Sunday, December16, 2018 L-36.com


Marine Weather and Tides
Mercersburg, PA

Version 3.4
What's New / NOTES
10/6/2018 Colors of tide XTide graphs changed to emphasize that they were upgraded. See next note. Comments welcome.
10/4/2018 I have fixed XTide and updated the harmonic files. There were some name changes so you might have to click EDIT to find the new station name.

Sunrise 7:24AMSunset 4:49PM Sunday December 16, 2018 10:30 PM EST (03:30 UTC) Moonrise 1:15PMMoonset 12:37AM Illumination 71% Phase: Waxing Gibbous; Moon at 9 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- 951 Pm Est Sun Dec 16 2018
.small craft advisory in effect until midnight est tonight...
.small craft advisory in effect from Monday morning through late Monday night...
Rest of tonight..NW winds 10 kt with gusts to 20 kt. Waves 1 ft.
Mon..NW winds 10 to 15 kt. Gusts up to 20 kt... Increasing to 30 kt in the afternoon. Waves 1 to 2 ft.
Mon night..NW winds 10 to 15 kt with gusts to 30 kt. Waves 1 to 2 ft.
Tue..NW winds 10 kt with gusts to 20 kt. Waves 1 ft.
Tue night..NW winds 5 kt. Waves less than 1 ft.
Wed..S winds around 5 kt. Waves 1 ft or less.
Wed night..S winds 5 kt. Waves less than 1 ft.
Thu..SE winds 10 to 15 kt. Waves 1 ft or less. Showers.
Fri..SW winds 10 kt. Waves 1 ft. Showers likely through the day, then a chance of showers through the night.
ANZ500 951 Pm Est Sun Dec 16 2018
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Low pressure off the coast of new jersey will continue to move northeast and away from the region. A cold front approaching from the great lakes will cross the waters late Monday. High pressure will follow through Wednesday. Small craft advisories will likely be needed for portions of the waters Monday night through Tuesday. Gales will be possible late Monday afternoon and Monday evening.


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 170308
afdctp
area forecast discussion
national weather service state college pa
1008 pm est Sun dec 16 2018

Synopsis
A slow moving storm system will move off the mid atlantic coast
overnight. High pressure will build in through mid week. A new
storm system will begin to affect the region for Thursday and
Friday.

Near term until 6 am Monday morning
Minor adjustments to clouds and dewpoints at 10 pm here.

Earlier discussion below.

After about 2 days of on and off rain, the rain is now east
of the area. Total rainfall ranged from less than .25 inches
across the far north, to upwards of 1.5 to 2.0 inches across
the far south. Just a few reports of a few snow flakes mixing in
this morning.

Area streams running high still. Several river points up high,
but below flood stage.

Minor adjustments to the fcst.

Early afternoon disc.

Radar is finally showing the echoes taking on a southerly
component to their movement, indicating the upper low is moving
off the coast and we are getting into the northerly flow on its
back side.

The focus of the steadiest of the spotty rain and drizzle will
continue to shift to the east and drier air will start to filter
in from the N and eventually nw. It has stayed relatively mild
so we haven't seen much in the way of wintry precip with a brief
period of sleet and or wet snow reported here in town from our
old soo and a coop observer down in franklin county.

The remainder of the day still looks soggy with occasional rain
and drizzle and maybe some wet snowflakes, the best chances
being over eastern zones.

Drier air will move in overnight with clouds beginning to break
over central and eastern areas later in the evening and
especially after midnight. A few snow showers will be possible
over western higher elevations, but with little or no
accumulation.

Overnight lows in the 20s to lower 30s will actually be some
5-10 deg milder than normal.

Short term 6 am Monday morning through 6 pm Monday
A weak secondary cold front looks like it will mainly wash out
in the NW flow behind the departing low, setting up a period of
lake effect and orographically enhanced snow shower activity.

Between the short trajectories over the lake in the nnw flow and
a fairly quick lowering over the inversion heights, it's not
expected to be much of an event with generally a coating to an
inch expected through tomorrow evening.

Highs Monday will range from around 30 over the north to the mid
40s se. These will be near normal over the milder SE to around 5
deg colder than they should be along the ny border.

