Monday, January25, 2021
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Marine Weather and Tides
Glassmanor, MD

Version 3.4
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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 7:17AMSunset 5:23PM Monday January 25, 2021 2:44 PM EST (19:44 UTC) Moonrise 2:23PMMoonset 4:51AM Illumination 93% Phase: Waxing Gibbous; Moon at 12 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- 1252 Pm Est Mon Jan 25 2021
This afternoon..E winds 5 kt. Waves less than 1 ft. Rain. Vsby 1 to 3 nm.
Tonight..E winds 5 to 10 kt. Waves 1 ft. Rain, snow with a chance of freezing rain. Vsby 1 to 3 nm.
Tue..E winds around 5 kt. Waves 1 ft. Rain.
Tue night..NW winds around 5 kt. Waves 1 ft.
Wed..NW winds 5 kt. Waves less than 1 ft.
Wed night..N winds 5 to 10 kt with gusts to 20 kt. Waves 1 ft. A chance of snow and rain.
Thu..NW winds 10 to 15 kt. Waves 1 ft.
Fri..NW winds 5 to 10 kt. Waves 1 ft.
ANZ500 1251 Pm Est Mon Jan 25 2021
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Low pressure will approach today before passing through Tuesday. High pressure will briefly return Wednesday, but low pressure may impact the waters Wednesday night and Thursday. High pressure will return late in the week. A small craft advisory may be needed for portions of the waters Tuesday, and again Thursday into Friday. Gale force winds will be possible on Thursday, possibly into Friday morning.


7 Day Forecast for Marine Location Near Glassmanor, MD
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location: 38.83, -77     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 251530 AAA AFDLWX

Area Forecast Discussion . UPDATED National Weather Service Baltimore MD/Washington DC 1030 AM EST Mon Jan 25 2021

SYNOPSIS. A frontal system will bring wintry precipitation to the region this evening into Tuesday. Another system may impact our region late Wednesday into early Thursday. High pressure builds into the early parts of this weekend before another system potentially impacts our region on Sunday.

NEAR TERM /THROUGH TUESDAY/.

Forecast confidence on p-type and specific snow/ice amounts continues to be lacking due to spread among guidance on temps aloft, isothermal layer seen on model soundings, and very cold sounding seen this morning at IAD. Tried to maintain as much as consistency with previous forecast as possible, however, some adjustments were made to the 90th percentile or reasonable worst case scenario for snow amounts now showing a max of 5 inches across the north and 2-3 inches (reasonable worst case) for areas around the Capital Beltway. This is to account for the higher than normal uncertainty in the forecast. Did also some adjustments to the precip onset graphic, a little quicker in the southwest and a little slower in the northeast mainly after 7PM. QPF amounts in the 18Z-00Z today time frame were also lowered somewhat in the southwest based on 06Z ECMWF ensembles and slow progression on precip on regional radars.

Previous afd .

The first band of precipitation should start to affect our region during the middle parts of this afternoon and should overspread from south to north through this evening. This precipitation will be driven by warm air overrunning the warm front and the cold air in place at the surface. As the precipitation moves into our region, it will likely fall as rain or a wintry mix of snow and freezing rain as surface temperatures will begin above freezing but are expected to slowly drop into this evening as weak cold air damming sets up. The exact nature of the precipitation is still uncertain as it will heavily depend how quickly the overruning warm air layer aloft can move northward into our region. Guidance is split on precipitation falling as a combination of snow and rain or more of wintry mix with a focus on freezing rain. General model trends have slowed the progression of the mid level warm layer which suggests that additional snow could occur ahead a transition over to freezing rain and a wintry mix.

The main surface low will progress through our region early Tuesday morning bringing the heaviest precipitation to our region between 21Z Monday and 6Z Tuesday. As the precipitation progresses further northward into parts of northern Virginia and up into northern Maryland, the temps in the thermal layer aloft will be much cooler which will lead to higher snow amounts along the northern parts of our forecast area. Areas along the Mason Dixon Line will likely see a heavier dose of snow and sleet as the warm layer is smaller which will prevent snow from full melting before it reaches the ground. The transition period to freezing rain and a wintry mix seems to occur during the 00Z to 6Z period on Tuesday with the best ice accumulations occurring between 00z and 12Z. As a starting point, I started with WPC QPF and blended in some Euro and NAM to bring totals down. I generally got ice totals of a tenth to a quarter of an inch. I adjusted ice amounts up over parts of the the Potomac Highlands, the Blue Ridge Mountains and the Allegheny front to account for HREF hinting at higher quarter inch plus ice amounts. Generally I went with 0.24 to 0.4 inches of ice for areas in western Maryland and eastern WV along with the higher elevations. We have issued Winter Storm Warnings for these areas. There remains some uncertainty on the thermal layer as some models have threshold freezing temps or almost isothermal atmospheric profiles. Precipitation should progress northeastward through our region and wintry precipitation should start to transition back over to all rain as the temperatures rise on Tuesday. Rain will continue to be possible through the afternoon periods on Tuesday with precip fully tapering off after 00Z on Wednesday. Afternoon temperatures on Tuesday will be slightly warmer in the upper 30s to low 50s in central Virginia.

