Thursday, July9, 2020
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Marine Weather and Tides
Halfway, MD

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 5:50AMSunset 8:41PM Thursday July 9, 2020 6:25 AM EDT (10:25 UTC) Moonrise 10:52PMMoonset 9:12AM Illumination 84% Phase: Waning Gibbous; Moon at 19 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- 436 Am Edt Thu Jul 9 2020
Rest of the overnight..E winds 5 kt. Waves less than 1 ft. Patchy fog. Vsby 1 to 3 nm.
Today..E winds 5 to 10 kt. Waves 1 ft.
Tonight..NE winds 5 to 10 kt. Waves 1 ft. A chance of showers.
Fri..N winds 5 to 10 kt. Waves 1 ft. Showers likely.
Fri night..W winds 5 to 10 kt. Waves 1 ft.
Sat..SW winds 5 kt. Waves less than 1 ft. Showers likely with a chance of tstms.
Sat night..W winds around 5 kt. Waves 1 ft. A chance of showers and tstms.
Sun..SW winds around 5 kt. Waves 1 ft. A chance of showers and tstms.
Mon..W winds around 5 kt. Waves 1 ft. A chance of tstms. A chance of showers. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 436 Am Edt Thu Jul 9 2020
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Low pressure along the north carolina coast will lift northward through tonight, moving near or just east of the delmarva peninsula on Friday, lifting to our northeast Friday night. A cold front is poised to encroach on the waters late Saturday into Sunday, lingering nearby into early next week. Gale force wind gusts may be possible over portions of the waters early Friday morning, potentially requiring the need for a gale warning during this time.


7 Day Forecast for Marine Location Near Halfway, MD
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location: 39.62, -77.79     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 090747 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 347 AM EDT Thu Jul 9 2020

SYNOPSIS. Low pressure will slowly move up the Mid-Atlantic Coast through Friday before moving off to the northeast Friday night. The low may develop tropical characteristics during this time so this will have to be monitored. An upper-level trough will build overhead Saturday while a cold front passes through the area. The upper-level trough will hang around for early next week.

NEAR TERM /THROUGH TONIGHT/. Areas of low clouds and fog are expected through early this morning as low-level moisture is trapped underneath the nocturnal inversion. This should mix out by mid-morning for most areas.

Low pressure off the North Carolina coast will slowly drift northward up the Mid-Atlantic Coast through tonight. Upper-level high pressure overhead this morning will build northeast into upstate New York and New England during this time. This upper- level high should remain close enough for today so that many location end up dry with sunshine. The exceptions will be along the Allegheny Highlands where an isolated storm is possible (even there most of the time will be dry and most areas will be dry), and across the Virginia Piedmont into southern Maryland where deeper moisture closer to the low may result in a few popup showers and perhaps an isolated storm. Subsidence from the upper-level high along with an onshore flow means more hot and humid conditions with highs in the upper 80s to lower 90s for most locations.

The low will continue to move northward tonight, and there is still some uncertainty as to how quickly the low moves north. The 00Z ECMWF is a little slower than the 00z GFS. If the faster solution is realized, then rain may overspread eastern areas (near and southeast of I-95) overnight, but if the slower solution is realized then the rain would hold off for most of the night. Left chance pops for now for areas near and east of I-95, but did continue with likely pops across extreme southern MD into the Tangier Sound. The forecast leans a little toward the slower solution given the current satellite imagery which shows that the deeper convection is displaced from the circulation. With low topped convection near the circulation, it may take longer for the system to speed up in its track to the north.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/. The low will continue to move up the Mid-Atlantic Coast Friday before moving away from the area Friday night. Did lean slightly toward the guidance with the slower solution for reasons mentioned in the paragraph above. This would likely bring showers and perhaps a thunderstorm to locations east of the Blue Ridge Mountains. A more potent upper-level trough axis will approach from the west Friday afternoon and this may trigger a few showers and thunderstorms around the Potomac Highlands and Shenandoah Valley.

Will have to continue to monitor this system because it may develop tropical characteristics, and there is still some model divergence as far as how heavy the rain will be and where it will be. It does appear more likely that the heaviest rain should remain to our east at this time though.

Drier conditions will likely return Friday night as the low moves away from the area. Still could see a few showers and perhaps a thunderstorm over the Potomac Highlands in response to the upper-level trough moving in from the west.

The upper-level trough will build overhead Saturday while a cold front slowly passes through the area later Saturday into Saturday night. This will bring the likelihood for showers and scattered thunderstorms. Some storms may be strong due to higher amounts of instability and increasing shear profiles. Convection should diminish later Saturday night with the loss of daytime heating.

LONG TERM /SUNDAY THROUGH WEDNESDAY/. Longwave trough will reside over the eastern U.S. Sunday, with our CWA situated between two embedded shortwave troughs. With a frontal boundary lingering to our south and east, and hot and humid conditions persisting, diurnal showers and thunderstorms will be possible Sunday afternoon. Do think the best coverage (chance POPs) will be relegated to our mountain zones where terrain circulations aid in development.

The secondary shortwave and primary trough axis will look to shift through the area on Monday, with the best lift remaining to our north. Will carry climo POPs with diurnally favored showers and thunderstorms Monday afternoon and early evening. Thereafter, heights are progged to rise as high pressure begins to take reigns over the region. This will result in a mainly dry forecast as we head into the middle portion of next week, but can't rule out an afternoon isolated shower or storm. With high pressure in control next week, above normal temperatures and elevated humidity will be sticking around.

