Monday, May29, 2017 L-36.com


Marine Weather and Tides
Mercersburg, PA

Version 3.4
What's New / NOTES
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 5:44AMSunset 8:32PM Monday May 29, 2017 1:15 PM EDT (17:15 UTC) Moonrise 8:52AMMoonset 11:22PM Illumination 18% Phase: Waxing Crescent; Moon at 4 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- 1032 Am Edt Mon May 29 2017
Rest of today..SW winds around 5 kt. Waves flat. Patchy fog late this morning. Isolated showers late this morning, then scattered showers with isolated tstms this afternoon. Vsby 1 to 3 nm.
Tonight..E winds 5 to 10 kt. Waves 1 ft or less. Patchy fog. Vsby 1 to 3 nm.
Tue..SE winds 5 kt. Waves less than 1 ft. A chance of showers and tstms. Patchy fog. Vsby 1 to 3 nm.
Tue night..W winds around 5 kt. Waves 1 ft or less. A chance of showers and tstms.
Wed..W winds 5 to 10 kt. Waves 1 ft or less. A chance of showers.
Wed night..W winds 5 kt. Waves less than 1 ft.
Thu..SW winds 5 to 10 kt. Waves 1 ft or less.
Fri..SW 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 1032 Am Edt Mon May 29 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A cold front will move toward the waters this afternoon...but stall and weaken by tonight. Another weak front will approach late Tuesday...also stalling and weakening. A third cold front will finally push through Wednesday night, with high pressure following on Thursday. A warm front will lift northward on Friday.

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 291616
afdctp
area forecast discussion
national weather service state college pa
1216 pm edt Mon may 29 2017

Synopsis
A trough of low pressure will stall out over central and
eastern pa today, before retreating back into the central
mtns tonight. Another cold front will push toward the region
Tuesday and combine with the lingering boundary to produce
numerous showers and scattered afternoon thunderstorms, some of
which could contain gusty winds and hail. Low pressure at the
surface and aloft will stay centered near james bay canada
through the rest of the week. This weather feature will supply
a period of slightly cooler than normal temperatures, and push a
few additional weak cold fronts through the commonwealth
accompanied by scattered showers and perhaps some isolated
afternoon and early evening thunderstorms.

Near term until 8 pm this evening
Weak surface front stalling over the susquehanna valley this
midday hour with plenty of clearing and a light to mdt westerly
wind across the central and western mtns of pa. To the east of
the boundary, cool and cloudy airmass will prevail with temps
only climbing slowly into the 60s. MAX temps elsewhere will be
mainly in the 70s, with mid-upper 70s likely in the central and
southern valleys to the SE of a kaoo to kunv line where the
llvl westerly downslope flow and heating will be maximized.

Differential heating along the western edge of the cloud
boundary across the susq valley will lead to a ribbon of
enhanced CAPE and moisture convergence which will help to
produce scattered showers and isolated tsra per the latest 14z
hrrr. The convection should drift to the east and greatly weaken
within 20-30 miles east of the stalled out llvl boundary.

Short term 8 pm this evening through 6 pm Tuesday
Brief ridging will allow the skies to clear over the western
two-thirds of the CWA this evening, and residual moisture may
lead to areas of fog, especially in the central valleys. The low
level moisture and low stratus deck AOB 1000 ft agl will push
gradually westward across the central mtns and west br susq
valley and stay intact through early Tuesday. Mins tonight will
dip into the 50s for most, as the dewpoints will be the bottom
limit.

A separate, weak sfc trough will be pushed into the area from
the northwest tonight. 8h temps fall a bit over the nw. Heights
fall just a little, too, so some precip is possible before
sunrise Tuesday over the northwestern third of the area, but it
should be light.

The trough begins to catch the stalled trough over the eastern
counties. The southerly or southeasterly wind will yield good
convergence and will crank up some showers and thunderstorms.

Have painted high pops for the area, but the amount severity of
destabilization is in question with the clouds in the NE early
in the day. NAM cranks out 1500joules of CAPE and LI drops to -2
or so in the mid-day and aftn on tues. SPC marginal risk of svr
wx for day 2 (tues) is painted across our eastern half, focused
on the peak heating time. Will continue to mention this in the
hwo.

