Wednesday, April25, 2018 L-36.com


Marine Weather and Tides
Olney, MD

Version 3.4
What's New / NOTES
3/3/2018 - There is a new GOES Satellite for the east coast that required rewriting that part of the code. Please report any issues.
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.

Sunrise 6:14AMSunset 7:57PM Wednesday April 25, 2018 2:28 AM EDT (06:28 UTC) Moonrise 2:25PMMoonset 3:08AM Illumination 75% Phase: Waxing Gibbous; Moon at 10 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- 134 Am Edt Wed Apr 25 2018
Overnight..NE winds 10 kt. Waves 1 ft. Rain. Patchy fog. Vsby 1 to 3 nm.
Wed..NW winds 5 to 10 kt. Waves 1 ft. Scattered showers. Patchy fog. Vsby 1 to 3 nm.
Wed night..NW winds 10 kt. Waves 1 ft.
Thu..NW winds 5 to 10 kt. Waves 1 ft.
Thu night..S winds 5 kt. Waves less than 1 ft. Showers likely.
Fri..SE winds 5 kt. Waves less than 1 ft. Showers likely.
Fri night..SW winds around 5 kt. Waves 1 ft. A chance of showers.
Sat..NW winds around 5 kt. Waves 1 ft. A chance of showers in the morning.
Sun..NW winds 5 to 10 kt. Waves 1 ft.
ANZ500 134 Am Edt Wed Apr 25 2018
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Low pressure will move northward from the carolinas tonight before passing overhead Wednesday. High pressure will then move near the area Thursday. Another low pressure system may affect the waters by overnight Thursday into Friday. A cold front will pass through the waters Saturday and high pressure will return for Sunday. Small craft advisories may be needed Thursday.

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


Area Discussion for - Baltimore, MD/Washington
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Fxus61 klwx 250153
afdlwx
area forecast discussion
national weather service baltimore md washington dc
953 pm edt Tue apr 24 2018

Synopsis
Low pressure over south carolina will slowly move up the mid-
atlantic coast tonight before passing by to our east Wednesday.

A cold front will pass through Wednesday evening and high
pressure will return for Thursday. Low pressure may impact the
area overnight Thursday into Friday before a cold front passes
through Saturday. High pressure will return by the end of the
weekend.

Near term until 6 am Wednesday morning
As low pressure lifts northeast toward the forecast area, the
moist conveyor will be lifting north into pennsylvania and new
jersey. East onshore flow remains, with overrunning isentropic
lift present. Thus, the rain has transitioned into a light
rain drizzle scenario, with low clouds and areas of fog. As the
center of the low approaches, believe that the upglide will
decrease somewhat-- enough to gradually decrease pops from cat
to likely... And for central virginia potomac highlands, to a
high end chance by dawn. With such a setup, temperatures won't
be falling far tonight... With upper 40s west and lower 50s east
by dawn.

Short term 6 am Wednesday morning through Thursday night
Steady rain will end by 12z everywhere as onshore flow
weakens and low pressure passes just to the east. Not much in
the way of forcing available to generate precip, but can't
completely ruled out a few showers as weak instability develops
with passage of upper level trof axis. Otherwise, most cloudy
skies with some breaks in the clouds possible over the va
piedmont in the afternoon.

Very weak high pressure builds Wed night and thu. A second area
of low pressure will move across the area Thu night with
increasing chances of showers.

Long term Friday through Tuesday
On Friday, a upper level 500mb trough will be situated over the
midwestern us. A 500mb shortwave will move through the system and be
over our region on Friday. The associated sfc low pressure
system will shift into the region from the southwest. The exact
location of this sfc low is still uncertain as the 12z GFS keeps
the low further north and west in northern maryland and pa. The
00z euro has the low approaching and moving east north east
just to our south. The difference between solutions is that the
gfs tries to keep the majority of the precipitation to the north
and west of our forecast area while the euro tries to take the
low further southward. The 12z euro run may bring the low
further north like the GFS increasing the the chances for higher
precip amounts. As of now, this seems like a fairly weak
frontal passage that will bring light precipitation. The front
associated with this sfc low will likely move out of our
forecast area by early Saturday morning. Temperatures will rise
Friday up into 60s with some areas reaching the 70s due to warm
air advection from the south to southwest. A isolated
thunderstorm wouldn't be out of the question on Friday.

Behind the weak frontal passage, a strong high pressure will build
into the area from the upper midwest and the great lakes
region. The high will remain over the region through early next
week leading to clear skies and temperatures close to average
for this time of the year with temperatures in the upper 60s to
low 70s.

Aviation 02z Wednesday through Sunday
The synoptically forced precipitation has lifted north of the
terminals. With residual moisture, lift, and onshore flow...

low clouds and fog has developed in the light rain and drizzle.

Terminals are bouncing between MVFR and ifr, but believe that
ifr and even lifr will prevail overnight. Aside from cho, am
forecasting no lower than ifr at this time. If it were to go
lower, believe that CIGS would be the culprit.

Gradual improvement expected Wed as the low moves northeast of
the terminals, but it will be a slow process. If we're lucky,
thenVFR will return mid-late afternoon. Otherwise it will wait
until early evening.

No flight restrictions anticipated thu. The first part of the
day may be breezy (from the northwest) in the pressure gradient
in the wake of the departing low, but gusts should not
significantly exceed 20 kt.

Clouds will increase on Friday as a low pressures system moves in
from our south. Brief lowering of cloud bases and visibility will be
possible if showers and isolated thunderstorms move through the
region. Sub-vfr conditions will be possible on Friday. Clearing skies
along with light winds are expected over the weekend leading toVFR
conditions.

