Monday, August21, 2017 L-36.com


Marine Weather and Tides
Halfway, MD

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 6:28AMSunset 7:59PM Monday August 21, 2017 12:38 AM EDT (04:38 UTC) Moonrise 5:12AMMoonset 7:05PM Illumination 1% Phase: Waning Crescent; Moon at 29 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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ANZ538 Patapsco River Including Baltimore Harbor- 1032 Pm Edt Sun Aug 20 2017
Rest of tonight..S winds 5 kt. Waves flat.
Mon..S winds 5 to 10 kt. Waves 1 ft or less. Scattered showers and tstms.
Mon night..S winds 5 to 10 kt. Waves 1 ft. Scattered showers and tstms.
Tue..SW winds 5 to 10 kt. Waves 1 ft.
Tue night..SW winds 5 to 10 kt. Waves 1 ft. A chance of showers and tstms.
Wed..NW winds 5 to 10 kt. Waves 1 ft. A chance of showers and tstms.
Wed night..N winds 5 kt. Waves less than 1 ft.
Thu..N winds 5 kt. Waves less than 1 ft.
Fri..N winds 5 kt. Waves less than 1 ft. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 1032 Pm Edt Sun Aug 20 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure will move offshore through tonight. A cold front will cross the waters late Tuesday night into early Wednesday. High pressure will return for the second half of the week. Small craft advisories will likely be needed Monday night through Wednesday night.

7 Day Forecast for Marine Location Near Halfway, MD
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location: 39.62, -77.79     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 210131 aaa
afdlwx
area forecast discussion... Updated
national weather service baltimore md washington dc
931 pm edt Sun aug 20 2017

Synopsis
High pressure over the area will move offshore tonight through
Monday. A cold front will approach the area Tuesday before
passing through Wednesday. High pressure will build in behind
the boundary for Thursday through Saturday.

Near term through Monday High pressure will remain in
control of the area through tonight although it will be moving
east with a light srly flow developing over western areas. Hi-
res guidance show isold random showers developing overnight, but
global models show nothing. Have kept mention of isold showers
but removed thunder given strong inversion around 700 mb seen on
00z iad sounding. Overall, sounding came in drier than 12 hrs
ago, so the risk of showers looks iffy.

Moisture and heat advect northward quickly during the day mon
leading to large instability values. Hi-res guidance show cape
values exceeding 2000 j kg due to temps in the low 90s and
dewpoints in the mid 70s. Convection may be limited due to
rising heights, but global and hi-res models show afternoon
convection developing which may become severe due to large cape
values and decent 0-6km shear. Risk appears greatest over
eastern areas. Heat indices will be around 100f. Raised
temperatures a few degs for both Mon and Tue with heat advisory
criteria possible for tue.

Short term Monday night through Tuesday night
Convection will likely be ongoing Monday night mainly near i-95
and east. Little change to the environment overnight into
Tuesday so leftover boundaries may cause a pop-up shower and
thunderstorm into Tuesday morning.

Warm and humid conditions will continue Tuesday as a cold front
crosses the ohio valley. Showers and thunderstorms are
possible... Especially late Tuesday into Tuesday night across
northern and central portions of the CWA closer to the cold front.

Some storms may be strong to severe given the instability and
strengthening shear profiles.

Long term Wednesday through Sunday
Most of the guidance is in decent agreement that the cold front
won't clear southern parts of the CWA (cho to southern md) by
Wednesday afternoon, which means another round of scattered showers
and thunderstorms will be possible for these areas. With the upper
trough diving down 0-6 km shear still modestly high (especially for
august), can't rule out a few strong to isolated severe storms for
this corridor Wednesday afternoon and early evening, as well.

A rather strong area of high pressure for this time of year (~1025
mb) will drop across the great lakes Wednesday night into Thursday
which should push the front well south. The high pressure center
will gradually weaken as it drifts just north of the area Friday
into the weekend, which should result in below average temperatures
and humidity with mainly clear and dry weather conditions.

Aviation 02z Monday through Friday
Light flow AOB 10 kts today gradually veers from W to SE by
evening. Lamp met guidance wants to bring in widespread ifr
vsbys but given climo synoptic setup believe this is over done.

