Ashton-Sandy Spring, MD Marine Weather and Tide Forecast
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Marine Weather and Tide Forecast for Ashton-Sandy Spring, MD


December 5, 2023 9:18 PM EST (02:18 UTC)
Sunrise 7:10AM   Sunset 4:46PM   Moonrise  12:00AM   Moonset 12:57PM 

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. Privacy and Cookie policy

Marine Forecasts
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ANZ538 Patapsco River Including Baltimore Harbor- 633 Pm Est Tue Dec 5 2023
.small craft advisory in effect from Wednesday morning through Wednesday evening...
Tonight..N winds 5 kt. Waves less than 1 ft. Scattered showers.
Wed..NW winds 10 to 15 kt with gusts to 20 kt. Waves 1 ft. Scattered showers.
Wed night..NW winds 5 to 10 kt. Gusts up to 20 kt until early morning. Waves 1 ft.
Thu..W winds 5 to 10 kt. Waves 1 ft.
Thu night..SW winds around 5 kt. Waves 1 ft or less.
Fri..S winds 5 kt. Waves less than 1 ft.
Fri night..SW winds 5 kt. Waves less than 1 ft.
Sat..S winds 5 to 10 kt. Waves 1 ft or less.
Sun..S winds 10 to 15 kt...increasing to 20 kt in the afternoon, then becoming w. Waves 2 ft. Rain through the day. Showers likely in the evening, then a chance of showers after midnight.

ANZ500 633 Pm Est Tue Dec 5 2023
Synopsis for the tidal potomac and md portion of the chesapeake bay..
a quick moving low pressure system will cross the area through early Wednesday. High pressure will build over the region Thursday through Friday night. Small craft advisories may be needed Saturday night.


7 Day Forecast for Marine Location Near Ashton-Sandy Spring, MD
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Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 060208 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 908 PM EST Tue Dec 5 2023

SYNOPSIS
A clipper system will cross the area through Wednesday. High pressure will build over the region Thursday through Friday night. A strong frontal system will likely impact the region on Sunday.

NEAR TERM /THROUGH WEDNESDAY/
A trough axis is pushing through the mid Ohio Valley this evening, with a weak surface low near Parkersburg, WV. These features will continue to quickly make their way eastward through tonight, and will be the focal point for unsettled weather through Wednesday morning.

While the precipitation spreading toward central Maryland is a little more notable than a lot of guidance showed at this stage, the forecast, especially for snow, seems largely on track.
Upstream radar returns show the heaviest precipitation on track toward Grant, Pendleton, and Highland Counties. Snow is expected to persist longer in these areas as well, as the tilt of the trough axis will support some drying in Garrett County toward dawn. There remains some uncertain regarding QPF east of the Allegheny Front and the amount of snow on the higher ridges in these areas. Recent model QPF is rather splotchy, although some localize 2 inch amounts can't be ruled out.

It will be a struggle to realize much snow at lower elevations despite temperatures falling into the mid 30s. Surface dew points will likely remain above freezing until the column starts drying toward dawn and precipitation ends. Rates likely won't be strong enough for dynamical cooling either. Therefore, any flakes should they occur would likely be limited to the increasing elevations west of I-95. It's also looking possible Baltimore/northeast Maryland may see little to no precipitation at all.

Previous discussion:

As we move through the evening, precipitation is likely to overspread much of the region. This will generally be an elevation-based event in regards to snowfall accumulation.

The Northern Virginia Blue Ridge zone was placed under a Winter Weather Advisory for tonight into early Wednesday morning due to favorable overlap of cold temperatures and increased lift. To the west, the advisory was extended until 1pm Wednesday for western Grant southward to western Highland; the DGZ will lower, upslope-enhanced precipitation will linger, and winds will increase resulting in (1) lingering higher snowfall rates, and (2) reduced visibility. Snowfall totals should be limited to coating to areas NW of US-29, with two exceptions: (1) 1 to 3 inches of snow is expected along the crest of the Northern Virginia Blue Ridge, and possibly some of the higher foothills surrounding the Shenandoah Valley, and (2) around 3 to 6 inches along and west of the Allegheny Front (isolated slightly higher totals can't be ruled out here). West-facing slopes will be most favored given the wind direction/synoptic setup, with the highest totals generally above 2500 feet.

Heading east toward the DC/Baltimore metro areas into the Fredericksburg to southern MD region, more marginal low-level temperatures could result in occasional snow mixing with rain showers, but accumulation is not anticipated at the moment.

As the system moves offshore by Wednesday afternoon, winds will increase out of the W/NW. A few gusts to 30 mph are possible, but persistent cloud cover may result in sub-optimal mixing and thus the current forecast has prevailing gusts about 4-8 mph lower than that. Either way, it will turn out brisk.

SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/
Partial clearing is expected Wednesday night as high pressure and broad ridging approach the Mid-Atlantic. Winds may stay up a bit and prevent ideal radiational cooling, but in areas where the sky becomes a bit more clear and the wind goes calm, temperatures may plummet several degrees below currently advertised values. This would be most likely across the lowlands of north-central VA.

A mid/upper wave will pivot to the north Thursday as troughing departs. The low levels look a bit dry, but the day will probably end up mostly cloudy with a mid/high level overcast. If there is enough moisture, there could be just enough lift for some sprinkles or flurries near/north of I-70. Otherwise, dry and slightly milder/less breezy conditions are expected through Thursday night.

LONG TERM /FRIDAY THROUGH TUESDAY/
A deep upper trough will dig across the Rockies and Northern Plains on Friday. Further downstream, we'll have shortwave ridging overhead. At the surface, a strong area of low pressure will track across southeastern Manitoba into far western Ontario. High pressure will progress offshore to the east of the Carolinas. This will place us in southerly flow at low levels. Southerly winds will allow warmer air to work back into the area. Temperatures on Friday will top out in the mid 50s to low 60s for most beneath partly cloudy skies.

The primary area of low pressure over Canada will track northeastward toward Hudson Bay on Saturday, leaving a sharp frontal boundary draped south-southwestward through the Great Lakes and Mississippi Valley. A secondary area of low pressure will develop along this frontal boundary in the Mississippi Valley as troughing starts to sharpen to its west. High pressure will remain in place offshore keeping us in southerly flow again locally. It will be another mild day beneath mostly sunny skies. Temperatures will once again top out in the mid 50s to low 60s.

The aforementioned area of low pressure will rapidly intensify as it tracks into the Great Lakes Saturday night, and then eventually Ontario/Quebec on Sunday. Meanwhile, the system's mid-upper level shortwave will assume a negative tilt as it progresses overhead by later Sunday into Sunday night. This system will produce a soaking rainfall across the area Sunday into Sunday night, with ensemble means from both the EPS and GEFS between a half of an inch and an inch. Some ensemble members also show some limited surface-based instability developing Sunday afternoon. If this were to occur, there could be a threat for some thunderstorms, and potentially even severe thunderstorms, given very strong winds in place just above the surface. We'll continue to monitor this potential over the upcoming days.

As the system's cold front moves through Sunday night, much cooler air will filter back into the area. Rain may change over to snow along the Allegheny Front before ending. Winds may potentially be strong both ahead of and behind the cold front Sunday afternoon through Sunday night. Depending on how the system evolves, wind headlines may potentially be needed.

Drier conditions are expected on Monday as low pressure progresses well off to our north. Winds will remain gusty out of the west to southwest. Spread with respect to the temperature forecast on Monday is considerable, but ensemble means favor high temperatures in the 40s to lower 50s at the moment.

AVIATION /02Z WEDNESDAY THROUGH SUNDAY/
Light rain is overspreading the region this evening, although it will take some time for the airmass to saturate and lower ceilings (only MRB at MVFR as of 9 PM). Reduced CIGs/VSBYs are likely especially west of US-15 late tonight into Wednesday morning as a clipper low brings a round of showers, which may even mix with snow (especially at MRB, where a period of all snow is also possible after about 06z tonight). For BWI and MTN, there is a bit more uncertainty, as the majority of precip may drop to the south. Overall, IFR appears most likely at MRB, CHO, and IAD, although it's not a complete certainty. Recent guidance began cutting back on low ceilings, so tried to start a trend in that direction. Also removed any mention of snow from BWI and DCA, as low level thermal profiles may not support snow until the precipitation ends. It could also be a stretch at IAD, but left it in for now. Precipitation should end around sunrise Wednesday with ceilings improving thereafter.

VFR conditions are expected later Wednesday morning through Thursday. Gusty W/NW winds Wednesday may gust to around 25 kts.

VFR conditions appear likely on both Friday and Saturday. Conditions may deteriorate to sub-VFR Saturday night as rain and low ceilings move into the area. Winds will be out of the south on both Friday and Saturday.

MARINE
Winds should remain less than 15 kts through tonight out of the N/NW. A clipper system will swing through tonight into Wednesday with 20-30 kt gusts likely in its wake out of the W/NW from late Wednesday morning into the evening.

Winds begin to taper a bit Wednesday night, especially over narrower waterways, but 20-25 kt gusts likely persist over the wider waters until at least daybreak on Thursday.

Thursday brings lighter westerly winds over the waters, with no marine hazards expected at this time. Sub-SCA level southerly winds are expected over the waters on both Friday and Saturday.

TIDES/COASTAL FLOODING
Northwesterly flow weakened this afternoon resulting in increasing anomalies. Some sensitive sites may approach action stage tonight. Anomalies likely decrease Wednesday as winds increase out of the NW. Flow becomes southerly Thursday and persists through most of the weekend increasing tidal anomalies and likely bringing sensitive locations to action by the end of the week.