Long term Monday night through Sunday
Tuesday still appears that a drier, colder northwest flow
regime will settle in. The best potential for lake enhanced
snow showers in the mountains appears to be Monday into Monday
night. Relatively shallow moisture should keep accumulations on
the light side.

As ridging briefly pushes in mid-week, Wednesday into Thursday looks
dry and seasonable.

For later in the week... A potent large scale upper trof digging
through the southern plains mid week will force a surface low
northward along the spine of the appalachian mountains Friday
into Saturday, then to the st. Lawrence valley on Sunday. With
an expected track across western pa, abundant warm air will
precede the system bringing another rainstorm to central pa.

Precipitation may again end as some snow towards the latter part
of the storm as cold air wraps in behind. At this point this
appears limited and confined mainly to the higher elevations.

But time will tell.

Aviation 03z Monday through Friday
Low pressure and associated rain is pushing east of the area
this evening. Residual low level moisture ascending the appalachians
will produce ifr lifr CIGS overnight from kbfd south through
kjst. Elsewhere, downsloping flow will result in progressively
higher CIGS east of the mountains.

A cold front will sweep through the region late Monday morning,
accompanied by scattered snow showers over the northwest
mountains. Early low CIGS across the high terrain of the
appalachians will lift during the day, as drier air aloft mixes
to the surface behind the fropa. Model soundings and SREF href
probability charts support fairly widespread MVFR stratocu
across central pa by afternoon, with lowVFR CIGS likely at the
lower elevation airfields over the susq valley (kipt kmdt klns).

Gusty northwest winds will follow the passage of the front
across the entire region. Bufkit soundings support frequent
gusts of around 30kts behind the front and lasting into Monday
evening.

Outlook
Tue-wed... No sig wx expected.

Thu... Pm rain low CIGS possible.

Fri... Rain low CIGS possible, especially in the morning.

Ctp watches warnings advisories
None.

Synopsis... La corte martin
near term... La corte martin
short term... La corte
long term... Ceru gartner
aviation... Fitzgerald


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BLTM2 - 8574680 - Baltimore, MD 80 mi37 min N 6 G 11 42°F 43°F1012.2 hPa
WASD2 - 8594900 - Washington, DC 80 mi31 min WNW 5.1 G 8 42°F 41°F1013.4 hPa (+0.0)
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 84 mi31 min NW 12 G 13 42°F 1012.4 hPa (+0.4)

Wind History for Baltimore, MD
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hagerstown, Washington County Regional Airport, MD12 mi38 minWNW 810.00 miOvercast41°F36°F82%1014 hPa

Wind History from HGR (wind in knots)
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Last 24hrNE11NE16NE13
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1 day agoNW6N7N6N9N10N9N12N8N8N6N10N7N6N7N8NE10N3N10N8N8N10N11N7NE9
2 days agoNW4N4NW5N6NW4NW4NW5NW5NW4NW4NW3CalmNW4N3CalmCalmNW4CalmN4N5NW3N5N3N4

Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Sun -- 12:34 AM EST     Moonset
Sun -- 02:38 AM EST     2.48 feet High Tide
Sun -- 07:20 AM EST     Sunrise
Sun -- 09:01 AM EST     0.01 feet Low Tide
Sun -- 01:11 PM EST     Moonrise
Sun -- 03:10 PM EST     2.54 feet High Tide
Sun -- 04:47 PM EST     Sunset
Sun -- 09:39 PM EST     0.17 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.62.22.42.52.21.71.10.50.100.10.51.322.42.52.42.11.50.90.50.20.20.4

Tide / Current Tables for Chain Bridge, one mile below, D.C.
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Chain Bridge
Click for Map
Sun -- 12:34 AM EST     Moonset
Sun -- 02:33 AM EST     2.48 feet High Tide
Sun -- 07:20 AM EST     Sunrise
Sun -- 08:56 AM EST     0.01 feet Low Tide
Sun -- 01:11 PM EST     Moonrise
Sun -- 03:05 PM EST     2.54 feet High Tide
Sun -- 04:47 PM EST     Sunset
Sun -- 09:34 PM EST     0.17 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.72.22.42.52.21.710.50.100.10.61.322.42.52.421.40.90.40.20.20.4

Weather Map and Satellite Images
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wmap_A
GOES Local Image of    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 State College, PA (22,6,7,8)
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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.