Sunday, January16, 2022
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Marine Weather and Tides
Mercersburg, PA

Version 3.4
NOTICE
3/30/2021 -- ANZ330 has been split into ANZ331 and ANZ332. Click EDIT in Marine Forecast and select your new zone.
1/26/2021 -- The West Coast Satellite images havd been updated. They now use GEOS-17.
1/1/2021 -- The 7 day forecast are now working well. Thank you NOAA for your support.

Sunrise 7:27AMSunset 5:13PM Sunday January 16, 2022 7:49 PM EST (00:49 UTC) Moonrise 3:54PMMoonset 6:48AM Illumination 100% Phase: Full Moon; Moon at 14 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- 637 Pm Est Sun Jan 16 2022
.gale warning in effect through Monday afternoon...
Tonight..E winds 25 kt...becoming S after midnight. Gusts up to 35 kt. Waves 2 to 3 ft. Rain, freezing rain and snow this evening, then rain likely with a slight chance of snow after midnight. Vsby 1 nm or less...increasing to 1 to 3 nm after midnight.
Mon..SW winds 15 to 20 kt...becoming W 20 to 25 kt in the afternoon. Gusts up to 40 kt. Waves 2 ft.
Mon night..W winds 15 to 20 kt with gusts to 40 kt. Waves 2 ft.
Tue..W winds 10 to 15 kt with gusts to 25 kt. Waves 1 ft.
Tue night..SW winds 5 to 10 kt. Waves 1 ft.
Wed..S winds 5 to 10 kt. Waves 1 ft.
Wed night..W winds 5 to 10 kt. Waves 1 ft. A chance of rain.
Thu..NW winds 5 to 10 kt. Waves 1 ft.
Fri..N winds 5 to 10 kt. Waves 1 ft. A chance of snow through the night.
ANZ500 637 Pm Est Sun Jan 16 2022
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Low pressure will approach the waters today before passing through tonight into early Monday. Strong winds associated with the low will impact our waters this evening and into Monday. Gale warnings and small craft advisories may be needed for portions of the waters into Tuesday. Thereafter, high pressure will build along the southeast coast into the middle of the week.


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 161937 AFDCTP

Area Forecast Discussion National Weather Service State College PA 237 PM EST Sun Jan 16 2022

SYNOPSIS. A winter storm will bring snow and mixed precipitation to the region tonight into Monday, followed by windy conditions Monday afternoon and Monday night. An Alberta Clipper is likely to track north of Pennsylvania the middle of next week.

NEAR TERM /THROUGH TONIGHT/. Dewpoints in the single digits below and above zero across northern and central areas this afternoon, preceding the shift to ESE llvl flow that will moisten the low levels ahead of the approaching winter storm.

Winter Storm Warnings remain in effect for the northern tier and southward to the west of I-99, across the Alleghenies, and into the Laurels, along with Blair and nrn parts of Centre/Clinton/ Lycoming Counties which were added to the warning this morning. Overall, confidence continues to increase in heavier rates materializing for this evening to achieve the higher end amounts of the previously advertised ranges. For the rest of the forecast area, a Winter Weather Advisory is in effect for snow amounts of 2-6 inches before a changeover to a wintry mix.

Snow onset right on time over the Laurel Highlands early this afternoon, and will be rapidly spreading northward over the rest of the region by evening. Expect snow to start in the central mountains after 4 pm, and over the northern tier after 6 pm. We are particularly going to be keying on at least one west-east oriented heavy snow band within the shield of steady snow during the mid to late evening hours, as strong frontogenesis in the 850-500 mb layer and fairly deep pockets of negative moist EPV amply support heavy meso scale snowbands. Model diagnostics from NAM/GFS and HREF all strongly depict northward propagating swaths of saturated negative EPV coincident with moderate to strong frontogenetical circulation lifting northward into central and northern PA this evening through late tonight, which will horizontally constrict and intensify updrafts of the CSI banding to result in snowfall rates exceeding 1-2" per hour for a 3 to 5 hour period across much of the area. High confidence in the timing of these snowfall rates, mainly between 6-8 PM across the southern tier, 7-11 PM along I-80, and 10 PM-1 AM in the northern tier, as well as the the intensity of this banding allowed us to shift snowfall totals to the higher end of the previously forecast ranges. This bumped a few counties/portions of counties into Warning Criteria (Blair, Nrn Centre, Nrn Clinton and Nrn Lycoming) with others still straddling the fence bordering the eastern periphery of existing warnings. The main CSI/frontogenetical band will pivot over NW PA late tonight into early Monday morning, and become further enhanced by deformation and vigorous isentropic ascent as it becomes SW-NE oriented after midnight. Snowfall rates of >2 inches/hr are possible in Warren and McKean counties mainly between 2 AM and 5 AM with 1+ inch/hr rates lasting through about 7 AM.

