Wednesday, August12, 2020
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Marine Weather and Tides
Marumsco, VA

Version 3.4
NOTICE
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 6:19AMSunset 8:08PM Wednesday August 12, 2020 7:22 PM EDT (23:22 UTC) Moonrise 11:59PMMoonset 1:48PM Illumination 34% Phase: Waning Crescent; Moon at 24 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 Pm Edt Wed Aug 12 2020
Rest of this afternoon..SE winds 5 kt. Waves less than 1 ft. Showers and tstms likely.
Tonight..NE winds around 5 kt. Waves 1 ft or less. Showers likely with a chance of tstms.
Thu..E winds around 5 kt. Waves 1 ft. Showers and tstms likely.
Thu night..NE winds around 5 kt. Waves 1 ft. Showers likely with a chance of tstms.
Fri..NE winds 5 kt. Waves less than 1 ft. A chance of showers.
Fri night..NE winds 5 kt. Waves less than 1 ft. A chance of showers.
Sat..E winds 5 kt. Waves less than 1 ft. A chance of showers. A chance of tstms.
Sun..NE winds around 5 kt. Waves 1 ft. Showers and tstms likely through the day, then a chance of showers through the night. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 437 Pm Edt Wed Aug 12 2020
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A front will stall over the middle atlantic through Thursday, then drift southward through early this weekend.


7 Day Forecast for Marine Location Near Marumsco, VA
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location: 38.61, -77.23     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 121912 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 312 PM EDT Wed Aug 12 2020

SYNOPSIS. A front will stall over the Middle Atlantic through Thursday, then drift southward Friday into Saturday. The front will then lift back northward through the end of the weekend as low pressure lifts into the Ohio River Valley.

NEAR TERM /UNTIL 6 PM THIS EVENING/. Showers and thunderstorms are forming within an unstable, uncapped environment early this afternoon as a weak cold front drops southward into our area. This front, as well as the bay breeze and terrain circulations are serving as the main foci for convective initiation. Flow throughout the column is very weak, so convection will be rather disorganized/chaotic in nature, with individual cells not moving much at all before collapsing on themselves. Movement of storms should largely be driven by propagation/formation of new cells along cold pool driven outflow from nearly stationary parent cells.

Precipitable water values have climbed to in excess of 2 inches along and southeast of I-95. When combined with MLCAPE values of 2000-3000 J/kg, very heavy rainfall rates will be possible in stronger storms. Very high instantaneous rainfall rates were already observed last night near Manassas (around 2-3 inches per hour), with comparatively much lower instability and slightly lower precipitable water values. So with the greater instability in place, more vigorous updrafts this afternoon should be able to process even greater amounts of the moisture rich airmass, leading to even higher rainfall rates than were observed overnight. So despite the disorganized, chaotic nature of the storms expected today (and resultant limited potential for training of cells), the threat for flash flooding appears to be significant, in large part due to the very high rainfall rates and low flash flood guidance values (following recent heavy rains). As a result, WPC has placed much of the area in a moderate risk for excessive rainfall and a Flash Flood Watch is in effect for the entire area until 11 PM. With the chaotic nature of the storms today, it is tough to pinpoint individual areas where the greatest impacts will be felt, since things like outflow boundary collisions could be what results in prolonged periods of rain in one given spot. However it's worth noting that the background environment appears slightly more favorable for flash flooding along and southeast of I-95/66, where the highest instability and precipitable water values will reside. In that same area, profiles will contain less mid-upper level dry air, which should lead to both more efficient rainfall processes.

The overall threat for damaging winds appears to be low, but non-zero. With nearly no background flow in place, any damaging winds would need to be driven by strong downdrafts. SPC mesoanalysis currently indicates that the highest DCAPE values reside to the north and west of I-95/66 (where the presence of some mid- upper level dry air will help to aid in evaporationally driven downdraft accelerations). While an isolated water loaded downburst can't be ruled out anywhere, think the greatest risk for damaging winds will be along and northwest of I-95/66 within the higher DCAPE air. Due to this low-end threat, SPC has placed a sizeable portion of the forecast area in a marginal risk for damaging winds this afternoon.

SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/. Storms should gradually wind down this evening, but an uptick in storm coverage is expected again later tonight as a shortwave disturbance passes to our northwest. In response to this shortwave, winds at 850 hPa will switch around to out of the south- southeast, and begin to overrun the stalled boundary. Within the moist, uncapped environment, this small change may be enough to spark the development of additional showers and thunderstorms late tonight into early tomorrow morning. Most model guidance is focusing this additional activity to the east of the Blue Ridge. These storms may pose a threat for additional flash flooding, especially if they move over areas impacted by storms today. After the disturbance passes by, the frontal boundary will sag off to the south, shifting the focus for heavier rainfall in the afternoon to southern portions of the forecast area (central Virginia to southern Maryland).

Additional showers and thunderstorms will be possible Thursday Night through Friday Night, as winds shift around to easterly north of the front. Coverage of showers and storms may begin to uptick Friday Night as a trough centered over the Ohio Valley moves closer to the area.

LONG TERM /SATURDAY THROUGH TUESDAY/. The front that is producing showers and thunderstorms over our area will return back northward Saturday into Sunday as a wave of low pressure lifts into the Ohio River Valley. Additional showers and thunderstorms seem likely during this time, with additional heavy rainfall possible.

