Thursday, June21, 2018 L-36.com


Marine Weather and Tides
St. James, MD

Version 3.4
What's New / NOTES
5/20/2018 -- NOAA is having problems with the data feed that I use to draw the graphs. They are aware of the issue and working to resolve it. Sometimes changing the location by about a mile will give a correct graph. 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.

Sunrise 5:42AMSunset 8:43PM Thursday June 21, 2018 4:25 AM EDT (08:25 UTC) Moonrise 1:28PMMoonset 12:57AM Illumination 55% Phase: First Quarter Moon; Moon at 8 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- 408 Am Edt Thu Jun 21 2018
.small craft advisory in effect from Friday morning through Friday evening...
Rest of the overnight..W winds 5 kt. Waves less than 1 ft. Isolated showers.
Today..N winds around 5 kt. Waves 1 ft.
Tonight..E winds around 5 kt. Waves 1 ft. Scattered showers.
Fri..E winds 10 to 15 kt with gusts to 20 kt. Waves 1 ft. Showers likely.
Fri night..E winds 5 to 10 kt. Gusts up to 20 kt in the evening. Waves 1 ft. Showers likely.
Sat..S winds 5 to 10 kt. Waves 1 ft. Showers likely.
Sat night..SW winds 5 to 10 kt. Waves 1 ft. Scattered showers and tstms.
Sun..W winds around 5 kt. Waves 1 ft.
Mon..N winds 5 to 10 kt. Waves 1 ft. A chance of showers. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 408 Am Edt Thu Jun 21 2018
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Low pressure will track from west virginia east over the waters along a stalled front overnight. The front will then drop farther south Thursday as high pressure briefly builds from the ohio valley to new england. The front will then return north as a warm front Friday night into Saturday as the high moves offshore and low pressure moves from the midwest to the great lakes. A small craft advisory may be needed for a portion of the waters Friday into Saturday.

7 Day Forecast for Marine Location Near St. James, MD
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location: 39.59, -77.77     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 210759
afdlwx
area forecast discussion
national weather service baltimore md washington dc
359 am edt Thu jun 21 2018

Synopsis
A front will remain stalled over the mid-atlantic through
tonight before slowly returning north as a warm front Friday
into Saturday. Low pressure will move from the ohio valley to
the eastern great lakes during this time, then eastward across
new england Sunday bring a cold front across the region. High
pressure will then build in from the eastern great lakes and
remain in control through the middle of next week.

Near term through tonight
A weak surface low (the one which generated showers and
thunderstorms yesterday evening) has moved eastward along a
stalled front off the southern new jersey coast as of early this
morning. The frontal zone along which it tracked is rather
diffuse, but should re-focus itself across central virginia
later today. NVA in the wake of a largely convectively-induced
shortwave should result in partial clearing behind the surface
front over northeastern maryland southwest to the dc metro for a
time this afternoon with breaks of Sun expected. Clouds will
linger along the front in central virginia as showers and
scattered thunderstorms re-develop, some becoming quite heavy
by mid to late afternoon into this evening (see hydrology
section for details on heavy rain threat flash flood watch).

The forward (northeastward) progression of showers tonight may
be hindered some, as the front should remain largely stalled due
to easterly flow developing around high pressure departing off
the new england coast. For this reason, sided with the somewhat
slower NAM sref pops as opposed to the quicker gfs, which keeps
coverage more scattered over much of maryland and the washington
dc baltimore metro areas through much of the night.

Short term Friday through Saturday night
Rounds of showers and scattered thunderstorms are expected to
re-invigorate and spread northeastward across virtually the
entire mid-atlantic Friday afternoon into Friday night, before
departing to the northeast Saturday morning along and ahead of
the slowly advancing warm front. See the hydrology section for
details on the heavy rain flooding threat.

Hedging on the side of climatology, the warm front will likely
get stuck near the potomac river Saturday, enhancing low-level
directional shear. Speed shear increasing in the 0-6 km layer to
around 50 knots with around 40 kts at 850 mb. This couple with
abundant low-level moisture should lead to an environment
favorable for scattered strong to severe storms and perhaps a
couple supercells where best instability is pooled over
southeastern parts of the cwa. Gusty winds or an isolated
tornado would be possible in this scenario. SPC has southern
maryland to the fredericksburg virginia area in a marginal risk,
with uncertainties in more robust instability given poor lapse
rates aloft.

The warm front should lift further north by Saturday evening,
with waning isentropic lift and diurnally decreasing instability
leading to a decrease in convection overnight.

Long term Sunday through Wednesday
A broad area of low pressure will be moving through new england on
Sunday. One boundary may be located just to our south, but the
stronger cold front will be descending southward from the great
lakes ahead of a sharper upper level trough. These features may
result in some showers and thunderstorms during the afternoon and
evening, but deep layer westerly flow may limit the coverage. Warm
and moderately humid conditions will likely persist ahead of the
front.

While some ensemble members have a slower frontal progression
through the area on Monday, the 00z deterministic models have it
south of the area. In addition, the upper level trough axis vort max
is now progged to be centered more over new england. Thus the
forecast will trend cooler and drier.

By Tuesday, there is good model agreement on high pressure building
in from the northwest, resulting in dry weather and near to slightly
below normal temperatures. The high will begin to move offshore
Wednesday. Temperatures will begin to rebound, but precipitation
chances will remain low.

