Friday, August18, 2017 L-36.com


Marine Weather and Tides
Dahlgren Center, VA

Version 3.4
What's New / NOTES
6/25/2017 - NOAA is having a major issue that impact the 7 day forecast load times. Many users are reporting problems. The issue has been reported.
5/23/2017 - Worked with NOAA again to speed up the 7 day forecast load times. Thanks to them for being responsive.
5/19/2016 - There were issues with the 3 day airport observation history. I switched to another data source. Let me know if you see any issues with the data feeds.

Sunrise 6:24AMSunset 7:58PM Friday August 18, 2017 12:14 PM EDT (16:14 UTC) Moonrise 1:54AMMoonset 4:36PM Illumination 14% Phase: Waning Crescent; Moon at 26 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- 1030 Am Edt Fri Aug 18 2017
.small craft advisory in effect through late tonight...
Rest of today..SW winds 5 to 10 kt. Gusts up to 20 kt this afternoon. Waves 1 ft. A chance of showers with a slight chance of tstms late this morning, then showers likely with a chance of tstms this afternoon.
Tonight..W winds 5 to 10 kt. Gusts up to 20 kt until early morning. Waves 1 ft. Showers likely with a chance of tstms.
Sat..W winds 5 kt. Waves less than 1 ft.
Sat night..W winds around 5 kt. Waves 1 ft or less.
Sun..NE winds around 5 kt. Waves 1 ft or less.
Sun night..SE winds around 5 kt. Waves 1 ft or less.
Mon..S winds around 5 kt. Waves 1 ft. A chance of tstms. A chance of showers.
Tue..SW winds around 5 kt. Waves 1 ft. A chance of showers and tstms. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 1030 Am Edt Fri Aug 18 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A cold will approach the waters today before passing through tonight. A pressure trough will remain nearby for Saturday and Sunday while high pressure positions itself just to our north and west. The high will move offshore early next week. Small craft advisories may be needed Monday night and Tuesday.

7 Day Forecast for Marine Location Near Dahlgren Center, VA
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location: 38.32, -77.03     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 181510
afdlwx
area forecast discussion
national weather service baltimore md washington dc
1110 am edt Fri aug 18 2017

Synopsis
A cold front will approach from the west today before crossing
the region tonight. Surface high pressure will build in
Saturday, but an upper level disturbance will cross the region
Saturday night. A warm front will advance back north across the
region early next week, followed by a strong cold front in the
middle of the week.

Near term through tonight
Low clouds have struggled to break this morning, but are slowly
doing so. Otherwise, forecast is generally on track. Added in
enhanced wording for this afternoon evening t-storms, and
pondering a flash flood watch along and east of i-95. Will
decide on this potential over next couple hours.

Previous discussion...

the cold front will approach our area from the west later today
while a surface trough develops overhead... Most likely between
the appalachian mountains and blue ridge mountains. A southerly
flow ahead of the cold front will continue to usher in hot and
very humid conditions. Dewpoints are likely to be in the upper
60s and lower 70s this afternoon west of the blue ridge
mountains with mid to upper 70s most likely east of the blue
ridge mountains. Low-level temps are progged to be about a
degree celsius higher compared to yesterday. Therefore... Max
temps are forecast to be a couple degrees hotter for most
locations. This will cause MAX temps to top off in the mid to
upper 80s for valley locations west of the blue ridge mountains
with lower 90s near the washington and baltimore metropolitan
areas into central virginia and southern central maryland. The
combination of heat and very high humidity will cause heat
indices to top off near 105 degrees near the urban corridor from
baltimore through washington dc toward fredericksburg. A heat
advisory has been issued for these areas.

The high heat and humidity will cause moderate to high amounts
of instability to develop this afternoon. Showers and
thunderstorms are likely to develop along and ahead of the cold
front... Especially this afternoon and evening. Shear profiles
will strengthen a bit as an upper-level trough digs over the
great lakes. The strengthening shear profiles along with the
moderate to high instability suggests that some storms may
become severe... With damaging winds and large hail being the
primary threats. An isolate tornado cannot be ruled
out... Especially toward the waters where surface winds may be
backed a bit. Confidence is low since the magnitude of low-
level shear profiles should be weak.

Pwats are progged to be near or even above 2 inches... Especially
east of the blue ridge mountains where the higher dewpoints are.

