Tuesday, December1, 2020
Privacy Policy
L-36.com

Marine Weather and Tides
Mercersburg, PA

Version 3.4
NOTICE
8/26/2020 The 7 day forecast is taking about 5 seconds to load but it will eventually load. NOAA is still working on it.
8/18/2020 NOAA continues to have trouble. Wind guest will occasionally be left off graphs. I am working with NOAA to resolve the issue.
12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed.
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.

Sunrise 7:11AMSunset 4:48PM Tuesday December 1, 2020 3:19 AM EST (08:19 UTC) Moonrise 5:49PMMoonset 8:20AM Illumination 99% Phase: Waning Gibbous; Moon at 16 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
    EDIT      (on/off)   Help
ANZ538 Patapsco River Including Baltimore Harbor- 1242 Am Est Tue Dec 1 2020
.small craft advisory in effect from 9 am est this morning through this afternoon...
Overnight..SW winds 10 kt. Waves 1 ft.
Tue..W winds 10 to 15 kt with gusts to 25 kt. Waves 1 to 2 ft.
Tue night..W winds 10 to 15 kt with gusts to 20 kt. Waves 1 ft.
Wed..W winds 10 kt with gusts to 20 kt. Waves 1 ft.
Wed night..W winds 5 to 10 kt. Waves 1 ft.
Thu..W winds 5 kt. Waves less than 1 ft.
Thu night..SW winds around 5 kt. Waves 1 ft or less.
Fri..NW winds around 5 kt. Waves 1 ft. A chance of showers.
Sat..W winds 5 kt. Waves less than 1 ft. A chance of showers through the day.
ANZ500 1242 Am Est Tue Dec 1 2020
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Strong low pressure will depart to the north into new york and quebec through Tuesday. High pressure will build from the midwest to off the southern middle atlantic coast Wednesday into Thursday, then another low pressure system will likely approach from the tennessee river valley Friday. Small craft advisories may be needed Wednesday.


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


Area Discussion for - State College, PA
      (on/off)   Help   NOTE: mouseover dotted underlined text for definition
FXUS61 KCTP 010415 AFDCTP

Area Forecast Discussion National Weather Service State College PA 1115 PM EST Mon Nov 30 2020

SYNOPSIS. An upper level low will lift from TN to southern Quebec by Wednesday. Colder temperatures will occur Tuesday and Wednesday accompanied by a brisk west to northwest wind and frequent snow showers across the western mountains. Several inches of snow accumulation expected on the ridges near and to the west of Route 219. Seasonably cool air and fair weather will settle in through the weekend.

NEAR TERM /UNTIL 8 AM TUESDAY MORNING/. Snow is starting in the Laurels, but not quite yet in the NW where temps are also still in the m30s. Only slowed the arrival of precip in the NW some as they are inside the big dry slot. Clouds will keep temps up and keep the transition to snow gradual except over the Laurels where it should just start out as snow in the higher elevs and work down to the valleys in a few hours. No changes to accums for the fcst.

Prev . Other than a brief mention for an hour at Meadville, there has not yet been any SN in the state. Precip shield inching ino PA. The temps are now down into the m30s in Warren Co and the Laurels, and YNG is a mix at 00Z. So it's really close to mixing and changing as the precip shield advances/expands. Wind gusts still up in the 20s in the Laurels, and will likely continue for most of the night. No changes to SF numbers. Flags look well-placed.

Prev . Primary sfc low tracking into the Laurel Highlands early this afternoon while secondary deepens near triple point low over my southeast counties. Lancaster and York Counties just missed out on severe threat with strong shear and best CAPE setting up farther east, where TOR Watch is in effect for areas east and south.

Steadiest rainfall has lifted east and north of central PA early this afternoon as a well defined dry slot overspreads the area this afternoon from south to north. As high clouds peel to the north, warmer/shallow low clouds are left for this afternoon and much of tonight over Central PA and the Susq Valley.

