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Marine Weather and Tides
Version 3.4 |
10/6/2018 Colors of tide XTide graphs changed to emphasize that they were upgraded. See next note. Comments welcome. 10/4/2018 I have fixed XTide and updated the harmonic files. There were some name changes so you might have to click EDIT to find the new station name. |
Sunrise 6:51AM | Sunset 5:57PM | Saturday February 23, 2019 3:51 PM EST (20:51 UTC) | Moonrise 10:52PM | Moonset 9:33AM | Illumination 80% | ![]() |
ANZ535 Tidal Potomac From Key Bridge To Indian Head- 339 Pm Est Sat Feb 23 2019
.small craft advisory in effect Sunday afternoon...
.gale warning in effect from Sunday afternoon through Sunday evening...
Rest of this afternoon..E winds 5 kt. Waves less than 1 ft. Rain.
Tonight..S winds around 5 kt. Waves 1 ft. Rain. Vsby 1 to 3 nm.
Sun..W winds 15 to 20 kt with gusts to 30 kt. Waves 1 to 2 ft. Showers likely.
Sun night..W winds 15 to 20 kt with gusts to 40 kt. Waves 2 ft.
Mon..NW winds 10 to 15 kt with gusts to 40 kt. Waves 2 ft.
Mon night..NW winds 5 to 10 kt. Gusts up to 20 kt in the evening. Waves 1 ft.
Tue..N winds 5 kt. Waves less than 1 ft.
Wed..W winds around 5 kt. Waves 1 ft.
.small craft advisory in effect Sunday afternoon...
.gale warning in effect from Sunday afternoon through Sunday evening...
Rest of this afternoon..E winds 5 kt. Waves less than 1 ft. Rain.
Tonight..S winds around 5 kt. Waves 1 ft. Rain. Vsby 1 to 3 nm.
Sun..W winds 15 to 20 kt with gusts to 30 kt. Waves 1 to 2 ft. Showers likely.
Sun night..W winds 15 to 20 kt with gusts to 40 kt. Waves 2 ft.
Mon..NW winds 10 to 15 kt with gusts to 40 kt. Waves 2 ft.
Mon night..NW winds 5 to 10 kt. Gusts up to 20 kt in the evening. Waves 1 ft.
Tue..N winds 5 kt. Waves less than 1 ft.
Wed..W winds around 5 kt. Waves 1 ft.
ANZ500 339 Pm Est Sat Feb 23 2019
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Low pressure will approach the middle mississippi river valley tonight, strengthening as it moves northeastward across the great lakes into canada through Sunday. High pressure will build from the northern great plains toward the great lakes and eventually into the northeast through the first half of next week. Gale conditions are likely overnight Sunday and Monday.
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Low pressure will approach the middle mississippi river valley tonight, strengthening as it moves northeastward across the great lakes into canada through Sunday. High pressure will build from the northern great plains toward the great lakes and eventually into the northeast through the first half of next week. Gale conditions are likely overnight Sunday and Monday.
7 Day Forecast for Marine Location Near Kemps Mill, MD
Hourly EDIT Helplocation: 39.63, -77.79 debug
Area Discussion for - Baltimore, MD/Washington
  (on/off)  Help NOTE: mouseover dotted underlined text for definitionFxus61 klwx 231958 afdlwx area forecast discussion national weather service baltimore md washington dc 258 pm est Sat feb 23 2019 Synopsis Strong low pressure will move northeastward across the western great lakes this weekend, bringing a warm front northward into the area by early Sunday. A cold front approaching from the ohio valley will quickly follow Sunday afternoon. High pressure will then build from the great lakes into new england through much of next week. Meanwhile, an area of low pressure may approach from the ohio valley during the middle of the week, and again by the end of the week. Near term through tonight Low pressure is will move from the central CONUS into the great lakes tonight. A stationary boundary to its east will be lifted north as a warm front through tonight, but with surface high pressure over new england and the parent surface low passing so far west, our area will remain on the cool side of the boundary. An upper-level disturbance will pass through late this afternoon and another upper-level disturbance will move into the area overnight. Overrunning warm moist advection has allowed for light rain across most areas. Steadier rain has occurred over central virginia where the overrunning is deeper, and also closer to the upper-level disturbance that is passing through. The heavier rain may taper off for a bit this evening behind the disturbance, but areas of light rain and drizzle remain likely as warm and moist air from the gulf of mexico overruns the surface colder air in place. Temperatures are expected to hold near or below freezing for elevations between 1500 and 4000 feet or so with cold air draining in from high pressure to the north. A glaze of ice freezing rain expected through this afternoon. A winter weather advisory remains in effect until 6 pm, but that advisory may need to be expanded into tonight, especially across the ridges of western maryland. The next disturbance is expected to pass through overnight. A steadier rain will develop after midnight, and with