Thursday, October28, 2021
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Marine Weather and Tides
Williamsport, 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 7:34AMSunset 6:15PM Thursday October 28, 2021 4:44 PM EDT (20:44 UTC) Moonrise 11:16PMMoonset 1:40PM Illumination 45% Phase: Third Quarter Moon; Moon at 23 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- 438 Pm Edt Thu Oct 28 2021
.small craft advisory in effect through late tonight...
.gale warning in effect from Friday morning through Friday evening...
Rest of this afternoon..SE winds 10 kt. Waves 1 ft.
Tonight..E winds 5 to 10 kt with gusts to 25 kt. Waves 1 ft. Showers likely.
Fri..E winds 15 to 20 kt with gusts to 35 kt. Waves 2 ft. Showers. Vsby 1 nm or less.
Fri night..E winds 10 to 15 kt with gusts to 25 kt... Becoming se 5 kt after midnight. Waves 1 ft. A chance of showers.
Sat..S winds 5 kt. Waves less than 1 ft. A chance of showers.
Sat night..SW winds 5 kt. Waves less than 1 ft.
Sun..W winds 5 to 10 kt. Waves 1 ft.
Mon..NW winds around 5 kt. Waves 1 ft or less.
ANZ500 438 Pm Edt Thu Oct 28 2021
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure will shift offshore later today. A large area of low pressure will track into the region tonight into Friday, promoting a strong onshore flow. The low will gradually lift away from the area by the end of the weekend. Gale warnings are in effect for all waters for Friday morning into Friday night. Small craft advisories will likely follow after gale conditions diminish into early Saturday.


7 Day Forecast for Marine Location Near Williamsport, MD
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location: 39.58, -77.81     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 281940 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 340 PM EDT Thu Oct 28 2021

SYNOPSIS. High pressure overhead will start to move off to the east tonight ahead of the new low pressure system. Strong low pressure builds into the area late tonight and into Friday from the southwest, bringing several potential impacts to the area. Large upper low will continue to meander throughout the weekend leading to continued cool and unsettled conditions. High pressure returns by Monday.

NEAR TERM /UNTIL 6 AM FRIDAY MORNING/. High pressure has begun moving offshore of the Delmarva, this will continue throughout the rest of the afternoon as it gets pushed away by a large scale upper level low pressure system poised to bring significant impacts to the area by late tonight and into Friday. Some high and mid-level clouds have begun to move into the area over the last several hours but with subsidence nearby, will continue to stay dry over the next few hours.

As an associated warm front of the large upper-level low moves further northeast into our area late this evening, some showers will begin to move into portions of central VA by later tonight. Latest water vapor imagery depicts a large, rich moisture plume from just off the southeast coast moving into the Mid-Atlantic region currently. Temperatures will be a bit warmer tonight than last night as we get closer to the warm sector of the front later this evening, keeping temps in the upper 40s to low 50s across most areas. Another important impact that will begin to ramp up tonight will be the winds across the higher elevations, particularly the Allegheny Front as well as along the ridge tops of the Blue Ridge Mountains.

SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/. By early Friday morning, impacts will begin to ramp up for the upper low pressure system tracking throughout the Mid-Atlantic region. Still expecting the heaviest rainfall to occur from Friday morning through Friday afternoon. Widespread 1 to 2 inches is expected across most areas with some localized higher amounts, particularly for two areas. The first being across the higher elevations along the Blue Ridge Mountains with totals possibly getting up to 4 plus inches across the areas with orographic enhancement in this region's favor for higher amounts. The other will be for any localized areas along the southeastern portions of the forecast areas from DC metro southward where the potential for a few strong embedded storms could develop along the warm front tomorrow late morning into the early afternoon. Main threats would be for heavy rain, damaging winds with a nonzero chance for an isolated tornado.

Any locally stronger storm may produce a higher rainfall total in a short amount of time. With that being said, Flood Watches have been hoisted for the 1) windward side of the Blue Ridge Mountains and just east as well as 2) near the metropolitan areas. The watches are in effect during the day on Friday. Should guidance continue to increase, additions to the flood watches may be made.

Another important impact Friday will be the winds across the entire forecast area. In particular, the higher elevations will be gusting quite a bit higher than the lower elevations, leading to a Wind Advisory being issued for areas along the Allegheny Front and portions of the Blue Ridge Mountains from 8 PM tonight through early Friday afternoon. Winds along the waters and just onshore will also be very gusty during the day on Friday and headlines have been issued for these areas as well, see Marine section for details. Another important feature that may produce significant impacts will be with strong southeasterly flow, coastal flooding will be reaching levels that have not been met in almost 20 years, see Tides/Coastal Flooding section for details.