Lull in the precip will persist through early tonight beneath the dry slot and within a region of shallow cold advection in as filling sfc low lifts NNE into central NY state. Again, expect some breaks in the clouds with just some patchy drizzle on the ridges or a few stray showers east of the Allegheny Front.

Farther northwest, the eastern edge of cold conveyor belt/ synoptic snow will set up near the Route 219 corridor early tonight, before sliding slowly east overnight into early Tuesday along with deepening cold air. Accums start to pick up in the predawn hours in the NW Mountains, but the bulk of accumulation won't come until daylight and last into Tuesday night and Wednesday.

SHORT TERM /8 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/. Really good signal for multiple bands of enhanced frontogenetical LES likely within the broader snow area early Tuesday as depicted by the HREFV2 along with good upstream fetch off Lake Huron and a decent length of Central and Western Lake Erie. Broad area of llvl instability extends well inland to the Central and NC Mountains as well, meaning that frequent snow showers (open cellular) of varying intensity are expected over much of central and north central PA throughout the day Tuesday, Compact mid and upper short waves moving through the base of upper low lifting northward across the Alleghenies Tuesday morning will lead to some brief periods of mod to heavy snow near and to the west of a line from KJST to KFIG and KELZ.

Winter Weather Advisory (beginning at 09Z Tuesday) is well placed, to include Mckean, Elk and Clearfield counties where storm total snowfall should be in the 2-5 inch range, with the highest totals near and to the West of Route 219. Rain showers early Tuesday morning to the SE of the Allegheny Front will gradually mix with and change to mainly snow showers during the day.

Storm total snowfall has ramped up a bit over Warren County with 10-14" amounts expected over the west/northwest. Despite duration event, these looks sufficient to push the area into Warning criteria, and have upgraded existing Winter Weather Advisory to Winter Storm Warning for snow for Warren county. Elsewhere, snow amounts are similar to previous, from this one- two punch of synoptic/cold conveyor belt, then LES/Upslope enhanced snows . 3-5 inches across the Laurels and 4-8 inches across much of McKean County.

The snow will likely impact both commutes AM and PM on Tues. Daytime may keep the ratios/numbers down some if we can manage to get above 32F. Chance of precipitation will be minimal to the SE of Interstate 81 on Tuesday.

LONG TERM /TUESDAY NIGHT THROUGH MONDAY/. For this evening update, the PoPs are lower than prev fcsts in many of the periods. The potential phasing of the nrn and srn streams for a decent storm this weekend is just not working out. They appear to be separated by just enough time/distance as they pass thru the area that Central PA may be largely dry over the weekend. However, the position of the jet streaks will still keep us looking closely for the next few days. The W/NW flow will keep a low chc 20-30 PoPs in the fcst for the NW half of the area. Temps look rather seasonable for Thurs-Mon.

Prev . Lake effect snow showers and localized squalls will continue Tuesday night into early Wednesday before fading into Wednesday evening. Additional accumulations should range between 1 and 3 inches over the Laurel Highlands and NW Alleghenies (along and west of US219) with locally higher amounts (3-6" range) possible in the primary and secondary NW PA snowbelts and ridgetops in Cambria/Somerset Counties. Travel disruptions are likely to continue with a winter storm warning (Warren Co.) and winter weather advisory remaining in effect. It will be seasonably cold and blustery with wind chills in the 20s and 30s a better indicator of what it will feel like outside. Max temps should bottom out Wednesday and trend modestly warmer into the weekend.

Thursday looks dry before the pattern turns more active and unsettled from Friday into early next week. A pair of upper level troughs carving out over the Eastern U.S. should ensure a prolonged stretch of seasonably cool/near average to slightly cooler than average sensible weather in CPA into next week. For the time being, it seems the western and northern Alleghenies have the best shot seeing some snow Friday PM-early Saturday with some lake enhancement. More uncertainty late in the weekend into early next week owing to how the second upper trough evolves or closes off but higher POPs are again shaded over the Allegheny mtns.

