Monday, November30, 2020
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Marine Weather and Tides
Silver Spring, 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 7:05AMSunset 4:47PM Monday November 30, 2020 11:41 AM EST (16:41 UTC) Moonrise 5:06PMMoonset 7:15AM Illumination 100% Phase: Full Moon; Moon at 15 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- 945 Am Est Mon Nov 30 2020
.gale warning in effect until 6 pm est this evening...
.small craft advisory in effect from 6 pm est this evening through this evening...
Rest of today..S winds 15 to 20 kt with gusts to 35 kt. Waves 1 to 2 ft. Rain late this morning, then numerous showers with a slight chance of tstms this afternoon. Vsby 1 to 3 nm late this morning.
Tonight..W winds 5 to 10 kt. Gusts up to 20 kt early in the evening. Waves 1 ft.
Tue..W winds 10 to 15 kt. Gusts up to 20 kt. Waves 1 ft.
Tue night..SW winds 5 to 10 kt. Waves 1 ft.
Wed..W winds 5 to 10 kt. Waves 1 ft.
Wed night..W winds around 5 kt. Waves 1 ft.
Thu..SW winds around 5 kt. Waves 1 ft.
Fri..W winds 5 kt. Waves less than 1 ft. A chance of showers. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 945 Am Est Mon Nov 30 2020
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A strong storm system will affect our marine areas through this evening. High pressure will build from the midwest to off the southern middle atlantic coast Wednesday into Thursday, then another low pressure system will likely approach from the tennessee river valley Friday. Small craft advisories may be needed Tuesday into Wednesday.


7 Day Forecast for Marine Location Near Silver Spring, MD
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location: 39, -77     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 301524 AAA AFDLWX

Area Forecast Discussion . UPDATED National Weather Service Baltimore MD/Washington DC 1024 AM EST Mon Nov 30 2020

SYNOPSIS.

Strong low pressure will move across the area this afternoon and off to the northeast this evening. High pressure will gradually build over the area by Thursday morning. Another storm system may impact the area at the end of the week or early next week.

NEAR TERM /UNTIL 6 PM THIS EVENING/.

Steady rainfall has ended but a new round of showers with some embedded thunder per GLM is working its way northeastward in association with a low pressure lifting NNE. Given strong wind profiles and limited instability, a risk of severe wx exists mainly in the 17Z-20Z time frame. Short lines capable of producing damaging wind guss and perhaps an isolated brief tornado are possible mainly east of Rt 15. Svr threat should end by 21Z.

SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/. By early this evening, the upper low which materalizes from the mentioned phasing process will track from the Ohio Valley into the Central Appalachians. Substantial cooling of the column is expected to take shape with 700-mb temperatures dropping around 10 to 15 degrees over a 24 hour period. Precipitation over along and west of the Allegheny Front will switch over to snow by later this evening. Forecast soundings show moisture should be shallow at the onset which would mitigate initial accumulation potential. Heading into the overnight hours, a steady period of westerly upslope takes shape across far western Maryland and east-central West Virginia. The heaviest snow is likely to fall from early Tuesday morning into the evening. Consequently, a Winter Storm Warning is in effect for Garrett County with Winter Weather Advisories out for western portions of Grant and Pendleton Counties. Expect 4 to 6 inches of snow with isolated amounts approaching 8 inches over higher elevations of western Garrett County. Some lingering snow showers are possible into Tuesday night as the upper low lifts into New England. Wednesday should provide tranquil weather across the region as a shortwave ridge moves through.

After a warm start to the work week, a pronounced cool down will arrive in earnest. Tuesday's temperatures may be around 20 degrees lower than the previous day as highs struggle to escape the 40s. Higher elevations are to stay in the upper 20s to low 30s. Blustery conditions will lower wind chills into the low/mid 30s across the DC and Baltimore metro areas. By mid- week, temperatures may creep back up to low 50s in a few spots. Departures from climatology will run around 4 to 8 degrees, a bit higher in the mountains.