Long term Tuesday night through Sunday
The long term period will be dominated by a large upper level
low the will be slowly moving through the upper great lakes and
southern canada. As that quasi stationary low slowly moves to
the northeast, it will bring surges of cool moist air across the
region.

Several successive shortwave will move through mid to late week
which will bring the possibility of scattered showers with
preference for the majority of the QPF (albeit quite light at
that) to be across the typical west-nwrly flow upslope prone
areas of the laurel highlands and NW mtns. The chance for any
thunder will be very minimal Wed and Thursday.

Generally dry NW flow occurs late in the week into next weekend as
a 1020 sfc high over the upper midwest Friday evening builds SE twd
the region. Pops thur night through Fri night will be 30 percent or
less.

Late in the week the models begin to diverge on the location
and timing of the upper level low so there is less confidence on
precipitation late in the week. However depending where the
boundary sets up there could be periods of showers Friday
through Saturday, though currently should be mainly along the
southern border.

Aviation 16z Monday through Friday
Widespread subVFR CIGS will be difficult to clear east of a
line from kipt to kseg and kmdt this afternoon, and if so, it
will be only for a brief few-svrl hour period. Llvl easterly
flow of 5-10 kts will likely persist over, and to the east of
the susq valley with MVFR to ifr CIGS andVFR to MVFR vsbys in
light fog hz.

Sct-bknVFR strato CU and CU will occur across the western two
thirds of the state thanks to a drying, light to moderate
westerly llvl wind.

Depending on how much clearing occurs remains this evening,
widespread fog formation is possible region-wide tonight. Later
on, expect the stalled out boundary across the susq valley to
drift westward back to the allegheny front (kaoo, kunv and kipt)
by... Or shortly after 04z Tuesday.

Outlook
Tue... Morning ifr stratus likely across much of central and se
pa, then breaks in lifting of the cloud deck leading to MVFR to
low-endVFR conditions with showers becoming more numerous
during the late morning and afternoon hours. Also, scattered
afternoon tsra with brief, localized greater reductions.

Wed... Chance of showers.

Thu... No sig wx expected.

Fri... Chance of showers and thunderstorms.

Ctp watches warnings advisories
None.

Synopsis... Lambert
near term... Lambert
short term... Lambert dangelo
long term... Lambert ceru martin
aviation... Lambert gartner


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BLTM2 - 8574680 - Baltimore, MD 80 mi45 min E 1.9 G 4.1 66°F 68°F1013 hPa
WASD2 - 8594900 - Washington, DC 80 mi45 min SSW 2.9 G 6 74°F 67°F1012.3 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 84 mi45 min ESE 2.9 G 4.1 65°F 1013.6 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 mi22 minWNW 1410.00 miA Few Clouds78°F59°F52%1013.1 hPa

Wind History from HGR (wind in knots)
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Last 24hrSE7S4S15
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S3SE3CalmCalmNW5E3CalmCalmCalmE3CalmS3CalmS5S5SW5SW43NW8W10W14
1 day agoCalmN4NE6NW4CalmCalmNW3CalmCalmCalmCalmSE3NE3CalmCalmNW3CalmCalmCalmE3CalmS3SW3Calm
2 days agoW6W11W12
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W11W11NW11NW15NW9NW7NW6CalmW3S3CalmSW4E3S3E3CalmE4SW3CalmCalmCalm

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Mon -- 05:46 AM EDT     Sunrise
Mon -- 06:31 AM EDT     0.16 feet Low Tide
Mon -- 09:51 AM EDT     Moonrise
Mon -- 12:05 PM EDT     3.70 feet High Tide
Mon -- 07:20 PM EDT     -0.04 feet Low Tide
Mon -- 08:26 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
3.332.41.71.10.60.20.20.71.72.83.53.73.52.92.21.50.90.4-00.10.81.82.6

Tide / Current Tables for Chain Bridge, Washington, D.C.
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Chain Bridge
Click for Map
Mon -- 05:46 AM EDT     Sunrise
Mon -- 06:33 AM EDT     0.18 feet Low Tide
Mon -- 09:51 AM EDT     Moonrise
Mon -- 12:06 PM EDT     3.65 feet High Tide
Mon -- 07:22 PM EDT     -0.02 feet Low Tide
Mon -- 08:26 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
3.332.41.71.10.60.30.20.71.72.73.43.63.52.92.21.60.90.400.10.81.72.6

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 (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.