Marine
East flow across the waters this evening in advance of low
pressure. With low clouds and fog, mixing not ideal. Have
cancelled the small craft advisory for the potomac above indian
head. Believe an impulse will be supporting a burst of better
wind travelling up the bay tonight, so will be keeping the rest
for now.

Light winds expected on wed, then strengthening somewhat wed
night behind departing low. Marginal SCA conditions possible,
but confidence low ATTM for any sca.

A low pressure approaching from out south on Friday will lead to a
southerly flow and increasing clouds. The southerly flow will
likely warrant the need for small craft advisory on Friday as winds
flow up the chesapeake bay. Over the weekend, a strong high pressure
will be present leading to clear skies and lighter winds. Sca
unlikely Saturday and Sunday as of now.

Tides coastal flooding
Water levels running about a foot above astronomical normals
this evening, with most of that increase coming during the
daytime evening hours Tuesday. The departures are a pinch higher
than that for the tidal potomac below the 301 bridge. Based on
these trends and current projections, piney point will brush the
minor threshold tonight. With continued south east flow into
tomorrow, departures will be steady or continue to rise
slightly. Therefore, anticipate a repeat tomorrow morning.

Therefore, have issued a coastal flood advisory for st marys co
for the next two tide cycles.

Although water will be running high, it is unclear whether any
other sites will be affected. If there isnt enough northwest
wind to push water out on Wed (which is a real possibility),
then annapolis may briefly touch minor flood too. Also, SW dc
forecast to come just inches away for the next few cycles. Will
be monitoring those sites, but not enough confidence to issue
anything at this time.

Lwx watches warnings advisories
Dc... None.

Md... Coastal flood advisory until 2 pm edt Wednesday for mdz017.

Va... None.

Wv... None.

Marine... Small craft advisory until 4 am edt Wednesday for anz530>534-
537>543.

Small craft advisory until midnight edt tonight for anz536.

Synopsis... Lfr
near term... Hts
short term... Lfr
long term... Jmg
aviation... Hts jmg
marine... Hts lfr jmg
tides coastal flooding... Hts


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WASD2 - 8594900 - Washington, DC 19 mi41 min NE 2.9 G 5.1 55°F 56°F1012.1 hPa
BLTM2 - 8574680 - Baltimore, MD 27 mi41 min E 6 G 8 55°F 56°F1012.6 hPa
FSNM2 29 mi41 min E 8.9 G 13 55°F 1012.4 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 29 mi41 min E 7 G 8.9 55°F 1012.8 hPa
BSLM2 - Chesapeake Bay, MD 32 mi119 min ENE 1.9 52°F 1014 hPa52°F
APAM2 - 8575512 - Annapolis, MD 33 mi41 min 56°F 1012.1 hPa
TPLM2 - Thomas Point, MD 38 mi29 min S 2.9 G 2.9 56°F 53°F1013.2 hPa (-2.7)56°F
CPVM2 38 mi59 min 56°F 56°F
TCBM2 - 8573364 - Tolchester Beach, MD 44 mi41 min E 7 G 12 56°F 54°F1012.6 hPa

Wind History for Washington, DC
(wind in knots)    EDIT      (on/off)   Help
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Gaithersburg - Montgomery County Airport, MD5 mi33 minNNE 56.00 miLight Rain Fog/Mist53°F52°F96%1015.4 hPa
College Park Airport, MD14 mi52 minN 44.00 miOvercast53°F52°F97%1012.5 hPa
Fort Meade / Tipton, MD16 mi53 minENE 42.50 miOvercast54°F51°F94%1013.5 hPa
Washington/Reagan National Airport, DC, VA20 mi37 minNNE 610.00 miLight Rain56°F53°F90%1012 hPa
Baltimore, Baltimore-Washington International Airport, MD21 mi35 minENE 102.00 miHeavy Rain Fog/Mist55°F55°F100%1012.2 hPa
Washington/Dulles International Airport, DC, VA24 mi37 minN 65.00 miRain Fog/Mist53°F53°F100%1012.2 hPa

Wind History from GAI (wind in knots)
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Last 24hrE5E5543E12
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1 day agoSE4E3CalmCalmSE4SE6SE4SE64SE8SE10S9SE14SE11
G17
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SE13SE10SE8SE13SE7SE6E53E4
2 days agoCalmCalmCalmCalmCalm4E5NE64
G14
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Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Wed -- 04:07 AM EDT     Moonset
Wed -- 05:27 AM EDT     3.20 feet High Tide
Wed -- 06:18 AM EDT     Sunrise
Wed -- 12:11 PM EDT     0.32 feet Low Tide
Wed -- 03:26 PM EDT     Moonrise
Wed -- 05:51 PM EDT     3.20 feet High Tide
Wed -- 07:55 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.30.71.42.22.83.23.12.72.21.610.60.30.51.122.63.13.22.92.41.81.30.8

Tide / Current Tables for Chain Bridge, Washington, D.C.
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Chain Bridge
Click for Map
Wed -- 04:07 AM EDT     Moonset
Wed -- 05:28 AM EDT     3.23 feet High Tide
Wed -- 06:18 AM EDT     Sunrise
Wed -- 12:10 PM EDT     0.27 feet Low Tide
Wed -- 03:26 PM EDT     Moonrise
Wed -- 05:51 PM EDT     3.23 feet High Tide
Wed -- 07:55 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.20.61.42.22.93.23.22.82.21.510.50.30.41.11.92.73.13.232.41.81.20.7

Weather Map and Satellite Images
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GOES Local Image of Mid-Atlantic    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
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Wind Forecast for Baltimore, MD/Washington (2,6,7,8)
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Ground Weather Radar Station Sterling, VA
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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 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.