Sunday, April30, 2017 L-36.com


Marine Weather and Tides
Mantua, VA

Version 3.4
What's New / NOTES
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.
3/12/2015 - Added section for Gulf current for users in the GMZ marine zones.
This was requested by a user. If you have requests, please let me know.

Sunrise 6:09AMSunset 8:02PM Sunday April 30, 2017 10:49 AM EDT (14:49 UTC) Moonrise 9:01AMMoonset 11:44PM Illumination 21% Phase: Waxing Crescent; Moon at 5 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- 1032 Am Edt Sun Apr 30 2017
.small craft advisory in effect from Monday morning through Monday afternoon...
Rest of today..S winds 5 to 10 kt. Waves 1 ft.
Tonight..S winds 5 to 10 kt. Waves 1 ft.
Mon..S winds 10 to 15 kt with gusts to 25 kt. Waves 1 to 2 ft.
Mon night..SW winds 10 to 15 kt with gusts to 25 kt. Waves 1 to 2 ft. Showers and tstms likely.
Tue..SW winds 10 to 15 kt with gusts to 25 kt. Waves 1 ft.
Tue night..W winds 5 to 10 kt. Gusts up to 20 kt in the evening. Waves 1 ft.
Wed..NE winds 5 to 10 kt. Waves 1 ft. A chance of showers through the night.
Thu..SE winds 5 kt. Waves less than 1 ft. Showers likely. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 1032 Am Edt Sun Apr 30 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A backdoor cold front will stall over the area today, and retreat northward tonight. A stronger cold front will approach from the west Monday before passing through Monday night. High pressure will build overhead Tuesday into Wednesday. Low pressure may impact the waters late in the week. A small craft advisory will likely be needed for the waters Monday night and Tuesday.

7 Day Forecast for Marine Location Near Mantua, VA
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location: 38.84, -77.25     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 301358
afdlwx
area forecast discussion
national weather service baltimore md/washington dc
958 am edt Sun apr 30 2017

Synopsis
A front which is draped across the area will lift north as a
warm front later today. A stronger cold front move east of the
mississippi river tonight and approach the appalachians by
Monday morning. This front will cross the region Monday evening.

High pressure will bring cooler and drier weather during the
middle of the week.

Near term /through tonight/
At 9 am surface front in form of wind shift is located from near
franklin WV to warrenton to chesapeake beach. Low clouds are
farther north than that line. While it appears the southern edge
is trying to scatter into cumulus, am a little concerned erosion
may be on the slow side since winds north of the boundary are
verifying with a more northeasterly component than originally
progged. While this could have some effect on the temperature
gradient, the already-warm start means portions of the baltimore
area are already nearing their highs despite the clouds.

Temperatures are on their way to the 80s south of the boundary.

There is still a bit of uncertainty in the details of how
convection will transpire today. In the bigger picture, though,
it will be safe to say that north of the boundary surface-based
instability will be nil. To the south, SBCAPE will be in the
neighborhood of 1500-2500 j/kg with more than adequate deep
shear (30-35 kt bulk 0-6km layer). The struggle once again is
finding the trigger. Believe that terrain and frontal
convergence will be that mechanism, suggesting that the potomac
highlands will be the favored location. 12z rnk sounding has
very dry mid-level air which is expected to advect northward,
and all regional soundings show multiple stable layers. Thus am
continuing the previous thinking that coverage will be scattered
at best. If a stronger updraft can develop, gusty winds will be
a threat.

Short term /Monday through Tuesday night/
Instability quickly dissipates with the loss of diurnal heating,
and have removed pops for the nighttime hours. Area will be
north of the warm front, in an air mass with 60s dewpoints, so
patchy fog development will once again be a concern. Otherwise,
it should be a quiet night. Lows won't be far removed from
dewpoints.

On Monday, a well defined cold front will be approaching the
area. There are still some timing differences amongst guidance.

This bigger disparity, though, is whether thunderstorms will
develop along the front or along a pre-frontal trough. The gfs
is the quickest solution, keying on pre-frontal convection in a
diurnally favored timeslot. If this happens, then strong to
severe thunderstorms will be possible. Other solutions suggest
thunderstorms will be nearer the front, and timed more in the
evening. The challenge will be how much instability will
generated; more than ample shear is present. Pops will be likely
to categorical nonetheless, with emphasis on the later afternoon
and evening hours.

