Friday, July28, 2017 L-36.com


Marine Weather and Tides
Hollymead, 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 6:13AMSunset 8:27PM Friday July 28, 2017 1:01 PM EDT (17:01 UTC) Moonrise 10:47AMMoonset 10:52PM Illumination 26% 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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ANZ536 Tidal Potomac From Indian Head To Cobb Island- 1100 Am Edt Fri Jul 28 2017
.small craft advisory in effect from Saturday morning through Saturday evening...
Rest of today..S winds 5 kt. Waves less than 1 ft. Showers likely.
Tonight..E winds 5 kt...becoming N late. Waves 1 ft. Showers and tstms. Vsby 1 nm or less.
Sat..N winds 5 to 10 kt with gusts to 20 kt. Waves 1 ft. Showers. Vsby 1 nm or less.
Sat night..N winds 5 to 10 kt. Gusts up to 20 kt in the evening. Waves 1 ft. A chance of showers.
Sun..N winds 5 to 10 kt. Waves 1 ft.
Sun night..N winds 5 kt. Waves less than 1 ft.
Mon..W winds around 5 kt. Waves 1 ft.
Tue..SW winds around 5 kt. Waves 1 ft. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 1100 Am Edt Fri Jul 28 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Low pressure will approach the waters today and then intensify as it moves over the mid atlantic tonight. The low is expected to stall out over the delmarva peninsula Saturday into early Sunday before moving out to sea late Sunday into Monday. A small craft advisory may be needed Sunday into Monday. A gale warning may be needed for portions of the waters Saturday afternoon through Saturday night.

7 Day Forecast for Marine Location Near Hollymead, VA
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location: 38.08, -78.42     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 281523
afdlwx
area forecast discussion
national weather service baltimore md washington dc
1123 am edt Fri jul 28 2017

Synopsis
Upper-level low pressure system will intensify as it moves into the
area through tonight. The low will slowly pass through the area
Saturday before gradually moving away from the coast Saturday night
into Monday. High pressure is expected to build overhead early next
week.

Near term through tonight
We are already issuing ffw's just west of washington dc. Radar
estimates up to 3" of rain in an hour in eastern montgomery
county. The 12z iad sounding had a pwat of 1.77" and that should
continue to increase this afternoon. We are hearing reports of
water rescues.

See the mesoscale precip discussion that wpc issued at 1040 am -
excellent discussion of the meteorology expected for this
afternoon and evening.

I remain most worried about northern va up to the pa border - as
i've seen in writing this does appear to bear some similarity to
nor'easters and makes me think of some of the bigger snowfalls
i've seen here where the cho area might get 8" and central
md eastern WV over 20" - as the low pivots off the coast snow
will cease in the central shen valley but a band will hang on
for many hours from balt and westward. Obviously we're not
talking snow here but believe the rain will hang on through
midday Sat across the aforementioned region.

Flash flood watch area remains the same but we have pushed the
start up to 14z.

A storm total of 2- 4+ inches is possible on average over the
watch area.

Coverage expected to increase by afternoon, with the heaviest
rainfall expected from late afternoon into the overnight as the
surface low rides crosses the area as it traverses the frontal
boundary.

While hydro issues are the primary threat today... Some severe
thunderstorm potential does exist... With a marginal risk from spc.

The primary threat is isolated strong wind gusts due to modest
instability and relatively strong shear profiles. While we are
nopt outlooked for a tornado threat we feel spin ups could be a
concern given low level helicity this evening. This is not in a
normal quandrant on the hodograph given the easterly flow but
still bears watching.

Short term Saturday through Sunday night
Surface low remains east of the area Saturday with trowal
precipitation remaining over the area (some of which could be of
moderate intensity). Soils expected to be saturated over much of the
area... So while precipitation Saturday should be a bit lighter in
intensity... Any additional precipitation could exacerbate hydro
issues.

Cloud cover and nearby precipitation will keep temperatures in the
60s to l70s Saturday.

Drying out Sunday as low moves far enough to our east keeping
precipitation east of the area.

Long term Monday through Thursday
High pressure will be building across the mid atlantic for the
beginning of next week, providing an extended period of tranquil
weather. The only concern will be whether a cold front will drop
down into the area to provide a focus for showers thunderstorms
Thursday. There will be plenty of time to resolve that detail.

Temperatures will start the week mild-- almost cool-- for the last
day of july, and gradually warm through the week.

Aviation 15z Friday through Tuesday
Low pressure will approach the terminals today before moving
overhead and intensifying tonight. MVFR going to ifr later
today. Widespread showers and thunderstorms are expected to
develop with locally heavy rain and subsequent flight
restrictions at times. Some storms may also contain gusty winds.

More rain is likely Saturday as the low stalls out near the
delmarva peninsula. Gusty north to northeast winds are also
possible during this time. Improving conditions Sunday as
surface low shifts well east of the area.