The NW mountains (Warren and McKean Counties) still appear to be the sweet spot in our CWA, especially since most hires guidance shows the deformation band traveling nearly parallel to its axis with heavy snow persisting for several hours. This area will also stay mostly snow or all snow. Snowfall totals of 12-15" are posted for this area.

Despite the ambient cold air mass, change to mixed precipitation is still expected farther south and east, first in the lower Susq by 7-8PM and then moving swiftly northward just behind the heavy snow. Most of the QPF from the storm will fall as snow, and thus ice quanity/loading is less of a concern on top of the snow. The changeover should reach I-80 between 10 PM Sunday and 2 AM Monday, but will coincide with precipitation rates dramatically falling off as the CSI banding and frontogenetical forcing lift north and shut off the deep upward vertical motions supporting heavy precip, and mixed precip will generally be light. There is still uncertainty with the timing of the changeover over parts of the central mountains where the cold air is more entrenched, and a couple hours difference in timing could result in a few inches more/less snow, since the snowfall rates will likely be near 1-1.5 inch/hr just ahead of the changeover. Sleet and even rain are not out of the question to reach the NY border after midnight.

A few hundredths of an inch of ice accretion are most probable southwest and central potions of our CWA, where temps are most likely to linger near 32F as precip mixes with rain. As mentioned earlier, impacts from ice are expected to be limited as there will already be snow on the ground. Temperatures rising above 32 (and actually to near 40F) will prohibit ice accumulations in the lower Susq Valley. Dry slot overspreads most of the central and east overnight, not far behind the warm air intrusion, leaving lingering precip to be spotty after the several hour burst of snow this evening. Snow, however, will continue over the northwest for most of the night, adding to totals there.

SHORT TERM /MONDAY/. Lingering lighter snow and increasingly gusty winds are expected into Monday morning across the Alleghenies, as intensifying surface low lifts into NY state and deformation band lifts through central PA. Relatively deep moisture, combined with orographic forcing, should produce a few inches of additional snow accumulation Monday along the favored lake effect snow region and the Laurel Highlands, with a light coating likely downwind (east) of the mountains. Bufkit soundings support fairly widespread wind gusts Monday in excess of 30kts with 40kts possible along the Alleghenies / Laurel Highlands. These winds should produce considerable blowing/drifting across the Alleghenies with locally poor visibilities on Monday. A Wind Advisory was discussed with neighboring offices but left for later shifts (eve or mid) to collaborate.

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/. The winter storm will have departed out of our area by Monday evening. On the backside of the low pressure system, CAA and NW flow will prompt lake-effect and upslope snow showers in the usual areas (NW PA and Laurels). As the moisture associated with the storm system leaves us, the lake- enhanced/upslope snow will be fairly minimal with mainly less than 1 inch amounts. It will be quite blustery Monday night into Tuesday as well. Temperatures will drop onto the teens and 20s by Tuesday morning along with gusty winds up to 35-45kts.

Lingering lake effect snow showers and flurries in NW PA for the day. Clearing skies but cold in the Southeast with winds dying down during the day.

Both the ECENS and GEFS track an Alberta Clipper across southern Ontario next Wednesday, keeping the bulk of its precipitation north of the border. Light precip may fall along the Northern Tier, Tuesday night before frontal precip falls Wednesday evening across Western PA. Southwest flow and associated warm advection preceding the trailing cold front should result in a marked warmup with highs Wednesday several degrees above average.

Passage of the trailing cold front is likely to be accompanied by a round of snow or rain showers, then a cold northwest flow behind the front should generate lake effect snow showers Wed PM through Thu PM across the Alleghenies. Progged inversion heights look fairly low, indicating light snow accums.

The bulk of medium range guidance supports dry and cold weather late in the week, as surface high builds in from the Grt Lks. A deepening upstream trough appears likely to spawn a developing coastal low next weekend. The bulk of model guidance keeps the low far enough east to miss central Pa, but several ensemble members are further west, supporting low POPs for snow across the southeast counties. Early next week we could see unsettled and cold weather again with upper level troughing over the eastern US. Shortwaves diving down from Canada may bring rounds of chilly temperatures and lake effect snow for next week.

