Tuesday, January16, 2018 L-36.com

Marine Weather and Tides
Grasonville, MD

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 7:18AMSunset 5:09PM Tuesday January 16, 2018 4:16 AM EST (09:16 UTC) Moonrise 6:54AMMoonset 4:59PM Illumination 0% Phase: New Moon; Moon at 29 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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ANZ540 Eastern Bay- 331 Am Est Tue Jan 16 2018
Rest of the overnight..NE winds 5 kt. Waves flat.
Today..SE winds 5 kt. Waves flat.
Tonight..N winds 5 to 10 kt. Waves 1 ft or less. Snow likely. Vsby 1 to 3 nm.
Wed..NW winds 10 kt with gusts to 20 kt. Waves 1 to 2 ft. A chance of snow.
Wed night..NW winds 10 to 15 kt with gusts to 20 kt. Waves 1 to 2 ft.
Thu..W winds 10 kt with gusts to 20 kt. Waves 2 ft.
Thu night..W winds 5 to 10 kt. Waves 1 ft.
Fri..SW winds 5 kt. Waves less than 1 ft.
Sat..SW winds 5 kt. Waves less than 1 ft.
ANZ500 331 Am Est Tue Jan 16 2018
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A cold front will approach from the west today and cross the waters tonight. Low pressure will develop offshore Wednesday. High pressure will return for late in the week. A small craft advisory may be needed for the waters late Tuesday night through Thursday.

7 Day Forecast for Marine Location Near Grasonville, MD
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location: 38.88, -76.25     debug

Area Discussion for - Philadelphia/Mount Holly, PA
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Fxus61 kphi 160233
area forecast discussion
national weather service mount holly nj
933 pm est Mon jan 15 2018

High pressure centered in eastern canada will lose its influence on
our region tonight and Tuesday as a clipper low approaches from the
great lakes region. The low will weaken to our north as another area
of low pressure forms off the mid-atlantic coast Tuesday night.

The coastal low is then expected to move northeast toward cape
cod on Wednesday and the canadian maritimes Wednesday night.

High pressure builds in from the southeastern states late in the
week before progressing offshore this weekend. A cold front may
move in from the west by next Monday.

Near term until 6 am Tuesday morning
For the 930 pm update, adjusted the temperatures and dew points
based on the latest observations. This included an upward
adjustment at several places given a slower temperature drop.

The 00z sterling, va and upton, ny roabs showed a moist
layer(s) at and below 850 mb, which will tend to keep lower
clouds in across much of the area through the night. No changes
to the pops at this time, however light snow may struggle with
an eastward extent for awhile.

Otherwise, deep southwesterly flow becomes established across the
region overnight, with a strong (135+ kt) 250-mb jet streak
stretching from the ohio tennessee valleys northeastward into new
england. A positively-tilted trough will move into the great lakes
region overnight, with warm-air advection occurring across much of
the mid-atlantic downstream of the trough. With pre-established
onshore flow, the aforementioned warm advection and low-level cloud
deck should prevent much cooling from occurring. Overnight low
temperatures are generally about 5-8 degrees cooler than max
temperatures today.

Several perturbations embedded in the flow will aid in large-scale
lift across the region, though the strongest source(s) will be in
the low levels. Models are in good overall agreement regarding the
development of snow overnight to our west with a general progression
into the southern poconos, lehigh valley, and northwest new jersey
very late tonight (after 3 am). Lift is generally weak, and
moisture will not be plentiful to begin with. Model QPF through
12z Tuesday is generally under a tenth of an inch in these areas
(which maybe would muster an inch). However, this will be a
long- duration light snow that begins during the overnight
period (with totals reaching advisory levels by Tuesday
evening). Thus, a winter weather advisory GOES into effect for
the aforementioned areas at 5 am. The main impacts from this
storm will likely be after this period, however.

Short term 6 am Tuesday morning through 6 pm Tuesday
A long-duration light snow should continue through much of the day
in the southern poconos, lehigh valley, and northwest new jersey.

There will be little progress eastward of the precipitation during
the day as the approaching trough pivots to a more neutral tilt
during this period (and reloads in the southern stream). It looks
like the next tier of counties zones (western chester county, pa,
northeastward to somerset county, nj) will see precipitation begin
by around noon, though temperatures will be near above freezing.

Nevertheless, given the onset of precipitation will be during this
time and the antecedent cold, started the winter weather advisory
for these areas at noon. At this point, it looks like the main
impacts will be after the daylight hours, however. Indeed,
temperatures may approach or exceed freezing even in reading and
allentown during the afternoon, so some melting of snow (at least on
treated surfaces) may occur during this time. Total QPF through 00z
Wednesday in the advisory area will be around a tenth to a quarter
of an inch, which may generate snow up to an inch or so in the
southeast portions of the advisory up to 2-3 inches in the southern
poconos (without considering melting).

