Thursday, August13, 2020
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Marine Weather and Tides
Passapatanzy, 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 6:22AMSunset 8:07PM Thursday August 13, 2020 12:51 PM EDT (16:51 UTC) Moonrise 12:00AMMoonset 2:47PM Illumination 27% 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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ANZ536 Tidal Potomac From Indian Head To Cobb Island- 1037 Am Edt Thu Aug 13 2020
Rest of today..E winds 5 kt. Waves less than 1 ft. A chance of tstms. Showers likely late this morning, then a chance of showers this afternoon.
Tonight..NE winds 5 kt. Waves less than 1 ft. A chance of showers and tstms.
Fri..NE winds 5 kt. Waves less than 1 ft. Showers and tstms likely.
Fri night..NE winds 5 kt. Waves less than 1 ft. A chance of showers and tstms.
Sat..E winds 5 to 10 kt. Waves 1 ft. Showers and tstms likely.
Sat night..E winds 5 to 10 kt. Waves 1 ft. Showers and tstms.
Sun..N winds 5 to 10 kt. Waves 1 ft. Showers likely with a chance of tstms in the morning, then a chance of showers and tstms.
Mon..NW winds 5 kt. Waves less than 1 ft. A chance of showers and tstms. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 1037 Am Edt Thu Aug 13 2020
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A front will be stalled over the middle atlantic today. It will slowly shift south of the region Friday and Saturday before returning north by early next week.


7 Day Forecast for Marine Location Near Passapatanzy, VA
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location: 38.34, -77.31     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 131428 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1028 AM EDT Thu Aug 13 2020

SYNOPSIS. A front will stall over the Middle Atlantic today, 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 /THROUGH TONIGHT/. Current thinking is in line with the previous forecast. A complex of thunderstorms that developed this morning is in the process of stratifying out. Still have multiple ongoing flash flood and and flood warnings from that activity. Expect stratiform light rain to persist over the next 1-2 hours across the southeastern half of the forecast area. Eventually we should see an uptick in shower/thunderstorm activity across the higher terrain in southwestern portions of the forecast area within upslope low- level flow. An additional stray popup shower or thunderstorm can't be ruled out elsewhere, but this morning's rain and cloud cover may keep activity this afternoon somewhat limited over the metro areas. If additional activity were to develop this afternoon, it wouldn't take much to cause flooding, given heavy rainfall across much of the area both yesterday and again this morning. A Flash Flood Watch remains in effect for all of the forecast area until 11 PM tonight Previous discussion follows.

Stalled front in the vicinity combined with a tropical air mass and passing shortwave energy promises to make the next few days interesting. For this morning, a fairly significant vort max and shortwave will move through shortly. This is already starting to cause storms to develop, and expect coverage to expand northward, maxing out during rush hour. Locally heavy rain is very possible and given the rain we had yesterday in some areas, a flash flood watch seemed prudent. Ran the watch through this evening as expect more storms to fire in the afternoon, but highest coverage likely occurs this morning with the shortwave. Exhaustion of CAPE and modest height rises/anticyclonic flow this afternoon likely keep coverage a bit reduced. Some sun will break through, but highs will only be in the 80s. By comparison, tonight looks like we will be between upper level features, so evening convection will diminish and do not expect a refiring overnight. Lows in the 60s to 70s.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/. Front will make some southward progress Friday night through Saturday night as upper low to the west strengthens/sharpens. This will result in better afternoon storm coverage Friday, and then better rain/storm coverage overall Saturday. As the atmosphere being tapped is not going to change, even if the immediate low level one does somewhat behind the front, expect the heavy rain threat to persist through Saturday night. With the continued clouds and storms, highs will continue to be in the 80s, with Saturday being the cooler day as the front drops further south. Lows will be in the 60s to 70s, not much change.

LONG TERM /SUNDAY THROUGH WEDNESDAY/. The aforementioned frontal boundary continues to lift northward on Sunday, with low pressure riding along it across the area into Sunday evening. This will again bring thunderstorms to the area. Heavy rainfall again will be possible with these. Temperatures will be well below average on Sunday, with highs struggling to reach 80 for most.

Beyond Sunday, looks like a brief lull in activity could occur early in the week. However, still a great deal of uncertainty there, as the upper-level pattern remains unsettled nearby. But Monday and Maybe Tuesday could see the area in zonal flow, with less coverage of showers/storms. Highs each day in the low to mid 80s.

By the middle of next week upper-level flow may once again buckle, allowing for more disturbed weather across the region. However, timing of that is still up in the air at this point. This time of year typically brings about weakly forced events, so can be a bit tough to nail down this far out. Continue to monitor latest forecasts for new info.

