Friday, January24, 2020
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Marine Weather and Tides
Rock Hall, 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 7:17AMSunset 5:18PM Friday January 24, 2020 2:20 PM EST (19:20 UTC) Moonrise 7:19AMMoonset 5:05PM Illumination 0% Phase: New Moon; Moon at 29 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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ANZ531 Chesapeake Bay From Pooles Island To Sandy Point- 1244 Pm Est Fri Jan 24 2020
.small craft advisory in effect from 6 pm est this evening through Saturday morning...
This afternoon..E winds 10 kt. Waves 1 ft.
Tonight..E winds 10 to 15 kt with gusts to 25 kt. Waves 2 to 3 ft. Rain. Vsby 1 nm or less.
Sat..SE winds 10 to 15 kt with gusts to 20 kt... Becoming W 5 to 10 kt in the afternoon. Waves 1 to 2 ft. Showers. Vsby 1 to 3 nm.
Sat night..W winds 5 to 10 kt. Waves 1 ft.
Sun..W winds 5 to 10 kt with gusts to 20 kt. Waves 2 ft.
Sun night..W winds 10 kt. Waves 1 ft.
Mon..NW winds 5 to 10 kt. Waves 1 ft.
Tue..NW winds 5 to 10 kt. Waves 1 ft.
ANZ500 1244 Pm Est Fri Jan 24 2020
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A low pressure system will move across the waters on Saturday. Northwest flow ahead of weak high pressure will build behind this system. Small craft advisories may be needed Saturday through Sunday and again on Tuesday.


7 Day Forecast for Marine Location Near Rock Hall, MD
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location: 39.15, -76.35     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 241916 CCA AFDLWX

Area Forecast Discussion . CORRECTED National Weather Service Baltimore MD/Washington DC 216 PM EST Fri Jan 24 2020

SYNOPSIS. Low pressure will approach the area this evening before passing through late tonight into Saturday. The low will move northeastward into New England Saturday night through Sunday and high pressure will return for the early and middle portions of next week.

NEAR TERM /THROUGH TONIGHT/. Mid afternoon surface analysis shows an area of low pressure near Peoria, Illinois, beneath an upper low tracking northeastward toward southern Lake Michigan. A frontal occlusion extends southward through the Ohio and Tennessee River Valleys to a new low developing near Pensacola, Florida. A warm/coastal front extends northeastward up the southeast coast, with cool air damming (CAD) noted in the lee of the Appalachians due to high pressure situated over the upper Saint Lawrence River Valley. Despite the wedge, the distance of surface high pressure has rendered CAD weak enough to allow temperatures over virtually all of the Mid-Atlantic to rise above freezing.

Southeasterly low-level flow between the low over Illinois and the high north of New England is banking abundant Atlantic moisture into the Mid-Atlantic, with southwest flow aloft advecting in moisture from the Gulf of Mexico. Periods of rain (mainly light through nightfall) are expected across parts of the central Virginia Piedmont and central Shenandoah Valley, enhanced in the adjacent higher terrain due to upslope flow. Further to the northeast over northern Virginia and central Maryland including the DC/Baltimore metro areas, any rain should hold off until later this evening.

Upper troughing will take on a negative tilt as it moves into the Great Lakes, and its associated surface front (occlusion) will approach from the lower Ohio River Valley tonight. The second area of low pressure will deepen as it moves over the piedmont of North Carolina this evening, and then track northeastward generally along or just east of I-95 overnight. Moisture advection will continue to increase and funnel northward along and ahead of this frontal system. Given the deep forcing and abundant moisture, a band of moderately heavy rain is expected to pivot west to east across the entire region overnight. The heaviest rain will probably last about 2 or 3 hours in any one location (generally 9PM to midnight west of I-81, midnight to 3AM between I-81 and US-15, 3AM to 6AM for the I- 95 corridor, lingering until 9AM near the Chesapeake Bay).

Rainfall rates in excess of half an inch per hour are possible, with areal average amounts of 1 to 2 inches expected. Taller, eastern facing slopes along the Blue Ridge will likely eclipse 3 inches. Flash Flood Guidance (FFG) values are lowest across portions of eastern West Virginia between the Allegheny Front and the foothills just west of I-81, and in the DC/Baltimore metros. These are the areas most likely to see any isolated or nuisance flooding issues, though widespread flooding or flash flooding are not currently expected due to the relatively progressive nature of the heaviest rain, lack of deeper convective instability and below normal rainfall over the last few weeks. Therefore, no Flood Watches have been issued.

Temperatures should hold generally steady overnight with warm air advection on southeasterly flow offsetting diurnal cooling.