Lingering snow showers will be possible late Tuesday into early Wednesday along the Allegheny front due to some westerly up slope induced snow showers. Overnight temperatures will be seasonable in the 30s.

SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/. Weak ridging builds to the north of our region on Wednesday. Winds will become more northwesterly but will remain light. Skies should remain mostly cloudy with brief periods of sun. A frontal boundary will remain stalled to our south over parts of the Carolinas. A surface low is forecast to form along this boundary and move eastward to the south of our region. High pressure will build over the northeastern US which will help funnel cooler air into our region during the later parts of Wednesday and into Thursday. As the low moves to our south and pulls off the eastern seaboard, precipitation on the northern and northwestern edges of the system could move up into our region. Since temperature will be well below freezing aloft, any precipitation that falls will fall as either rain or snow. Any precipitation should transition fully to snow by 6Z on Thursday. Daytime temperatures on Wednesday will trend upwards into the 40s with overnight lows in the mid to upper 20s to low 30s.

LONG TERM /THURSDAY THROUGH SUNDAY/. Guidance has gradually come into better agreement regarding the system Thursday, with more models now keeping the storm suppressed to the south and bombing too late to bring much impact to our area other than wind. Thursday looks chilly and windy, but otherwise, generally dry. Will have to watch for a northward trend as we get closer, but certainly at this moment, the trend is our friend (if you don't like snow).

Upper disturbance with a possible surface reflection will pass to our northeast Friday. This could result in a few flurries or a snow shower with continued gusty northwest winds (but not as strong as Thursday), but otherwise, fairly dry for the end of the week.

High pressure will dominate Saturday with a little moderation in temps. However, by Sunday, another system is pushing northeastward towards us, with warm advection precip breaking out in our region by day's end. Cold air looks marginal by this point, so while a mix may start, this again looks like a system which will transition to more liquid than frozen. The low track towards the lower Great Lakes certainly will not help keep the cold air around, though some damming could result in more wintry mix in the favored spots northwest of I-95.

AVIATION /16Z MONDAY THROUGH FRIDAY/. Overcast skies along with winds becoming easterly are expected through this morning. A mix of rain and wintry precipitation will start to impact our terminals early this afternoon with CHO being the first impacted. Precipitation should overspread all terminals by 00z with MVFR visibilities and ceilings likely with IFR ceilings possible. Icing will be a big concern for terminals west of I-95 and north of DC. DCA should see minimal wintry impacts from this system. The best chance for freezing rain and ice will be between 00Z and 12Z Tuesday morning. Wintry precipitation should transition over to all rain by the middle parts of Tuesday morning and precipitation should start to taper for all terminals by late afternoon. VFR conditions should return by Wednesday morning with winds becoming westerly Tuesday afternoon and then northwesterly by Wednesday. VFR conditions expected through Wednesday but wintry precipitation could impact our terminals once again late Wednesday and into early Thursday with the most likely impacted terminals being CHO.

Strengthening storm off the coast will likely bring gusty north to northwest winds of 25-35 knots Thursday, with winds diminishing a bit Friday. VFR otherwise Thursday and Friday as high pressure builds in.

MARINE. Low chance for Small Craft Advisory Conditions today but a brief surge of winds will be possible early Tuesday morning which may require a brief SCA. SubSCA conditions expected Tuesday into Wednesday afternoon. A strong low pressure passing to the south and southeast of our waters will likely bring high end Small Craft Advisory winds to all off our waters early Thursday morning. I can't fully rule out a brief period of Gale conditions for our southern Chesapeake Bay zones early on Thursday.

Strengthening storm off the coast will bring a good chance of gales Thursday as it slowly moves away. Winds should relax a bit Friday as high pressure slowly builds in, but Small Craft Advisories still looks probable at week's end.

