Friday, September18, 2020
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Marine Weather and Tides
St. James, MD

Version 3.4
NOTICE
8/26/2020 The 7 day forecast is taking about 5 seconds to load but it will eventually load. NOAA is still working on it.
8/18/2020 NOAA continues to have trouble. Wind guest will occasionally be left off graphs. I am working with NOAA to resolve the issue.
12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed.
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.

Sunrise 6:54AMSunset 7:15PM Friday September 18, 2020 7:00 AM EDT (11:00 UTC) Moonrise 7:07AMMoonset 7:22PM Illumination 1% Phase: Waxing Crescent; Moon at 1 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- 437 Am Edt Fri Sep 18 2020
.small craft advisory in effect through this evening...
Rest of the overnight..NE winds 5 kt. Waves less than 1 ft. Showers likely.
Today..N winds 10 to 15 kt. Waves 1 ft. Showers likely.
Tonight..N winds 10 to 15 kt. Waves 1 ft.
Sat..N winds 5 to 10 kt. Waves 1 ft.
Sat night..NE winds 5 kt. Waves less than 1 ft.
Sun..NE winds 5 to 10 kt. Waves 1 ft.
Sun night..NE winds 5 kt. Waves less than 1 ft.
Mon..NW winds around 5 kt. Waves 1 ft.
Tue..NW winds 5 kt. Waves less than 1 ft.
ANZ500 437 Am Edt Fri Sep 18 2020
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A cold front will cross the middle atlantic early today as the remnants of sally move off the carolina coast. Canadian high pressure will follow for the weekend into early next week. Small craft advisories may be needed 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 180807 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 407 AM EDT Fri Sep 18 2020

SYNOPSIS. A cold front will cross the Middle Atlantic early today as the remnants of Sally move off the Carolina coast. Canadian high pressure will follow for the weekend into early next week.

NEAR TERM /THROUGH TONIGHT/. Patchy fog or light drizzle north of U.S. 50 and along and west of the Blue Ridge Mountains through daybreak. Areas to the south and east will see light rain or moderate drizzle end from northwest to southeast by daybreak.

Cloudy skies will break for some sunshine around midday today and continue through this afternoon. High pressure will build in from the northwest today and tonight, bringing dry conditions and cooler temperatures, especially at night. A gusty northerly wind of 25 to 30 mph is possible around midday and this afternoon.

High temperatures should reach 70 degrees for most of the region this afternoon. Temperatures will be cool tonight, generally in the 40s and 50s.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/. The cooler temperatures will prevail Saturday with highs in the 60s. Low temperatures Saturday night will likely dip into the 40s for most, with 30s in outlying areas where winds go light. Patchy frost is possible where temperatures dip into the middle 30s.

High pressure will remain in control Sunday and Sunday night, as well. Cooler than average temperatures expected with a steady north to northeast wind.

LONG TERM /MONDAY THROUGH THURSDAY/. A relatively quiet pattern will reign through the long term. At the start, northerly flow aloft will dominate as a closed low sits over the western Atlantic and a ridge is positioned over the south- central US. This will result in a cool high pressure centered over the St. Lawrence Valley to our north and a surface low (Teddy?) well east of the coast, with a northerly surface flow as well.

The upper-level pattern will continue essentially unchanged on Tuesday, though the surface high will shift further south towards the southern Appalachians while the surface low (Teddy?) will shift northward well off the coast.

By Wednesday, the closed upper low will open up and lift northeast, with the upper ridge migrating eastward. This will allow surface low pressure (Teddy?) to retreat northeast further away into the Canadian Maritimes with surface high pressure to our south, allowing a milder flow of air to reach us.

By Thursday, the upper ridge will be over our region, but weakening and transient by this point as another upper shortwave approaches from the northwest. At the surface, this will mean we have a cold front approaching from the northwest, but a mild air mass will remain in place.

With no features of significance actually crossing our region, the chance of precip will be near zero, but temperatures will change noticeably, with below normal readings Monday rising to slightly above normal by Thursday.

AVIATION /08Z FRIDAY THROUGH TUESDAY/. Brief IFR conditions at a few terminals due to low cigs and/or visbis to start this morning. Otherwise, VFR conditions will gradually unfold from northwest to southeast with arrival of drier air and a modest northerly wind.

