Saturday, March25, 2017 L-36.com


Marine Weather and Tides
Williamsport, MD

Version 3.4
What's New / NOTES
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.
3/12/2015 - Added section for Gulf current for users in the GMZ marine zones.
This was requested by a user. If you have requests, please let me know.

Sunrise 7:03AMSunset 7:30PM Saturday March 25, 2017 9:44 AM EDT (13:44 UTC) Moonrise 4:45AMMoonset 3:56PM Illumination 4% Phase: Waning Crescent; Moon at 28 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- 731 Am Edt Sat Mar 25 2017
Today..SW winds 5 to 10 kt. Waves 1 ft. Isolated showers this afternoon.
Tonight..SE winds 5 to 10 kt. Waves 1 ft.
Sun..SE winds 5 to 10 kt. Waves 1 ft. A chance of rain with patchy drizzle.
Sun night..SE winds 5 to 10 kt. Waves 1 ft. Rain likely.
Mon..SW winds 5 to 10 kt. Waves 1 ft. A chance of showers.
Mon night..SW winds around 5 kt. Waves 1 ft.
Tue..NW winds around 5 kt. Waves 1 ft. A chance of showers.
Wed..N winds 5 kt. Waves less than 1 ft. A chance of showers in the morning.
ANZ500 731 Am Edt Sat Mar 25 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure will remain over bermuda through today. A backdoor cold front will pass through the area tonight before returning north as a warm front Monday. A cold front is expected to cross the chesapeake bay region Tuesday night. Small craft advisories are possible for portions of the waters late tonight into Sunday and more likely Sunday night through Monday. Another small craft advisory is possible Wednesday behind the cold front.

7 Day Forecast for Marine Location Near Williamsport, MD
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location: 39.58, -77.81     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 250802
afdlwx
area forecast discussion
national weather service baltimore md/washington dc
402 am edt Sat mar 25 2017

Synopsis
High pressure over the western atlantic will be in control
today. A back door cold front will drop southwestward into the
area later tonight and Sunday. The front will lift back to the
north on Monday. Another cold front will drop back south across
the region later Tuesday or Tuesday night. The front will
stall to the south of our area through the rest of the week.

Near term /until 6 pm this evening/
As of 3am, an approximate 1032mb surface high pressure is
centered near bermuda, 1006mb low pressure is centered over
eastern oklahoma, and 1034mb surface high pressure is centered
over northern ontario. The canadian high pressure will shift
southeast to new england through tonight. This will cause a
backdoor cold front to cross the northern half of the CWA with
the bermuda high causing southerly flow south of the cold front.

Today, very warm with temperatures 10 to 15 degrees above
normal. Most uncertain area for maxt today is the northern tier
of counties where the southern section of an anafrontal zone
will persist. Thicker clouds and chances for rain may keep
temperatures in the mid 60s. Mid to upper 70s prevail south of
the anafront.

Short term /6 pm this evening through Monday night/
Confidence in a backdoor front and subsequent onshore flow/cold
air damming has increased, so temperatures were lowered below
guidance consensus particularly around baltimore where low 50s
are currently expected. Also, patchy drizzle was added to the
Sunday forecast generally blue ridge and east. A sharp gradient
between warm southerly flow and cool easterly flow is expected
over southern portions of the cwa. Subsequent shifts will need
to focus on this for the maxt forecast.

Guidance shifts the cad wedge north Sunday night. However, it
is wise to hold onto an onshore flow and lower temperatures
longer than guidance, so gradual improvement is given for
Monday.

Low pressure currently over oklahoma will continue to drift
northeast reaching the the midwest tonight before dissipating
over the great lakes under a northern stream ridge Sunday night.

A second low currently along the california coast will reach
the midwest Monday night before reaching the eastern great lakes
Tuesday (and also dissipating) per 00z ecmwf/gfs. Continued
moist southwesterly flow warrants high chance pops with slight
chance for thunder for the lwx CWA Monday. Possibly a break in
action, so Monday night was kept low at this time.