During the day, a coastal low will develop near or off the carolina
coast. This will reinforce onshore flow to the north, with strong
isentropic lift as surface flow surrounding the surface low becomes
increasingly rotational. This will likely begin to enhance
precipitation rates late in the day (and should deepen the
associated lift, especially as the low approaches), so the snow
rates may increase near the evening commute... Something to monitor

Temperatures have trended upward given the westward trend of the
aforementioned coastal low (closer proximity to stronger warm moist
advection). Bumped temperatures up 3-5 degrees in most areas from
inherited grids during the day tomorrow, though this is uncertain
owing to the plethora of competing factors regarding surface warming
and the large spread in the guidance for a 24-hour forecast
(generally 7-12 degrees among statistical guidance). Tricky
forecast, to say the least.

Long term Tuesday night through Monday
Tuesday night and Wednesday... Primary surface low associated with a
clipper system is expected to weaken over the great lakes region as
it transfers its energy to a secondary low just off the mid-atlantic
coast Tuesday evening. The coastal low will continue to deepen as it
tracks northeastward to about 150 miles east of the nj coast by
early Wednesday morning and then close to nantucket by late
Wednesday afternoon. Today's models have trended notably westward
with the track of the secondary low (a common model bias we have
seen with just about every coastal storm so far this winter).

With support from today's 12z guidance, snowfall amounts with the
latest forecast sent this afternoon are notably higher than previous
iterations. Models are in reasonably good agreement regarding the
synoptic pattern with some important differences on the mesoscale
(i.E., strength and placement of frontogenetical lift to support
mesoscale snow banding on the n-nw side of the developing coastal
low). Accordingly, there is moderate to high confidence that
snowfall totals for this event will increase across the CWA from se
to NW (with the heaviest snow falling along and N W of the fall
line where winter weather advisories are in effect). There is
also higher certainty that a period of moderate to locally heavy
snow (snowfall rates 1"+ per hour) will fall north of i-78
Tuesday night (this is when low- level convergence becomes
focused along a sharpening trough that extends n-nwwd from the
coastal low). Snow will end quickly from west to east Wednesday
morning, although it may linger around into the afternoon or
early evening near the coast and across southern de.

The greatest uncertainty in the snowfall forecast is for east-
central nj. The majority of the models indicate the low will not
organize quickly enough to be able to expand the deeper lift
atlantic moisture and heavier snowfall back westward into coastal nj
Tuesday night. However, if the abovementioned model trends continue,
we will have to increase accumulations across middlesex-monmouth-
ocean and perhaps nearby counties.

Wednesday night... Gusty NW winds behind the coastal low will advect
colder air into the region. A chilly night is expected with forecast
lows ranging from the single digits in the snow-covered southern
poconos to the upper teens in phila and near the coast. We do not
expect a second coastal low to impact the area Wednesday night with
all models backing off on this scenario.

Thursday through Sunday night... Broad high pressure builds across
the southeastern CONUS late in the week before gradually moving off
the southeast coast next weekend. Our region will initially be
situated in westerly flow on the northern periphery of the high that
eventually becomes more southerly as the high starts to move
offshore, resulting in a warm up that starts Friday and continues
into the weekend with highs in the 50s possible by Sunday. Expect a
dry stretch through the weekend.

Monday... Low pressure is forecast to track to our northwest across
the great lakes. Rain chances increase from west to east ahead of a
cold front on Monday. Highs well into the 50s are forecast for

Aviation 03z Tuesday through Saturday
The following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.

Overnight... Mainly MVFR ceilings, however at some terminals there
could be times through about 06z when the MVFR ceiling scatters
out. Light snow is forecast to develop in the lehigh valley and
southern poconos closer to daybreak. Light east or northeast
winds, should become light and variable at most terminals.

Moderate confidence.

Tuesday... MVFR ceilings overall, with the most precipitation (mostly
light snow) remaining west of i-95. Snow is only included at abe and
rdg during the daytime, where sub-vfr visibilities are expected.

Winds generally light and variable, with perhaps a southeast
component becoming dominant by later in the day. Moderate


Tuesday night and Wednesday morning... Some light snow is expected
with low ceilings and reduced visibility.

Wednesday afternoon through Saturday... MainlyVFR.

The small craft advisory south of little egg inlet, nj has been
extended through 15z (10 am) Tuesday. This is due to the seas
remaining more elevated longer across the southern waters.

Elsewhere, the small craft advisory remains in effect through
tonight for the northern atlantic coastal waters. The trend
will be downward with winds and seas tonight, but models have
been much too low with seas thus far (as usual with onshore
flow events). Thus, expect at least the seas to be above
criteria through most if not all of the night (especially
southern waters), though winds are diminishing. For delaware
bay, sub-advisory conditions are expected tonight and Tuesday.


Tuesday night... No marine headlines are anticipated.

Wednesday through Thursday night... SCA conditions are expected
with NW wind gusts of 25-30 kt expected in wake of a coastal
storm. Light freezing spray is expected.

Friday and Saturday... Winds and seas below SCA thresholds.

