Thursday, August5, 2021
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Marine Weather and Tides
Ashton-Sandy Spring, MD

Version 3.4
NOTICE
3/30/2021 -- ANZ330 has been split into ANZ331 and ANZ332. Click EDIT in Marine Forecast and select your new zone.
1/26/2021 -- The West Coast Satellite images havd been updated. They now use GEOS-17.
1/1/2021 -- The 7 day forecast are now working well. Thank you NOAA for your support.

Sunrise 6:11AMSunset 8:16PM Thursday August 5, 2021 12:47 AM EDT (04:47 UTC) Moonrise 2:03AMMoonset 5:38PM Illumination 10% Phase: Waning Crescent; Moon at 27 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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ANZ538 Patapsco River Including Baltimore Harbor- 1214 Am Edt Thu Aug 5 2021
Overnight..N winds 5 kt. Waves less than 1 ft.
Thu..N winds 5 kt. Waves flat.
Thu night..S winds 5 kt. Waves flat.
Fri..S winds 5 to 10 kt. Waves 1 ft or less.
Fri night..S winds 5 to 10 kt. Waves 1 ft.
Sat..S winds 5 kt. Waves less than 1 ft.
Sat night..SW winds around 5 kt. Waves 1 ft or less.
Sun..SW winds around 5 kt. Waves flat.
Mon..S winds 5 to 10 kt. Waves 1 ft or less.
ANZ500 1214 Am Edt Thu Aug 5 2021
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure will remain stretched from the northeast to the ohio river valley through late this week. Meanwhile, a series of low pressure systems will pass by to our south and east off the carolina coast. High pressure will shift into the atlantic ocean this weekend.


7 Day Forecast for Marine Location Near Ashton-Sandy Spring, MD
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location: 39.15, -77     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 050111 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 911 PM EDT Wed Aug 4 2021

SYNOPSIS. High pressure will remain stretched from the Northeast to the Ohio River Valley through Friday. Meanwhile, a series of low pressure systems will pass by to the south and east off the Carolina coast. High pressure will shift into the Atlantic Ocean this weekend and remain there through early next week.

NEAR TERM /UNTIL 6 AM THURSDAY MORNING/. There has been little change in the surface pattern with a stalled frontal zone along the coastline of the Carolinas. Cyclonic flow around the offshore waves of low pressure has maintained a steady dose of north to northeasterly winds over the Mid-Atlantic region. Conditions remain dry with below normal temperatures and low (for August) dew points overnight. With winds diminishing in strength and mostly clear skies, some patchy fog may develop over the Potomac Highlands as well as along areas of I-81. Lows bottom out in the upper 50s to low 60s, locally higher in the DC and Baltimore metro areas.

SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/. An upstream shortwave currently over the Mid-South region is forecast to lift northeastward during the next 24 hours. Enhanced vertical motions associated with this system could spawn some showers and thunderstorms over portions of the Alleghenies eastward toward the I-81 corridor. Some limiting factors exist which include the less than optimal moisture and vertical shear topping out around 15 to 20 knots. With instability values rising into the 1,000 to 1,500 J/kg range, some gusty winds could materialize within a stronger cell. A few showers may spawn as early as the late morning over Highland and Pendleton Counties as the shortwave arrives by 15Z. Locations downstream should remain dry with high temperatures warming back up into the mid 80s. Although some high clouds may lift northward with the upper jet from convection in the southeastern U.S., there should be a greater deal of sunshine on Thursday. Overnight temperatures continue to rise with lows about 5 degrees warmer than the prior night.

With the mentioned system eventually lifting into New England, shortwave ridging will set up over the region. Mid-level heights rise by about 6 dm over the 24 hours leading into Friday. This will ultimately crank temperatures back up into the low 90s with the usual cool spots in the higher terrain staying in the 70s to low 80s. Conditions remain dry underneath this ridge axis with return southerly flow allowing humidity levels to creep back up. This will make for a milder night on Friday with lows getting back into the low 70s across the I-95 corridor and points eastward.

LONG TERM /SATURDAY THROUGH WEDNESDAY/. For Saturday, a shortwave trough centered along the Ohio Valley down into the southern U.S. will move across the region. Thoughts remain the same in regards to precipitation potential, with some showers/storms possible over the higher terrain. Additionally, an area of low pressure looks to form just offshore along a pre- existing frontal boundary along the east coast as the shortwave moves through, so additional rainfall is possible across our extreme southern areas, but lots of uncertainty at this time, so will keep POPs at the low end of chance. Temperatures will be right around seasonal averages, with highs in the mid to upper 80s.

Beyond that comes the return of heat and humidity as high pressure settles over the western Atlantic, resulting in southerly/southwesterly flow once again. Additionally, an upper- level ridge will build overhead through the middle of the week, with gradual height rises expected. As a result, temperatures increase a few degrees each day, with highs in the low 90s Sunday, then rising into the mid 90s by Tuesday. With dew points in the upper 60s to low 70s, heat indices will near 100 on Monday and Tuesday, especially near and east of I-81. Along with this will come the slight chance of a pop-up storm each afternoon near the Allegheny Highlands due to terrain circulations. However, do think the upper ridge limits coverage greatly.

