move to the northeast Monday and Tuesday. This will
allow for a return southeast to southerly flow to bring the
humidity levels up and a chance of showers or a thunderstorms. The
discrepancy remains between the european models and GFS models as to
how many and how far north will showers and thunderstorms develop.

The european model keeps most, if not all, of our CWA dry through
Tuesday. The GFS model brings an upper level disturbance across our
region late Monday into Tuesday; thus, the chance for showers and
thunderstorms could be higher and farther north. Temperatures will
remain a few degrees below average, but humidity levels will rise
some.

Aviation 14z Wednesday through Sunday
Afternoon evening showers and storms can be expected through
Friday as a cold front slowly transits the area, bringing
periods of subVFR conditions. Patchy fog could also yield
MVFR ifr vis, mostly likely at mrb cho.

Vfr conditions for all terminals Saturday and Sunday. We can't
rule out a shower or thunderstorm near cho late Sunday into
Sunday night, which could briefly reduce conditions to MVFR.

Winds northeast around 5 knots Saturday and Saturday night. Winds
becoming easterly 5 to 10 knots Sunday.

Marine
Sca conditions expected over the waters today as the gradient
increases and a cold front nears the ohio valley. The gradient
is expected to relax overnight and remain below SCA criteria
Thursday and Friday. The front will drift over the waters on
Thursday, lingering nearby into Friday. As such, afternoon and
evening showers storms can be expected, some of which will
deliver strong gusty winds.

No marine hazards expected Saturday and Sunday. Winds northeast
around 5 knots Saturday and Saturday night. Winds becoming easterly
around 10 knots Sunday into Sunday evening.

Lwx watches warnings advisories
Dc... None.

Md... None.

Va... None.

Wv... None.

Marine... Small craft advisory until 7 pm edt this evening for anz530-
531-535-536-538-539-542.

Small craft advisory until midnight edt tonight for anz532>534-
537-540-541-543.

Synopsis... Bkf
near term... Mm bkf
short term... Bkf
long term... Klw
aviation... Mm bkf klw
marine... Mm bkf klw


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 43 mi45 min S 11 G 13 84°F 84°F1014.3 hPa
BSLM2 - Chesapeake Bay, MD 61 mi105 min S 5.1 82°F 1015 hPa73°F
BLTM2 - 8574680 - Baltimore, MD 64 mi45 min WSW 2.9 G 5.1 1013.7 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Leesburg / Godfrey, VA11 mi60 minSSW 310.00 miFair81°F73°F79%1015.2 hPa
Winchester Regional, VA20 mi60 minSSE 510.00 miFair82°F69°F66%1014.6 hPa
Washington/Dulles International Airport, DC, VA20 mi83 minS 410.00 miPartly Cloudy82°F71°F69%1014.5 hPa
Eastern WV Regional Airport/Shepherd Field, WV23 mi82 minN 010.00 miFair82°F71°F69%1013.9 hPa

Link to 5 minute data for KJYO

Wind History from JYO (wind in knots)
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Last 24hrNE3SE5W3NE5CalmS15
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CalmSE4W4CalmCalmSW7S4CalmCalmCalmCalmCalmS3CalmCalmCalmS3SW3
1 day agoW7NW5NW6NW5NW6W3CalmE6W14
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2 days agoE3S4SW6SW5S7SW3SE10S6SW4NE8
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Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Wed -- 12:41 AM EDT     3.19 feet High Tide
Wed -- 06:27 AM EDT     Sunrise
Wed -- 07:27 AM EDT     0.67 feet Low Tide
Wed -- 11:58 AM EDT     Moonset
Wed -- 01:02 PM EDT     2.96 feet High Tide
Wed -- 07:23 PM EDT     0.42 feet Low Tide
Wed -- 07:55 PM EDT     Sunset
Wed -- 11:14 PM EDT     Moonrise
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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3.13.22.92.41.91.30.90.70.711.62.32.832.82.41.81.20.70.40.50.71.32.2

Tide / Current Tables for Chain Bridge, one mile below, D.C.
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Chain Bridge
Click for Map
Wed -- 12:37 AM EDT     3.19 feet High Tide
Wed -- 06:27 AM EDT     Sunrise
Wed -- 07:22 AM EDT     0.67 feet Low Tide
Wed -- 11:58 AM EDT     Moonset
Wed -- 12:57 PM EDT     2.96 feet High Tide
Wed -- 07:18 PM EDT     0.42 feet Low Tide
Wed -- 07:55 PM EDT     Sunset
Wed -- 11:14 PM EDT     Moonrise
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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3.13.22.92.41.81.30.90.70.711.62.32.832.82.41.81.20.70.40.50.81.42.3

Weather Map and Satellite Images
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wmap_A
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 (12,3,4,5)
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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.