AVIATION /07Z THURSDAY THROUGH MONDAY/. Areas of low clouds and fog are expected early this morning and IFR conditions are possible, especially across the eastern terminals. Any low clouds and fog should burn off by mid- morning.

Low pressure will move up the Mid-Atlantic Coast through Friday before moving off to the northeast Friday night. Showers and perhaps a thunderstorm are possible, especially Friday across the eastern terminals. Also, subVFR cigs from low clouds are likely late tonight into Friday morning due to an easterly flow from the Atlantic.

The low will move away from the area Friday night, but patchy low clouds and fog are possible. There is a better chance for stronger thunderstorms Saturday afternoon and evening as a cold front passes through the terminals.

Predominate VFR conditions expected Sunday through Monday as a light westerly flow prevails. Afternoon/evening showers and storms may bring brief episodes of sub VFR VIS/CIGs, but much of the period will feature VFR.

MARINE. Low pressure will slowly move up the Mid-Atlantic Coast through Friday before moving off to the northeast Friday night. An increasing gradient will gradually cause northeast winds to increase tonight into Friday before turning toward the north and eventually northwest Friday night. An SCA is in effect for the bay and lower Tidal Potomac during this time. The strongest winds are most likely late tonight through midday Friday with gusts around 30 knots possible south of Drum Point. The SCA may need to be extended in area to include the upper Tidal Potomac River, but confidence is too low at this time due to uncertainties with the track and strength of the low.

Will have to continue to monitor the low, because it may develop tropical characteristics and there is still some uncertainty in regards to its exact track.

A cold front will pass through the waters later Saturday into Saturday night. A few stronger storms are possible Saturday afternoon and evening.

Light westerly breezes will maintain sub SCA conditions over the waters the second half of the weekend and into early next week. Diurnally driven showers and thunderstorms could pose a gusty wind threat, but given the synoptic features at play, coverage looks to be isolated to scattered at best over the waters.

TIDES/COASTAL FLOODING. Light east southeast winds early this morning is leading to elevated tidal anomalies across our waters. However, the threat for minor tidal flooding currently exists only at Annapolis and DC SW Waterfront this morning, with many other sites expected to hold in action stage. Anomalies have trending downward a touch the last couple of hours at Annapolis, likely a result of the lighter winds. So the issuance of an Advisory will be a game time decision (8-9z) as our current forecast just exceeds minor flood stage during high tide this morning around 9am. High tide at DC is late in the morning, and with a current forecast just touching minor flood, will monitor trends early this morning before making a decision there.

Easterly winds are expected to increase later today and persist tonight into early Friday morning as low pressure tracks up the Mid- Atlantic coast. This will bring a continued threat for minor tidal flooding through the high tide cycle Friday morning, with the threat subsiding thereafter as northerly flow emerges.

LWX WATCHES/WARNINGS/ADVISORIES. DC . None. MD . None. VA . None. WV . None. MARINE . Small Craft Advisory from 6 AM to 6 PM EDT Friday for ANZ530- 531-538-539. Small Craft Advisory from 6 PM this evening to 6 PM EDT Friday for ANZ532>534-537-540>543.

SYNOPSIS . BJL NEAR TERM . BJL SHORT TERM . BJL LONG TERM . BKF AVIATION . BJL/BKF MARINE . BJL/BKF TIDES/COASTAL FLOODING . BKF


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 66 mi55 min W 1 G 1 77°F 86°F1014.1 hPa
BLTM2 - 8574680 - Baltimore, MD 69 mi55 min SW 1 G 1.9 77°F 84°F1014 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 72 mi55 min SSE 5.1 G 6 78°F 1014.3 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hagerstown, Washington County Regional Airport, MD7 mi92 minN 010.00 miFair75°F66°F76%1014.9 hPa
Eastern WV Regional Airport/Shepherd Field, WV18 mi32 minN 010.00 miFair68°F64°F87%1014.2 hPa

Link to 5 minute data for KHGR

Wind History from HGR (wind in knots)
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Last 24hrCalmCalmNW43S536S7S5S9S8
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1 day agoE3Calm3S3SE4E5SE4E4SE6E7E5E5S4E4E4NE5E4SE3W3CalmS3CalmCalmCalm
2 days agoCalmCalm3W6S3CalmS54SE54S76S96E4E8E11E7S13NW3SW3CalmS3E5

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Thu -- 12:17 AM EDT     3.05 feet High Tide
Thu -- 05:51 AM EDT     Sunrise
Thu -- 06:46 AM EDT     0.40 feet Low Tide
Thu -- 10:10 AM EDT     Moonset
Thu -- 12:28 PM EDT     3.21 feet High Tide
Thu -- 07:21 PM EDT     0.29 feet Low Tide
Thu -- 08:35 PM EDT     Sunset
Thu -- 11:47 PM EDT     Moonrise
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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32.92.51.91.30.80.50.40.71.52.32.93.23.22.82.21.610.60.30.40.91.72.4

Tide / Current Tables for Chain Bridge, one mile below, D.C.
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Chain Bridge
Click for Map
Thu -- 12:12 AM EDT     3.05 feet High Tide
Thu -- 05:51 AM EDT     Sunrise
Thu -- 06:41 AM EDT     0.40 feet Low Tide
Thu -- 10:10 AM EDT     Moonset
Thu -- 12:23 PM EDT     3.21 feet High Tide
Thu -- 07:16 PM EDT     0.29 feet Low Tide
Thu -- 08:35 PM EDT     Sunset
Thu -- 11:47 PM EDT     Moonrise
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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32.92.41.81.20.80.50.40.81.52.32.93.23.12.72.11.510.60.30.411.82.5

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 (6,6,7,8)
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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.