AVIATION /01Z THURSDAY THROUGH MONDAY/. VFR conditions are expected through Friday. Any showers on Thursday most likely stay west of the KMRB and KCHO terminals. Winds remain out of the north to northeasterly direction today, occasionally gusting up to 15 knots or so. These diminish in strength into tonight with return southerly flow by Friday.

Low end chance of showers and storms this weekend, but should largely avoid the terminals, so VFR conditions are expected. Best chance probably resides at MRB, but even that is fairly low at this time. Could see some early morning fog each morning as humidity returns.

MARINE. Winds are diminishing as low pressure passes east of the area, and expect an eventual return of sub-SCA winds for Thursday into Friday.

A few showers and storms are possible over the waters Saturday afternoon as another low pressure forms to our southeast. Winds should generally remain below SCA, but can't rule out some brief gusty winds in any storms Saturday afternoon/evening.

For Sunday, winds remain below SCA criteria with only a slight chance of a storm developing along the Bay breeze during the afternoon.

TIDES/COASTAL FLOODING. Caution stages will persist at Annapolis for the high tide cycles on Friday and Saturday given periods of onshore flow.

LWX WATCHES/WARNINGS/ADVISORIES. DC . None. MD . None. VA . None. WV . None. MARINE . Small Craft Advisory until 8 AM EDT Thursday for ANZ534-543. Small Craft Advisory until midnight EDT tonight for ANZ537.

SYNOPSIS . BRO NEAR TERM . BRO/RCM SHORT TERM . BRO LONG TERM . CJL AVIATION . BRO/CJL/RCM MARINE . BRO/CJL/RCM TIDES/COASTAL FLOODING . BRO/CPB


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 19 mi47 min Calm G 4.1 74°F 81°F1019.7 hPa (+0.7)
BLTM2 - 8574680 - Baltimore, MD 24 mi47 min ESE 2.9 G 4.1 73°F 80°F1019.1 hPa (+0.7)
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 25 mi47 min E 6 G 6 73°F 1019.4 hPa (+0.8)
FSNM2 26 mi47 min E 6 G 7 72°F 1019.3 hPa (+0.6)
APAM2 - 8575512 - Annapolis, MD 30 mi47 min N 1.9 G 2.9 71°F 80°F1019 hPa (+0.6)
BSLM2 - Chesapeake Bay, MD 30 mi77 min Calm 60°F 1019 hPa60°F
44063 - Annapolis 32 mi29 min E 5.8 G 7.8 70°F 78°F1020.3 hPa
CPVM2 34 mi47 min 73°F 64°F
TPLM2 - Thomas Point, MD 35 mi47 min NE 7 G 7 72°F 78°F1020.4 hPa (+0.7)62°F
TCBM2 - 8573364 - Tolchester Beach, MD 40 mi47 min ESE 1.9 G 1.9 65°F 79°F1019.8 hPa (+0.8)

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Gaithersburg - Montgomery County Airport, MD9 mi51 minN 010.00 miFair61°F59°F93%1021.4 hPa
College Park Airport, MD12 mi72 minN 010.00 miFair62°F59°F89%1019.6 hPa
Fort Meade / Tipton, MD13 mi52 minN 010.00 miFair59°F59°F100%1020.7 hPa
Baltimore, Baltimore-Washington International Airport, MD18 mi53 minN 010.00 miFair66°F59°F78%1019.4 hPa
Washington/Reagan National Airport, DC, VA20 mi55 minN 010.00 miMostly Cloudy72°F59°F64%1019.7 hPa
Camp Springs / Andrews Air Force Base, MD23 mi51 minN 010.00 miFair63°F59°F86%1019.8 hPa

Link to 5 minute data for KGAI

Wind History from GAI (wind in knots)
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Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Thu -- 12:46 AM EDT     0.56 feet Low Tide
Thu -- 03:03 AM EDT     Moonrise
Thu -- 06:13 AM EDT     Sunrise
Thu -- 07:03 AM EDT     3.19 feet High Tide
Thu -- 01:58 PM EDT     0.49 feet Low Tide
Thu -- 06:37 PM EDT     Moonset
Thu -- 07:41 PM EDT     2.77 feet High Tide
Thu -- 08:15 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.60.60.81.32.12.733.232.621.510.70.50.71.31.92.42.72.82.41.91.3

Tide / Current Tables for Benning Bridge, D.C.
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Benning Bridge
Click for Map
Thu -- 12:40 AM EDT     0.60 feet Low Tide
Thu -- 03:03 AM EDT     Moonrise
Thu -- 06:12 AM EDT     Sunrise
Thu -- 06:59 AM EDT     3.32 feet High Tide
Thu -- 01:52 PM EDT     0.52 feet Low Tide
Thu -- 06:36 PM EDT     Moonset
Thu -- 07:37 PM EDT     2.88 feet High Tide
Thu -- 08:14 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.60.60.91.52.22.83.23.33.12.62.11.510.70.50.81.422.52.82.92.51.91.3

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NOTE: This section has been updated as of 1/26/2021. If the image you are expecting is not showing, please let me know. You may use the EDIT function to update your location.
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