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Winter Weather Advisory until 7 AM EST Wednesday for MDZ001.
VA...Winter Weather Advisory until 1 PM EST Wednesday for VAZ503.
Winter Weather Advisory until 8 AM EST Wednesday for VAZ507.
WV...Winter Weather Advisory until 1 PM EST Wednesday for WVZ501- 505.
MARINE...Small Craft Advisory from 9 AM Wednesday to midnight EST Wednesday night for ANZ530>532-535-536-538>540-542.
Small Craft Advisory from 7 AM Wednesday to 7 AM EST Thursday for ANZ533-534-537-541-543.


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesinHgDewPt
WASD2 - 8594900 - Washington, DC 19 mi48 min E 1.9G4.1 45°F 45°F30.01
BLTM2 - 8574680 - Baltimore, MD 24 mi48 min N 4.1G5.1 49°F
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 25 mi48 min NE 1.9G2.9 44°F
FSNM2 26 mi48 min N 5.1G5.1 30.01
APAM2 - 8575512 - Annapolis, MD 30 mi48 min N 2.9G2.9 43°F 52°F30.01
BSLM2 - Chesapeake Bay, MD 30 mi48 min WNW 1 40°F 30.0135°F
44043 - Patapsco, MD 32 mi30 min ENE 3.9G3.9 43°F 46°F0 ft
44063 - Annapolis 32 mi30 min N 3.9G5.8 42°F 47°F
CPVM2 34 mi48 min 45°F 34°F
TPLM2 - Thomas Point, MD 35 mi18 min NNE 6G6 45°F 30.04
TCBM2 - 8573364 - Tolchester Beach, MD 40 mi48 min ESE 2.9G2.9 41°F 30.03

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Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisSkyWeatherTempDewPtRHinHg
KGAI MONTGOMERY COUNTY AIRPARK,MD 9 sm9 mincalm10 smOvercast Lt Rain 39°F36°F87%30.01
KCGS COLLEGE PARK,MD 12 sm8 mincalm10 smOvercast41°F34°F75%30.02
KFME TIPTON,MD 13 sm9 mincalm10 smOvercast37°F34°F87%30.04
KBWI BALTIMORE/WASHINGTON INTL THURGOOD MARSHALL,MD 18 sm24 minNE 0310 smOvercast45°F30°F57%30.01
KDCA RONALD REAGAN WASHINGTON NATIONAL,VA 21 sm26 minNE 0510 smOvercast45°F34°F66%30.02
KADW JOINT BASE ANDREWS,MD 24 sm23 mincalm10 smClear39°F30°F70%29.99

Wind History from GAI
(wind in knots)


Tide / Current for Chain Bridge, D.C.
   
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Chain Bridge
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Tue -- 12:51 AM EST     Last Quarter
Tue -- 02:04 AM EST     2.52 feet High Tide
Tue -- 07:11 AM EST     Sunrise
Tue -- 08:35 AM EST     0.21 feet Low Tide
Tue -- 12:57 PM EST     Moonset
Tue -- 02:39 PM EST     2.45 feet High Tide
Tue -- 04:46 PM EST     Sunset
Tue -- 08:52 PM EST     0.30 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Chain Bridge, D.C., Tide feet
12
am
2.1
1
am
2.4
2
am
2.5
3
am
2.4
4
am
2
5
am
1.4
6
am
0.9
7
am
0.5
8
am
0.3
9
am
0.2
10
am
0.5
11
am
1.1
12
pm
1.7
1
pm
2.2
2
pm
2.4
3
pm
2.4
4
pm
2.2
5
pm
1.7
6
pm
1.1
7
pm
0.7
8
pm
0.4
9
pm
0.3
10
pm
0.5
11
pm
0.9



Tide / Current for Benning Bridge, D.C.
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Benning Bridge
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Tue -- 12:51 AM EST     Last Quarter
Tue -- 02:00 AM EST     2.62 feet High Tide
Tue -- 07:11 AM EST     Sunrise
Tue -- 08:29 AM EST     0.22 feet Low Tide
Tue -- 12:57 PM EST     Moonset
Tue -- 02:35 PM EST     2.55 feet High Tide
Tue -- 04:45 PM EST     Sunset
Tue -- 08:46 PM EST     0.31 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Benning Bridge, D.C., Tide feet
12
am
2.2
1
am
2.5
2
am
2.6
3
am
2.5
4
am
2
5
am
1.4
6
am
0.9
7
am
0.5
8
am
0.3
9
am
0.3
10
am
0.6
11
am
1.2
12
pm
1.8
1
pm
2.3
2
pm
2.5
3
pm
2.5
4
pm
2.2
5
pm
1.7
6
pm
1.1
7
pm
0.6
8
pm
0.4
9
pm
0.3
10
pm
0.5
11
pm
1




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