Wednesday, July17, 2019 L-36.com


Marine Weather and Tides
Indian Head, MD

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Sunrise 5:57AMSunset 8:33PM Wednesday July 17, 2019 4:59 AM EDT (08:59 UTC) Moonrise 8:19PMMoonset 5:28AM Illumination 100% Phase: Full Moon; Moon at 15 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- 436 Am Edt Wed Jul 17 2019
.small craft advisory in effect from 3 pm edt this afternoon through this evening...
Rest of the overnight..S winds 5 kt. Waves less than 1 ft.
Today..S winds 5 to 10 kt. Gusts up to 20 kt in the afternoon. Waves 1 ft.
Tonight..SW winds 5 to 10 kt. Gusts up to 20 kt in the evening. Waves 1 ft. Scattered showers and tstms.
Thu..W winds 5 kt. Waves less than 1 ft. Scattered showers and tstms.
Thu night..W winds around 5 kt. Waves 1 ft or less.
Fri..W winds around 5 kt. Waves 1 ft or less.
Fri night..SW winds 5 kt. Waves less than 1 ft.
Sat..W winds around 5 kt. Waves 1 ft.
Sun..SW winds around 5 kt. Waves 1 ft or less. A chance of showers and tstms. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 436 Am Edt Wed Jul 17 2019
Synopsis for the tidal potomac and md portion of the chesapeake bay.. The remnants of barry will pass north of the waters later today into Thursday. High pressure will build over the southeastern states for Friday into the weekend.


7 Day Forecast for Marine Location Near Indian Head, MD
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location: 38.62, -77.2     debug


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 170800
afdlwx
area forecast discussion
national weather service baltimore md washington dc
400 am edt Wed jul 17 2019

Synopsis
The remnants of barry will move eastward across pennsylvania
through tonight, then slowly drift into the western atlantic on
Thursday. High pressure will build over the southeastern united
states Friday through the weekend. A cold front will approach
from the great lakes and pennsylvania early next week.

Near term through tonight
Today is expected to be a few degrees hotter than yesterday.

850 925 hpa temperatures are progged to have risen about 1-2 c
from 24 hours ago, hence the expectation of hotter surface
temperatures. There is just a pinch more wind (albeit pretty
light) out of the southwest, and that may help dew points drop
to around 70 or into the lower 70s, instead of holding in the
mid 70s (where they are starting out this morning). The
combination of heat and humidity is expected to result in heat
indices of around 105 in the i-95 corridor, where a heat
advisory remains in effect. Further west, heat indices in the
upper 90s to around 100 are expected, just shy of headline
criteria but still hot nonetheless.

As the remnant circulation of barry drifts into pennsylvania
this afternoon and evening, a surface pressure trough is
expected to sharpen out ahead of it over the mid-atlantic. Given
the hot, humid and unstable airmass in place, this should be
enough to initiate scattered to numerous showers and
thunderstorms this afternoon, congealing into loosely organized
clusters (thanks to modest mid-level flow approaching 30 kts),
then pushing eastward this evening. A (very) weak cold front is
expected to drop out of pennsylvania this evening, and this may
provide additional focus across northern northeastern maryland.

Given high humidity, heavy rainfall is possible in any
thunderstorm. See hydro section below for the heavy rain
threat. Thunderstorms may also tap into mid-level flow and
become organized enough to produce isolated damaging downburst
winds later this afternoon into this evening.

Shower and thunderstorm activity should diminish after midnight
with the loss of heating and as better forcing scoots off toward
the northeast.

Short term Thursday through Friday night
More cloud cover is expected Thursday as a surface front tailing
behind barry's remnants slowly drops into the area and weakens.

This should lead to earlier initiation of showers and a few
thunderstorms, albeit less widespread than Wednesday given
expected weaker forcing and slowly lower temps humidity.

Heat indices may approach 100 on Thursday, but current
expectation is that they will largely fall just shy of
criteria (which is 100 west of the blue ridge and 105 east of
the blue ridge).

Low-level airmass warms appreciably on Friday. 850 925 hpa temps
of 25 30 c respectively still look likely, which would result in
surface temperatures in the upper 90s to around 100. This
combined with humid air in place (dew points likely mixing into
the upper 60s to around 70) would result in heat indices of 100
to 110 during the afternoon hours. Excessive heat watches may be
needed for Friday into the weekend by later today or tonight,
especially given the prolonged nature of the threat of dangerous
heat. Of note, the heat index in urban areas (i.E. Dc baltimore)
may not drop below 90 at night with high dew point air pooling
near the tidal potomac river baltimore inner harbor and ambient
air temperatures holding in the lower 80s through the night. All
of these factors point to a potentially dangerous heat event
Friday through the upcoming weekend.

