Saturday, July21, 2018 L-36.com


Marine Weather and Tides
Dahlgren, VA

Version 3.4
What's New / NOTES
5/20/2018 -- NOAA is having problems with the data feed that I use to draw the graphs. They are aware of the issue and working to resolve it. Sometimes changing the location by about a mile will give a correct graph. 3/3/2018 - There is a new GOES Satellite for the east coast that required rewriting that part of the code. Please report any issues.

Sunrise 6:00AMSunset 8:30PM Saturday July 21, 2018 3:46 AM EDT (07:46 UTC) Moonrise 2:19PMMoonset 12:32AM Illumination 59% Phase: Waxing Gibbous; Moon at 8 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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ANZ536 Tidal Potomac From Indian Head To Cobb Island- 132 Am Edt Sat Jul 21 2018
.small craft advisory in effect from 11 am edt this morning through this evening...
Overnight..E winds 5 kt. Waves less than 1 ft. A chance of showers.
Sat..NE winds 10 to 15 kt. Gusts up to 20 kt. Waves 2 ft. Rain. Vsby 1 nm or less.
Sat night..NW winds 10 to 15 kt with gusts to 20 kt...diminishing to 5 kt late. Waves 1 to 2 ft. A chance of showers. Patchy fog. Vsby 1 to 3 nm.
Sun..SE winds 5 to 10 kt. Waves 1 ft. Showers likely with a chance of tstms.
Sun night..SE winds 5 to 10 kt. Waves 1 ft. Showers likely with a chance of tstms.
Mon..SE winds 5 to 10 kt. Waves 1 ft. Showers with a chance of tstms.
Mon night..SE winds 5 to 10 kt. Waves 1 ft. Showers likely.
Tue..S winds 5 to 10 kt. Waves 1 ft. Showers likely. A chance of tstms in the afternoon, then a chance of showers after midnight.
Wed..S winds 5 to 10 kt. Waves 1 ft. Showers likely. A chance of tstms through the night, then a chance of showers after midnight. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 132 Am Edt Sat Jul 21 2018
Synopsis for the tidal potomac and md portion of the chesapeake bay.. An area of low pressure will move near the delmarva coastline Saturday before another low approaches from the west on Sunday and stalls out into early next week. Gale conditions are possible over the lower maryland chesapeake bay Saturday.

7 Day Forecast for Marine Location Near Dahlgren CDP, VA
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location: 38.31, -77.06     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 210110
afdlwx
area forecast discussion
national weather service baltimore md washington dc
910 pm edt Fri jul 20 2018

Synopsis
An area of low pressure over the southeast will move northeast
and off of the DELMARVA peninsula Saturday. Meanwhile, a broad
and slow moving low pressure system will drop from the upper
midwest into the ohio valley by the end of the weekend.

Near term until 6 am Saturday morning
Surface ridging remains off the new england coast this evening.

Warm advection through the atmosphere is resulting mid-high
level cloudiness. Have increased skycover substantially for
tonight. Expect this trend to continue as clouds thicken and
lower due to moisture advection into the area.

A couple of bands of showers thunderstorms in west virginia have
weakened and subsequently dissipated as they moved toward more
stable air over the mountains. Recent hrrr rap runs keep rain
from the west away from forecast area.

It's a different story to the south of the area. Ahead of the
broad troughing, low pressure has developed near sav. This low
will be lifting north along the coast late tonight, with the
potential for rain increasing after midnight, but more so toward
early morning. Overnight lows will be in the 60s.

Short term 6 am Saturday morning through Sunday night
The low will continue its northerly progression Saturday along
the DELMARVA peninsula. The ECMWF continues to be one of the
farthest east models. Regardless, this situation bears watching
as a strong low level jet will be wrapping around the low with
its nose focused on eastern portions of our forecast area.

Trajectories bring tropical moisture and deep warm cloud layers
from the gulf of mexico. Some periods of moderate to heavy rain
appear likely. The question is how much convective potential can
be realized, because that could lead to excessive rainfall
rates. As it is, rainfall will be very efficient, with 2+ inch
totals by the time the system pulls away. Will let later shifts
determine the need for a flood watch given the uncertainties in
the duration of heavy rainfall and banding features. Greater
concern lies near and east of i-95, including baltimore and
washington. There will likely be a gap with little to no precip
in central parts of the cwa, with potential showers and storms
associated with the upper level low affecting far southwestern
zones. Thick clouds and precip will hold temperatures in the
70s.