VFR conditions again tonight through Sunday night.

No restrictions are expected Monday and Tuesday as high pressure should dominate with northerly winds and clear to partly cloudy skies. Little if any fog is anticipated as well.

MARINE. Small craft Advisories are in effect through tonight. These may need to be expanded in time through Saturday midday. Otherwise, no marine hazards Saturday night through Sunday night.

Small Craft Advisory conditions are possible Monday and Tuesday as surface high pressure to the north and west interacts with a potential low pressure (Teddy?) as it passes well to our east.

TIDES/COASTAL FLOODING. Northerly flow behind a cold front today should cause water levels to decrease especially over the upper tidal Potomac River and upper reaches of the Chesapeake Bay, but excess water will probably get trapped over the lower parts of the bay. This water may return north later this weekend.

LWX WATCHES/WARNINGS/ADVISORIES. DC . None. MD . None. VA . None. WV . None. MARINE . Small Craft Advisory until 6 AM EDT Saturday for ANZ530>533- 536-538>542. Small Craft Advisory until 6 AM EDT Saturday for ANZ534-537- 543. Small Craft Advisory until midnight EDT tonight for ANZ535.

SYNOPSIS . RCM/KLW NEAR TERM . KLW SHORT TERM . KLW LONG TERM . RCM AVIATION . RCM/KLW MARINE . RCM/KLW TIDES/COASTAL FLOODING . DHOF/RCM


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 63 mi43 min N 2.9 G 8 68°F 75°F1012.4 hPa
BLTM2 - 8574680 - Baltimore, MD 67 mi43 min NNE 7 G 9.9 65°F 76°F1012 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 71 mi43 min N 8.9 G 9.9 65°F 1012.2 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 mi68 minNNW 67.00 miFair59°F55°F90%1014.5 hPa
Eastern WV Regional Airport/Shepherd Field, WV17 mi68 minN 510.00 miFair59°F57°F93%1013.4 hPa
Frederick Municipal Airport, MD24 mi66 minNNE 47.00 miFair59°F57°F94%1013.5 hPa

Link to 5 minute data for KHGR

Wind History from HGR (wind in knots)
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Last 24hrCalmCalmCalmCalmCalmCalmW4CalmCalmSE3CalmCalmCalmCalmCalmNW3N4CalmCalmNW5NW6NW6N6NW7
1 day agoCalmCalmCalmS7S9SW10S9
G16
SW9SW6SE10S12S8S6S4S6S5S3S3CalmCalmCalmSE4CalmCalm
2 days agoN6N4N6NE5CalmCalmNE33CalmCalmCalmSW3S3SE3E5SE4CalmCalmCalmCalmCalmCalmCalmCalm

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Fri -- 04:15 AM EDT     0.05 feet Low Tide
Fri -- 06:53 AM EDT     Sunrise
Fri -- 08:04 AM EDT     Moonrise
Fri -- 09:48 AM EDT     3.64 feet High Tide
Fri -- 04:35 PM EDT     -0.05 feet Low Tide
Fri -- 07:11 PM EDT     Sunset
Fri -- 08:19 PM EDT     Moonset
Fri -- 10:11 PM EDT     3.74 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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2.31.50.90.40.10.20.91.92.93.53.63.32.61.810.40-00.51.52.63.43.73.6

Tide / Current Tables for Chain Bridge, one mile below, D.C.
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Chain Bridge
Click for Map
Fri -- 04:10 AM EDT     0.05 feet Low Tide
Fri -- 06:52 AM EDT     Sunrise
Fri -- 08:04 AM EDT     Moonrise
Fri -- 09:43 AM EDT     3.64 feet High Tide
Fri -- 04:30 PM EDT     -0.05 feet Low Tide
Fri -- 07:11 PM EDT     Sunset
Fri -- 08:19 PM EDT     Moonset
Fri -- 10:06 PM EDT     3.74 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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2.21.50.80.30.10.21233.53.63.22.51.710.4000.61.62.73.53.73.5

Weather Map
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wmap_A
GEOS 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.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East
Ground Weather Radar Station Sterling, VA
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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 numerous 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.