MVFR vsbys CIGS psbl cho mrb included in taf, maybe iad bwi mtn
by daybreak but not confident enough to put in TAF at these
sites. May be vcsh near cho this aftn 20-23z but again
confidence too low coverage too sparse for taf.

Brief break in clouds (from bkn to sct) between 14-18z tue, then
back to bkn E of blue ridge (all terminals except mrb) W pop up
shower or TSTM seeming plausible 18-00z timeframe. Too sparse this
far out for mention in TAF just yet. Brief vsby restrictions psbl.

Tstm psbl Wed pm near cho, should stay S of dca iad unless
front slows its southward progress. Otherwise mainlyVFR. Generally
nw flow AOB 10 kts.

Marine
High pressure will hold over the waters through tonight. The
high will move offshore Monday through Monday night and a cold
front will approach the waters Tuesday through Tuesday night.

The boundary will pass through Wednesday and high pressure will
build over the waters for late next week. A small craft advisory
may be needed for portions of the waters Monday night through
Wednesday night.

Isolated thunderstorms are possible over the waters late tonight
through Monday morning. Scattered thunderstorms are possible Monday
afternoon and evening. Some storms may produce gusty
winds... Especially later Monday into Monday evening. A few showers
and thunderstorms are possible later Tuesday into Wednesday ahead of
a cold front as well... And some of these storms have the potential
to be strong to locally severe.

Northerly pressure surge channeling behind cold frontal
passage Wednesday into Wednesday night will likely require the
issuance of small craft advisories.

Lwx watches warnings advisories
Dc... None.

Md... None.

Va... None.

Wv... None.

Marine... None.

Update... Lfr
products... Hsk dfh woody!


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 66 mi51 min ESE 1 G 5.1 78°F 83°F1021.5 hPa
BLTM2 - 8574680 - Baltimore, MD 69 mi51 min Calm G 4.1 77°F 83°F1021.6 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 72 mi51 min S 4.1 G 5.1 77°F 1021.9 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hagerstown, Washington County Regional Airport, MD7 mi46 minN 010.00 miFair72°F63°F73%1022.8 hPa
Eastern WV Regional Airport/Shepherd Field, WV18 mi46 minN 010.00 miFair68°F64°F87%1021.6 hPa

Wind History from HGR (wind in knots)
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Last 24hrCalmCalmNE3CalmCalmS4S3CalmNW5CalmE4NW4CalmCalmW5W5W6CalmSE4SE4SE4SE3E6Calm
1 day agoW4W6SW43SE3CalmW5W4SW5SW5W6NW7W53SW8W9SW7W8SW3NW7
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2 days agoS5S3S3SE4S4S63S9S6S9S7S8S10SW12
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Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Mon -- 03:05 AM EDT     0.07 feet Low Tide
Mon -- 06:10 AM EDT     Moonrise
Mon -- 06:27 AM EDT     Sunrise
Mon -- 08:45 AM EDT     3.67 feet High Tide
Mon -- 02:31 PM EDT     New Moon
Mon -- 03:46 PM EDT     -0.06 feet Low Tide
Mon -- 07:54 PM EDT     Sunset
Mon -- 08:00 PM EDT     Moonset
Mon -- 09:17 PM EDT     3.42 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.40.80.30.10.31.12.133.53.73.32.61.91.30.70.1-00.41.42.333.43.32.7

Tide / Current Tables for Chain Bridge, Washington, D.C.
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Chain Bridge
Click for Map
Mon -- 03:03 AM EDT     0.07 feet Low Tide
Mon -- 06:10 AM EDT     Moonrise
Mon -- 06:27 AM EDT     Sunrise
Mon -- 08:43 AM EDT     3.67 feet High Tide
Mon -- 02:31 PM EDT     New Moon
Mon -- 03:44 PM EDT     -0.06 feet Low Tide
Mon -- 07:54 PM EDT     Sunset
Mon -- 08:00 PM EDT     Moonset
Mon -- 09:14 PM EDT     3.40 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.30.80.30.10.31.12.233.63.63.32.61.91.20.60.1-00.51.42.33.13.43.22.7

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 (0,6,7,8)
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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.