Tuesday, December7, 2021
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Marine Weather and Tides
Point of Rocks, 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 7:15AMSunset 4:47PM Tuesday December 7, 2021 7:46 PM EST (00:46 UTC) Moonrise 10:54AMMoonset 8:28PM Illumination 15% Phase: Waxing Crescent; Moon at 4 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- 635 Pm Est Tue Dec 7 2021
Tonight..E winds around 5 kt. Waves flat.
Wed..S winds around 5 kt. Waves 1 ft. A chance of snow and rain. Vsby 1 to 3 nm.
Wed night..NW winds around 5 kt. Waves 1 ft.
Thu..W winds around 5 kt. Waves 1 ft.
Thu night..S winds around 5 kt. Waves 1 ft.
Fri..S winds 5 kt. Waves less than 1 ft.
Fri night..S winds 5 to 10 kt. Waves 1 ft. A chance of showers.
Sat..SW winds 10 to 15 kt...becoming W after midnight. Waves 1 ft. A chance of showers in the morning, then showers likely.
Sun..NW winds 5 to 10 kt. Waves 1 ft. A chance of showers in the morning.
ANZ500 635 Pm Est Tue Dec 7 2021
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure will persist over the region through tonight. Low pressure will pass south of the area late Wednesday. High pressure returns for Thursday before the next cold front crosses the area late Saturday. Small craft advisories may be needed Wednesday night into Thursday and again late Thursday night into the weekend. Gale conditions are possible Saturday through Saturday night.


7 Day Forecast for Marine Location Near Point of Rocks, MD
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location: 39.28, -77.53     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 071917 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 217 PM EST Tue Dec 7 2021

SYNOPSIS. High pressure will hold over the region through tonight. Low pressure will pass south of the area through late Wednesday. High pressure returns for Thursday and Friday. A strong cold front will swing through the region Saturday, bringing the potential for severe weather and flooding.

NEAR TERM /THROUGH WEDNESDAY/. Canadian surface high pressure directly overhead has kept things fairly quiet today with cooler than average temperatures. Mid-high level clouds continue to stream across the region as lobes of upper-level energy rotating about a upper low over Quebec/Ontario slide across the region.

A piece of that upper-level energy will sharpen and approach the region tonight from the Great Lakes. High pressure overhead will keep temperatures cool tonight, with lows down near/slightly below freezing. As this trough approaches the region, a weak surface low will develop to our south near NC coast. Thinking is that most of the moisture with this system will be pinched off to the south, and we do not look to be in a favorable jet stream position for much in the way of snow.

Virtually all guidance has come down markedly today in terms of snowfall amounts. Not that there was too much in the guidance this time yesterday, but even less so today. The GFS and NAM have now come into agreement with the ECMWF solutions in recent days, bringing little to no snow to the region. Do maintain a light dusting for portions of the area, as the NBM maintains at least some chance we at least see some flakes, perhaps up to a coating of snow on grassy surfaces. Temperatures will be relatively marginal, and given the light nature of this snow, would not be surprised to see some rain mixed in.

SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/. By Wednesday afternoon this system will be out of here, as it is a very quick hitter. Cold high pressure will build in Wednesday night into Thursday. Low temps on Wednesday night fall into the low to mid 20s, with highs on Thursday in the 40s for much of the area. Given the lack of cloud cover and relatively light winds Wednesday night, expect a few areas to even be a little colder due to radiational cooling effects.

Southerly winds pick up on Thursday night, so low temperatures are expected to be higher than Wednesday night, only reaching the upper 20s to low 30s.

LONG TERM /FRIDAY THROUGH MONDAY/. A warm front associated with a low over the lower plains is currently forecast to lift northward through our region early on Friday. This boundary may become the focus for some light precipitation mainly along the MD and PA border. Friday morning temperatures look to be above freezing which suggests that threat for any wintry precipitation remains low. Once this front passes to the north of our region, we will become positioned in the warm sector ahead of an approaching strong cold front. Warm air advection will increase Friday into Saturday leading to Friday afternoon temperatures rising up into the low to mid 50s. Continued warm advection will lead to overnight temperatures staying warm Friday evening and into Saturday morning. I have run a blend of NBM 50th and 75th percentile as I believe the NBM will be underdone in the strong warm air advection this late in the year.

A strong cold front will slowly approach from the west on Saturday and move through sometime Saturday afternoon into Sunday morning. Depending on the timing of the frontal passage, there is a decent potential that most guidance will under do the temperatures for Saturday. I have upped high temperatures for Saturday to use a mix of NBM 50th and 75th percentile to account for the strong WAA. High temperatures on Saturday could reach into the mid 70s. Ahead of this front, a flow originating from the gulf of mexico will lead to anomalous PW's in the 1.5 to 1.7 inch range on Saturday. This would be 2 to 3 standard deviations above normal for this time of year but the threat for flooding may be limited due to the progressive nature of the front. On top of the high PWs,strong winds of 40 to 50s knots at 850mb combined with a strong 150 knot jet streak will lead to an increased threat for QLCS storms capable of producing damaging winds. I believe on top of all these threats, the strong winds aloft could lead strong winds over our waters and the possibility for wind advisories for our higher elevations.

