Wednesday, July15, 2020
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Marine Weather and Tides
Kemps Mill, 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 5:54AMSunset 8:39PM Wednesday July 15, 2020 5:23 AM EDT (09:23 UTC) Moonrise 12:57AMMoonset 3:05PM Illumination 25% Phase: Waning Crescent; Moon at 25 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 Am Edt Wed Jul 15 2020
Rest of the overnight..W winds 5 kt. Waves less than 1 ft.
Today..SE winds around 5 kt. Waves 1 ft or less.
Tonight..SE winds 5 kt. Waves less than 1 ft.
Thu..SE winds 5 to 10 kt. Waves 1 ft.
Thu night..S winds 5 to 10 kt. Waves 1 ft.
Fri..SW winds 5 to 10 kt. Waves 1 ft. A chance of showers and tstms.
Fri night..SW winds around 5 kt. Waves 1 ft. A chance of showers and tstms.
Sat..SW 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. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 437 Am Edt Wed Jul 15 2020
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure will build across the area through today before moving offshore. A front may approach from the north late in the week, before lifting back north on Sunday. A small craft advisory may be needed for portions of the waters late Thursday.


7 Day Forecast for Marine Location Near Kemps Mill, MD
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location: 39.63, -77.79     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 150800 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 400 AM EDT Wed Jul 15 2020

SYNOPSIS. High pressure will build across the area today before moving offshore. A front will approach from the north late in the week, then return back north on Sunday.

NEAR TERM /THROUGH TONIGHT/. High pressure extends into the area from Quebec this morning while an upper level ridge axis approaches from the west. Broken altocumulus clouds are persisting across southern parts of the area, which in addition to some passing cirrus, are helping to limit valley fog.

Expect the moisture responsible for this morning's clouds to remain trapped under the subsidence inversion through the day. The biggest question is whether mixing allows them to become more scattered, or if some places end up a bit cloudier. The forecast is on the optimistic side at the moment, but may need to increase cloud cover some. In addition, as low level flow becomes more southerly, a theta-e ridge will nose into southwestern parts of the CWA. This may allow a stray shower or storm to develop along the terrain, though subsidence should limit vertical development and keep most of the area dry. Unless clouds are much thicker than expected, today should be a few degrees warmer than yesterday (upper 80s-lower 90s), and humidity should increase a little as well.

As the high moves over the Canadian Maritimes tonight, surface flow will become easterly/onshore, while southerly flow will continue just aloft. At a minimum, this overrunning should result in increased cloud cover. There are various solutions as to whether light showers (drizzle?) form as low level moisture increases late tonight. Have included slight chance PoPs for now across western parts of the area where better moisture coincides with uplift from the terrain. The clouds will hold lows in the upper 60s- lower 70s.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/. The high will remain positioned to the northeast on Thursday while low pressure passes through the Great Lakes with a trailing cold front. Winds will maintain an onshore/SE component east of the Blue Ridge, with southerly winds to the west. This may mean clouds will be tough to break, as well as limit instability, east of the Blue Ridge. To the west, there are questions about the duration of the cloud cover and whether there will be morning showers with a weak shortwave (and how long they would last). These factors will affect afternoon convective development there. At a minimum, thunderstorms appear decreasingly likely east of US 15, and have trimmed PoPs and thunder mention a bit (and possibly could go even further). Have continued with the idea that some instability will be able to develop west of I-81, and that the terrain and weak PVA will result in scattered thunderstorms. If instability is strong enough, deep shear may approach 30 kt, so a few strong to severe storms are possible. SPC has extended a Marginal Risk into the northwestern parts of the area. With the extra cloud cover, Thursday is looking a bit cooler now, mainly in the 80s, with some 90s possible in the south and west. For those tracking the DC 90-degree streak, both statistical (MOS) and top-performing numerical guidance/blends keep highs just short now.

Beyond Thursday evening, convective and feature evolution becomes a bit muddled. Have continued a chance of showers through Thursday night since some activity may continue along the frontal zone approaching from the north.

By Friday, the low passing to the north will allow south/southwest winds to develop, which should allow temperatures to rise back into the upper 80s-mid 90s. The actual surface front may be just to our north, but a pressure trough will likely extend across the area, and there may be weak shortwave energy. This all present opportunities for convective development, though exactly which part of the area has the highest chance is not clear at the moment. Will have to keep an eye on Friday night, because there may be a subtle low level wind max increasing moisture transport into the trough axis or front with precipitable water values over 2 inches. Could be an opportunity for a focused area of locally heavy rain that persists past the diurnal cycle, though we have a couple days of convective evolution to go through before getting there.

LONG TERM /SATURDAY THROUGH TUESDAY/. Weak high pressure will build in from the northwest Saturday and Saturday night. Light northerly winds will become southeasterly Saturday afternoon. A couple of showers and thunderstorms could develop over the higher terrain in the west, as well as along the Blue Ridge. Temperatures will be in the lower to middle 90s.