The heaviest portion of the rainfall and winds will begin to diminish by late Friday afternoon/evening but moisture will still be present for the remainder of the short term period as the upper low meanders just to our northwest. Saturday looks to be considerably drier than Friday but nonetheless will still be wet and maybe slightly breezy.Temperatures for the period will start out warmer before cooling off a few degrees into the low to mid 60s for the start of the weekend.

LONG TERM /SUNDAY THROUGH THURSDAY/. After the system exits to the northeast, ridging is expected to build into the region. With high pressure and zonal flow aloft, dry conditions with seasonal temperatures will continue through much of next week. However a shortwave may approach the CWA from the west Tuesday, bringing with it higher rain chances, increased cloud cover and slightly cooler temperatures. Another low pressure system may impact the region late in the week.

AVIATION /20Z THURSDAY THROUGH TUESDAY/. VFR conditions will continue through the rest of the afternoon as high pressure is nearby with light winds out of the northeast. A strong low pressure system will start to creep in tonight, leading to a gradual lowering of ceilings to MVFR from southwest (CHO) to the northeast. Uncertainty continues with how quickly this will happen with respect to the lowering of the ceilings.

As we get closer to late this evening, winds will begin to pick back up as high pressure continues to move further and further offshore. Winds will increase to 25 to 30 knots across a large portion of the area including all the terminals with some areas maybe touching closer to 35 to 40 knots briefly during the afternoon on Friday. MVFR to IFR conditions are expected due to low ceilings and occasional moderate to heavy rains as a warm front moves through the region. Thunderstorm chances remain low at this time but the best chance for any to happen would be at DCA, should any occur.

Sub-VFR conditions are likely at all terminals Saturday as low pressure settles nearby, leading to continued rain chances and light southerly winds across all terminals.

VFR conditions return Sunday and continues Monday as low pressure will continue to depart the region and high pressure builds back in from the west. Winds will remain generally out of the west.

MARINE. Sub-SCA conditions expected through this afternoon as high pressure continues to influence the region briefly. As high pressure moves further offshore, winds will begin to pick back up later this evening. With this, Small Craft Advisories are in effect for all of the waters starting at 6 PM and will end at 6 AM, where a Gale Warning will take its place. Confidence in these winds is highest across the lower Chesapeake Bay as well as the lower Potomac with water temperatures being a few degrees warmer and less stable air overhead leading to better chances of mixing down near the surface. Nonetheless, the Gale Warnings include all of the waters.

Gusts near the aforementioned area may be as high as 45 to 55 knots briefly during the day, leading to a Storm Warning being issued for the lower portions of the waters with an accompanying High Wind Warning along the shorelines of Calvert and St. Mary's counties in Maryland. Elsewhere, Wind Advisories have been issued along the shoreline north of Calvert county through the Cecil county shoreline for the potential of 40 knot gusts right along the shore inland.

Lighter southerly winds will begin Saturday during the late morning hours as low pressure tracks across the region. Small Craft Advisories will likely follow the Gale Warnings as they expire Friday night and into Saturday morning but should be short-lived in nature.

Low pressure will continue to depart the region Sunday as high pressure returns. An increased gradient may result in SCA conditions across portions of the waters both Sunday and Monday.

TIDES/COASTAL FLOODING.

NEW TIDES/COASTAL FLOODING INFORMATION WILL BE UPDATED SHORTLY

SEE PREVIOUS DISCUSSION BELOW

Despite NW offshore flow earlier tonight, water levels have risen substantially during the past 24 hrs much sooner than anticipated by most of the surge models except the CBOFS which showed water levels rising rather rapidly since yesterday. Water anomalies are already up to 2 ft at Straits Point and rising and Annapolis has been hovering around minor flood stage even as the astro tide is going into low tide. Surge models continue to indicate a moderate to high impact coastal flood event lasting several tide cycles (more than 48 hrs). Leaned toward the CBOFS first 24 hrs given its superior performance over the other deterministic surge models and ensemble probabilistic guidance (P-ETSS). This brings moderate coastal flooding much earlier than shown 24 hrs ago and even late yesterday evening. Straits Point will likely hit major flood category tonight. In the upper bay, water levels may hit moderate Saturday afternoon as SW winds may push water up the bay. Issued a Coastal Flood Watch for Harford and Cecil for Fri night into Sat and Advisories for tonight. Elsewhere, Coastal Flood Watches were upgraded to Warnings except at Prince Georges where there are unknown impacts of moderate category except minor flooding at the National Harbor.

