Sunday, November19, 2017 L-36.com


Marine Weather and Tides
Olney, MD

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 6:55AMSunset 4:52PM Sunday November 19, 2017 1:26 AM EST (06:26 UTC) Moonrise 7:44AMMoonset 6:03PM Illumination 0% Phase: New Moon; Moon at 0 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
    EDIT      (on/off)   Help
ANZ535 Tidal Potomac From Key Bridge To Indian Head- 1232 Am Est Sun Nov 19 2017
.gale warning in effect through this afternoon...
Overnight..SW winds 20 kt. Gusts up to 30 kt... Increasing to 40 kt late. Waves 2 ft. Showers.
Sun..NW winds 20 to 25 kt with gusts to 40 kt. Waves 2 ft.
Sun night..W winds 10 to 15 kt. Gusts up to 25 kt in the evening. Waves 1 ft.
Mon..W winds 10 kt with gusts to 20 kt. Waves 1 ft.
Mon night..SW winds 5 kt. Waves less than 1 ft.
Tue..SW winds 5 to 10 kt. Waves 1 ft.
Tue night..SW winds 5 to 10 kt. Waves 1 ft. A chance of showers.
Wed..N winds 5 kt. Waves less than 1 ft.
Thu..NW winds around 5 kt. Waves 1 ft.
ANZ500 1232 Am Est Sun Nov 19 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A strong cold front will move across the waters late tonight into early Sunday morning and high pressure will build to our south later Sunday through Monday. The high will move offshore Tuesday and a cold front will pass through late Tuesday night into Wednesday. A small craft advisory may be needed for portions of the waters Monday and Tuesday.

7 Day Forecast for Marine Location Near Olney, MD
   Hourly   EDIT   Help
location: 39.15, -77.07     debug


Area Discussion for - Baltimore, MD/Washington
      (on/off)   Help   NOTE: mouseover dotted underlined text for definition
Fxus61 klwx 190213
afdlwx
area forecast discussion
national weather service baltimore md washington dc
913 pm est Sat nov 18 2017

Synopsis
A powerful cold front will cross the region late tonight. High
pressure will slowly build south of the region late Sunday
through Monday before passing off the east coast on Tuesday.

Another cold front will cross the region Tuesday night, with
high pressure building back across the region for the latter
half of the week.

Near term through Sunday
Overall think the forecast for the cold front and upslope snow
is on track, with only minor refinements to the grids. Have
moved up the start of the wind advisory for the lower elevation
zones west of the blue ridge to 1 am, which is approximately
when the front will enter the area.

The nowcast portion of the forecast has been more challenging
though, as per usual, models are trying to lift the warm front
northward too quickly through the rain-induced cold pool in the
ridge valley region. The front has eked through winchester in
the past hour. Meanwhile south of the front, it has been quite
gusty (ssw-nne oriented valleys and va piedmont with some gusts
30-35 mph) and temperatures have surged into the upper 50s to
lower 60s.

Many areas will probably see temps rise as we pass midnight with
low 60s across much of the CWA (except northwest) early Sunday
morning as the cold front moves in.

After a lull in precip expected this evening, showers will move
in ahead of the cold front late this evening into the
overnight, with potentially a line of gusty showers right on the
front. Given strong pressure surge and potential for showers
right on the front to effectively mix this wind down, decided to
start wind advisory earlier than the synoptic wind would argue.

Its possible that some areas see their strongest winds with the
front itself. After frontal passage, temps will crash quickly
back from high 50s and low 60s down to the 40s, with sub-
freezing expected along the allegheny front. These areas will
also get upslope flow, so snow is expected to start accumulating
late tonight, and a winter weather advisory has been issued.

Most of the accumulation will likely be after sunrise Sunday.

Short term Sunday night through Monday night
Gusty winds are the main story as pressure rises rapidly behind
the strong cold front on Sunday. Best wind aloft and mixing
appear to coincide mid-late morning Sunday, with most likely
region to get 45+ mph gusts being north-central md, but given
uncertainty decided to issue for all of dc metro and areas
further west from there. As is typical, winds will diminish as
we head south through the va piedmont, so no advisory for cho
metro. Temps will have difficulty rising with strong cold
advection, but expect most places near i-95 to edge back into
the 50s during the day. Upslope flow will continue Sunday
morning along the allegany front, with continued snow showers.

There may be a lull midday, with another surge in snow showers
late in the day and early Sunday evening as another shortwave
moves through. Thus, went a bit long on the advisory to catch
both bursts. Accumulations will be somewhat elevation dependent,
but local amounts of 6-7 inches aren't out of the question.