Long term /Tuesday through Friday/
Guidance is not in great agreement regarding the weather systems
in our region through the long term. However, most models agree
that we will start out in the warm sector on Tuesday. Tuesday
morning, the GFS has low pressure near lake erie, while the ec
has the low furthe southwest over southern indiana. GFS sends
the low east across the st. Lawrence valley and brings a cold
front south in the evening, while the ec solution is slower and
weaker with the low, with any frontal passage delayed until at
least early Wednesday. This system will bring a threat of
showers and thunderstorms with, with notable instablity progged
across our region in the warm sector. By late Wednesday, both
models have the front south of, with high pressure from canada
pushing cooler and drier air into the region. The remainder of
the week appears to be in the cool sector north of the front.

While Thursday starts out dry, by day's end models bring another
low pressure wave eastward into the region, with an increasing
risk of rain by Thursday night and Friday. This system appears
less likely to bring any thunder with it as current guidance
generally keeps the warm sector away from us, resulting in a
cool and rainy end of march.

Aviation /08z Saturday through Wednesday/
Vfr under high pressure and southerly flow through today.

Backdoor cold front shifts west across the dc metros tonight
with onshore flow 10 to 15 knots through Sunday. Drizzle and ifr
conds eventually develop and spread east to west late tonight
through Sunday.

Southwesterly flow from low pressure to the west/north Monday
brings rain showers to the dc metros Monday.

Thunderstorms are the main concern Tuesday. This concern will
end at night and Wednesday looksVFR with some gusty NW winds
likely behind a cold front.

Marine
Southerly flow 10 to 15 knots today interrupted by a backdoor
cold front tonight. Onshore flow expected Sunday into Monday
before shifting south.

Generally sub-sca swly flow prevails Monday.

Thunderstorms are possible Tuesday. SCA possible behind a cold
front Wednesday.

Lwx watches/warnings/advisories
Dc... None.

Md... None.

Va... None.

Wv... None.

Marine... Small craft advisory until 6 am edt early this morning for
anz532>534-536-537-540>543.

Synopsis... Rcm
near term... Baj
short term... Baj
long term... Rcm
aviation... Baj/rcm
marine... Baj/rcm


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 64 mi45 min S 6 G 8 59°F 47°F1022.3 hPa (+1.4)
BLTM2 - 8574680 - Baltimore, MD 69 mi45 min Calm G 1.9 59°F 45°F1021.8 hPa (+1.5)
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 72 mi45 min WSW 6 G 7 59°F 1022.1 hPa (+1.4)

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hagerstown, Washington County Regional Airport, MD10 mi52 minS 810.00 miPartly Cloudy59°F48°F67%1022.5 hPa
Eastern WV Regional Airport/Shepherd Field, WV15 mi52 minSSW 510.00 miFair61°F48°F63%1021.5 hPa

Wind History from HGR (wind in knots)
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Last 24hrS8S7S10S11S9S9S12S12S11S9S5S7S7S9S7S8S7S6S7S9S8S8S7S8
1 day agoNE6Calm3SW83E3S5S5S8S7SE5SE4E5SE7SE9S6S9S10S8S8S10S11S6S11
2 days agoNW21
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N13NW6NW8NE34NW5NE4E3N4CalmCalmN4N5CalmN7

Tide / Current Tables for Chain Bridge, Washington, D.C.
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Chain Bridge
Click for Map
Sat -- 01:35 AM EDT     0.33 feet Low Tide
Sat -- 05:41 AM EDT     Moonrise
Sat -- 07:03 AM EDT     Sunrise
Sat -- 07:18 AM EDT     2.94 feet High Tide
Sat -- 01:53 PM EDT     0.27 feet Low Tide
Sat -- 04:54 PM EDT     Moonset
Sat -- 07:25 PM EDT     Sunset
Sat -- 07:36 PM EDT     3.02 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.60.40.40.71.52.22.72.92.82.41.81.20.70.40.30.51.222.6332.72.11.5

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Sat -- 01:34 AM EDT     0.30 feet Low Tide
Sat -- 05:41 AM EDT     Moonrise
Sat -- 07:03 AM EDT     Sunrise
Sat -- 07:18 AM EDT     2.99 feet High Tide
Sat -- 01:51 PM EDT     0.25 feet Low Tide
Sat -- 04:54 PM EDT     Moonset
Sat -- 07:25 PM EDT     Sunset
Sat -- 07:35 PM EDT     3.08 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.60.40.30.71.52.22.832.92.51.81.20.70.40.30.51.222.7332.72.11.5

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 (9,2,3,4)
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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.