Friday, August18, 2017 L-36.com


Marine Weather and Tides
Mercersburg, PA

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 6:25AMSunset 8:03PM Friday August 18, 2017 11:36 PM EDT (03:36 UTC) Moonrise 1:54AMMoonset 4:44PM Illumination 10% Phase: Waning Crescent; Moon at 26 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- 1031 Pm Edt Fri Aug 18 2017
Rest of tonight..W winds 10 kt. Waves 1 ft or less. A slight chance of showers.
Sat..W winds 5 kt. Waves less than 1 ft.
Sat night..N winds around 5 kt. Waves 1 ft or less.
Sun..NW winds around 5 kt. Waves flat.
Sun night..SE winds around 5 kt. Waves flat.
Mon..S winds around 5 kt. Waves flat.
Mon night..S winds 5 kt. Waves flat.
Tue..SW winds 5 to 10 kt. Waves 1 ft or less. A chance of showers and tstms.
Wed..NW winds 5 to 10 kt. Waves 1 ft. A chance of showers and tstms. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 1031 Pm Edt Fri Aug 18 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A cold will cross the waters tonight. A pressure trough will remain nearby for Saturday and Sunday while high pressure positions itself just to our north and west. The high will move offshore early next week. Small craft advisories may be needed Monday night and Tuesday.

7 Day Forecast for Marine Location Near Mercersburg , PA
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location: 39.79, -77.93     debug


Area Discussion for - State College, PA
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Fxus61 kctp 190129
afdctp
area forecast discussion
national weather service state college pa
929 pm edt Fri aug 18 2017

Synopsis
A cold front will pass east of the area tonight. An upper
trough will move across the region Saturday afternoon and
evening. Temperatures will stay above normal but rise even
higher each day through Tuesday as a ridge builds aloft. Another
cold front should trigger showers around mid-week and the week
should end on a cooler note.

Near term until 6 am Saturday morning
Satellite loop at 01z still showing a line of cumulus along
trailing cold front running from near kipt south to near khgr.

Will maintain the chance of a shower storm along and east of
this boundary through the late evening hours. Latest radar
trends and hrrr support pops of only around 20 pct across this
area through around midnight, then patchy fog will become the
issue. Latest SREF and downscaled NAM suggest the weakest
gradient and best chance of fog will be across the susq valley,
but patchy valley fog is also likely further west.

A push of drier air behind the cold front, along with light wind
and mostly clear skies, should allow temps to fall to near 60f
over the northwest counties and to the upper 60s in the
southeast part of the forecast area.

Short term 6 am Saturday morning through 6 pm Saturday
After a mostly sunny Saturday morning, a sharp upper trough
will swing eastward from the ohio valley, generating afternoon
showers and tstorms. Will maintain the highest pops across the
northwest counties, where passage of trough will coincide with
time of MAX heating during early to mid afternoon. SPC continues
to highlight the northwest half of the forecast area in a mrgl
risk. Model data showing decent mid level winds and deep layer
shear, but limiting factor will be only modest instability.

Expect convection to diminish in intensity coverage as it pushes
into eastern pa during the cooling hours of Saturday evening.

Long term Saturday night through Friday
The mid range models are all in good agreement on the timing and
strength of the passing shortwave Saturday night. Once that
passes, the heights will rise and become quasi-zonal. This will
bring fair weather to the region Sunday through Tuesday. Dry
westerly flow will also bring warm summertime temperatures with
Tuesday continually trending warmer. A new shortwave moving
through SRN canada will an bring an increasing chance for rain,
possibly as early as Tuesday afternoon over western sections of
the forecast area.

There are differences in timing of the rain with the ecmwf
suggesting it holds off until Tuesday night. Blended MOS pops
show a small chance of showers moving into western sections
Tuesday afternoon, but the highest pops are reserved for the
overnight.

Cyclonic flow aloft will then dominate the flow pattern through
Thursday. The cool air aloft will help trigger a few mainly
diurnal showers Wednesday and Thursday. The showers will tend to
favor northern and western higher elevations. Temperatures will
be significantly cooler for the second half of the week.

Aviation 01z Saturday through Wednesday
Last of the thunderstorms now pushing east out of lancaster
county. Still some residual showers over the lower susquehanna
valley, and northeast of kipt, but expect these to
dissipate push east over the next few hours.

Have removed all mention of tsra and shra from the 21z taf
updates.

Fog is expected for most of the area tonight, with MVFR to ifr
restrictions.

An upper level trough and rather strong forcing passing
directly overhead in the cooler air aloft could make scattered
shra tsra across the northern third half of pennsylvania on
Saturday afternoon.

Much drier air will make for a mainly-vfr sun-mon with only
valley fog in the am a potential issue.

Outlook
Sat... MainlyVFR, but with sct shra tsra northern 1 3.

Sun-mon... MainlyVFR, but restrictions in morning fog.

Tue-wed... Shra tsra poss.

Ctp watches warnings advisories
None.

Synopsis... Dangelo fitzgerald
near term... Fitzgerald
short term... Fitzgerald
long term... La corte ceru
aviation... Jung


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BLTM2 - 8574680 - Baltimore, MD 80 mi48 min WSW 1.9 G 2.9 76°F 84°F1010.6 hPa
WASD2 - 8594900 - Washington, DC 80 mi48 min SW 1.9 G 1.9 78°F 81°F1010.8 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 84 mi48 min SSW 5.1 G 7 76°F 1010.9 hPa

Wind History for Baltimore, MD
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hagerstown, Washington County Regional Airport, MD12 mi43 minSSW 510.00 miFair79°F73°F85%1012 hPa

Wind History from HGR (wind in knots)
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Last 24hrS8S5S3S3SE4S4S63S9S6S9S7S8S10SW12
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1 day agoCalm3NE6E5CalmCalmCalmNW5NW5NW6Calm33W4S6S7SE10S7S5SE8S8SE9S9S11
2 days agoSW4CalmSE3S3S4CalmCalmCalmCalmCalmCalmCalmCalmCalmNW3NW6NW4N6N7NE6NE4E3CalmCalm

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Fri -- 12:01 AM EDT     0.35 feet Low Tide
Fri -- 02:53 AM EDT     Moonrise
Fri -- 05:51 AM EDT     3.50 feet High Tide
Fri -- 06:24 AM EDT     Sunrise
Fri -- 01:07 PM EDT     0.26 feet Low Tide
Fri -- 05:38 PM EDT     Moonset
Fri -- 06:33 PM EDT     3.05 feet High Tide
Fri -- 07:58 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.40.51.22.12.93.43.53.22.72.11.510.50.30.51.222.6332.621.40.8

Tide / Current Tables for Chain Bridge, Washington, D.C.
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Chain Bridge
Click for Map
Fri -- 02:53 AM EDT     Moonrise
Fri -- 05:49 AM EDT     3.53 feet High Tide
Fri -- 06:24 AM EDT     Sunrise
Fri -- 01:04 PM EDT     0.24 feet Low Tide
Fri -- 05:38 PM EDT     Moonset
Fri -- 06:31 PM EDT     3.07 feet High Tide
Fri -- 07:58 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.30.51.22.12.93.43.53.22.721.40.90.50.20.51.222.7332.61.91.30.8

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

GOES Local Image of Mid-Atlantic    EDIT
Geos

Wind Forecast for State College, PA (23,6,7,8)
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Ground Weather Radar Station Sterling, VA
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weather_mapweather_map weather_map

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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.