High pressure will then slowly build eastward to our south
Sunday night and Monday. Upslope flow will diminish, allowing
snow showers along the allegany front to end late Sunday night,
and the gradient and winds aloft will both diminish as well,
allowing winds to die down. That said, we still expect it to be
breezy Monday. Otherwise, Monday will be cool but mostly sunny,
with highs in the 40s to lower 50s after a night of below
freezing temps region-wide. Not quite as chilly Monday night as
the high slips further east, but still dry and mostly clear.

Long term Tuesday through Saturday
A cold front will move across the lower great lakes region
Tuesday and approach the mid-atlantic region Tuesday night.

There is some uncertainty with this front as to whether it
produces precipitation or not late Tuesday and Tuesday night.

The GFS model hints of a dry frontal passage as a broad area of
high pressure covers the southeast u.S., not allowing for a
substantial moisture return flow. The european model hints of
measurable rainfall across the eastern two-thirds of our region
with high pressure farther offshore to allow for a modest
moisture return flow. We will keep slight chance of rain showers
and slight chance rain and or snow showers in the west, for
now. Temperatures will be a little chilly.

High pressure will make an attempt to build in behind the
weakening and departing cold front. Here again, there are
discrepancies as to how far east the high will build in the mid-
atlantic and whether or not the preceding cold front will stall
along the east coast, allowing for a possible low to develop
along it. The GFS model is weaker than the european with the
building area of high pressure, while the GFS tries to develop a
low along a stalled front. For now, we will lean toward dry and
chilly conditions with high pressure building into the region
Wednesday through Saturday.

Aviation 02z Sunday through Thursday
Mrb is still stuck north of the warm front although the main
issue now is light fog mist. Winds now se, so expect this
concern to be alleviated shortly. Elsewhere, gusty south wind
andVFR CIGS vis with a stray shower is the rule through this
evening. Later tonight, powerful cold front moves through with
possible MVFR restrictions in showers and cigs, and gusts
possibly up to 40 knots at frontal passage.VFR returns behind
the front for Sunday and Monday, but gusty winds expected to
continue Sunday with gusts still possibly reaching 40 knots,
particularly bwi mtn (much less chance at cho). Winds diminish
Monday as high pressure builds in.

Vfr conditions overall Tuesday through Wednesday night. Any
rain showers could produce a brief period of MVFR conditions
Tuesday night. Winds southwest 5 to 10 knots Tuesday and Tuesday
night. Winds becoming northwest 5 to 10 knots Wednesday and
Wednesday night.

Marine
In general winds will be sub-gale most of the night as the
potent low level jet will have trouble mixing down, though
winds are now approaching 30 knots in some locations. However,
with the cold front passage late tonight, we could see gusts to
40 knots, particularly if a line of showers develops right on
the front, so started the gale warning remains in effect. Best
gale period is probably going to be mid-late morning Sunday,
however, with diminishing winds thereafter. SCA will likely need
to continue after the gale ends Sunday night and Monday, then
sub- SCA may finally return Monday night for a time.

Small craft advisories possible Tuesday ahead of a cold front.

No marine hazards expected Tuesday night through Wednesday
night. Winds southwest 10 to 15 knots gusts up to 20 knots
Tuesday. Winds southwest around 10 knots Tuesday night. Winds
becoming northwest around 10 knots Wednesday and Wednesday
night.

Tides coastal flooding
Water levels have become steady on either side of a foot, with
only havre de grace's tide still occurring. Anomalies will
begin to decrease as winds become westerly late tonight across
the entire area, but water levels may not fall quickly enough to
prevent flooding during tomorrow morning's high tide cycle.

Given lower astronomical values, am thinking we can escape
flooding, although it will be close at straits point and
annapolis.

Lwx watches warnings advisories
Dc... Wind advisory from 4 am to 3 pm est Sunday for dcz001.

Md... Wind advisory until 3 pm est Sunday for mdz501.

Wind advisory from 1 am to 3 pm est Sunday for mdz003-502.

Wind advisory from 4 am to 3 pm est Sunday for mdz004>006-011-
013-014-016>018-503>508.

Coastal flood advisory until midnight est tonight for mdz508.

Coastal flood advisory until 10 pm est this evening for mdz011.

Va... Wind advisory until 3 pm est Sunday for vaz025-026-503-504-507-
508.

Wind advisory from 1 am to 3 pm est Sunday for vaz027>031.

Wind advisory from 4 am to 3 pm est Sunday for vaz040-052>054-
501-505-506.

Wv... Wind advisory until 3 pm est Sunday for wvz501-503-505-506.

Wind advisory from 1 am to 3 pm est Sunday for wvz050>053-055-
502-504.