AVIATION /14Z THURSDAY THROUGH MONDAY/. Patchy low clouds and fog will be an issue each of the next three late night/early morning periods as plentiful low level moisture will make its formation easy, if we have clearing. That said, higher clouds may limit this threat at the terminals. Otherwise, main concern will be for heavy downpours with lightning to produce sub-VFR conditions and gusty winds. Best coverage will generally be afternoon hours, though today, a disturbance makes storms a bit more likely in the morning.

Sub-VFR conditions expected at times on Sunday, as low pressure moves along a lifting frontal boundary over the area.

VFR conditions generally expected by Monday, in the wake of the low, but some showers and storms remain possible in the afternoon, but with less coverage.

MARINE. Generally sub-SCA conditions expected on the waters through Saturday. Main concern each day will be thunderstorms, primarily during the afternoon hours, though some may develop during the mornings. Gusty winds and even a few waterspouts will be possible with stronger storms.

SCA conditions possible on Sunday in onshore flow. By Monday, flow shifts offshore, but could remain close to (but should stay just below) SCA criteria.

HYDROLOGY. Significant rain fell in scattered areas around the CWA yesterday. While not everyone saw heavy rain, most of the CWA had some rain, so antecedent conditions are growing increasingly wet. With some locally heavy showers and storms expected this morning, it seemed prudent to issue a Flash Flood Watch, even though confidence on really heavy concentrated storms is not quite as high given somewhat reduced CAPE. Storm coverage may actually decrease significantly this afternoon, but confidence on this is not yet high. That said, would not be surprised if the watch was to be dropped early.

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

SYNOPSIS . RCM NEAR TERM . RCM/KJP SHORT TERM . RCM LONG TERM . CJL AVIATION . RCM/CJL MARINE . RCM/CJL HYDROLOGY . RCM


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
NCDV2 15 mi51 min Calm G 2.9 78°F 85°F1017.2 hPa (-0.4)
WASD2 - 8594900 - Washington, DC 40 mi51 min NNE 4.1 G 6 76°F 85°F1018.4 hPa (+0.0)
BSLM2 - Chesapeake Bay, MD 44 mi141 min ESE 1.9 1019 hPa
PPTM2 - 8578240 - Piney Point, MD 44 mi51 min NNE 8 G 12
SLIM2 - 8577330 - Solomons Island, MD 45 mi51 min N 8 G 8.9 77°F 84°F1017.6 hPa (+0.0)
COVM2 - 8577018 - Cove Point LNG Pier, MD 49 mi57 min N 12 G 14 1018.4 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Stafford, Stafford Regional Airport, VA9 mi56 minN 010.00 miMostly Cloudy77°F77°F100%1019.6 hPa
Fredericksburg, Shannon Airport, VA9 mi56 minN 010.00 miLight Rain76°F76°F100%1018.3 hPa
Quantico Marine Corps Airfield - Turner Field, VA12 mi55 minNNE 510.00 miMostly Cloudy79°F72°F79%1018.3 hPa

Link to 5 minute data for KRMN

Wind History from RMN (wind in knots)
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Last 24hrCalmCalmS7CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmNW6CalmCalmCalm
1 day agoCalmS4CalmCalmS4CalmS5CalmCalmCalmCalmCalmCalmCalmCalmNW6N3CalmCalmCalmCalmCalmCalmCalm
2 days agoS4S5S12S3S4S3CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmSW3E3S4

Tide / Current Tables for Clifton Beach, Maryland
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Clifton Beach
Click for Map
Thu -- 12:59 AM EDT     Moonrise
Thu -- 01:35 AM EDT     1.30 feet High Tide
Thu -- 06:22 AM EDT     Sunrise
Thu -- 08:18 AM EDT     0.30 feet Low Tide
Thu -- 02:23 PM EDT     1.11 feet High Tide
Thu -- 03:47 PM EDT     Moonset
Thu -- 07:46 PM EDT     0.23 feet Low Tide
Thu -- 08:04 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.21.31.31.210.70.50.40.30.30.50.70.911.11.10.90.70.40.30.20.30.50.7

Tide / Current Tables for Maryland Point Light, Maryland
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Maryland Point Light
Click for Map
Thu -- 12:23 AM EDT     1.24 feet High Tide
Thu -- 12:59 AM EDT     Moonrise
Thu -- 06:22 AM EDT     Sunrise
Thu -- 07:20 AM EDT     0.30 feet Low Tide
Thu -- 01:11 PM EDT     1.06 feet High Tide
Thu -- 03:47 PM EDT     Moonset
Thu -- 06:48 PM EDT     0.23 feet Low Tide
Thu -- 08:04 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.21.21.10.90.70.50.40.30.30.50.70.911.110.90.60.40.30.20.30.50.71

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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Wind Forecast for Baltimore, MD/Washington (12,3,4,5)
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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.