Cooler and drier air will overspread the area Monday night
(overnight) into Tuesday morning. We will have a glancing blow
from the upper trough axis during the day Tuesday, which will
sustain gusty winds much of the day. But since the air will be
drier and flow will be downsloping, don't believe that clouds
will be numerous. Temperatures will be closer to normal during
the day, with nighttime low in the 40s and 50s again.

Long term /Wednesday through Saturday/
High pressure will build into the region Wednesday. Cooler
conditions expected mid-week as northerly winds usher in cooler
and dryer conditions. High temps in the u60s/l70s expected wed.

A storm system will be coming together across the mississippi
valley Wed night. Warm air advection will begin across the
region Wed night-Thursday and clouds and showers are expected.

More showers are expected to move into the region Thu night-
Friday as the system becomes more dynamic. The upper level low
becomes a closed low Thu night and sfc low pressure will
continue to deepen across the ohio valley. This system may bring
thunderstorms capable of heavy rain as the wind field
strengthens and dewpts rise rapidly Friday. Timing is uncertain
and it is unknown at this time if conditions will be hazardous.

Low pressure will likely move overhead fri-night- Saturday.

Clouds and showers will likely keep temperatures below normal
mid-late week.

Aviation /14z Sunday through Thursday/
A backdoor cold front has slipped south of the metro terminals
but not to cho, providing a complicated flight category regime.

MVFR seems to be the rule on the north side of the boundary.

Have rather low confidence at how quickly the restrictions will
erode, especially since winds are verifying from a more
northeasterly direction. However, satellite shows the southern
edge of the clouds trying to erode. Expect bwi/mtn to be
affected the longest. Scattered thunderstorms should develop
south of the front, but direct impact at an airfield too limited
to forecast at this juncture... Am thinking the highest chance
will be near mrb.

Anything that does develop will dissipate with sunset tonight.

The air will be humid enough for more patchy fog development
overnight into early Monday morning. Will be keeping forecasts
at MVFR. Lower results certainly possible.

A well defined cold front will approach the terminals Monday,
and cross the region late Monday into Monday night. Numerous
thunderstorms anticipated along/ahead of the front, with brief
aob ifr along with locally gusty winds.

The front will clear the area late Monday night.VFR expected
through Wednesday. Rain will spread east Wednesday night into
Thursday.

Marine
A backdoor front has slipped to around chesapeake beach, and
further southward progression may be limited before gradually
returning northward. Flow will be northeast/east to its north,
and southeast/south to its south and shouldn't be much more
than 10 kt sustained, so small craft advisories are not
anticipated. This front will return to the north this evening.

Gradient flow (southerly) will increase overnight into Monday
ahead of a stronger cold front approaching from the west. A
small craft advisory GOES in effect after midnight tonight for
southern waters, and then for all waters on Monday. The front
itself will impact the marine area Monday night, although some
thunderstorms may develop ahead of the front Monday afternoon.

These thunderstorms may contain gusty winds.

Behind the front flow turns westerly. Mixed profiles appear
deep, and expect small craft conditions to extend into Tuesday.

A storm system may impact the waters late in the work week.

Showers and thunderstorms are possible as well as gusty winds
that may produce SCA conditions.

Tides/coastal flooding
Water levels running very close to astronomical normals this
morning. Anticipate that will remain the case through the next
two tide cycles. Estofs does suggest that water levels will rise
in the northern bay, but believe that is a result of a model
bias and am neglecting that solution.

After that, uncertainty grows as model solutions become more
divergent. Am providing a forecast of water levels below caution
stage Monday. South flow could sustain an increase. Some
solutions suggest these elevated levels could linger into
Tuesday, as winds will turn gusty but will be from the
west... And thus won't prompt a blowout.

Low pressure will come up the coast Thursday, which likely will
increase water levels from wherever they stand up to that
point.

Climate
Record highs were set at dca and iad yesterday, and record warm
lows were set at all three airports (dca, iad, and bwi). The
record warm low at dca was also a record for the month of april.

Records highs are less likely today as a backdoor front drops
down. However, the record warm lows are a possibility. Here are
the record highs/warm lows for Sunday:
washington dc... High 92 (in 1942); warm low 67 (in 1983).

Bwi airport... High 92 (in 1910); warm low 63 (in 1983).

Dulles airport.. High 86 (in 2007); warm low 64 (in 1983).

Lwx watches/warnings/advisories
Dc... None.

Md... None.

Va... None.

Wv... None.