copious amounts of moisture in place locally heavy rain is possible. In fact, a rumble of thunder cannot be ruled out due to elevated instability. In general around an inch of rain is expected in the washington and baltimore metropolitan areas with slightly higher amounts possible in southern maryland and the virginia piedmont. A little less rain (three quarters of an inch) is expected over eastern west virginia and western maryland. Confidence is not quite high enough for a watch at this time, given the breaks in steadier periods of rainfall along with little or no snow pack. However, localized flooding is possible because soils are already saturated due to the recent snow melt. Further south across west- central virginia, amounts of up to an inch and a half are possible. A little higher confidence in flooding threat here (where there is a flood watch through tonight). Short term Sunday through Monday night Low pressure will move into southern canada and the warm front will gradually lift through our area during the morning. Rain and drizzle to start will taper off from west to east during the morning hours. A strong cold front associated with the low will pass through the area Sunday afternoon into Sunday evening from west to east. Strong winds are expected behind the cold front for much of the area. A strong pressure gradient combined with a deep mixing layer and winds around 50-55 knots at the top of the mixing layer suggests that winds can be quite strong. A high wind warning is in effect for the blue ridge and catoctin mountains as well as the allegheny and potomac highlands. Wind gusts around 60 mph are expected across these areas. Do think that not quite all of the wind at the top of the mixing layer will make it into the valleys, since peak heating will be ending around the time of the maximum pressure gradient. However, it will still turn out windy with gusts around 45-55 mph across most of maryland, northern virginia, portions of central virginia and the valleys in eastern west virginia. Wind advisories are in effect for these areas. A strong gradient and cold advection means that Sunday night and Monday will turn out blustery and cold. Winds may a little for most areas Sunday night due to the loss of daytime heating. Therefore, allowed the wind advisories to expire. However, the high wind warnings continue for the ridges. Another pressure surge is expected early Monday morning through midday, and more gusts around advisory criteria (50 mph) are possible across much of the area. A wind advisory may be needed. High pressure will build overhead Monday night, causing winds to diminish but it will remain seasonably cold. Long term Tuesday through Saturday Canadian high pressure over the upper midwest on Tuesday will continue tracking eastward toward our region through midweek, and with zonal flow aloft, dry weather and below normal temperatures are forecast. A weak area of low pressure and a subtle shortwave will track to our north Wednesday night into Thursday, promoting the potential for upslope rain snow showers. High pressure is then expected to build to our north through weeks end. The GFS indicates a potential quick moving shortwave crossing the area Friday morning delivering a period of rain snow, however the ECMWF depicts a much stronger high over the mid atlantic, suppressing any precipitation well to our south. Will carry low end chance pops for now given the model discrepancy at day 6 7. |
Aviation 20z Saturday through Thursday Conditions will continue deteriorate this afternoon to MVFR levels (ifr at kcho). Ifr levels are expected to develop everywhere this evening and subifr conditions are possible overnight. Low clouds and fog rain drizzle will be around to start Sunday, but CIGS vsbys and drier air will gradually return later Sunday morning into Sunday afternoon. Strong winds are expected behind a cold front Sunday afternoon for kcho and kmrb, and late Sunday afternoon or early evening for the rest of the terminals. Gusts around 40 to 45 knots are possible. Isolated gusts around 50 knots cannot be completely ruled out. Winds will diminish some later Sunday night for most of the terminals, but another uptick in wind gusts around 40-45 knots are possible Monday morning. Winds will gradually diminish later Monday afternoon into Monday night as high pressure builds closer. PredominateVFR conditions expected Tuesday through Wednesday as canadian high pressure builds toward the region. Dry conditions and light winds will prevail as a result. Marine Winds should remain below SCA criteria tonight. A warm front will gradually pass through the waters Sunday morning through midday. A stronger gradient and increasing mixing layer will cause winds to increase during this time. A small craft advisory is in effect for the waters. A cold front will pass through late Sunday afternoon, and stronger winds are expected. Gusts around 40 to 45 knots are likely, and