LWX WATCHES/WARNINGS/ADVISORIES. DC . Flood Watch from Friday morning through Friday afternoon for DCZ001. Coastal Flood Warning from 8 PM this evening to 2 PM EDT Saturday for DCZ001. Coastal Flood Advisory until 8 PM EDT this evening for DCZ001. MD . Wind Advisory from 8 PM this evening to 2 PM EDT Friday for MDZ001. Coastal Flood Warning until 8 AM EDT Saturday for MDZ011-013- 016. Flood Watch from Friday morning through Friday afternoon for MDZ011-013-014-504-506. Coastal Flood Warning until 2 PM EDT Saturday for MDZ014-017. Wind Advisory from 10 AM to 6 PM EDT Friday for MDZ011-014-508. Coastal Flood Advisory until 6 PM EDT this evening for MDZ011- 016-018. High Wind Warning from 8 AM to 6 PM EDT Friday for MDZ017-018. Coastal Flood Watch from Friday evening through Saturday morning for MDZ008. Coastal Flood Advisory until 8 PM EDT Friday for MDZ008. Coastal Flood Warning until 2 PM EDT Saturday for MDZ018. Coastal Flood Watch from Friday evening through Saturday morning for MDZ508. Coastal Flood Advisory until 6 PM EDT Friday for MDZ508. VA . Wind Advisory from 8 PM this evening to 2 PM EDT Friday for VAZ503-504-507-508. Flood Watch from Friday morning through Friday afternoon for VAZ036>040-507-508. Coastal Flood Warning until 8 AM EDT Saturday for VAZ052-053- 055-057. Flood Watch from Friday morning through Friday afternoon for VAZ052>054. Coastal Flood Advisory until 6 PM EDT this evening for VAZ057. Coastal Flood Warning from 8 PM this evening to 2 PM EDT Saturday for VAZ054. Coastal Flood Advisory until 8 PM EDT this evening for VAZ054. WV . Wind Advisory from 8 PM this evening to 2 PM EDT Friday for WVZ501-505-506. MARINE . Flood Watch from Friday morning through Friday afternoon for ANZ535. Small Craft Advisory until 6 AM EDT Friday for ANZ530>543. Gale Warning from 6 AM to 8 PM EDT Friday for ANZ530>532-535- 536-538>540. Storm Warning from 6 AM to 6 PM EDT Friday for ANZ533-534-537- 541>543. Gale Warning from 6 PM to 8 PM EDT Friday for ANZ533-534-537- 541>543.

SYNOPSIS . ADM NEAR TERM . ADM SHORT TERM . ADM LONG TERM . CAS AVIATION . ADM/CAS MARINE . ADM/CAS TIDES/COASTAL FLOODING . BJL


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 64 mi74 min S 8G9.9 66°F 63°F1011 hPa
BLTM2 - 8574680 - Baltimore, MD 69 mi74 min SSE 2.9G7 63°F 67°F1011.3 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 72 mi74 min SE 8G9.9 61°F 1011.8 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hagerstown, Washington County Regional Airport, MD10 mi51 minSSE 710.00 miA Few Clouds63°F50°F63%1011.4 hPa
Eastern WV Regional Airport/Shepherd Field, WV15 mi51 minS 510.00 miOvercast62°F50°F65%1010.2 hPa

Link to 5 minute data for KHGR

Wind History from HGR (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 -- 02:00 AM EDT     2.91 feet High Tide
Thu -- 07:31 AM EDT     Sunrise
Thu -- 09:11 AM EDT     0.59 feet Low Tide
Thu -- 02:34 PM EDT     Moonset
Thu -- 02:55 PM EDT     2.55 feet High Tide
Thu -- 04:06 PM EDT     Last Quarter
Thu -- 06:12 PM EDT     Sunset
Thu -- 08:58 PM EDT     0.54 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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Tide / Current Tables for Chain Bridge, one mile below, D.C.
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Chain Bridge
Click for Map
Thu -- 01:55 AM EDT     2.91 feet High Tide
Thu -- 07:31 AM EDT     Sunrise
Thu -- 09:06 AM EDT     0.59 feet Low Tide
Thu -- 02:34 PM EDT     Moonset
Thu -- 02:50 PM EDT     2.55 feet High Tide
Thu -- 04:06 PM EDT     Last Quarter
Thu -- 06:12 PM EDT     Sunset
Thu -- 08:53 PM EDT     0.54 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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