Clearing should commence early next week as the low chases the front offshore. The flow may buckle a bit toward the middle of next week resulting in a return to unsettled weather, but details are fuzzy this far in advance, especially this time of the year when forcing mechanisms are often subtle.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/. The main aviation concern over the next couple days will be thunderstorm coverage. Coverage of storms is expected to increase today and Thursday. Best risk of storms will be afternoon/early evening, but could linger into the overnight hours. There are also some signs that storms may reform late tonight in the metro areas. As a result, have added another VCTS to IAD/BWI/DCA/MTN for late tonight into early tomorrow morning. Some patchy morning low clouds/fog will be possible at MRB/IAD/CHO during the overnights.

Sub-VFR conditions seem likely at times this weekend in onshore flow and renewed chances of showers and thunderstorms.

MARINE. No significant synoptic wind issues are expected through the next few days. The main concern through Thursday will be thunderstorms. Coverage will increase significantly today and Thursday, with gusty winds a threat from any storm. Best timing is afternoon and evening, though the risk may linger through tonight and Thursday night. Special Marine Warnings may be needed for any stronger storms.

Easterly/onshore flow may breach Small Craft Advisory (SCA) thresholds this weekend.

LWX WATCHES/WARNINGS/ADVISORIES. DC . Flash Flood Watch until 11 PM EDT this evening for DCZ001. MD . Flash Flood Watch until 11 PM EDT this evening for MDZ003>006- 011-013-014-016>018-501>508. VA . Flash Flood Watch until 11 PM EDT this evening for VAZ025>031- 036>040-050>057-501>508. WV . Flash Flood Watch until 11 PM EDT this evening for WVZ050>053- 055-501>506. MARINE . None.

SYNOPSIS . DHOF NEAR TERM . KJP SHORT TERM . KJP LONG TERM . DHOF AVIATION . DHOF/KJP MARINE . DHOF/KJP


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 21 mi53 min NNE 4.1 G 8.9 82°F 84°F1016.8 hPa
NCDV2 22 mi53 min SE 7 G 8.9 82°F 87°F1015.7 hPa
BSLM2 - Chesapeake Bay, MD 30 mi113 min NNW 1.9 1015 hPa
44062 - Gooses Reef, MD 43 mi35 min 81°F 85°F
SLIM2 - 8577330 - Solomons Island, MD 46 mi53 min E 5.1 G 5.1 82°F 86°F1016.4 hPa
APAM2 - 8575512 - Annapolis, MD 47 mi53 min NNE 1.9 G 4.1 78°F 86°F1017 hPa
COVM2 - 8577018 - Cove Point LNG Pier, MD 47 mi191 min W 4.1 G 6 1016.2 hPa
TPLM2 - Thomas Point, MD 47 mi83 min SE 12 G 13 77°F 83°F1017.5 hPa (+1.4)73°F
PPTM2 - 8578240 - Piney Point, MD 49 mi53 min SSE 4.1 G 5.1

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Quantico Marine Corps Airfield - Turner Field, VA8 mi27 minESE 610.00 miA Few Clouds82°F72°F72%1016.6 hPa
Fort Belvoir, VA9 mi27 minE 310.00 miPartly Cloudy83°F70°F68%1016.8 hPa
Manassas, Manassas Regional Airport/Harry P. Davis Field, VA17 mi27 minSE 710.00 miA Few Clouds84°F73°F72%1016.6 hPa
Stafford, Stafford Regional Airport, VA19 mi28 minE 310.00 miMostly Cloudy79°F79°F100%1017.6 hPa
Washington/Reagan National Airport, DC, VA20 mi31 minENE 1310.00 miMostly Cloudy81°F71°F72%1016.9 hPa
Camp Springs / Andrews Air Force Base, MD24 mi27 minENE 610.00 miFair77°F72°F84%1017.4 hPa

Link to 5 minute data for KNYG

Wind History from NYG (wind in knots)
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Last 24hrS9SW5SW5SW3S6S6SW5S6NW7NW5CalmCalm--SW3------S4SE3S17SW5S4S4SE6
1 day agoS7SE6S3SE6W5W4W3SW5S5SW4W5SW4S5S7S6--S6S7S8--S8S8S8S8
2 days agoSW6SW4CalmCalmSW6SW4SW4SW4SW3W3W3NW4W3CalmS4--S5--S5S5S5S12S10S8

Tide / Current Tables for High Point, Occoquan Bay, Virginia
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High Point
Click for Map
Wed -- 12:25 AM EDT     Moonrise
Wed -- 01:41 AM EDT     1.71 feet High Tide
Wed -- 06:20 AM EDT     Sunrise
Wed -- 08:30 AM EDT     0.44 feet Low Tide
Wed -- 02:22 PM EDT     1.47 feet High Tide
Wed -- 02:47 PM EDT     Moonset
Wed -- 08:01 PM EDT     0.32 feet Low Tide
Wed -- 08:06 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.51.71.71.61.310.80.60.50.50.60.91.21.41.51.41.310.60.40.30.40.50.9

Tide / Current Tables for Quantico Creek, Virginia
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Quantico Creek
Click for Map
Wed -- 12:25 AM EDT     Moonrise
Wed -- 01:39 AM EDT     1.53 feet High Tide
Wed -- 06:21 AM EDT     Sunrise
Wed -- 07:59 AM EDT     0.35 feet Low Tide
Wed -- 02:20 PM EDT     1.32 feet High Tide
Wed -- 02:47 PM EDT     Moonset
Wed -- 07:30 PM EDT     0.25 feet Low Tide
Wed -- 08:06 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.41.51.51.41.10.80.60.40.40.40.60.91.11.31.31.31.10.80.40.30.30.30.60.9

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.
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Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Baltimore, MD/Washington (19,4,5,8)
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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.