The low will pull away to the northeast Saturday evening, and
convection associated with the upper low will diminish with loss
of insolation, so overall there will be decreasing chances of
rain through the night. Low clouds and potentially some fog and
drizzle could linger though.

For Sunday and Sunday night, the regime will begin to be
influenced by the upper level low, with some indications of a
piece of energy and isentropic lift affecting the area from
southwest to northeast through the day. Have likely pops
overspreading the area. With a bit more insolation and steeper
lapse rates as the low nears, there will be a better chance of
thunderstorms compared to Sunday. High temperatures will sneak
back into the 80s with lows in the 60s and 70s.

Long term Monday through Friday
The aforementioned upper low will remain anchored just west of the
region Monday through Wednesday, thanks to a blocking upper-
level ridge over the northern atlantic. Thanks to the presence
of this upper level trough, showers and thunderstorms will be
likely through Wednesday, especially during the afternoon and
evening hours. MAX temperatures will only reach the mid 80s for
most areas, with overnight lows in the upper 60s to low 70s.

Given that pwat values will be consistently near or above 2
inches throughout this period, any showers or storms will likely
contain some heavy rain. Will be monitoring flood potential as
the timing gets closer and some of the fine details can be
worked out.

The upper level ridge over the northern atlantic should begin to
break down and move east on Thursday. This will allow for that
stubborn upper-level trough to move out of the area. However, a
surface low pressure will be moving through southern ontario into
southwestern quebec. This system will drag a cold front through the
area. Given the plentiful moisture over the region, the expectation
is for another round of showers and storms for the region on
Thursday.

Aviation 01z Saturday through Wednesday
Vfr conditions are expected through the night with a mix ofVFR
clouds and south southeast winds at 5-10 kt. Clouds will lower
late tonight, but it appears MVFR ceiling may arrive coincident
or after the arrival of rain early Saturday morning.

As low pressure moves up the coast, some periods of moderate to
heavy rain are likely through the day, particularly in the
metros. Have continued previous forecaster's theme of holding
tafs at MVFR during the day for now, but some periods of ifr are
possible.

The low will pull away Saturday evening, but it looks like low
clouds will persist into the night. Permitted ifr to slip into
forecast at that time. Furthermore, low level wind shear will be
a concern in the evening... Possibly commencing prior to
sundown... As an easterly low level jet curls inland in advance
of the low. Dca bwi mtn most likely to be affected, and thus
have a TAF mention, but iad certainly not out of the woods.

Upper level low pressure will be to our west on Sunday. While
ceilings should improve, showers and potential thunderstorms
could bring reductions at times. Rainfall will be more hit- or-
miss in nature, but thunder threat substantially higher.

Showers and thunderstorms will be possible each day Monday through
Wednesday in association with a nearly stationary trough located to
our west. The highest coverage of storms each day should be in the
afternoon and evening hours. Periodic sub-vfr conditions will be
possible as a result of these storms.

Marine
Winds strengthening this evening, with most of the maryland
bay tidal potomac below rte 301 bridge achieving small craft
advisory conditions. Have accepted solution suggesting an
overnight lull in winds. Am carrying SCA only for the lower
tidal potomac, chesapeake bay from drum point-smith point, and
tangier sound after 2am.

As low pressure moves up the coast Saturday, SCA conditions
will become likely, and have expended advisory to all waters.

Winds could be close to gale force, but have kept the forecast
shy for now due to poor mixing. Wind should subside later
Saturday night as the low pulls away. SCA conditions may reemerge
later Sunday into Sunday night in southerly flow due to the
tightening gradient with low pressure to the west.

Small craft advisories possible Monday and Tuesday with a southerly
flow ahead of an upper trough to our west. Showers and thunderstorms
will be possible each day Monday through Wednesday, with the highest
coverage of storms occurring in the evening.

Tides coastal flooding
Water levels are expected to rise tonight into Saturday as
onshore flow strengthens. Current forecasts on track. Annapolis
will come mighty close to minor threshold late tonight, and
southwest washington may be just over. Will monitor trends for
another hour or so. May end up issuing an advisory for SW dc.