LONG TERM /THURSDAY THROUGH SUNDAY/. A very blocky pattern is forecast by pretty much all medium range guidance later this week, with two highly anomalous ridges centered over southwestern to central Canada and over the North Atlantic Ocean up Davis Strait between Canada and Greenland. In between, two cutoff lows are forecast to be centered over Newfoundland Canada and near the middle Mississippi River Valley. This pattern has a -NAO/+PNA appearance to it, but with a lack of higher height anomalies/lack of stronger ridging over the North Pole itself, the result will probably be near to slightly below (as opposed to well below) normal temperatures locally.

With this type of amplified pattern also comes the potential for phasing of the two branches of the jet stream and increased storminess. Not unexpectedly, medium range guidance develops another area of low pressure at the surface ahead of the aforementioned cutoff low as it approaches the Tennessee River Valley. Also not unexpectedly is the uncertainty in the details regarding the track, strength and sensible weather impacts to our region.

Precipitation chances will likely peak on Friday based on the latest guidance and overall pattern. Given the current expectation that temperatures will be near to perhaps slightly below normal, any precipitation should fall in the form of mainly rain east of the higher terrain, though another period of upslope snow would be possible along and west of the Allegheny Front in this scenario.

High pressure and brisk conditions will likely return to the area for the weekend before another storm system possibly approaches early next week.

AVIATION /15Z MONDAY THROUGH FRIDAY/. Showers will continue and conditions will likely remain MVFR or lower through at least midday.

Conditions start to improve mid to late this afternoon, but isolated thunderstorms will become a risk, with strong wind gusts possible near convection, even though it may not contain lightning. Have not included thunder in the TAFs yet since there is not a consolidated/confident risk.

VFR likely by tonight through Tuesday night with mainly dry conditions but west-northwesterly winds will gust up to 25 knots at times. Continued VFR conditions expected on Wednesday with westerly wind gusts around 15 to 20 knots.

Mainly VFR Thu-Fri AM w/ light SW-S wind. Sub-VFR possible by late Fri PM due to increasing chc for RA as wind turns SE.

MARINE. Southeasterly winds will increase through mid morning. Despite weak mixing, a very strong gradient should overcome that, resulting in gusts around 35 to 40 knots. Consequently, Gale Warnings are in effect across all waters through 6 PM this evening.

Showers and isolated thunderstorms with strong winds may develop this afternoon as well, with a lower risk during the late morning. A waterspout can't be ruled out. Gales relax behind cold front this evening, but SCA gusts likely continue through Tuesday night, peaking during the daylight hours (and potentially dropping sub-SCA during the overnight on the sheltered waters). Marginal SCA conditions materialize on Wednesday given a steady period of cool westerly winds on top of the still mild waters.

A light southwesterly wind is forecast Thursday as high pressure passes to the south, becoming southerly Thursday night into Friday as the high moves offshore. The wind may begin to increase as it turns southeasterly ahead of a low pressure system approaching from the Tennessee River Valley by late Friday.

TIDES/COASTAL FLOODING.

Large spread is seen among various surge models with the P-ETSS the most pessimistic and also looking less likely to verify basen on latest observations from tide gauges. The forecast is based on a blend of ETSS and ESTOFS and have issued a CF.Y for Annapolis, Baltimore, and Washington DC.

The wind is forecast to become westerly by this evening. This should cause water levels to recede rather steadily through the middle of the week, precluding any further flooding concerns.

LWX WATCHES/WARNINGS/ADVISORIES. DC . Coastal Flood Advisory from 5 PM this afternoon to 10 PM EST this evening for DCZ001. MD . Coastal Flood Advisory from 3 PM this afternoon to 9 PM EST this evening for MDZ014. Winter Storm Warning from 1 AM Tuesday to 7 AM EST Wednesday for MDZ001. Coastal Flood Advisory from 4 PM this afternoon to 10 PM EST this evening for MDZ011. VA . None. WV . Winter Weather Advisory from 4 AM to 7 PM EST Tuesday for WVZ501-505. MARINE . Small Craft Advisory from 6 PM to 10 PM EST this evening for ANZ530>532-535-536-538>542. Gale Warning until 6 PM EST this evening for ANZ530>543. Small Craft Advisory from 6 PM this evening to 6 AM EST Tuesday for ANZ533-534-537-543.