Side note: some of the high resolution model guidance indicates there may be just enough dynamic cooling to result in a brief burst of snow on the back edge of the frontal precipitation band over the summits of the Allegheny Front (generally above 3500 feet). Impact wise, this seems minimal (not to mention the low probability of occurrence), but have added a small area of a chance of snow regardless after about 11PM.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/. Low pressure will continue to move across the region early Saturday morning as the parent H5 shortwave moves into New England. Periods of heavy rain will develop mainly after midnight Saturday before tapering off from west to east by Saturday AM. While the bulk of the rain will have moved to our east by daybreak Saturday, additional rain showers are likely to continue for the metro areas until late Saturday morning. Drying conditions will ensue Saturday afternoon as high pressure gradually works its way back into the region.

With strong westerly flow aloft, upslope snow is expected for extreme western portions of the Allegheny Front late Saturday into Sunday. Although with a lack of atmospheric moisture along with subsidence working its way back into the region, any upslope induced snow will be light in nature and be more confined to the higher elevations. Elsewhere, expect dry conditions to continue into early Monday.

LONG TERM /MONDAY THROUGH FRIDAY/. The early part of next week will be characterized by a broad area of upper-level low pressure over northern New England and eastern Canada. Several pieces of upper-level energy will be rotating around this upper-low, coming fairly close to our area.

A fairly robust piece of upper-level energy swings through late Monday, bringing the chance for some upslope snow sowers along the Allegheny Front. Otherwise, much of the area stays dry. Some rain will be possible in central/southern VA, but for now, looks to stay to our south. Meanwhile, high temperatures reach the mid 40s, so right around average. Much of the same Tuesday, but slightly cooler and drier. Upslope snow may continue, but thinking the chances are lower due to drier air in place, and less upper-level support.

Meanwhile, the southern branch of the jet stream is becoming more active during this time as well. An upper trough will be ejecting out of the southwest into the southern Plains Tuesday. This will induce low pressure along the Gulf Coast on Tuesday night into Wednesday, which will track to our south during the day on Wednesday. Additionally, a piece of shortwave energy will be diving out of the midwest on Wednesday as well, directly over the Mid- Atlantic. So, all this being said, with a marginally cold airmass in place Wednesday night, could see some rain or snow across the area. This could linger into Thursday, but would be too warm for snow at that point for most. High pressure will then briefly build into the region through Friday. Highs on Wednesday through Friday will stay in the low 40s.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/. Generally MVFR conditions (CIGs) will persist through the daylight hours. As low pressure approaches the region, rain will continue to develop through this evening from west to east. Rain will become heavy at times late tonight into the pre-dawn hours Saturday AM, reducing CIGs/VSBYs to IFR conditions across the terminals. Breezy conditions develop this evening and continue into Saturday with gusts up to 20 kts at times possible. Rain will begin to taper off from west to east by daybreak Saturday but will linger for DCA, BWI, and MTN until mid-AM Saturday. Drying conditions ensue Saturday afternoon as high pressure regains control of the region. VFR conditions are expected to return to the terminals by Saturday afternoon.

VFR conditions are expected Monday and Tuesday, although we will see a pretty consistent deck of mid-high clouds throughout the day on Monday, as an upper trough moves overhead. Tuesday remains dry and less cloudy. Winds will be out of the northwest at 5-10 knots, gusting up to 15 at times.

MARINE. Southeasterly flow aloft will increase markedly through this evening and especially overnight. Despite a low level inversion, model soundings indicate enough wind below the inversion to result in surface wind gusts of 20-25 kts. Air temperatures are forecast to be several degrees warmer than the water temperatures, which brings mixing into question somewhat. However, given the favorable wind direction and sharpening pressure falls, believe this will be offset. Therefore, have continued the Small Craft Advisory for the tidal Potomac River south of Indian Head, and the Maryland portion of the Chesapeake Bay and adjoining estuaries through 10AM Saturday (though the middle tidal Potomac River north of Cobb Island drops off at 6AM). Gusts over more sheltered waters may become more intermittent at times, but overall should maintain enough frequency to warrant maintaining the headline through the night.

Northwest flow is not particularly strong behind the departing system Saturday, with higher gusts seeming unlikely until a secondary cold front crosses Sunday. The ambient wind field is still marginal, though, and that combined with air temperatures several degrees warmer than the water again cast mixing into question.

No marine hazards are expected on Monday, but winds will be out of the northwest, gusting up to 15 knots. Slightly stronger wind gusts possible Tuesday, with Small Craft Advisory gusts possible.

TIDES/COASTAL FLOODING. Tidal anomalies are currently running around a half to three quarters of a foot above normal this afternoon. The anomalies are starting to increase due to an onshore flow. The onshore flow will continue to strengthen through early Saturday before slowly turning offshore later Saturday and Saturday night. Tidal anomalies will continue to increase during this time, and there is a possibility of minor tidal flooding near times of high tide late tonight through Saturday evening. Confidence is too low for a headline at this time since the astronomical higher of the high tides will be Saturday afternoon and evening, and this will be a little displaced from the onshore flow.