LWX WATCHES/WARNINGS/ADVISORIES. DC . None. MD . Winter Storm Warning until 7 AM EST Tuesday for MDZ001-501-502. Winter Weather Advisory from 4 PM this afternoon to 10 AM EST Tuesday for MDZ003>006-008-011-503>508. VA . Winter Storm Warning until 7 AM EST Tuesday for VAZ503-504-507- 508. Winter Weather Advisory until 7 AM EST Tuesday for VAZ025>031- 038>040-501-505-506. WV . Winter Storm Warning until 7 AM EST Tuesday for WVZ050-055- 501>506. Winter Weather Advisory from 4 PM this afternoon to 10 AM EST Tuesday for WVZ051>053. MARINE . None.

SYNOPSIS . LFR NEAR TERM . LFR SHORT TERM . JMG LONG TERM . RCM AVIATION . RCM/LFR MARINE . RCM/LFR/JMG


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 3 mi56 min 38°F 39°F1019 hPa
BSLM2 - Chesapeake Bay, MD 16 mi74 min S 2.9 38°F 1018 hPa21°F
APAM2 - 8575512 - Annapolis, MD 30 mi56 min 36°F 39°F1018.6 hPa
TPLM2 - Thomas Point, MD 30 mi44 min ENE 5.1 G 5.1 35°F 39°F1019.9 hPa (-2.6)20°F
CPVM2 34 mi56 min 35°F 20°F
NCDV2 35 mi56 min 40°F 39°F1017.8 hPa
44062 - Gooses Reef, MD 36 mi44 min ENE 5.8 G 5.8 37°F 41°F1 ft999.4 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 37 mi56 min 34°F 1019.2 hPa
FSNM2 37 mi56 min 34°F 1018.4 hPa
BLTM2 - 8574680 - Baltimore, MD 38 mi56 min 35°F 42°F1018.5 hPa
COVM2 - 8577018 - Cove Point LNG Pier, MD 44 mi80 min NNW 1.9 G 1.9 38°F 1019.4 hPa
SLIM2 - 8577330 - Solomons Island, MD 46 mi56 min 38°F 41°F1018.4 hPa
TCBM2 - 8573364 - Tolchester Beach, MD 48 mi56 min 35°F 38°F1019.1 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Washington/Reagan National Airport, DC, VA3 mi52 minE 410.00 miOvercast39°F23°F53%1019 hPa
Camp Springs / Andrews Air Force Base, MD7 mi48 minESE 310.00 miOvercast37°F21°F51%1019.2 hPa
College Park Airport, MD11 mi49 minE 410.00 miOvercast36°F15°F42%1018.6 hPa
Fort Belvoir, VA12 mi48 minE 510.00 miMostly Cloudy40°F24°F54%1018.6 hPa
Fort Meade / Tipton, MD22 mi49 minE 410.00 miOvercast36°F19°F52%1019.6 hPa

Link to 5 minute data for KDCA

Wind History from DCA (wind in knots)
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Last 24hrNW3CalmCalmW5SW5S4CalmS3S3SE4SE3SE3SE3E3E5E4NE4NE6E6NE8NE6NE6E6E4
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Tide / Current Tables for Reagan National Airport, Washington, D.C.
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Reagan National Airport
Click for Map
Mon -- 12:02 AM EST     0.09 feet Low Tide
Mon -- 04:51 AM EST     Moonset
Mon -- 05:46 AM EST     2.35 feet High Tide
Mon -- 07:19 AM EST     Sunrise
Mon -- 11:43 AM EST     0.04 feet Low Tide
Mon -- 02:22 PM EST     Moonrise
Mon -- 05:21 PM EST     Sunset
Mon -- 05:53 PM EST     2.75 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.10.30.81.41.92.32.32.11.50.90.40.100.30.91.72.32.62.72.521.50.90.5

Tide / Current Tables for Key Bridge, D.C.
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Key Bridge
Click for Map
Mon -- 12:10 AM EST     0.09 feet Low Tide
Mon -- 04:51 AM EST     Moonset
Mon -- 05:55 AM EST     2.27 feet High Tide
Mon -- 07:19 AM EST     Sunrise
Mon -- 11:51 AM EST     0.04 feet Low Tide
Mon -- 02:22 PM EST     Moonrise
Mon -- 05:21 PM EST     Sunset
Mon -- 06:02 PM EST     2.65 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.10.20.71.31.82.12.321.50.90.40.100.20.71.52.12.52.62.52.11.510.5

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.
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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 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.