Saturday, November18, 2017

Marine Weather and Tides
Arnold, 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 6:52AMSunset 4:50PM Saturday November 18, 2017 8:22 PM EST (01:22 UTC) Moonrise 6:45AMMoonset 5:23PM 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
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ANZ538 Patapsco River Including Baltimore Harbor- 632 Pm Est Sat Nov 18 2017
.gale warning in effect through Sunday afternoon...
Tonight..S winds 10 to 15 kt with gusts to 25 kt... Becoming sw 20 kt with gusts to 40 kt late. Waves 1 to 2 ft. A chance of showers this evening, then showers after midnight.
Sun..W winds 20 to 25 kt with gusts to 40 kt. Waves 3 ft.
Sun night..W winds 15 to 20 kt. Gusts up to 30 kt... Diminishing to 20 kt after midnight. Waves 1 to 2 ft.
Mon..W winds 10 to 15 kt with gusts to 20 kt. Waves 1 ft.
Mon night..SW winds 5 to 10 kt. Waves 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 to 10 kt. Waves 1 ft or less.
Thu..NW winds 5 kt. Waves less than 1 ft.
ANZ500 632 Pm Est Sat Nov 18 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 Arnold, MD
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location: 39.03, -76.53     debug

Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 181956
area forecast discussion
national weather service baltimore md washington dc
256 pm est Sat nov 18 2017

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 tonight
Warm front has been very slowly pushing northward across the cwa
this afternoon. As of this writing it stretches from near bel
air md southwestward to around front royal va and west towards
petersburg wv. It should start to move again over the next few
hours as southerly flow continues to increase just above the
surface and ongoing rain showers diminish, so we still think
warmer air will envelope the entire region this evening. Many
areas will probably see temps rise as we pass midnight and we
could be into the low 60s across much of the CWA early Sunday
morning as the cold front moves in. Southerly winds have not
been very effectively mixing down even in the warm sector, with
gusts mainly in the 20 kt range, with a few gusts closer to 40
knots at the higher elevations of western va and eastern wv
where the wind advisory starts early.

After a lull in precip expected this evening, showers will move
in ahead of the cold front later 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 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 20z Saturday through Thursday
Mrb has gotten stuck north of the warm front and has gone ifr
with low CIGS from the rain. Expect this to lift later this
afternoon or evening, but timing it out is tricky given
persistetnce of light rain and low level cold air. 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
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.

Sca all waters at present as storm system approaches. SCA should
be the rule tonight as the potenti low level jet will still have
trouble mixing down. 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
tonight. 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

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

Tides coastal flooding
Strait's point peaked below flood stage this afternoon. The
lower of the two astronomical tides is tonight so despite
gradually increasing anomalies it shouldn't hit again this
evening. Highest anomalies are in the northern part of the bay
so expect solid minor tidal flooding at
annapolis baltimore havre de grace. Dc SW waterfront may come
close as well but not enough confidence for a headline just yet
but will monitor. It's a bit odd to see havre de grace hitting
minor but not strait's point, probably because winds are more
west of south near the mouth of the bay pushing water out, while
winds north of southern md are more southerly trapping water
further north. 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.

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 4 am to 3 pm est Sunday for mdz003>006-011-

Coastal flood advisory from 7 pm this evening to midnight est
tonight for mdz508.

Coastal flood advisory until 9 pm est this evening for mdz014.

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-

Wind advisory from 4 am to 3 pm est Sunday for vaz027>031-040-

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

Wind advisory from 4 am to 3 pm est Sunday for wvz050>053-055-

Winter weather advisory from 4 am to 11 pm est Sunday for

Marine... Small craft advisory until 6 pm est this evening for

Gale warning from 6 pm this evening to 6 pm est Sunday for

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

Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
TPLM2 - Thomas Point, MD 10 mi82 min S 21 G 23 56°F 54°F
BSLM2 - Chesapeake Bay, MD 20 mi52 min S 11 58°F 1000 hPa45°F

Wind History for Francis Scott Key Bridge NE Tower, MD
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1 day
2 days

Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Bay Bridge Field, MD11 mi42 minS 12 G 2510.00 miFair57°F46°F67%1000.3 hPa
Fort Meade / Tipton, MD13 mi37 minS 7 G 1410.00 miFair57°F42°F59%1000.7 hPa
Baltimore, Baltimore-Washington International Airport, MD13 mi28 minS 510.00 miOvercast58°F44°F60%999.5 hPa
Baltimore, Inner Harbor, MD18 mi88 minno data mi57°F41°F55%1000.5 hPa
College Park Airport, MD21 mi36 minS 610.00 miFair60°F43°F55%999.7 hPa
Baltimore / Martin, MD22 mi37 minSSE 810.00 miOvercast55°F48°F77%1000.7 hPa
Camp Springs / Andrews Air Force Base, MD23 mi26 minS 17 G 2110.00 miFair58°F44°F59%1000.4 hPa

Wind History from NAK (wind in knots)
Last 24hr--------------W7W5NW8NW9NW10
1 day agoSE5CalmW3CalmCalmCalmCalm3CalmCalmW336W4W15
2 days agoN5N4N4CalmW3NW3N6N5N5N4N5NE8NE8NE6N5CalmCalmNW3E3CalmCalmCalmCalmSE6

Tide / Current Tables for Brewer Point, Maryland
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Brewer Point
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Sat -- 12:03 AM EST     0.20 feet Low Tide
Sat -- 05:00 AM EST     0.75 feet High Tide
Sat -- 06:42 AM EST     New Moon
Sat -- 06:45 AM EST     Moonrise
Sat -- 06:52 AM EST     Sunrise
Sat -- 11:09 AM EST     -0.00 feet Low Tide
Sat -- 04:49 PM EST     Sunset
Sat -- 05:22 PM EST     Moonset
Sat -- 05:49 PM EST     1.11 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Tide / Current Tables for Baltimore Harbor Approach, Maryland Current
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Baltimore Harbor Approach
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Sat -- 02:34 AM EST     0.00 knots Slack
Sat -- 05:05 AM EST     0.57 knots Max Flood
Sat -- 06:42 AM EST     New Moon
Sat -- 06:44 AM EST     Moonrise
Sat -- 06:52 AM EST     Sunrise
Sat -- 07:45 AM EST     -0.00 knots Slack
Sat -- 10:41 AM EST     -0.67 knots Max Ebb
Sat -- 01:22 PM EST     0.00 knots Slack
Sat -- 04:49 PM EST     Sunset
Sat -- 05:00 PM EST     1.14 knots Max Flood
Sat -- 05:22 PM EST     Moonset
Sat -- 08:26 PM EST     -0.00 knots Slack
Sat -- 11:43 PM EST     -1.05 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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

GOES Local Image of Mid-Atlantic    EDIT

Wind Forecast for Baltimore, MD/Washington (20,4,5,8)
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Ground Weather Radar Station Dover AFB, DE
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weather_mapweather_map weather_map

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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 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 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.