Friday, November27, 2020
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Marine Weather and Tides
North Chevy Chase, 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 7:03AMSunset 4:49PM Friday November 27, 2020 5:30 PM EST (22:30 UTC) Moonrise 3:33PMMoonset 4:17AM Illumination 94% Phase: Waxing Gibbous; Moon at 13 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- 343 Pm Est Fri Nov 27 2020
Rest of this afternoon..N winds 5 kt. Waves less than 1 ft. Scattered sprinkles.
Tonight..NW winds around 5 kt. Waves 1 ft. Scattered sprinkles.
Sat..NW winds 5 to 10 kt. Waves 1 ft.
Sat night..NW winds around 5 kt. Waves 1 ft.
Sun..S winds around 5 kt. Waves 1 ft.
Sun night..SE winds 5 kt. Waves less than 1 ft. Rain likely.
Mon..W winds 5 to 10 kt. Waves 1 to 2 ft. Showers, mainly in the morning.
Tue..W winds 5 to 10 kt. Waves 1 ft.
ANZ500 343 Pm Est Fri Nov 27 2020
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A cold front will cross the waters early Saturday. Small craft advisories may be needed for Saturday behind the front. A strong storm system will affect the region early next week with gale force conditions possible.


7 Day Forecast for Marine Location Near North Chevy Chase, MD
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location: 39, -77.09     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 271933 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 233 PM EST Fri Nov 27 2020

SYNOPSIS.

Weak high pressure remains situated over our region this afternoon. A weak cold front will pass through our region on Saturday with high pressure returning for the second half of the weekend. A strong system will impact our region late Sunday through early Tuesday. High pressure builds into our region from the south Tuesday through the middle parts of next week.

NEAR TERM /THROUGH SATURDAY/.

Weak high pressure is stretched over the the Northeastern US and parts of the mid-Atlantic this afternoon which has led to a very weak flow throughout our region. A weak disturbance aloft has kept skies mostly cloudy this afternoon. Current temperatures are running in the mid to upper 50s to lower 60s and I don't expect temperatures rise no more than one to two degrees over the next few hours. Overnight lows should be slightly cooler in the 30s and low 40s but will be limited from falling further due to lingering overnight clouds.

A weak cold front will pass through our region on Saturday. Moisture will be limited with this frontal passage and the wind shift be minimal behind the front. After the front passes through our region Saturday afternoon, skies will slowly clear with stronger high pressure building into our region from lower midwest and Tennessee River Valley. A brief surge of winds will be possible with the frontal passage with gusts of 15 to 25 knots possible Saturday afternoon. Little to no precipitation is expected for the majority of our region but some isolated to scattered upslope precipitation will be possible along and west of the Allegheny Front. Daytime high temperatures on Saturday will be cooler in the mid to upper 50s. High pressure will move overhead of our region Saturday evening which will lead to clear skies and light winds overnight and into Sunday morning. The coldest temps of the weekend will occur Saturday evening with overnight lows in the low to mid 30s.

SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/.

Weak upper level ridging will be in place over our region on Sunday with high pressure slowly shifting eastward out of our region later in the day. Clear skies along with light winds will continue through Sunday afternoon. The main change in the winds will be a slight shift out of the south but moisture transport should be minimal. Daytime temperatures will be similar to Saturday if not slightly cooler due to a lower morning start than the previous two days.

The weather pattern starts to change late Saturday afternoon and into Saturday evening. High pressure shifts off the coast and winds become more southeasterly. A strong frontal system will approach our region from the southwest Saturday evening. An upper level trough will move through parts of the southern US while a surface low slowly moves northeastward along the western side of the Appalachians. A secondary low is forecast to form off the east coast and move eastward early on Monday. The low moving along the Appalachians is forecast to occlude toward the upper level low and a triple point low will form as the system approaches our region. Precipitation associated with this system will start to impact our region after 00z Monday and widespread precipitation is forecast by 12Z. There remains some uncertainty on the timing and position of the multiple lows but a threat for strong gusty and thunderstorms will continue to be possible on Monday.

LONG TERM /MONDAY THROUGH FRIDAY/.

More agreement beginning to churn on the location of the cutoff low that will be impacting the area by late Sunday night into early Monday morning. Most models are agreeing on the center of the low to be over the WV/OH border by 12z Monday. Any variations in the dynamics of this system could cause a major shift in the forecast. For now, expect the likelihood for heavy rain and isolated instances of damaging winds possible Monday during the afternoon and early evening. Surface convective instability remains questionable at this point for the potential for thunderstorms. Given the chance for strengthening low and mid-level wind fields during the time period, expect gusty winds to be our main concern for Monday into early Tuesday. Flooding concerns remain low at this time given the speed of this system with QPF values only reaching around 1.25" for a 36 hour timeframe.

Upslope snow threat for along and west of the Allegheny Front will be the main concern after the low moves off and backside cold air moves in. This will continue from around Monday night until possibly Wednesday morning, confidence in duration and intensity is low at this time with respect to wintry impacts for those particular areas. On Monday, temperatures will be the warmest for the extended period at around 60F with this surge of moisture from the SSW keeping us in a warm, unstable pattern. Conditions should dry out for most of the area (aside from wintry precip for the western zones) Tuesday into Thursday with high pressure building in from the deep south. After the low passes on Monday night/Tuesday morning, we will see temperatures drop into the low to mid 40s for most of the workweek with overnight lows possibly getting to at or below freezing. Our western zones will be a few degrees colder for the duration, allowing for the chance for the wintry precip to occur at higher elevations.