AVIATION /19Z SUNDAY THROUGH FRIDAY/. Generally VFR ahead of the snowstorm this afternoon, with low clouds from easterly flow at IPT and MDT.

Expect snow and associated IFR/LIFR visibility to quickly spread south to north across CPA airspace btwn 21Z Sun-00Z Mon. A strong low level jet (LLJ) from the east will draw warm air aloft and result in a ptype transition from snow to wintry mix and rain across the central and eastern terminals btwn 00-06Z Mon. We increased LLWS to 40-50kt for the 16/06Z TAF cycle based on the strength of the aforementioned LLJ. Mixed precip transitions back to all snow by 12Z Monday with snow tapering off east of the mtns into the afternoon. There is very high confidence in widespread sub-VFR conditions between 00-18Z Monday.

Cold and blustery NW flow will keep IFR/LIFR snow showers going at KBFD/KJST into Monday night with improving conditions expected east of the Alleghenies. The combination of snow showers, strong winds, and blowing snow should all contribute to significantly reduced visibility across the western 1/3 of the airspace.

Outlook .

Mon . IFR/MVFR trending MVFR/VFR central to eastern airfields Mon night. Wind gusts 25-40kt from 280-310 degrees.

Tue . MVFR N/W early trending VFR with snow showers fading and winds decreasing.

Wed . PM rain/snow showers possible.

Thu . Snow showers possible NW airspace.

Fri . Chance snow showers NW and South.

CTP WATCHES/WARNINGS/ADVISORIES. Winter Weather Advisory until 1 PM EST Monday for PAZ019-042- 045-046-049>053-058. Winter Storm Warning until 7 PM EST Monday for PAZ010-011-017. Winter Storm Warning until 7 PM EST Monday for PAZ024-033. Winter Storm Warning until 1 PM EST Monday for PAZ012-018-041. Winter Weather Advisory until 1 PM EST Monday for PAZ026>028- 035. Winter Weather Advisory until 1 AM EST Monday for PAZ036-056- 063>066. Winter Weather Advisory until 1 AM EST Monday for PAZ057-059. Winter Storm Warning from 6 PM this evening to 7 PM EST Monday for PAZ004>006-037. Winter Storm Warning until 1 PM EST Monday for PAZ025-034.

SYNOPSIS . DeVoir/Colbert NEAR TERM . DeVoir/Colbert SHORT TERM . Colbert LONG TERM . Fitzgerald/Wagner AVIATION . Steinbugl/Wagner


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BLTM2 - 8574680 - Baltimore, MD 80 mi56 min E 19G25 31°F 39°F1008.3 hPa
WASD2 - 8594900 - Washington, DC 80 mi56 min ENE 6G11 31°F 36°F1007.2 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 84 mi56 min ENE 20G26 30°F 1008.3 hPa

Wind History for Washington, DC
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Last 24 hrN3
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hagerstown, Washington County Regional Airport, MD12 mi57 minN 81.00 miLight Snow Fog/Mist18°F15°F88%1011.5 hPa

Link to 5 minute data for KHGR

Wind History from HGR (wind in knots)
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Last 24 hrN7N4N5N5N50N4N40N5N5NE30E4E400NE7NE5N10N9N10N11N8
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2 days agoN4NW4NW6N3NW5N8N7NW5N5N400NW3NW5NW10N11N12N16N16
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Tide / Current Tables for Chain Bridge, D.C.
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Chain Bridge
Click for Map
Sun -- 01:59 AM EST     -0.02 feet Low Tide
Sun -- 06:41 AM EST     Moonset
Sun -- 07:25 AM EST     Sunrise
Sun -- 07:37 AM EST     2.30 feet High Tide
Sun -- 01:44 PM EST     -0.02 feet Low Tide
Sun -- 03:53 PM EST     Moonrise
Sun -- 05:11 PM EST     Sunset
Sun -- 07:46 PM EST     2.65 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Chain Bridge, D.C., Tide feet
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Tide / Current Tables for Chain Bridge, one mile below, D.C.
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Chain Bridge
Click for Map
Sun -- 01:54 AM EST     -0.02 feet Low Tide
Sun -- 06:41 AM EST     Moonset
Sun -- 07:25 AM EST     Sunrise
Sun -- 07:32 AM EST     2.30 feet High Tide
Sun -- 01:39 PM EST     -0.02 feet Low Tide
Sun -- 03:53 PM EST     Moonrise
Sun -- 05:11 PM EST     Sunset
Sun -- 07:41 PM EST     2.65 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Chain Bridge, one mile below, D.C., Tide feet
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Weather Map
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