a gale warning is in effect for the waters late Sunday afternoon through Sunday evening. The gale warning may need to be extended for overnight Sunday and Monday as another pressure surge passes through the waters. Confidence was too low at this time to do so, thinking there may be a break in the stronger winds for a period late Sunday night. Winds will gradually diminish late Monday and Monday night as high pressure builds overhead. Mainly sub SCA conditions are expected Tuesday through Wednesday as canadian high pressure builds toward the region, delivering gentle to moderate northerly breezes. Hydrology Highest confidence in higher rainfall totals over an inch and subsequently the threat for areal flooding is over west-central virginia tonight, which is where the current flood watch lies. Further north, rainfall amounts may come in a little shy of an inch, but saturated ground and or snowmelt lends to a non-zero flood threat just about everywhere. East of the blue ridge to the i-95 corridor should average near an inch, with slightly higher amounts possible over southern maryland. Outside of the areal flood watch, mainstem river flooding may be the biggest threat given these waterways will be catching all the excess runoff. Lwx watches warnings advisories Dc... Wind advisory from 3 pm to 10 pm est Sunday for dcz001. Md... High wind warning from 10 am Sunday to 10 am est Monday for mdz501. Winter weather advisory until 6 pm est this evening for mdz501. High wind warning from 1 pm Sunday to 10 am est Monday for mdz003-004-502. Wind advisory from 3 pm to 10 pm est Sunday for mdz005-006-011- 013-014-016>018-503>508. Va... High wind warning from 10 am Sunday to 10 am est Monday for vaz503-504-507-508. Flood watch through late tonight for vaz025-036-037-503-504- 508. Winter weather advisory until 6 pm est this evening for vaz503- 504-507-508. Wind advisory from 1 pm to 10 pm est Sunday for vaz025>031- 036>040-501-505. Wind advisory from 3 pm to 10 pm est Sunday for vaz052>054-506. Wv... High wind warning from 10 am Sunday to 10 am est Monday for wvz501>503-505-506. Winter weather advisory until 6 pm est this evening for wvz501- 503-505-506. High wind warning from 1 pm Sunday to 10 am est Monday for wvz050>052-055-504. Wind advisory from 1 pm to 10 pm est Sunday for wvz053. Marine... Small craft advisory from 9 am to 3 pm est Sunday for anz532>534-537-540>543. Gale warning from 3 pm Sunday to midnight est Sunday night for anz530>543. Small craft advisory from noon to 3 pm est Sunday for anz530- 531-535-536-538-539. Synopsis... Bjl near term... Bjl short term... Bjl long term... Bkf aviation... Bjl bkf marine... Bjl bkf hydrology... Dhof bjl |
Weather Reporting Stations
EDIT (on/off)  Help NOTE: Click on distance to see the station location on a mapStations | Dist | Age | Wind | Air Temp | Water Temp | Waves | Pressure | DewPt |
WASD2 - 8594900 - Washington, DC | 66 mi | 40 min | ENE 4.1 G 7 | 39°F | 41°F | 1026.9 hPa | ||
BLTM2 - 8574680 - Baltimore, MD | 69 mi | 40 min | E 5.1 G 8 | 39°F | 39°F | 1026.7 hPa | ||
FSKM2 - 8574728 - Francis Scott Key Bridge, MD | 73 mi | 34 min | E 6 G 8 | 38°F | 1027 hPa |
Wind History for Washington, DC
(wind in knots) EDIT (on/off)  Help4 PM | 5 PM | 6 PM | 7 PM | 8 PM | 9 PM | 10 PM | 11 PM | 12 AM | 1 AM | 2 AM | 3 AM | 4 AM | 5 AM | 6 AM | 7 AM | 8 AM | 9 AM | 10 AM | 11 AM | 12 PM | 1 PM | 2 PM | 3 PM | |
Last 24hr | NW | NW G7 | NW | W G6 | NW | E | SE | NE G5 | E G4 | NW | SE | NE G6 | E G5 | E G5 | E | E | NE G8 | E | NE | SE G5 | SE | E | NE | NE G7 |
1 day ago | W | NW | NW | N | NW G8 | N G12 | NW G9 | NW G11 | W | SE | NW | -- | N G8 | N G8 | NE G7 | N G7 | N | NE G8 | NW G4 | W | W G7 | W | ||
2 days ago | NE | E | NE G5 | N | NE | NE | N | W | NW | W | W | W | SW | W | SW | W | SW | SW | SW | S | W G8 | NW |
Airport Reports
EDIT (on/off)  Help Click EDIT to display multiple airportsAirport | Dist | Age | Wind kt | Visibility | Sky/Weather | Temp | DewPt | Humidity | Pressure |
Hagerstown, Washington County Regional Airport, MD | 6 mi | 59 min | E 4 | 2.50 mi | Overcast with Haze | 37°F | 32°F | 82% | 1026.9 hPa |
Eastern WV Regional Airport/Shepherd Field, WV | 18 mi | 59 min | N 0 | 7.00 mi | Overcast | 37°F | 30°F | 79% | 1025.6 hPa |
Wind History from HGR (wind in knots)
4 PM | 5 PM | 6 PM | 7 PM | 8 PM | 9 PM | 10 PM | 11 PM | 12 AM | 1 AM | 2 AM | 3 AM | 4 AM | 5 AM | 6 AM | 7 AM | 8 AM | 9 AM | 10 AM | 11 AM | 12 PM | 1 PM | 2 PM | 3 PM | |
Last 24hr | Calm | Calm | Calm | Calm | Calm | Calm | Calm | Calm | E | NE | E | Calm | Calm | Calm | E | Calm | E | E | Calm | Calm | S | S | SE | E |
1 day ago | NW | W | W | NW | NW | W | Calm | W | SW | N | N | NW | NW | NW | NW | Calm | N | Calm | Calm | NW | Calm | Calm | NW | Calm |
2 days ago | SE | SE | SE | SE | E | Calm | NW | E | NE | Calm | NW | Calm | Calm | S | Calm | SE | SE | S | Calm | SW | W | W | W | NW |
Tide / Current Tables for Chain Bridge, D.C.