Aviation 08z Thursday through Monday
Any patchy restrictions should lift by mid morning.VFR expected
today for most terminals. However showers and thunderstorms will
become likely INVOF cho by mid-afternoon and persist through
much of the night. More scattered coverage northeastward toward
mrb iad tonight. Winds will generally be NE AOB 10 kts through
tonight before increasing Friday with gusts around 20 kts
possible. Showers accompanying restrictions also become more
widespread late tonight through Friday night before diminishing
early Saturday as winds become southwesterly in the wake of an
advancing warm front. Scattered strong convection is possible
Saturday afternoon, but predominatelyVFR is expected.

Showers and thunderstorms will be possible Sunday afternoon and
evening as a cold front moves toward the region.VFR conditions are
expected Monday as the front moves to the south.

Marine
Sca posted Friday Friday evening in increasing easterly flow.

Otherwise generally light winds expected outside of perhaps more
isolated SW gusts Saturday. Isolated stronger convection could
result in localized higher wind gusts Saturday afternoon and
evening as well.

West winds on Sunday will become northerly by Monday as a cold front
pushes south through the waters. Wind speeds are still a bit
uncertain at this time, but they could be near small craft advisory
thresholds. Thunderstorms will also be possible ahead of the front
Sunday afternoon and evening.

Hydrology
Pwats exceeding 2-2.25 inches by this evening over central
virginia is quite concerning given potential repeated rounds of
convection with a front stalled overhead. Also, 925-850 mb flow
increases out of the east to 25-30 kts increasing moisture
advection and resulting in an upslope component. Rainfall
amounts by Friday morning will average 1 to 2 inches, with
locally much higher amounts possible.

The heavy rain threat spreads further northeastward Friday
afternoon and night as the warm front advances. Additional
watches may be required.

Tides coastal flooding
Tidal anomalies have risen slightly to around a half foot, but
should remain steady through today with light northerly wind.

Afterward, easterly winds will develop and result in further rises.

If the surge is quick, some sensitive locations may approach minor
flood thresholds Friday night, although most guidance has peak
anomalies and the highest chance of minor flooding Saturday night
after winds turn southerly. A cold frontal passage will end the
threat on Sunday.

Lwx watches warnings advisories
Dc... None.

Md... None.

Va... Flash flood watch from 3 pm edt this afternoon through late
tonight for vaz025-026-029-036>040-050-051-503-504-507-
508.

Wv... Flash flood watch from 3 pm edt this afternoon through late
tonight for wvz505-506.

Marine... Small craft advisory from 6 am Friday to midnight edt Friday
night for anz530>543.

Synopsis... Dhof
near term... Dhof
short term... Dhof
long term... Ads
aviation... Ads dhof
marine... Ads dhof
hydrology...

tides coastal flooding...



Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 63 mi38 min Calm G 1 78°F1006.8 hPa
BLTM2 - 8574680 - Baltimore, MD 67 mi38 min NW 1.9 G 4.1 78°F1006.5 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 71 mi38 min WNW 5.1 G 5.1 72°F 1006.6 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hagerstown, Washington County Regional Airport, MD9 mi33 minSSE 31.50 miFog/Mist70°F69°F97%1008.1 hPa
Eastern WV Regional Airport/Shepherd Field, WV17 mi33 minN 010.00 miOvercast70°F69°F97%1006.7 hPa
Frederick Municipal Airport, MD24 mi41 minN 07.00 miFair70°F69°F100%1008.1 hPa

Wind History from HGR (wind in knots)
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Last 24hrN3N3NW5NW53CalmCalmW3W6S8CalmS3E4CalmN5NW7S5W3S6CalmSE3SW4S3S4
1 day agoN11N3CalmCalmSW3W5NW8NW12N11N11NE8N11N6NE8NE5N8NE5E4E4E3CalmCalmCalmN3
2 days ago--S4S5S3S4SW6S654S6W7SE9S5S6W7SW7SW5SW4SW4SW4S4S5S5Calm

Tide / Current Tables for Chain Bridge, Washington, D.C.
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Chain Bridge
Click for Map
Thu -- 01:54 AM EDT     Moonset
Thu -- 03:49 AM EDT     3.30 feet High Tide
Thu -- 05:43 AM EDT     Sunrise
Thu -- 10:34 AM EDT     0.26 feet Low Tide
Thu -- 02:24 PM EDT     Moonrise
Thu -- 04:13 PM EDT     3.08 feet High Tide
Thu -- 08:37 PM EDT     Sunset
Thu -- 10:51 PM EDT     0.13 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.122.73.23.332.51.91.30.70.30.30.81.62.32.83.132.51.91.30.70.30.1

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Thu -- 01:54 AM EDT     Moonset
Thu -- 03:46 AM EDT     3.30 feet High Tide
Thu -- 05:43 AM EDT     Sunrise
Thu -- 10:31 AM EDT     0.30 feet Low Tide
Thu -- 02:24 PM EDT     Moonrise
Thu -- 04:10 PM EDT     3.08 feet High Tide
Thu -- 08:37 PM EDT     Sunset
Thu -- 10:49 PM EDT     0.18 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.22.12.83.23.332.41.81.20.70.40.40.81.62.42.93.12.92.51.81.20.70.30.2

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.
target = "new">Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Baltimore, MD/Washington (4,6,7,8)
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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.