Winter weather advisory from 4 am to 11 pm est Sunday for
wvz501-505.

Marine... Gale warning until 6 pm est Sunday for anz530>543.

Synopsis... Rcm
near term... Ads rcm
short term... Rcm
long term... Klw
aviation... Ads rcm klw
marine... Ads rcm klw
tides coastal flooding... Dhof ads


Weather Reporting Stations
   EDIT       (on/off)   Help   NOTE: Click on distance to see the station location on a map
Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BSLM2 - Chesapeake Bay, MD 32 mi57 min S 11 62°F 996 hPa51°F
TPLM2 - Thomas Point, MD 38 mi27 min S 21 G 23 60°F 55°F

Wind History for Washington, DC
(wind in knots)    EDIT      (on/off)   Help
Last
24hr
1 day
ago
2 days
ago

Airport Reports
    EDIT      (on/off)   Help   Click EDIT to display multiple airports
AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Gaithersburg - Montgomery County Airport, MD5 mi31 minS 810.00 miRain57°F52°F83%997.8 hPa
College Park Airport, MD14 mi41 minS 710.00 miMostly Cloudy61°F50°F67%994.9 hPa
Fort Meade / Tipton, MD16 mi42 minSSW 11 G 1610.00 miOvercast61°F50°F68%995.9 hPa
Washington/Reagan National Airport, DC, VA20 mi35 minSSW 20 G 2410.00 miLight Rain and Breezy64°F51°F63%995.3 hPa
Baltimore, Baltimore-Washington International Airport, MD21 mi33 minSSW 8 G 227.00 miLight Rain61°F53°F75%994.5 hPa
Washington/Dulles International Airport, DC, VA24 mi35 minS 14 G 249.00 miLight Rain58°F53°F84%994.5 hPa

Wind History from GAI (wind in knots)
2
AM
3
AM
4
AM
5
AM
6
AM
7
AM
8
AM
9
AM
10
AM
11
AM
12
PM
1
PM
2
PM
3
PM
4
PM
5
PM
6
PM
7
PM
8
PM
9
PM
10
PM
11
PM
12
AM
1
AM
Last 24hrS5SE4SE7S5S7SE9--S9SW8S5
G14
SW9SE7S6S4S8S8S11
G18
S12
G18
S9S12
G24
SW11
G27
S9
G21
S11
G20
S8
1 day agoNW9NW11NW9NW9NW7NW11
G17
NW10NW7
G14
NW9
G18
NW8
G16
NW12
G16
NW7NW11NW7NW7W3CalmCalmSE3CalmSE4CalmCalmSE3
2 days agoS33SW5SW4CalmCalmCalm3W5W9W10
G18
NW14
G23
NW9NW11
G23
NW12
G21
NW10
G16
NW14
G22
NW9
G17
NW7
G16
NW14
G24
NW13
G16
NW5NW7NW8

Tide / Current Tables for Chain Bridge, D.C.
   EDIT   RT Ports Option   Weekend mode (on/off)   (on/off)   Help   One Week of Data
Chain Bridge
Click for Map
Sun -- 03:32 AM EST     -0.05 feet Low Tide
Sun -- 06:55 AM EST     Sunrise
Sun -- 07:43 AM EST     Moonrise
Sun -- 09:04 AM EST     2.79 feet High Tide
Sun -- 03:26 PM EST     0.04 feet Low Tide
Sun -- 04:51 PM EST     Sunset
Sun -- 06:03 PM EST     Moonset
Sun -- 09:14 PM EST     3.12 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.50.90.4000.51.322.62.82.621.30.80.30.10.10.61.52.32.93.132.5

Tide / Current Tables for Chain Bridge, Washington, D.C.
   EDIT      (on/off)   Help   One Week of Data
Chain Bridge
Click for Map
Sun -- 03:30 AM EST     -0.10 feet Low Tide
Sun -- 06:55 AM EST     Sunrise
Sun -- 07:43 AM EST     Moonrise
Sun -- 09:03 AM EST     2.83 feet High Tide
Sun -- 03:24 PM EST     -0.01 feet Low Tide
Sun -- 04:51 PM EST     Sunset
Sun -- 06:03 PM EST     Moonset
Sun -- 09:13 PM EST     3.15 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.50.90.4-0-00.51.32.12.62.82.621.30.70.300.10.61.52.32.93.132.5

Weather Map and Satellite Images
       (on/off)   Help
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 (1,6,7,8)
      (on/off)   Help

Ground Weather Radar Station Sterling, VA
   (on/off)   Help
weather_mapweather_map weather_map

Ad by Google

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.