AVIATION /20Z FRIDAY THROUGH WEDNESDAY/.

VFR conditions expected through Sunday. Winds will remain light out of the west to northwest through Saturday with a brief period of 15 to 25 knots gusts Saturday afternoon behind a weak front. High pressure will return for the second half off the weekend with light winds continue through Sunday. A strong surface low will start to impact all terminals early Monday morning. As rain moves into our region, some MVFR conditions can't be ruled out early Monday morning but there remains some uncertainty at this time.

Sub-VFR conditions expected most of Monday with gusty winds (25-30 knots). Ceilings and visibility restrictions within heavier pockets of rain, leading to some instances of IFR conditions. We'll remain windy for Tuesday after low pressure passes.

MARINE.

SubSCA conditions expected through the rest of today but low end small craft winds will be possible Saturday afternoon as a front moves through our marines areas. SubSCA return Saturday evening and into Sunday. A strong system will impact our marine areas early Monday morning.

SCAs and Gales possible Monday with low pressure passing through our waters. Winds will shift from the southeast to westerly by late Monday night. SCAs likely to remain through Tuesday behind the passing low.

TIDES/COASTAL FLOODING.

Strong onshore flow Monday into Monday night may lead to minor coastal flooding.

LWX WATCHES/WARNINGS/ADVISORIES. DC . None. MD . None. VA . None. WV . None. MARINE . None.

SYNOPSIS . JMG NEAR TERM . RCM/JMG SHORT TERM . JMG LONG TERM . ADM AVIATION . JMG/ADM MARINE . RCM/BRO/JMG/ADM TIDES/COASTAL FLOODING .


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 10 mi42 min W 1 G 1 58°F 50°F1016.3 hPa
BSLM2 - Chesapeake Bay, MD 25 mi60 min NE 1.9 1015 hPa
APAM2 - 8575512 - Annapolis, MD 32 mi42 min NNE 1.9 G 2.9 55°F 54°F1015.6 hPa
BLTM2 - 8574680 - Baltimore, MD 33 mi42 min SW 1.9 G 4.1 54°F 54°F1015.6 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 33 mi42 min SSE 4.1 G 4.1 53°F 1016 hPa
44063 - Annapolis 34 mi30 min 3.9 G 3.9 54°F 54°F1020.9 hPa (-1.1)
FSNM2 34 mi42 min ESE 4.1 G 4.1 56°F 1015.6 hPa
TPLM2 - Thomas Point, MD 35 mi30 min N 5.1 G 5.1 54°F 54°F1017 hPa (-1.0)47°F
CPVM2 37 mi42 min 54°F 47°F
44062 - Gooses Reef, MD 47 mi30 min NE 3.9 G 3.9 55°F 55°F
NCDV2 47 mi48 min Calm G 0 58°F 55°F1015.3 hPa
TCBM2 - 8573364 - Tolchester Beach, MD 47 mi48 min E 1 G 1.9 55°F 53°F1016.1 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
College Park Airport, MD9 mi55 minN 010.00 miPartly Cloudy56°F42°F61%1016.3 hPa
Washington/Reagan National Airport, DC, VA10 mi38 minNNW 310.00 miMostly Cloudy58°F45°F62%1016.4 hPa
Gaithersburg - Montgomery County Airport, MD12 mi34 minN 05.00 miOvercast with Haze55°F42°F62%1017.9 hPa
Camp Springs / Andrews Air Force Base, MD17 mi34 minN 010.00 miOvercast53°F44°F72%1016.6 hPa
Fort Meade / Tipton, MD18 mi55 minN 010.00 miPartly Cloudy54°F46°F77%1016.9 hPa
Fort Belvoir, VA19 mi34 minN 010.00 miOvercast58°F45°F62%1016.5 hPa
Washington/Dulles International Airport, DC, VA19 mi38 minN 010.00 miMostly Cloudy54°F46°F75%1016.3 hPa

Link to 5 minute data for KCGS

Wind History from CGS (wind in knots)
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Last 24hrN4CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmN3CalmCalmCalm
1 day agoS5CalmCalm--CalmCalmCalmCalmCalmCalmCalmCalmS5S5SW7W3W8W5CalmCalmW3W5N4N4
2 days agoCalmCalmCalmCalmCalmCalmS3S3CalmCalmS3S7CalmCalmS3S4SW8
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Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Fri -- 12:43 AM EST     0.11 feet Low Tide
Fri -- 04:17 AM EST     Moonset
Fri -- 06:28 AM EST     2.62 feet High Tide
Fri -- 07:04 AM EST     Sunrise
Fri -- 12:45 PM EST     0.07 feet Low Tide
Fri -- 03:32 PM EST     Moonrise
Fri -- 04:47 PM EST     Sunset
Fri -- 06:46 PM EST     2.90 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.20.10.51.11.72.32.62.62.11.50.90.50.20.10.41.11.82.42.82.92.62.11.40.9

Tide / Current Tables for Chain Bridge, one mile below, D.C.
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Chain Bridge
Click for Map
Fri -- 12:38 AM EST     0.11 feet Low Tide
Fri -- 04:17 AM EST     Moonset
Fri -- 06:23 AM EST     2.62 feet High Tide
Fri -- 07:04 AM EST     Sunrise
Fri -- 12:40 PM EST     0.07 feet Low Tide
Fri -- 03:32 PM EST     Moonrise
Fri -- 04:47 PM EST     Sunset
Fri -- 06:41 PM EST     2.90 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.20.10.51.21.82.32.62.52.11.50.90.40.10.10.41.11.92.42.82.92.621.40.9

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.