Long term Saturday through Tuesday
Our prolonged stretch of hot and humid conditions will continue
through the weekend. Conditions will turn more active early next
week, leading up to an eventual break from the heat and humidity by
the middle of next week.

On Saturday, an extensive, zonally elongated ridge will be in
place across much of the conus. An extremely hot and humid airmass
will be in place beneath the ridge, with much of the eastern two-
thirds of the CONUS experiencing well above normal temperatures.

Locally, a weak anticyclone at 500 hpa embedded within the larger
ridge will become centered nearly overhead. Subsidence in the
vicinity of this feature should limit coverage of showers and
thunderstorms, but a few thunderstorms can't be ruled out in
response to daytime heating, especially over the higher terrain. The
main story weatherwise will be the heat. 850 hpa temps are forecast
to soar to 23-25 c by Saturday afternoon, which should translate to
high temperatures around or possibly just above 100 degrees for
lower elevation locations. Conditions will also be humid, with
dewpoints around 70. This will lead to heat indices potentially
approaching or exceeding 110. Heat advisories or excessive heat
warnings will likely be needed for much of the area.

The ridge will begin to buckle a bit on Sunday to our north, but
we'll still be entrenched well within the core of the hot and humid
air. Temperatures will be a degree or two cooler, with highs in the
upper 90s to near 100, with dewpoints once again around 70. As a
result, heat advisories or excessive heat warnings will likely be
needed once again. With slight height falls as the ridge starts to
weaken, coverage of afternoon thunderstorms may be slightly higher
compared to Saturday. However, overall coverage is expected to
remain low, and predominantly confined to higher elevation areas or
along the bay breeze.

On Monday, a fairly impressive trough by late july standards will
dig southward across eastern portions of the conus, driving a cold
front southward toward our area. In advance of the approaching
trough and it's associated cold front, showers and thunderstorms are
expected to develop Monday afternoon. With ample instability in
place ahead of the front, and 20-35 knots of 0-6 km shear in
association with the approaching trough, some of the storms could be
on the stronger side. With precipitable water values in excess of 2
inches, any storms that form could produce very heavy rainfall as
well, potentially leading to a threat for flash flooding.

Tuesday's weather will be dependent on the southward progression of
the aforementioned 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, dry advection will still be ongoing well to
the north of the wind shift. It's possible that the "front" is
to our south, but we still have moisture rich air in place
(dewpoints around 70). However it's also possible that the front
drives further south, allowing the drier air to work in at the
surface. Afternoon showers and thunderstorms will be possible where
the moisture rich air is still in place. As a result the highest
chances for storms will reside further to the south, where they'll
be situated closer to the front. By the middle of next week much
cooler and drier air is expected to work into the region.

Aviation 08z Wednesday through Sunday
MainlyVFR expected through midday. Shower and thunderstorm
development is likely, but specific time place of restrictions
is tough beyond a few hours with thunderstorms. Any thunderstorm
will likely drop conditions to ifr or possibly lower given humid
airmass and heavy rain potential. Gusty winds are possible in
and near thunderstorms, as well as frequent lightning.

Patchy fog is possible tonight, especially in areas that receive
heavier rain this afternoon and evening, but the threat should
be tempered by the presence of mid level cloud cover.

Showers and a few thunderstorms are possible again Thursday,
though should be less widespread. Winds today through Thursday
will generally be SW AOB 10 kts, except this afternoon when a
few gusts to near 20 kts are possible, higher in stronger
thunderstorm clusters.

MainlyVFR but very hot and humid Friday.

PrevailingVFR conditions are expected this weekend. However, brief
reductions to sub-vfr conditions will be possible in association
with any thunderstorms that move over the terminals.

Marine
Sca later this afternoon into this evening with tightening sw
gradient. Synoptically marginal, but convection outflow will
enhance gusts during this time. Otherwise, sub SCA conditions
expected through Friday.

Sub-sca level winds are expected on in light southerly flow this
weekend. Thunderstorms will be possible over the waters each
afternoon this weekend. Special marine warnings may be needed for
any of the stronger storms that move over the waters.