Therefore... Thunderstorms will contain torrential downpours and
isolated flash flooding is a concern. Did consider a flash flood
watch with the update this morning. There is a chance for the
outflow boundary to become parallel to the storm motion and this
could enhance the threat for flash flooding. The farther
east... The better the chance. Latest hires guidance (hrrr and
ncar ensembles) suggest that the highest rainfall amounts will
be near or even just east of the bay. This combined with the
fact that storms should be moving due to the increasing shear
are reasons why we held off on a watch with this cycle.

However... It will have to be monitored closely throughout the
day.

The best chance for storms will be during the middle afternoon
hours west of the blue ridge mountains... Late this afternoon
into early this evening for the washington and baltimore
metropolitan areas... And this evening across southern maryland.

Drier air should move in behind the cold front tonight... But
winds will be light. Therefore... Patchy fog is possible
overnight.

Short term Saturday through Sunday night
Drier and less humid conditions are expected behind the front
Saturday... But an upper-level disturbance will pass through late
in the afternoon into the evening. An isolated
shower thunderstorm cannot be ruled out. However... Much of the
day Saturday will turn out dry with sunshine.

High pressure will build overhead overnight Saturday through
Sunday... Bringing dry conditions along with lower humidity. The
high will begin to shift offshore Sunday night and a return flow
will develop.

Long term Monday through Thursday
Ridge of surface high pressure will slide offshore on Monday
allowing for the development of return southerly flow and increasing
low level moisture. Thus, we'll some increase in chances for
isolated-scattered afternoon evening showers thunderstorms. In
addition, warmth humidity will also trend back upward, with highs
back to near or above 90f and dew points in the 70s for both Monday
and Tuesday.

A potent upper trough and cold front will then move through the
great lakes on Tuesday and across the mid-atlantic and northeast on
Wednesday, with additional chances for showers thunderstorms.

Cooler and drier high pressure will follow the front for later next
week.

Aviation 15z Friday through Tuesday
Cigs vsbys have been slow to improve, but are slowly doing so
from west to east. However... Showers and thunderstorms are
likely later this afternoon into this evening. Some
thunderstorms will produce gusty winds and torrential rainfall
that can briefly reduce CIGS vsbys to ifr or below. Drier air
will move in behind a cold front tonight... But winds may become
light and this will allow for patchy fog to develop toward
morning.VFR conditions are expected later Saturday through
Sunday night for most of the time. Cannot rule out an isolated
shower thunderstorm late Saturday afternoon and evening... But
most areas should be dry.

MainlyVFR is expected for Monday and Tuesday, although some
brief reductions are possible in isolated to scattered
showers thunderstorms each afternoon evening. There is also the
possibility for patchy late night early morning low clouds fog.

Marine
Have added SCA to all waters this afternoon for gusty winds
ahead of and along front storms. Special marine warnings will
likely be needed as well.

Southerly winds continue to channel up the middle portion of the
bay and lower tidal potomac river early this morning. A small
craft advisory remains in effect. Will continue with the sca
for later this morning into this afternoon across the middle
portion of the bay and lower tidal potomac river... But there may
be a lull in the gusts during this time. Winds should pick up
ahead of a cold front late this afternoon. The cold front will
pass through tonight and an SCA is in effect for most of the bay
and lower tidal potomac overnight into early Saturday for
northwest winds. However... It will be marginal.

Showers and thunderstorms are likely ahead of the cold
front... Especially late this afternoon and evening.

Thunderstorms will be capable of producing gusty winds. An
isolated waterspout or thunderstorm with large hail cannot be
ruled out as well. Special marine warnings may be needed.

High pressure will build toward the waters later Saturday
through Sunday night. However... An upper-level disturbance will
pass through the waters Saturday evening. An isolated
shower thunderstorm cannot be ruled out... But most areas will
be dry.

Sub-sca conditions likely to continue Monday, although southerly
return flow will be on the increase, and SCA conditions then
become possible Monday night and Tuesday. Additionally, a few
afternoon evening showers thunderstorms are possible both Monday
and Tuesday.

Tides coastal flooding
Southerly flow will continue to cause elevated water levels
through today. Anomalies are high enough to cause straits to
touch with the midday high tide, so issued cfa for st. Mary's
through tonight. A second round of minor flooding is possible
with tonight's high tide cycle at our other more sensitive
sites of annapolis and dc southwest waterfront. Will need to
watch the less sensitve sites as well as baltimore also touched
in the last high tide cycle.