Weak high pressure should remain in control Sunday. Most areas could be rain-free. A pop-up thunderstorm in the Potomac Highlands Sunday afternoon could venture eastward into northern and central Virginia. Also, a bay breeze or sea breeze thunderstorm could develop over eastern and southern Maryland. Showers and a thunderstorm or two could linger Sunday night as a cold front approaches from the north. Temperatures should be in the middle 90s.

A cold front could stall across our region Monday through Wednesday. Several rounds of showers and thunderstorms could form along this front. Thunderstorm activity should be mainly in the west and north on Monday, across our southern zones on Tuesday, and anywhere across our CWA on Wednesday. Definitely, the unsettled pattern continues as weak boundaries interact with differential heating and high humidity. Temperatures each of the three days will be in the middle 90s.

AVIATION /08Z WEDNESDAY THROUGH SUNDAY/. High pressure passing by to the north will keep conditions VFR today with light southeast winds developing. There are some VFR cigs over central VA which could expand north. With a marine influence tonight, some low clouds (MVFR most likely, but perhaps IFR) may develop, most likely at BWI/MTN, but all locations east of the Blue Ridge stand a chance. These clouds will likely eventually mix out Thursday. However, their influence will limit thunderstorm chances, with most activity remaining near or west of a CHO-MRB line. Low clouds may return for Thursday night.

There should be a higher chance of storms area-wide (but perhaps still scattered) on Friday as a trough axis crosses the area.

VFR conditions Saturday through Sunday night. MVFR to IFR conditions possible mainly near MRB and CHO terminals Saturday with possible MVFR conditions at other terminals Saturday night into Sunday. Winds northwest becoming light and variable around 5 knots Saturday and Saturday night, then south to southwest 5 knots Sunday and Sunday night. Winds gusty in any thunderstorms.

MARINE. High pressure will be in control today with light southeast winds developing. Could be a couple hours of SCA gusts on the Bay this evening, but confidence is low on such a short time window. Stronger SE flow will develop by Thursday, with potential SCA conditions by Thursday evening. Most storms should stay west of the waters on Thursday.

South winds should remain below SCA criteria on Friday, but there will be a greater chance of afternoon thunderstorms, potentially lasting into the night.

No marine hazards expected Saturday through Sunday night. Winds northwest becoming south 5 to 10 knots Saturday and Saturday night. Winds mainly south 5 to 10 knots Sunday into Sunday night.

TIDES/COASTAL FLOODING. Tides will gradually increase with each passing cycle as light northerly winds become east then southeasterly. There is a possibility of minor coastal flooding along the northern and central Chesapeake Bay shoreline Thursday night into Friday morning as a surface high pressure center widens and builds over southern New England and along the Jersey Shore. Tides could be about a foot above normal.

LWX WATCHES/WARNINGS/ADVISORIES. DC . None. MD . None. VA . None. WV . None. MARINE . None.

SYNOPSIS . ADS NEAR TERM . ADS SHORT TERM . ADS LONG TERM . KLW AVIATION . ADS/KLW MARINE . ADS/KLW TIDES/COASTAL FLOODING . KLW


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 66 mi53 min 85°F
BLTM2 - 8574680 - Baltimore, MD 69 mi53 min 80°F
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 73 mi173 min 1018 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hagerstown, Washington County Regional Airport, MD6 mi30 minE 310.00 miA Few Clouds67°F57°F71%1020.7 hPa
Eastern WV Regional Airport/Shepherd Field, WV18 mi30 minN 010.00 miFair60°F57°F93%1019.7 hPa

Link to 5 minute data for KHGR

Wind History from HGR (wind in knots)
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Last 24hrCalmNW3Calm4NW9W7NW9N12
G18
NW6N9W6W10NW8NW5NW6W3NW3NE4CalmCalmCalmCalmCalmE3
1 day agoCalmS3S33W653NW53S4SE6CalmNW5W4W4W3NW3NW4CalmCalmN4CalmNW3Calm
2 days agoS4E3S5S7S7SW6CalmS7SW7SW8SE7S6N7NE3N8NW6CalmW3CalmSW3W3CalmSE4Calm

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Wed -- 01:55 AM EDT     Moonrise
Wed -- 05:07 AM EDT     3.12 feet High Tide
Wed -- 05:55 AM EDT     Sunrise
Wed -- 11:54 AM EDT     0.64 feet Low Tide
Wed -- 04:00 PM EDT     Moonset
Wed -- 05:41 PM EDT     2.68 feet High Tide
Wed -- 08:32 PM EDT     Sunset
Wed -- 11:27 PM EDT     0.49 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.71.222.633.132.621.410.70.60.81.31.92.42.62.72.41.81.20.70.5

Tide / Current Tables for Chain Bridge, Washington, D.C.
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Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.


Weather Map
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wmap_A
GEOS Local Image of Mid-Atlantic    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 (5,6,7,8)
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Ground Weather Radar Station Sterling, VA
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