EDIT RT Ports Option Weekend mode (on/off) (on/off)  Help One Week of DataChain Bridge
Click for Map
Sat -- 05:49 AM EST -0.40 feet Low Tide
Sat -- 06:49 AM EST Sunrise
Sat -- 09:30 AM EST Moonset
Sat -- 11:27 AM EST 3.28 feet High Tide
Sat -- 05:54 PM EST Sunset
Sat -- 06:22 PM EST -0.38 feet Low Tide
Sat -- 10:48 PM EST Moonrise
Sat -- 11:58 PM EST 3.06 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Click for Map
Sat -- 05:49 AM EST -0.40 feet Low Tide
Sat -- 06:49 AM EST Sunrise
Sat -- 09:30 AM EST Moonset
Sat -- 11:27 AM EST 3.28 feet High Tide
Sat -- 05:54 PM EST Sunset
Sat -- 06:22 PM EST -0.38 feet Low Tide
Sat -- 10:48 PM EST Moonrise
Sat -- 11:58 PM EST 3.06 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
12 am | 1 am | 2 am | 3 am | 4 am | 5 am | 6 am | 7 am | 8 am | 9 am | 10 am | 11 am | 12 pm | 1 pm | 2 pm | 3 pm | 4 pm | 5 pm | 6 pm | 7 pm | 8 pm | 9 pm | 10 pm | 11 pm |
3 | 2.4 | 1.6 | 0.9 | 0.2 | -0.2 | -0.4 | 0 | 0.9 | 2 | 2.8 | 3.2 | 3.2 | 2.7 | 2 | 1.3 | 0.6 | 0 | -0.3 | -0.3 | 0.4 | 1.4 | 2.3 | 2.9 |
Tide / Current Tables for Chain Bridge, one mile below, D.C.
EDIT (on/off)  Help One Week of DataChain Bridge
Click for Map
Sat -- 05:43 AM EST -0.40 feet Low Tide
Sat -- 06:49 AM EST Sunrise
Sat -- 09:30 AM EST Moonset
Sat -- 11:22 AM EST 3.28 feet High Tide
Sat -- 05:54 PM EST Sunset
Sat -- 06:17 PM EST -0.38 feet Low Tide
Sat -- 10:48 PM EST Moonrise
Sat -- 11:53 PM EST 3.06 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Click for Map
Sat -- 05:43 AM EST -0.40 feet Low Tide
Sat -- 06:49 AM EST Sunrise
Sat -- 09:30 AM EST Moonset
Sat -- 11:22 AM EST 3.28 feet High Tide
Sat -- 05:54 PM EST Sunset
Sat -- 06:17 PM EST -0.38 feet Low Tide
Sat -- 10:48 PM EST Moonrise
Sat -- 11:53 PM EST 3.06 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
12 am | 1 am | 2 am | 3 am | 4 am | 5 am | 6 am | 7 am | 8 am | 9 am | 10 am | 11 am | 12 pm | 1 pm | 2 pm | 3 pm | 4 pm | 5 pm | 6 pm | 7 pm | 8 pm | 9 pm | 10 pm | 11 pm |
2.9 | 2.3 | 1.5 | 0.8 | 0.2 | -0.3 | -0.4 | 0.1 | 1 | 2.1 | 2.9 | 3.3 | 3.2 | 2.7 | 2 | 1.2 | 0.6 | -0 | -0.4 | -0.2 | 0.5 | 1.5 | 2.3 | 2.9 |
Weather Map and Satellite Images
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GOES 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
Wind Forecast for Baltimore, MD/Washington (15,3,4,5)
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Ground Weather Radar Station Sterling, VA
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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. |