Hydrology
High pwats near 2 inches and deep warm cloud layer depths will
contribute to a heavy rain threat. Storm motions should be quick
enough to preclude a more widespread flash flood risk, but mid
level flow roughly parallel to a southward dropping front this
evening may enhance the threat somewhat over northern and
northeastern maryland.

Tides coastal flooding
Tides are running a bit above normal, and with general southerly
flow over the next 24 to 36 hours, this trend should continue.

Though elevated, tides should remain below minor thresholds.

Climate
Record heat is possible later this week into this weekend. A
summary of records that may be threatened will be added to this
section by 5 am.

Lwx watches warnings advisories
Dc... Heat advisory from 11 am this morning to 8 pm edt this evening
for dcz001.

Md... Heat advisory from 11 am this morning to 8 pm edt this evening
for mdz011-013-014-016>018-504-506-508.

Va... Heat advisory from 11 am this morning to 8 pm edt this evening
for vaz052>057.

Wv... None.

Marine... Small craft advisory from 3 pm this afternoon to midnight edt
tonight for anz530>543.

Synopsis... Dhof
near term... Dhof
short term... Dhof
long term... Kjp
aviation... Dhof kjp
marine... Dhof kjp
hydrology... Dhof
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 20 mi65 min S 6 G 8.9 81°F 85°F1015.4 hPa
NCDV2 22 mi65 min S 2.9 G 5.1 79°F 88°F1014.9 hPa
44062 - Gooses Reef, MD 42 mi47 min SW 12 G 14 80°F 1016.3 hPa
SLIM2 - 8577330 - Solomons Island, MD 45 mi65 min SSW 8.9 G 11 80°F 84°F1015.5 hPa
TPLM2 - Thomas Point, MD 45 mi59 min S 11 G 13 81°F 83°F1016.3 hPa (-1.1)75°F
44063 - Annapolis 46 mi47 min SSW 7.8 G 9.7 81°F 83°F1015.4 hPa
APAM2 - 8575512 - Annapolis, MD 46 mi65 min 81°F 1014.7 hPa
COVM2 - 8577018 - Cove Point LNG Pier, MD 46 mi65 min SW 12 G 14 79°F 1016.5 hPa
PPTM2 - 8578240 - Piney Point, MD 49 mi65 min SSW 8 G 9.9

Wind History for Washington, DC
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Fort Belvoir, VA8 mi63 minN 010.00 miMostly Cloudy76°F73°F91%1015.4 hPa
Quantico Marine Corps Airfield - Turner Field, VA9 mi63 minWSW 310.00 miFair81°F73°F79%1015.8 hPa
Manassas, Manassas Regional Airport/Harry P. Davis Field, VA18 mi63 minN 010.00 miFair75°F73°F94%1016.4 hPa
Washington/Reagan National Airport, DC, VA19 mi67 minS 810.00 miOvercast80°F72°F76%1015.5 hPa
Stafford, Stafford Regional Airport, VA20 mi64 minN 010.00 miFair77°F71°F82%1017.3 hPa
Camp Springs / Andrews Air Force Base, MD23 mi2.1 hrsS 510.00 miPartly Cloudy78°F70°F77%1016.3 hPa

Wind History from DAA (wind in knots)
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Last 24hrCalmCalmCalmCalmCalmCalmW3S3SE4SE7SW4SE3SE3SE3SE4CalmCalmSE7S4CalmCalmCalmSE3Calm
1 day agoCalmCalmCalmNW3CalmCalmCalmCalmW6W6SW6NW4NW8W4S4CalmCalmCalmCalmCalmCalmCalmCalmCalm
2 days agoCalmCalmCalmCalmNW4W7W6W6W8W9W10
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Tide / Current Tables for High Point, Occoquan Bay, Virginia
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High Point
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Wed -- 02:12 AM EDT     0.20 feet Low Tide
Wed -- 05:57 AM EDT     Sunrise
Wed -- 06:28 AM EDT     Moonset
Wed -- 08:05 AM EDT     1.88 feet High Tide
Wed -- 03:00 PM EDT     0.11 feet Low Tide
Wed -- 08:31 PM EDT     Sunset
Wed -- 08:38 PM EDT     1.65 feet High Tide
Wed -- 09:18 PM EDT     Moonrise
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.60.30.20.30.61.11.51.81.91.81.51.10.80.50.30.10.30.61.11.41.61.61.41.1

Tide / Current Tables for Marshall Hall, 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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Wind Forecast for Baltimore, MD/Washington (4,6,7,8)
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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.