LWX WATCHES/WARNINGS/ADVISORIES. DC . None. MD . None. VA . None. WV . None. MARINE . Small Craft Advisory from 6 PM this evening to 10 AM EST Saturday for ANZ530>533-537>542. Small Craft Advisory until 10 AM EST Saturday for ANZ534-543. Small Craft Advisory from 6 PM this evening to 6 AM EST Saturday for ANZ536.

SYNOPSIS . BJL NEAR TERM . DHOF SHORT TERM . MSS LONG TERM . CJL AVIATION . MSS/CJL MARINE . DHOF/CJL TIDES/COASTAL FLOODING . BJL


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
TCBM2 - 8573364 - Tolchester Beach, MD 7 mi56 min 51°F 40°F1023.7 hPa
FSNM2 10 mi62 min 47°F 1022.9 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 11 mi50 min 46°F 1023.5 hPa
CPVM2 11 mi50 min 42°F
APAM2 - 8575512 - Annapolis, MD 13 mi50 min 47°F 1022.6 hPa
BLTM2 - 8574680 - Baltimore, MD 15 mi50 min 48°F 38°F1023.2 hPa
TPLM2 - Thomas Point, MD 18 mi20 min N 8 G 8.9 44°F 39°F1023.5 hPa (-3.2)40°F
BSLM2 - Chesapeake Bay, MD 32 mi110 min ESE 2.9 1024 hPa
CHCM2 - 8573927 - Chesapeake City, MD 39 mi56 min 52°F 38°F1024.6 hPa
WASD2 - 8594900 - Washington, DC 40 mi50 min 50°F 40°F1022.9 hPa
CA2 - 8571892 - Cambridge, MD 42 mi56 min 51°F 39°F1022.7 hPa

Wind History for Tolchester Beach, MD
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Bay Bridge Field, MD12 mi35 minENE 610.00 miOvercast54°F42°F67%1023 hPa
Baltimore / Martin, MD14 mi22 minNE 510.00 miOvercast50°F42°F76%1023.7 hPa
Annapolis, United States Naval Academy, MD14 mi2.4 hrsENE 39.00 miMostly Cloudy43°F35°F74%1025.7 hPa
Baltimore, Inner Harbor, MD16 mi26 minno data mi50°F39°F66%1023.2 hPa
Baltimore, Baltimore-Washington International Airport, MD17 mi26 minE 910.00 miOvercast50°F37°F63%1022.8 hPa
Fort Meade / Tipton, MD23 mi32 minE 510.00 miOvercast46°F37°F71%1023.7 hPa
Phillips Army Air Field / Aberdeen, MD24 mi82 minE 67.00 miOvercast50°F39°F67%1025.1 hPa

Link to 5 minute data for KMTN

Wind History from MTN (wind in knots)
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Last 24hrCalmCalmCalmCalmCalm--CalmCalmCalmCalmCalmCalmW3CalmCalmCalmCalmCalmCalmCalmNE5NE6NE7NE5
1 day agoSE4E4SE3CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmNE3CalmCalmS3SE3
2 days agoNW11
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Tide / Current Tables for Baltimore (Chesapeake Bay), Maryland
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Baltimore (Chesapeake Bay)
Click for Map
Fri -- 01:06 AM EST     4.06 feet Low Tide
Fri -- 05:53 AM EST     4.72 feet High Tide
Fri -- 07:18 AM EST     Moonrise
Fri -- 07:18 AM EST     Sunrise
Fri -- 11:58 AM EST     3.79 feet Low Tide
Fri -- 04:44 PM EST     New Moon
Fri -- 05:05 PM EST     Moonset
Fri -- 05:16 PM EST     Sunset
Fri -- 06:42 PM EST     5.37 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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4.24.14.14.34.54.74.74.64.44.243.83.83.94.14.54.85.15.35.45.354.84.6

Tide / Current Tables for Baltimore Harbor Approach, Maryland Current
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Baltimore Harbor Approach
Click for Map
Fri -- 02:35 AM EST     0.00 knots Slack
Fri -- 05:00 AM EST     0.51 knots Max Flood
Fri -- 07:17 AM EST     Moonrise
Fri -- 07:18 AM EST     Sunrise
Fri -- 07:34 AM EST     -0.00 knots Slack
Fri -- 10:27 AM EST     -0.62 knots Max Ebb
Fri -- 01:04 PM EST     0.00 knots Slack
Fri -- 04:44 PM EST     New Moon
Fri -- 04:48 PM EST     1.16 knots Max Flood
Fri -- 05:06 PM EST     Moonset
Fri -- 05:16 PM EST     Sunset
Fri -- 08:15 PM EST     -0.00 knots Slack
Fri -- 11:35 PM EST     -1.09 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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-1-0.6-0.20.10.40.50.40.2-0.1-0.4-0.6-0.6-0.4-00.40.81.11.210.60.1-0.4-0.8-1.1

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.
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Wind Forecast for Baltimore, MD/Washington (14,3,4,5)
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Ground Weather Radar Station Dover AFB, DE
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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.