Minor flooding will once again be a concern Saturday night at
straits point and dc SW waterfront, but other sites will need to
be monitored as well. There may be a momentary decrease in
water levels, but they will rise again later Sunday into
Monday... And guidance indicates it will be more so than early in
the weekend.

Lwx watches warnings advisories
Dc... None.

Md... None.

Va... None.

Wv... None.

Marine... Small craft advisory until 2 am edt Saturday for anz531>533-
539>542.

Small craft advisory from 11 am Saturday to 2 am edt Sunday
for anz530>533-538>542.

Small craft advisory until 2 am edt Sunday for anz534-537-543.

Small craft advisory from 11 am to 11 pm edt Saturday for
anz535-536.

Synopsis... Ads
near term... Hts ads
short term... Ads
long term... Cjl
aviation... Hts ads cjl
marine... Hts ads cjl
tides coastal flooding... Hts ads


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
NCDV2 1 mi34 min ENE 1.9 G 4.1 75°F 81°F1014.6 hPa
PPTM2 - 8578240 - Piney Point, MD 30 mi34 min ESE 8 G 8.9
SLIM2 - 8577330 - Solomons Island, MD 32 mi28 min S 13 G 16 73°F 82°F1015.5 hPa
COVM2 - 8577018 - Cove Point LNG Pier, MD 36 mi34 min SE 12 G 16 73°F 1016.4 hPa
LWTV2 - 8635750 - Lewisetta, VA 38 mi40 min SSE 5.1 G 6 76°F 82°F1015.2 hPa
44062 - Gooses Reef, MD 38 mi26 min E 12 G 14 75°F 1016.4 hPa
BSLM2 - Chesapeake Bay, MD 38 mi136 min ESE 1.9 71°F 1017 hPa65°F
WASD2 - 8594900 - Washington, DC 39 mi28 min E 2.9 G 6 74°F 83°F1015.9 hPa
44042 - Potomac, MD 43 mi26 min SE 14 G 18 78°F 1014.4 hPa

Wind History for Piney Point, MD
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Quantico Marine Corps Airfield - Turner Field, VA19 mi50 minE 610.00 miA Few Clouds74°F68°F82%1016 hPa
Fredericksburg, Shannon Airport, VA21 mi51 minN 010.00 miFair68°F63°F85%1015.6 hPa
Stafford, Stafford Regional Airport, VA22 mi51 minN 010.00 miFair66°F65°F100%1017.3 hPa

Wind History from NYG (wind in knots)
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Last 24hrNW4NW4NW5NW4CalmS3S5S6S6S7SW7S10SE11SE10SE11S10SE10SE10SE9S12S12S8E5E6
1 day agoNW6NW5--NW8NW5NE6NE7NE5NE3CalmS3S3S4S3E3E6SE6SE8SE9S9S10S10
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Tide / Current Tables for Dahlgren, Upper Machodoc Creek, Virginia
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Dahlgren
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Sat -- 01:31 AM EDT     Moonset
Sat -- 05:04 AM EDT     0.42 feet Low Tide
Sat -- 06:01 AM EDT     Sunrise
Sat -- 10:53 AM EDT     1.82 feet High Tide
Sat -- 03:19 PM EDT     Moonrise
Sat -- 05:17 PM EDT     0.25 feet Low Tide
Sat -- 08:27 PM EDT     Sunset
Sat -- 11:38 PM EDT     2.04 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.91.61.20.80.50.40.50.81.11.51.71.81.71.41.10.70.40.30.30.611.41.82

Tide / Current Tables for Upper Cedar Point Light, Potomac River, Maryland
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Upper Cedar Point Light
Click for Map
Sat -- 01:32 AM EDT     Moonset
Sat -- 06:01 AM EDT     Sunrise
Sat -- 06:06 AM EDT     0.13 feet Low Tide
Sat -- 12:05 PM EDT     1.21 feet High Tide
Sat -- 03:19 PM EDT     Moonrise
Sat -- 06:08 PM EDT     0.11 feet Low Tide
Sat -- 08:27 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.41.210.70.50.30.10.20.40.711.11.21.10.90.60.40.20.10.20.40.711.2

Weather Map and Satellite Images
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GOES 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 (3,6,7,8)
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Ground Weather Radar Station Sterling, VA
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Disclaimer:
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 numerious 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.