Wednesday, December11, 2019
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Marine Weather and Tides
National Harbor, MD

Version 3.4
NOTICE
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.
6/2/2019. Many thanks to a user for reporting an error on one of the Edit pages. The switch to PHP 7.2 caused many pages that previously worked to quit working. I fixed many but I still depend on users to report ones I missed. Please report errors HERE or send an email to me at L-36.com. Allen

Sunrise 7:14AMSunset 4:48PM Wednesday December 11, 2019 12:03 AM EST (05:03 UTC) Moonrise 4:35PMMoonset 6:29AM Illumination 100% Phase: Full Moon; Moon at 14 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- 938 Pm Est Tue Dec 10 2019
.small craft advisory in effect until 3 am est Wednesday...
Rest of tonight..NW winds 10 kt. Gusts up to 20 kt late this evening and early morning. Waves 1 ft. Showers late this evening, then rain or snow showers with vsby 1 to 3 nm.
Wed..W winds 5 to 10 kt. Waves 1 ft. A chance of snow showers. Vsby 1 to 3 nm.
Wed night..NW winds 5 kt. Waves less than 1 ft.
Thu..E winds around 5 kt. Waves 1 ft.
Thu night..NE winds around 5 kt. Waves 1 ft or less.
Fri..NE winds around 5 kt. Waves 1 ft. A chance of rain.
Fri night..N winds around 5 kt. Waves 1 ft. Rain.
Sat..W winds 5 kt. Waves less than 1 ft. A chance of showers.
Sun..NW winds 5 to 10 kt. Waves 1 ft.
ANZ500 938 Pm Est Tue Dec 10 2019
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Low pressure will drag its trailing cold front across the region through Wednesday. High pressure will follow Wednesday night through Thursday. Another low pressure system developing over the northern gulf of mexico will move northeastward toward the region Friday into Saturday. Small craft advisories may be needed Wednesday night and again Friday night.


7 Day Forecast for Marine Location Near National Harbor, MD
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location: 38.8, -77.03     debug


Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 110215 AFDLWX

Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 915 PM EST Tue Dec 10 2019

SYNOPSIS. A cold front will push east of the Mid Atlantic overnight allowing cold air to rush across the area. Canadian high pressure will then build across the region Wednesday afternoon through Thursday. Another, stronger low pressure system will then develop in the Gulf of Mexico and push northward across the eastern United States Friday and Saturday.

NEAR TERM /THROUGH WEDNESDAY/. As of 9pm, the cold front is located along the Atlantic coast, pushing offshore. Temperatures across the area still too warm to support snow for most except for the highest of ridge tops, but believe this will change rapidly based on the intensity of cold advection. Radar character suggests at least a mix possible across northern Maryland/Eastern West Virginia. In addition, forcing mechanisms aloft (right rear quad of upper jet) will be pushing in behind the front, supporting dynamic cooling as well.

As the cold air pushes in, expecting a changeover from rain to snow across much of the area as we head into late tonight and early Wednesday morning. Snow will start earliest at the higher elevations including the Blue Ridge, so snow will start there around 9-10 PM or so, with much of the rest of the area changing between midnight and 5 AM from west to east. This remains unchanged from the previous forecast.

Still some indication of dry air intrusion at the low-mid levels behind the cold front (current radar depicting some of these patches), but thinking the abundant forcing should be plenty to overcome this. Generally between I-81 and I-95, expecting 1-2 inches of accumulation, primarily on grassy surfaces. Along the I-95 corridor itself, expecting less than an inch. Along the Blue Ridge, could see areas of 3-5+ inches though, where the longest period of snow is, and the best combination of forcing mechanisms. Wet roads and warm road temperatures will likely keep accumulations off of roads. However, more intense banding is possible where the best forcing lines up, so could see a quick inch on roads for those that end up directly under any heavier band. Some of the hi-res guidance hints at strong banding over southern Maryland as well, so will need to monitor guidance trends, though surface temps exceeding 60 over southern Maryland Tuesday afternoon cast uncertainty in accumulation and impacts.

