Thursday, July18, 2019 L-36.com


Marine Weather and Tides
National Harbor, MD

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Sunrise 5:56AMSunset 8:32PM Thursday July 18, 2019 1:11 PM EDT (17:11 UTC) Moonrise 8:56PMMoonset 6:24AM Illumination 97% Phase: Waning Gibbous; Moon at 16 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- 1036 Am Edt Thu Jul 18 2019
Rest of today..SW winds 5 kt. Waves less than 1 ft. A chance of showers and tstms late this morning, then showers likely with a chance of tstms this afternoon.
Tonight..W winds 5 kt. Waves less than 1 ft.
Fri..SW winds around 5 kt. Waves 1 ft.
Fri night..SW winds 5 kt. Waves less than 1 ft.
Sat..W winds around 5 kt. Waves 1 ft.
Sat night..W winds around 5 kt. Waves 1 ft.
Sun..W winds around 5 kt. Waves 1 ft or less. A chance of showers and tstms.
Mon..NW winds around 5 kt. Waves 1 ft or less. Showers and tstms likely, then a chance of showers after midnight. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 1036 Am Edt Thu Jul 18 2019
Synopsis for the tidal potomac and md portion of the chesapeake bay.. The remnants of barry will move into the western atlantic through tonight. High pressure will build over the southeastern states for Friday into the weekend. A cold front will approach the waters from the great lakes and pennsylvania Sunday night, and cross the waters early next week.


7 Day Forecast for Marine Location Near National Harbor, MD
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location: 38.8, -77.03     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 181519
afdlwx
area forecast discussion
national weather service baltimore md washington dc
1119 am edt Thu jul 18 2019

Synopsis
An upper level disturbance will depart into the western
atlantic through tonight. High pressure will build over the
southeastern united states Friday through the weekend. A cold
front approaching from the great lakes and pennsylvania will
cross the region early next week.

Near term through tonight
Weak low pressure crossing the forecast area this morning. With
lower heights and spokes of vorticity ejecting through the mid-
level flow, the environment could support showers thunderstorms
if they were to develop. Modifying the 12z lwx RAOB for forecast
afternoon conditions (lower 90s temps and lower 70s dewpoints)
yields MLCAPE near 1250 j kg, so mature storms could pose an
isolated wind (downburst) threat. A mrgl severe threat has been
added for the delmarva, incl most of metro baltimore, which
appears warranted.

The morning sounding also indicated over 2 inches of
precipitable water with small mbe vectors, so heavy rainfall
will also be a concern. Believe storm motions will be just fast
enough (20 kt) to preclude an organized flood threat, but any
deviation from that could be problematic... As would any repeated
storms. No flood watch at this time, but the heavy rainfall tag
is in the forecast.

The best composite of cam timing suggests showers will likely
develop before noon near the catoctins northern blue ridge,
with the most active time frame place during the afternoon east
of the blue ridge. Believe most of this will be east of the bay
by nightfall.

Warm and humid tonight with lows in the 70s and patchy fog
possible, especially in any areas that receive rain today given
decreasing cloud cover.

Short term Friday through Saturday night
The excessive heat watch has been adjusted to highlight the
period of greatest concern (when the high temperature criteria
will be met). Otherwise, no changes to the forecast have been
made. It will be a hot weekend, with a ridge overhead. A pop
up thunderstorm can't completely be ruled out especially near
the mountains each afternoon given the heat and humidity.

There's also a low chance over northern maryland in the evening
if and when anything develops upstream over the eastern great
lakes and finds its way across pennsylvania before falling apart
under the ridge.

Long term Sunday through Wednesday
Our prolonged stretch of hot and humid conditions will continue
through Sunday and possibly into Monday. A cold front will pass
through the area early next week, bringing a threat for strong
thunderstorms and flash flooding. Cooler and drier air behind the
front will filter into the area by the middle of next week.

By Sunday, the massive ridge across much of the CONUS will begin to
break down, as an extensive trough centered over hudson bay starts
to dig southward toward the great lakes. We'll still be entrenched
well within the core of the hot and humid air at the surface.

However, temperatures should be a degree or two cooler than
Saturday, with highs in the upper 90s. When coupled with dewpoints
in the low 70s, heat indices will exceed 105 degrees over much of
the area, and potentially reach 110 degrees in some areas. As a
result a excessive heat watch is in effect for much of the area
through 10 pm Sunday evening. With slight height falls as the ridge
starts to weaken, and ample instability given the heat and humidity,
afternoon thunderstorms will be possible. The highest coverage of
storms is expected to reside over the higher terrain, while the bay
breeze could also act to focus the development of storms. With
little flow through the column, storms are expected to be pulse-like
in nature. As a result, the threat for organized severe
thunderstorms should remain low, although localized downbursts can't
be ruled out.