AVIATION /04Z TUESDAY THROUGH SATURDAY/. Rain and snow now starting to wrap around into the western airspace. Expect a prolonged period of IFR or below across the western 1/3 of the airspace with wrap- around snow transitioning to lake- effect/orographic snow showers overnight and through Tuesday. Winds will increase with gusts over 25kts across the western 1/2 of the airspace by Tuesday morning. Mainly VFR expected over the southeast overnight and Tuesday.

Outlook .

Wed . Ceiling restrictions possible NW, otherwise VFR.

Thu . Mainly VFR conditions.

Fri-Sat . Chance of rain and snow showers especially over the western airspace.

CLIMATE. Top-5 warmest November tracking at Harrisburg with an average temperature of 49.8 degrees (+5.6F). Above average temperatures to close out the month should ensure a top-3 finish.

Here are the rankings through 11/29:

1. 51.3 in 1931 2. 50.0 in 1975 3. 49.8 in 2020 4. 49.5 in 2015 5. 49.3 in 1999

CTP WATCHES/WARNINGS/ADVISORIES. Winter Weather Advisory from 4 AM Tuesday to noon EST Wednesday for PAZ005-010-017. Winter Storm Warning until noon EST Wednesday for PAZ004. Winter Weather Advisory until 7 AM EST Wednesday for PAZ024- 033.

SYNOPSIS . DeVoir/Dangelo NEAR TERM . DeVoir/Dangelo SHORT TERM . DeVoir/Dangelo/Martin LONG TERM . Steinbugl AVIATION . Steinbugl/Travis CLIMATE .


Weather Reporting Stations
   EDIT       (on/off)   Help   NOTE: Click on distance to see the station location on a map
Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BLTM2 - 8574680 - Baltimore, MD 80 mi49 min NW 4.1 G 8.9 47°F 54°F999.3 hPa
WASD2 - 8594900 - Washington, DC 80 mi49 min NW 1.9 G 6 48°F 51°F1000.5 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 84 mi49 min W 11 G 13 47°F 999.7 hPa

Wind History for Washington, DC
(wind in knots)    EDIT      (on/off)   Help
4
AM
5
AM
6
AM
7
AM
8
AM
9
AM
10
AM
11
AM
12
PM
1
PM
2
PM
3
PM
4
PM
5
PM
6
PM
7
PM
8
PM
9
PM
10
PM
11
PM
12
AM
1
AM
2
AM
3
AM
Last
24hr
E2
G7
NE4
G7
NE3
G8
NW7
NE1
SE4
--
W8
G17
S4
W1
S6
G9
S5
SW5
SW7
G10
NW6
G11
NW3
NW4
G14
NW4
G9
NW7
NW6
G10
NW5
G11
NW4
G8
NW4
NW1
G4
1 day
ago
SW2
NW1
SW1
S2
S1
--
SE2
S6
S6
S4
S4
G8
S6
S5
SE1
SE2
SE2
G5
--
S1
G4
S4
G7
SW2
G6
S3
E2
N1
G6
NE2
G6
2 days
ago
--
S1
--
--
S4
NW7
G11
N3
G8
NW14
G20
NW13
G17
NW9
G16
NW8
G14
NW8
G14
NW4
G7
NW4
--
NW2
NW4
SE1
--
S1
NW2
NE1
NW2

Airport Reports
    EDIT      (on/off)   Help   Click EDIT to display multiple airports. Follow links for more data.
AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hagerstown, Washington County Regional Airport, MD12 mi26 minWSW 1110.00 miOvercast41°F30°F67%1000.9 hPa