Precip moves out quickly Wednesday morning, and sunshine will return. Combined with warm ground and temps in the 30s to low 40s, much of the snow should end up melting quickly by the afternoon.

SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/. Arctic high pressure will build in from the Great Lakes and Canada, then dominate Wednesday night through Thursday. Dry and cold conditions are expected during this time. Lows may reach the teens Wednesday night in spots, and highs Thursday likely stay in the 30s across much of the region.

The next system organizing near the Gulf Coast will start to bring warm advection northward Thursday night. Models are gradually coming to a better consensus with precipitation approaching the I-64 corridor by around daybreak Friday, at which time a warm nose aloft coupled with cold surface temperatures could result in freezing rain.

LONG TERM /FRIDAY THROUGH TUESDAY/. A shortwave moving through the broad trough over the Midwest will kick off a low pressure system over the Gulf of Mexico Friday. This low is forecast to track up through the southeast. There is some slight disagreements on the exact track of the surface low between the 12Z ECMWF and GFS. The GFS keeps the low slightly further east, tracking just along the East Coast, while the ECMWF keeps the low further inland. What both models do agree on is a cold air damming signature resulting in at or near freezing temperatures for locations near and west of the Blue Ridge.

The exact track will determine for how long cold air lingers. Overall, models have been trending towards a warmer solution as southerly flow ahead of the precip shield scours out some of the cold air prior to precip onset. However, do think there will be some light freezing rain for locations west of the Blue Ridge for late Friday, continuing overnight, before changing to all rain by Saturday morning. Elsewhere, temperatures at the surface will be above freezing thus expecting a plain rain event throughout Saturday late afternoon. As the surface low shifts further northeastward and starts to occlude, additional precip due to upsloping is possible Sunday for locations mainly along and west of the Allegheny Front.

High pressure will build briefly back over our region Sunday into early Monday before a warm front lifts northward through our area Monday afternoon into Tuesday, resulting in our next chance at precipitation.

AVIATION /02Z WEDNESDAY THROUGH SUNDAY/. Temperatures will fall tonight as the cold front pushes through the region. Rain will change to snow at all terminals by Wednesday morning. MRB will be the first to change over, at roughly 03z, with IAD/CHO changing over between 04z-06z, and DCA/BWI/MTN changing over by 09z or so. These are rough time periods, but most guidance is in good agreement on timing at this point. Not expecting a lot of snow (<1 inch for all except MRB, who may get 1-2 inches).

VFR returns by midday Wednesday and persists through Thursday night, though a risk of FZRA exists down at CHO late Thursday night as the next system approaches.

Areas of rain and/or freezing rain will bring MVFR or IFR conditions to the terminals on Friday. Primary threat for freezing rain will be at MRB, with areas east most likely to stay all rain. Rain again on Saturday could lead to sub-VFR conditions at times.

MARINE. Northwest flow picked up behind the cold front that crossed the waters. With good mixing/strong cold advection, 20 kt gusts being realized. Have added the entire Maryland portion of the Chesapeake Bay/Tidal Potomac River to a Small Craft Advisory overnight, and then taper it back Wed morning as building high pressure helps the gradient relax and allow winds to drop below SCA levels. However, a reinforcing shot of cold air Wednesday night could reinvigorate the winds briefly.

As a surface low tracks through our region, gusty winds are expected over the waters Friday night into Saturday. Small Craft Advisories will be possible during this period.