The aforementioned trough will continue to dig southward during the
Sunday night through Monday timeframe, driving a surface cold front
southward into the mid-atlantic. There are timing differences in the
guidance with respect to the southward progression of the front. The
front could work it's way into our area as early as Sunday night (as
depicted by the 00z euro), or it may hang to our north through the
morning Monday. However, it's fairly clear that the front will work
it's way into our area at some point on Monday, and serve as a focus
for the development of showers and thunderstorms. With the larger
scale trough approaching from the northwest, deep-layer flow and
resultant shear will start to increase. If the front holds to our
north, allowing instability to build through the day, a more
organized severe thunderstorm threat may materialize. However, if
the front surges south Sunday night, less instability would be in
place, minimizing the severe threat. Most guidance has the front
slowing it's forward progress as it moves into the area Monday
through Monday night. The slow moving front, coupled with
precipitable water values in excess of two inches raises concerns
about flash flooding Monday into Monday night.

Tuesday's weather will be dependent on the southward progression of
the surface front. Although it's likely that the wind
shift and thermal boundary (what many would call the front) will be
situated to our south, moisture rich air will still be in place
just north of the front. If the front is unable to progress well to
our south, afternoon showers and thunderstorms may be possible. As
the highest chances for storms will reside further to the southeast,
where they'll be situated closer to the front. Cooler and drier air
is expected to work into the region on Wednesday, leading to dry
conditions.

Aviation 15z Thursday through Monday
MainlyVFR expected through Saturday night. Possible exceptions
would be in any thunderstorm that develops this afternoon, or
any patchy fog that develops during the overnight early morning
hours. Generally west flow AOB 10 kts expected. Best chance for
thunderstorms today appears to be near east of the blue ridge
between 17-22z, with best fog potential between 8-12z near
outlying terminals or in areas that receive rain this afternoon.

PrevailingVFR conditions are expected on Sunday. However, brief
reductions to sub-vfr conditions will be possible in association
with any thunderstorms that move over the terminals. Conditions may
deteriorate to sub-vfr on Monday as a cold front moves into the
area.

Marine
Gradient should relax today as a trough axis weakens and drifts
east through the day, though gusty winds are possible in and
near any thunderstorms that develop this afternoon (which may
require smws).

Sub-sca level winds are expected in light southerly flow on Sunday.

Thunderstorms will be possible over the waters Sunday and
Monday. Special marine warnings may be needed for any of the
stronger storms that move over the waters.

Tides coastal flooding
Tides remain a bit elevated, but should gradually fall with
light westerly flow over the next couple days. Therefore,
flooding is not anticipated.

Climate
The record daily warm low temperature for iad for july 18th is
74 degrees, set in 2005 and 1969.

As a reference, here are the warm temperature records for
Friday through this weekend:
record daily high temperatures
jul 19 jul 20 jul 21
dca 102 (1930) 106 (1930) 104 (1926)
bwi 103 (1930) 102 (1930) 104 (1930)
iad 98 (1977) 101 (1980) 101 (1991)
record daily warm low temperatures
jul 19 jul 20 jul 21
dca 81 (1930) 82 (2015) 82 (1987)
bwi 80 (1942) 80 (1930) 83 (1930)
iad 77 (2013) 75 (2015) 77 (1987)
highest july temperatures
highest MAX warmest low
dca 106 (7 20 1930) 84 (7 24 2011, 7 23 2011, 7 16 1983)
bwi 107 (7 10 1936) 83 (7 21 1930)
iad 105 (7 22 2011) 78 (7 24 2010, 7 8 2010)
all-time highest temperatures
highest MAX warmest low
dca 106 (7 20 1930, 8 6 1918) 84 (7 24 2011, 7 23 2011, 7 16 1983)
bwi 107 (7 10 1936) 83 (8 5 1930, 7 21 1930, 6 6 1925)
iad 105 (7 22 2011) 79 (8 8 2007)
longest stretches of consecutive days with high temperatures at or
over 100 degrees at iad:
2 (7 7-8 2012, 7 21-22 2011, 7 6-7 2010, 8 16-17 1997, 7 16-17 1988
and 7 20-21 1980)
longest stretch of consecutive days with low temperatures at or over
80 degrees at dca:
5 (7 16-20 2013)
longest stretch of consecutive days with low temperatures at or over
80 degrees at bwi:
4 (8 8-11 1900)
temperature records for the washington dc area have been kept at
what is now ronald reagan washington national airport (dca) since
1941. Additional temperature records observed downtown extend the
period of record back to 1872.

Temperature records for the baltimore md area have been kept at what
is now baltimore-washington international thurgood marshall airport
(bwi) since 1950. Additional temperature records observed downtown
extend the period of record back to 1872.

Temperature records for the sterling dulles va area have been kept
at what is now washington dulles international airport (iad) since
1960.