Lwx watches warnings advisories
Dc... Heat advisory until 8 pm edt this evening for dcz001.

Md... Heat advisory until 8 pm edt this evening for mdz011-013-014-
016-504-506.

Coastal flood advisory until 3 am edt Saturday for mdz017.

Va... Heat advisory until 8 pm edt this evening for vaz052>057.

Wv... None.

Marine... Small craft advisory until 9 am edt Saturday for anz531-532-
539-540.

Small craft advisory until 9 am edt Saturday for anz533-534-
537-541-543.

Small craft advisory until 1 am edt Saturday for anz530-535-
536-538-542.

Synopsis... Bjl
near term... Bjl rcm
short term... Bjl
long term... Mm
aviation... Bjl mm rcm
marine... Bjl mm rcm
tides coastal flooding... Bjl rcm


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
NCDV2 0 mi45 min SSW 4.1 G 8 83°F 83°F1010.7 hPa
PPTM2 - 8578240 - Piney Point, MD 29 mi45 min SSW 2.9 G 4.1
SLIM2 - 8577330 - Solomons Island, MD 31 mi45 min SW 6 G 11 83°F 82°F
COVM2 - 8577018 - Cove Point LNG Pier, MD 35 mi45 min SW 9.9 G 14 81°F 1012.4 hPa
BSLM2 - Chesapeake Bay, MD 36 mi105 min S 5.1 75°F 1011 hPa71°F
44062 - Gooses Reef, MD 36 mi35 min SSW 9.7 G 14 82°F 1012.3 hPa
LWTV2 - 8635750 - Lewisetta, VA 37 mi45 min SSW 8 G 9.9 83°F 81°F1011.7 hPa
WASD2 - 8594900 - Washington, DC 38 mi45 min S 8.9 G 11 82°F 80°F1010.6 hPa
44042 - Potomac, MD 42 mi35 min SSW 5.8 G 5.8 82°F 1011.1 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 mi79 minS 910.00 miPartly Cloudy82°F79°F90%1011.9 hPa
Fredericksburg, Shannon Airport, VA23 mi80 minS 510.00 miPartly Cloudy84°F77°F79%1011.5 hPa
Stafford, Stafford Regional Airport, VA23 mi80 minS 310.00 miFair83°F79°F87%1013.2 hPa

Wind History from NYG (wind in knots)
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Last 24hr----SE11SE7S13S15S12S9S10S7S6S9S10SW6SW4S10SW8SW9SW6SW5S4S10S9S11
1 day agoS5S7S5S43S5S5CalmNW5NW4NW6CalmNW6W4W4E3CalmCalm----S8S7S8S6
2 days agoW5W4W4NE3NE7NE4NE4NE5CalmNW6NW5NW5NW7NW5NW6NW6NW5NW4NW3NW3CalmS5S4S5

Tide / Current Tables for Dahlgren, Upper Machodoc Creek, Virginia
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Dahlgren
Click for Map
Fri -- 12:23 AM EDT     2.20 feet High Tide
Fri -- 02:54 AM EDT     Moonrise
Fri -- 06:25 AM EDT     Sunrise
Fri -- 06:56 AM EDT     0.39 feet Low Tide
Fri -- 12:42 PM EDT     1.87 feet High Tide
Fri -- 05:36 PM EDT     Moonset
Fri -- 07:04 PM EDT     0.19 feet Low Tide
Fri -- 07:57 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
2.22.21.91.61.20.80.50.40.50.81.21.61.81.91.71.410.60.30.20.30.61.11.6

Tide / Current Tables for Colonial Beach, Potomac River, Virginia
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Colonial Beach
Click for Map
Fri -- 02:54 AM EDT     Moonrise
Fri -- 06:25 AM EDT     Sunrise
Fri -- 06:29 AM EDT     0.40 feet Low Tide
Fri -- 12:15 PM EDT     1.86 feet High Tide
Fri -- 05:35 PM EDT     Moonset
Fri -- 06:37 PM EDT     0.21 feet Low Tide
Fri -- 07:57 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
2.22.11.81.410.60.40.40.611.41.71.91.81.61.20.80.50.30.20.40.81.31.8

Weather Map and Satellite Images
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Weather Map
wmap_A
IR Satellite Image from GEOS
east_satellite

GOES Local Image of Mid-Atlantic    EDIT
Geos

Wind Forecast for Baltimore, MD/Washington (12,3,4,5)
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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.