The front should pass through our region by early Sunday morning leading to a shift of winds out of the west to northwest and a brief return too cooler but still above normal temperatures in the mid 50s. High pressure is forecast to build into our region Sunday through the middle parts of next week with much drier and continued above normal temperatures.

AVIATION /18Z TUESDAY THROUGH SUNDAY/. VFR conditions continue through tonight, but clouds will be on the increase as low pressure develops to our south. Latest thinking on snowfall has come down from previous forecasts with only CHO TAF explicitly having snow at this time. Can't rule out some light snow at the other TAF sites (except for MRB which seems likely to get none at this point). Timing would be between 12z-18z roughly, and if there are any accumulations they will be light and should be relegated to grassy surfaces.

Any lingering snow departs no Wednesday afternoon with high pressure returning through Thursday. This will result in VFR conditions area-wide.

VFR conditions are expected on Friday with winds become south to southwesterly. A front will approach from the west on Saturday leading to strengthening winds out of the south along with the possibilities for gusts of 20 to 30 knots. A strong flow aloft could lead to a threat for LLWS especially right ahead of the frontal passage. Strong winds becoming westerly behind the front will continue into Saturday evening. Light winds and clear skies return on Sunday.

MARINE. A few rogue gusts here and there on the tidal Potomac to near SCA criteria, so an MWS is out for that. Otherwise, diminishing winds expected through Wednesday, with no marine hazards expected at this time.

SCA conditions possible again Wednesday night into Thursday between strengthening low pressure offshore and building high pressure from the west.

A southerly channeling flow on Friday may lead to Small Craft Conditions on Friday. Increasing winds associated with a strong cold front will lead to the potential for a long duration Gale conditions Saturday afternoon into evening.

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

SYNOPSIS . CJL NEAR TERM . CJL SHORT TERM . CJL LONG TERM . JMG AVIATION . CJL/JMG MARINE . CJL/JMG


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 39 mi149 min WNW 1G1.9 45°F1022.9 hPa
BLTM2 - 8574680 - Baltimore, MD 50 mi149 min N 1.9G4.1 49°F1022.3 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 53 mi119 min NW 5.1G6 40°F 1023.1 hPa

Wind History for Washington, DC
(wind in knots)    EDIT      (on/off)   Help
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This dayS7
NW16
G26
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NW11
G31
NW9
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NW6
G14
W4
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G11
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SE2
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G13
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G18
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G15
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ago
SE2
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NW2
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S3
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N2
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G5
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G7
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SE2
G6
SE3
G6
SE2
G6
E2
G5

Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Frederick Municipal Airport, MD13 mi60 minN 010.00 miFair34°F25°F70%1023 hPa
Leesburg / Godfrey, VA14 mi52 minN 010.00 miFair36°F21°F56%1023 hPa
Gaithersburg - Montgomery County Airport, MD21 mi51 minN 010.00 miFair32°F19°F59%1024.9 hPa
Washington/Dulles International Airport, DC, VA23 mi55 minENE 410.00 miMostly Cloudy35°F17°F48%1022.7 hPa

Link to 5 minute data for KFDK

Wind History from FDK (wind in knots)
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--SW4W7W40W5W6W8W8W4W8W4W6000
1 day ago0000000NW300000S7SW7SW12
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2 days ago00W500000SE4000000000S5S5S50SE40

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Tue -- 05:19 AM EST     -0.36 feet Low Tide
Tue -- 07:13 AM EST     Sunrise
Tue -- 10:42 AM EST     2.76 feet High Tide
Tue -- 10:51 AM EST     Moonrise
Tue -- 04:46 PM EST     Sunset
Tue -- 05:17 PM EST     -0.26 feet Low Tide
Tue -- 08:27 PM EST     Moonset
Tue -- 10:58 PM EST     3.20 feet High 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
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2.5
1
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1.8
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1.1
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0.5
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0
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-0.3
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0.4
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1.4
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2.2
10
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2.7
11
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2.7
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2.4
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1.7
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1.1
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0.5
4
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0
5
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-0.2
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-0.2
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0.5
8
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1.5
9
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2.4
10
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3
11
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3.2


Tide / Current Tables for Chain Bridge, one mile below, D.C.
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Chain Bridge
Click for Map
Tue -- 05:14 AM EST     -0.36 feet Low Tide
Tue -- 07:13 AM EST     Sunrise
Tue -- 10:37 AM EST     2.76 feet High Tide
Tue -- 10:51 AM EST     Moonrise
Tue -- 04:46 PM EST     Sunset
Tue -- 05:12 PM EST     -0.26 feet Low Tide
Tue -- 08:27 PM EST     Moonset
Tue -- 10:53 PM EST     3.20 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Chain Bridge, one mile below, D.C., Tide feet
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2.5
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1.8
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1.1
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-0.2
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0.5
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1.5
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2.2
10
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2.7
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2.7
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2.3
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-0.1
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2.5
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3
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3.2


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