Lwx watches warnings advisories
Dc... Excessive heat watch from Friday morning through Friday
evening for dcz001.

Excessive heat watch from Saturday morning through Saturday
evening for dcz001.

Excessive heat watch from Sunday morning through Sunday
evening for dcz001.

Md... Excessive heat watch from Friday morning through Friday
evening for mdz003>006-011-013-014-016>018-503>508.

Excessive heat watch from Saturday morning through Saturday
evening for mdz003>006-011-013-014-016>018-503>508.

Excessive heat watch from Sunday morning through Sunday
evening for mdz003>006-011-013-014-016>018-503>508.

Va... Excessive heat watch from Friday morning through Friday
evening for vaz028-030-031-052>057-501-502-505-506.

Excessive heat watch from Saturday morning through Saturday
evening for vaz028-030-031-052>057-501-502-505-506.

Excessive heat watch from Sunday morning through Sunday
evening for vaz028-030-031-052>057-501-502-505-506.

Wv... Excessive heat watch from Friday morning through Friday
evening for wvz051>053.

Excessive heat watch from Saturday morning through Saturday
evening for wvz051>053.

Excessive heat watch from Sunday morning through Sunday
evening for wvz051>053.

Marine... None.

Synopsis... Hts dhof
near term... Hts dhof
short term... Hts dhof
long term... Kjp
aviation... Dhof kjp
marine... Hts dhof kjp
tides coastal flooding... Dhof
climate... Dhof


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 5 mi72 min NW 2.9 G 6 88°F 85°F1012 hPa (-0.3)
TPLM2 - Thomas Point, MD 32 mi72 min SE 2.9 G 4.1 83°F 83°F1012.8 hPa (-0.4)78°F
APAM2 - 8575512 - Annapolis, MD 32 mi72 min 88°F 1011.1 hPa (-0.4)
44063 - Annapolis 33 mi48 min S 3.9 G 5.8 85°F 87°F1012.2 hPa
NCDV2 33 mi78 min WSW 6 G 7 87°F 87°F1011.5 hPa
44062 - Gooses Reef, MD 37 mi54 min SW 5.8 G 5.8 85°F 1013 hPa
CPVM2 37 mi72 min 83°F 82°F
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 39 mi78 min SE 5.1 G 5.1 84°F 1011.7 hPa
FSNM2 39 mi78 min SSE 2.9 G 5.1
BLTM2 - 8574680 - Baltimore, MD 40 mi84 min SW 1.9 G 5.1 87°F 83°F1011.1 hPa
COVM2 - 8577018 - Cove Point LNG Pier, MD 44 mi72 min W 5.1 G 8 87°F 1012.8 hPa (+0.0)
SLIM2 - 8577330 - Solomons Island, MD 45 mi72 min WSW 11 G 12 88°F 84°F1011.7 hPa (-0.3)

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Washington/Reagan National Airport, DC, VA4 mi80 minVar 510.00 miMostly Cloudy87°F72°F61%1012.1 hPa
Camp Springs / Andrews Air Force Base, MD9 mi76 minSW 310.00 miA Few Clouds88°F73°F62%1012.6 hPa
Fort Belvoir, VA9 mi76 minWSW 310.00 miMostly Cloudy88°F73°F63%1012.4 hPa
College Park Airport, MD14 mi89 minW 410.00 miMostly Cloudy0°F0°F%1012.2 hPa
Fort Meade / Tipton, MD24 mi90 minWSW 810.00 miMostly Cloudy84°F75°F74%1012.9 hPa

Wind History from DCA (wind in knots)
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Last 24hrS12S9S12S15
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S6S3S4S3S6CalmS5CalmS5S6S4CalmS6SW4S5S655W7
1 day agoS10S9S9S9S6S6S5S6S16S9SW7SW4S6SW6S8S6S7S7S9S8S9S10S7S11
2 days agoN11N10N8N8N7NE4N5SE8SE5SE4SE4S4SE4E5E3E3S3SE3CalmS5S4S7SE4S6

Tide / Current Tables for Alexandria, Virginia
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Alexandria
Click for Map
Thu -- 04:06 AM EDT     0.37 feet Low Tide
Thu -- 05:57 AM EDT     Sunrise
Thu -- 07:24 AM EDT     Moonset
Thu -- 09:58 AM EDT     3.24 feet High Tide
Thu -- 04:50 PM EDT     0.25 feet Low Tide
Thu -- 08:30 PM EDT     Sunset
Thu -- 09:55 PM EDT     Moonrise
Thu -- 10:30 PM EDT     2.90 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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21.40.90.60.40.51.11.92.63.13.232.51.91.30.80.40.30.61.322.52.92.8

Tide / Current Tables for Riverview, Potomac River, Maryland
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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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GOES Local Image of Mid-Atlantic    EDIT
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Wind Forecast for Baltimore, MD/Washington (13,3,4,5)
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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.