LWX WATCHES/WARNINGS/ADVISORIES. DC . None. MD . Winter Weather Advisory from midnight tonight to 7 AM EST Wednesday for MDZ003. Winter Weather Advisory from 2 AM to 8 AM EST Wednesday for MDZ004>006-503-505-507. VA . Winter Weather Advisory until 7 AM EST Wednesday for VAZ507- 508. Winter Weather Advisory from midnight tonight to 7 AM EST Wednesday for VAZ025>031-040-501. Winter Weather Advisory from 2 AM to 8 AM EST Wednesday for VAZ505-506. WV . Winter Weather Advisory from midnight tonight to 7 AM EST Wednesday for WVZ050>053-055. MARINE . Small Craft Advisory until 3 AM EST Wednesday for ANZ530>532- 535-536-538>540. Small Craft Advisory until 7 AM EST Wednesday for ANZ533-537- 541-542. Small Craft Advisory until noon EST Wednesday for ANZ534-543.

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


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 5 mi46 min N 9.9 G 15 41°F 44°F1021.5 hPa
BSLM2 - Chesapeake Bay, MD 17 mi94 min NNW 7 43°F 1020 hPa40°F
APAM2 - 8575512 - Annapolis, MD 32 mi46 min 43°F 1020.4 hPa
TPLM2 - Thomas Point, MD 32 mi64 min WNW 18 G 19 43°F 47°F1022 hPa (+2.9)40°F
44063 - Annapolis 33 mi28 min NNW 18 G 23 42°F 46°F1021.6 hPa
NCDV2 33 mi58 min NNW 8.9 G 13 43°F 49°F1020 hPa
44062 - Gooses Reef, MD 37 mi28 min N 19 G 23 43°F 1020.8 hPa
CPVM2 37 mi52 min 43°F
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 39 mi46 min WNW 12 G 15 41°F 1021.7 hPa
BLTM2 - 8574680 - Baltimore, MD 40 mi52 min NNW 8 G 13 41°F 46°F1020.8 hPa
SLIM2 - 8577330 - Solomons Island, MD 45 mi46 min NNW 13 G 20 44°F 48°F1020.1 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Washington/Reagan National Airport, DC, VA4 mi72 minNNW 13 G 2010.00 miLight Rain42°F36°F79%1021.6 hPa
Camp Springs / Andrews Air Force Base, MD9 mi2.1 hrsNW 1010.00 miLight Rain43°F39°F86%1020 hPa
Fort Belvoir, VA9 mi2.1 hrsNW 14 G 1810.00 miLight Rain45°F38°F80%1020 hPa
College Park Airport, MD14 mi68 minNW 10 G 1510.00 miOvercast40°F32°F74%1021.7 hPa
Fort Meade / Tipton, MD24 mi70 minNW 8 G 1410.00 miOvercast39°F35°F87%1022 hPa

Link to 5 minute data for KDCA

Wind History from DCA (wind in knots)
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Last 24hrS13S17S12S14S13S10S14S10S12SW10SW10SW6SW3CalmN11NW7N6NW8NW12NW15NW13NW13
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1 day agoS3CalmSE6SW3W4S4S5S6S6S8S9S7S8S10S9S9S9S12S13S13S14S16
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2 days agoCalmNE3NE4CalmCalmCalmCalmCalmCalmS3S6S6S8S8S10S6S3S4SE5S4SW4SE9S6S5

Tide / Current Tables for Alexandria, Virginia
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Alexandria
Click for Map
Wed -- 01:41 AM EST     -0.05 feet Low Tide
Wed -- 06:29 AM EST     Moonset
Wed -- 07:16 AM EST     Sunrise
Wed -- 07:19 AM EST     2.44 feet High Tide
Wed -- 01:26 PM EST     -0.07 feet Low Tide
Wed -- 04:35 PM EST     Moonrise
Wed -- 04:46 PM EST     Sunset
Wed -- 07:22 PM EST     2.90 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.30-00.311.72.22.42.31.91.30.70.2-0-00.31.122.62.92.82.41.81.2

Tide / Current Tables for Riverview, Potomac River, Maryland
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Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.


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.
Link to Loop



Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Baltimore, MD/Washington (0,6,7,8)
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Ground Weather Radar Station Sterling, VA
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