SYNOPSIS . BRO NEAR TERM . LFR SHORT TERM . BRO LONG TERM . BRO/DHOF AVIATION . LFR/DHOF MARINE . LFR/DHOF TIDES/COASTAL FLOODING . LFR


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 9 mi54 min SW 9.9 G 16 51°F996.4 hPa
BSLM2 - Chesapeake Bay, MD 22 mi72 min S 11 997 hPa
APAM2 - 8575512 - Annapolis, MD 28 mi54 min SSE 13 G 20 53°F996.6 hPa
44063 - Annapolis 29 mi36 min 21 G 25 59°F 53°F998.9 hPa
BLTM2 - 8574680 - Baltimore, MD 29 mi54 min S 5.1 G 9.9 53°F996.4 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 29 mi54 min S 12 G 15 996.7 hPa
FSNM2 29 mi54 min S 14 G 20 996.1 hPa
TPLM2 - Thomas Point, MD 31 mi42 min SE 27 G 30 60°F 53°F997 hPa (-3.4)60°F
CPVM2 32 mi72 min 61°F 60°F
TCBM2 - 8573364 - Tolchester Beach, MD 43 mi54 min S 11 G 16
44062 - Gooses Reef, MD 44 mi36 min S 19 G 21 58°F 55°F
NCDV2 47 mi54 min S 12 G 16

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
College Park Airport, MD4 mi47 minS 80.50 miOvercast61°F59°F94%996.3 hPa
Washington/Reagan National Airport, DC, VA10 mi50 minWSW 11 G 240.50 miRain Fog64°F62°F93%996.9 hPa
Camp Springs / Andrews Air Force Base, MD14 mi46 minSSE 18 G 2910.00 miOvercast and Breezy64°F63°F100%996.5 hPa
Fort Meade / Tipton, MD14 mi47 minSSW 7 G 160.25 miOvercast61°F60°F100%996.9 hPa
Gaithersburg - Montgomery County Airport, MD15 mi46 minSE 44.00 miRain Fog/Mist59°F57°F96%998.3 hPa
Fort Belvoir, VA21 mi1.8 hrsN 04.00 miRain Fog/Mist61°F59°F95%997.9 hPa
Baltimore, Baltimore-Washington International Airport, MD22 mi48 minSE 10 G 150.50 miHeavy Rain Fog61°F59°F93%996.8 hPa
Washington/Dulles International Airport, DC, VA24 mi50 minS 52.00 miLight Rain Fog/Mist58°F57°F97%996.6 hPa

Link to 5 minute data for KCGS

Wind History from CGS (wind in knots)
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Last 24hrS3CalmS3CalmS4CalmCalmCalmCalmCalmCalmCalmCalmN3CalmCalmCalmE4CalmNW3E5CalmS3SW7
1 day agoNW12
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NW5NW4CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalm
2 days agoCalmCalmN3CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmW7NW10
G15

Tide / Current Tables for Benning Bridge, D.C.
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Benning Bridge
Click for Map
Mon -- 02:52 AM EST     0.05 feet Low Tide
Mon -- 04:32 AM EST     Full Moon
Mon -- 07:06 AM EST     Sunrise
Mon -- 07:14 AM EST     Moonset
Mon -- 08:28 AM EST     2.62 feet High Tide
Mon -- 02:33 PM EST     0.07 feet Low Tide
Mon -- 04:46 PM EST     Sunset
Mon -- 05:05 PM EST     Moonrise
Mon -- 08:30 PM EST     3.06 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.10.60.20.10.311.72.32.62.62.11.50.90.40.10.10.41.22.12.7332.62

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Mon -- 02:58 AM EST     0.05 feet Low Tide
Mon -- 04:32 AM EST     Full Moon
Mon -- 07:07 AM EST     Sunrise
Mon -- 07:15 AM EST     Moonset
Mon -- 08:32 AM EST     2.53 feet High Tide
Mon -- 02:39 PM EST     0.07 feet Low Tide
Mon -- 04:46 PM EST     Sunset
Mon -- 05:06 PM EST     Moonrise
Mon -- 08:34 PM EST     2.94 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.10.60.200.30.91.62.22.52.52.11.50.90.40.10.10.41.11.92.62.92.92.62

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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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.