Marine... Small craft advisory from 8 am to 6 pm edt Monday for
anz530>532-535-536-538>540-542.

Small craft advisory from midnight tonight to 6 pm edt Monday
for anz534-537-543.

Small craft advisory from 4 am to 6 pm edt Monday for anz533-
541.

Synopsis... Hts
near term... Ads/hts
short term... Hts
long term... Hsk
aviation... Ads/hts
marine... Ads/hsk/hts
tides/coastal flooding... Hts
climate... Hts


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 12 mi50 min NE 2.9 G 6 74°F 68°F1019.6 hPa (+0.8)
BSLM2 - Chesapeake Bay, MD 29 mi140 min NNW 1 64°F 1020 hPa62°F
NCDV2 38 mi50 min WSW 7 G 11 78°F 68°F1019.4 hPa (+0.8)
APAM2 - 8575512 - Annapolis, MD 42 mi50 min 71°F 1020.4 hPa (+1.1)
44063 - Annapolis 43 mi40 min E 5.8 G 12 70°F 1020.6 hPa
TPLM2 - Thomas Point, MD 43 mi50 min E 14 G 15 69°F 61°F
BLTM2 - 8574680 - Baltimore, MD 46 mi50 min ESE 11 G 13 69°F 65°F1020.8 hPa (+0.9)
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 46 mi50 min ENE 7 G 8 68°F 1021.1 hPa (+1.0)
CPVM2 47 mi50 min 71°F 64°F
FSNM2 47 mi50 min E 9.9 G 13 69°F 1021 hPa (+1.0)
44062 - Gooses Reef, MD 48 mi40 min S 9.7 G 12 69°F 1020.9 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Fort Belvoir, VA8 mi52 minN 010.00 miOvercast79°F69°F74%1019.9 hPa
Washington/Reagan National Airport, DC, VA12 mi58 minNE 610.00 miOvercast75°F69°F82%1020.2 hPa
Washington/Dulles International Airport, DC, VA13 mi58 minNE 310.00 miMostly Cloudy74°F68°F82%1019.6 hPa
Manassas, Manassas Regional Airport/Harry P. Davis Field, VA17 mi54 minN 010.00 mi76°F70°F82%1020.7 hPa
College Park Airport, MD20 mi69 minNNE 310.00 miOvercast70°F63°F81%1020.7 hPa
Camp Springs / Andrews Air Force Base, MD20 mi1.9 hrsN 010.00 miOvercast74°F70°F89%1020.4 hPa
Quantico Marine Corps Airfield - Turner Field, VA23 mi54 minSSE 510.00 miPartly Cloudy76°F72°F88%1019.8 hPa
Leesburg / Godfrey, VA24 mi55 minENE 310.00 miOvercast72°F68°F88%1020.7 hPa

Wind History from DAA (wind in knots)
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Last 24hrW5S7S10S8S5W5SW4CalmS3CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmS3CalmCalmS3Calm
1 day agoCalmS5SE7S8S6SE3
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S6SE6SE5SE4CalmCalmCalmSE3CalmCalmCalmNW4CalmS5CalmCalmSW3W4
2 days agoS8S5SE6S7
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S5S6S5S6S5SW6SW5S4SW4CalmCalmCalmW3SE3CalmNW5N4

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Sun -- 12:10 AM EDT     3.29 feet High Tide
Sun -- 06:11 AM EDT     Sunrise
Sun -- 06:45 AM EDT     0.20 feet Low Tide
Sun -- 10:00 AM EDT     Moonrise
Sun -- 12:18 PM EDT     3.73 feet High Tide
Sun -- 07:39 PM EDT     0.04 feet Low Tide
Sun -- 08:00 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
3.33.12.61.91.20.70.30.20.61.42.53.43.73.63.12.41.71.10.50.10.10.51.52.4

Tide / Current Tables for Chain Bridge, Washington, D.C.
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Chain Bridge
Click for Map
Sun -- 12:12 AM EDT     3.25 feet High Tide
Sun -- 06:11 AM EDT     Sunrise
Sun -- 06:48 AM EDT     0.20 feet Low Tide
Sun -- 10:00 AM EDT     Moonrise
Sun -- 12:21 PM EDT     3.68 feet High Tide
Sun -- 07:42 PM EDT     0.03 feet Low Tide
Sun -- 08:00 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
3.23.12.61.91.20.70.30.20.51.42.53.33.73.63.12.41.71.10.60.20.10.51.42.4

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 (10,2,3,4)
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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.