Link to 5 minute data for KHGR

Wind History from HGR (wind in knots)
4
AM
5
AM
6
AM
7
AM
8
AM
9
AM
10
AM
11
AM
12
PM
1
PM
2
PM
3
PM
4
PM
5
PM
6
PM
7
PM
8
PM
9
PM
10
PM
11
PM
12
AM
1
AM
2
AM
3
AM
Last 24hrN4N7NE9NE10N6N7NW8NW5NW5W6SW3SW7W3SW5W10
G18
W11
G19
W6W9W5W11W7W11W8W11
1 day agoCalmSE43S5S4S5S5S4S6S6S6S6SE6SE6SE6SE5SE6SE5SE6SE9S9S8CalmSE4
2 days agoCalmW3S3W5SW3W7W12W6W10
G17
W15W9W12NW13NW5NW5CalmW3CalmCalmCalmCalmCalmS4Calm

Tide / Current Tables for Chain Bridge, D.C.
   EDIT   Weekend mode (on/off)   (on/off)   Help   One Week of Data
Chain Bridge
Click for Map
Tue -- 03:39 AM EST     0.06 feet Low Tide
Tue -- 07:08 AM EST     Sunrise
Tue -- 08:14 AM EST     Moonset
Tue -- 09:09 AM EST     2.49 feet High Tide
Tue -- 03:16 PM EST     0.08 feet Low Tide
Tue -- 04:46 PM EST     Sunset
Tue -- 05:48 PM EST     Moonrise
Tue -- 09:05 PM EST     2.94 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

12
am
1
am
2
am
3
am
4
am
5
am
6
am
7
am
8
am
9
am
10
am
11
am
12
pm
1
pm
2
pm
3
pm
4
pm
5
pm
6
pm
7
pm
8
pm
9
pm
10
pm
11
pm
1.40.90.40.10.10.41.11.92.32.52.41.91.30.70.30.10.20.61.42.22.82.92.82.3

Tide / Current Tables for Chain Bridge, one mile below, D.C.
   EDIT      (on/off)   Help   One Week of Data
Chain Bridge
Click for Map
Tue -- 03:34 AM EST     0.06 feet Low Tide
Tue -- 07:08 AM EST     Sunrise
Tue -- 08:14 AM EST     Moonset
Tue -- 09:04 AM EST     2.49 feet High Tide
Tue -- 03:11 PM EST     0.08 feet Low Tide
Tue -- 04:46 PM EST     Sunset
Tue -- 05:48 PM EST     Moonrise
Tue -- 09:00 PM EST     2.94 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

12
am
1
am
2
am
3
am
4
am
5
am
6
am
7
am
8
am
9
am
10
am
11
am
12
pm
1
pm
2
pm
3
pm
4
pm
5
pm
6
pm
7
pm
8
pm
9
pm
10
pm
11
pm
1.40.80.40.10.10.51.21.92.32.52.31.81.20.70.30.10.20.61.42.32.82.92.82.3

Weather Map
       (on/off)   Help Weather Map
wmap_A
GEOS 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.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East
Ground Weather Radar Station Sterling, VA
   (on/off)   Help
weather_mapweather_map weather_map


Cookie Policy:
This website uses cookies to save your settings. No personal information is saved. I do not collect statistics on your visit. You can disable cookies in your browser if you like but it is not recommended for this site. I do not sell cookies. Go to a bakery for that. In fact I do not sell anything. To disable cookies from L-36.com, please refer to the Help button in your browser.
Privacy Policy:
I do not sell or share any user data or anything else for that matter. The only personal information I save is in the site log which has a line for each page view which includes the IP address your browser sends in the header as well as which page you requested. I use this to block hackers and other bad actors. I do not use this raw data to create profiles on users. I periodically delete the log files. Google supplies the ads on this site. Because I do not track who you are, I cannot customize how these ads are served. They may be personalized to improve the ad experience. If you do not want personalized ads, please adjust the settings on the Google site HERE. NOTE: The best I can determine, this site is not subject to CCPA but I am doing my best to comply anyway.
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 numerous 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.