No aviation concerns in the new week anticipated under building
high pressure.

Marine
Low pressure will approach the waters today before strengthening
overhead tonight. The low will likely stall out near the delmarva
peninsula Saturday through Saturday night. Gusty winds are possible
with the low nearby... Especially tonight through Saturday night.

Small craft advisory in effect tonight through Saturday night
for the bay and for the 2 3 of the tidal potomac for the day
Saturday. Gale force winds are possible Saturday afternoon
evening... Though probability of occurrence is currently too low
for a warning.

During afternoon mixing in the wake of low pressure, momentum
transfer may be sufficient for small craft gusts Monday. Aside from
that, no flags expected as high pressure builds.

Hydrology
A flash flood watch is in effect through Saturday afternoon for
the northern 2 3 of the forecast area. Most likely rainfall
amounts during this time will be around 2 to 4 inches (with
locally higher amounts). This may cause instances of flash
flooding.

Pqpf from wpcs 70 member ensemble shows storm total precipitation of
1 3 5 inches at the 10 50 90th percentiles. Long-term nature of
the threat suggests that river flood risk could arise over the
weekend. Though, current mmefs guidance suggest any threat could
be localized... Particularly across the potomac river basin.

Tides coastal flooding
Water level departures starting to ease lower... A trend that's
likely to continue in light of anomalies of a half to 2 3rds of a
foot in the virginia waters. While onshore flow should be a
mitigating factor today, the duration of such winds will be minimal,
and will be followed by northerly blowouts. In the end, believe that
tides will reach action stage at worst today, and that would be for
vulnerable sections of the coastline such as straits point and
annapolis. This solution supported by not just etss but also snap-ex
ensemble guidance. Subsequent tide cycles should be unaffected.

Lwx watches warnings advisories
Dc... Flash flood watch through Saturday afternoon for dcz001.

Md... Flash flood watch through Saturday afternoon for mdz003>006-
011-013-014-016>018-501>508.

Va... Flash flood watch through Saturday afternoon for vaz027>031-
038>040-050>057-501-502-505>507.

Wv... Flash flood watch through Saturday afternoon for wvz050>053-
055-501>504.

Marine... Small craft advisory from 5 am Saturday to 7 am edt Sunday for
anz531>534-537-539>543.

Small craft advisory from 10 am to 7 pm edt Saturday for
anz530-535-536-538.

Update... Woody!
previous... Mse hts


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 92 mi43 min WNW 8 G 8.9 77°F 84°F1008.7 hPa

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Charlottesville-Albemarle Airport, VA4 mi68 minNW 410.00 miMostly Cloudy80°F71°F74%1009.6 hPa
Orange, Orange County Airport, VA23 mi66 minN 310.00 miOvercast73°F71°F94%1010.5 hPa
Louisa, Louisa County Airport/Freeman Field, VA24 mi66 minN 010.00 miPartly Cloudy82°F68°F62%1010.2 hPa

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Last 24hrS7SW6SW7SW5SW5SW4CalmSW3CalmCalmCalmCalmS5CalmCalm3CalmCalmCalmCalmN3N4NW4N4
1 day ago3CalmS4SW6SW75SW4SW4CalmCalmCalmCalmCalmCalmCalmS3CalmCalmCalmCalmS3SW8S7SW6
2 days agoNE7E6E10E5NE9NE9NE8NE10NE5N3NW3NW3CalmCalmCalmCalmCalmCalmCalmN3E3S4CalmN5

Tide / Current Tables for Fredericksburg, Rappahannock River, Virginia
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Fredericksburg
Click for Map
Fri -- 06:08 AM EDT     Sunrise
Fri -- 06:34 AM EDT     0.26 feet Low Tide
Fri -- 11:42 AM EDT     Moonrise
Fri -- 11:53 AM EDT     3.21 feet High Tide
Fri -- 06:53 PM EDT     0.15 feet Low Tide
Fri -- 08:23 PM EDT     Sunset
Fri -- 11:47 PM EDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
3.32.92.31.71.10.70.30.30.81.72.63.13.232.41.81.20.70.30.20.51.32.22.9

Tide / Current Tables for Massaponax, Rappahannock River, Virginia
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Massaponax
Click for Map
Fri -- 06:08 AM EDT     Sunrise
Fri -- 06:50 AM EDT     0.20 feet Low Tide
Fri -- 11:42 AM EDT     Moonrise
Fri -- 11:45 AM EDT     2.85 feet High Tide
Fri -- 07:08 PM EDT     0.11 feet Low Tide
Fri -- 08:22 PM EDT     Sunset
Fri -- 11:47 PM EDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
2.92.521.510.60.30.20.61.52.32.72.82.62.11.61.10.60.30.10.31.11.92.6

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 (13,3,4,5)
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Ground Weather Radar Station Sterling, VA
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weather_mapweather_map weather_map

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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.