An ice jam continues along the delaware river at trenton, and
flooding has been reported adjacent to the river in bucks and
mercer counties. Several road closures are in place between
morrisville and yardley in pa and along nj state highway 29 in

The ice is having an impact on the ability to accurately
forecast the river level in the trenton vicinity. Please use any
forecast levels with caution.

If you live near the delaware river in the trenton and yardley
vicinity, pay special attention to any additional information
that is issued regarding the delaware river. Additional ice jams
may form next weekend when milder conditions arrive.

Phi watches warnings advisories
Pa... Winter weather advisory from noon Tuesday to 10 am est
Wednesday for paz101-103-105.

Winter weather advisory from 5 am Tuesday to 6 am est
Wednesday for paz054-055-060>062.

Nj... Winter weather advisory from noon Tuesday to 10 am est
Wednesday for njz009-010.

Winter weather advisory from 5 am Tuesday to 6 am est
Wednesday for njz001-007-008.

De... None.

Md... None.

Marine... Small craft advisory until 10 am est Tuesday for anz452>455.

Small craft advisory until 6 am est Tuesday for anz450-451.

Synopsis... Klein
near term... Cms gorse
short term... Cms
long term... Klein
aviation... Cms gorse klein
marine... Cms gorse klein
hydrology... Cms klein

Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
TPLM2 - Thomas Point, MD 10 mi76 min NNW 2.9 G 4.1 28°F 32°F
CPVM2 11 mi46 min 29°F 25°F
APAM2 - 8575512 - Annapolis, MD 14 mi46 min 29°F 1031.1 hPa
TCBM2 - 8573364 - Tolchester Beach, MD 23 mi46 min N 1.9 G 2.9 29°F 32°F1031.9 hPa
CA2 - 8571892 - Cambridge, MD 23 mi46 min 29°F 31°F1032.3 hPa
44062 - Gooses Reef, MD 24 mi36 min N 3.9 G 5.8 29°F 1031.9 hPa
BSLM2 - Chesapeake Bay, MD 25 mi106 min Calm 27°F 1032 hPa24°F
FSNM2 28 mi46 min Calm G 1 28°F 1030.9 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 28 mi46 min ESE 1 G 1 28°F 1032 hPa
BLTM2 - 8574680 - Baltimore, MD 32 mi46 min Calm G 1 29°F 32°F1031.4 hPa
COVM2 - 8577018 - Cove Point LNG Pier, MD 34 mi46 min N 6 G 8 28°F 1032.1 hPa
SLIM2 - 8577330 - Solomons Island, MD 40 mi46 min N 4.1 G 4.1 29°F 34°F1031.2 hPa
WASD2 - 8594900 - Washington, DC 41 mi46 min S 1.9 G 2.9 30°F 33°F1031.8 hPa
DRSD1 - Delaware Reserve, DE 45 mi106 min NNW 2.9 29°F 1031 hPa29°F
BISM2 - 8571421 - Bishops Head, MD 47 mi46 min N 5.1 G 6 30°F 31°F1031.8 hPa

Wind History for Cambridge, MD
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1 day
2 days

Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Bay Bridge Field, MD8 mi41 minN 05.00 miFog/Mist28°F24°F86%1031.8 hPa
Easton / Newman Field, MD11 mi28 minN 010.00 miOvercast31°F24°F77%1032.8 hPa
Annapolis, United States Naval Academy, MD14 mi22 minN 03.00 miFog/Mist30°F28°F92%1031.7 hPa

Wind History from W29 (wind in knots)
Last 24hrNE6NE4NE4N6NE5NE6--NE6
1 day agoN15
2 days agoW9N7NW13

Tide / Current Tables for Claiborne, Eastern Bay, Maryland
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Tue -- 03:14 AM EST     0.58 feet High Tide
Tue -- 06:53 AM EST     Moonrise
Tue -- 07:21 AM EST     Sunrise
Tue -- 09:17 AM EST     -0.36 feet Low Tide
Tue -- 04:09 PM EST     1.13 feet High Tide
Tue -- 04:59 PM EST     Moonset
Tue -- 05:08 PM EST     Sunset
Tue -- 09:18 PM EST     New Moon
Tue -- 11:10 PM EST     -0.03 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Tide / Current Tables for Baltimore Harbor Approach, Maryland Current
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Baltimore Harbor Approach
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Tue -- 02:44 AM EST     0.00 knots Slack
Tue -- 05:09 AM EST     0.48 knots Max Flood
Tue -- 06:54 AM EST     Moonrise
Tue -- 07:22 AM EST     Sunrise
Tue -- 07:44 AM EST     -0.00 knots Slack
Tue -- 10:33 AM EST     -0.55 knots Max Ebb
Tue -- 01:06 PM EST     0.00 knots Slack
Tue -- 04:51 PM EST     1.09 knots Max Flood
Tue -- 04:59 PM EST     Moonset
Tue -- 05:08 PM EST     Sunset
Tue -- 08:18 PM EST     -0.00 knots Slack
Tue -- 09:18 PM EST     New Moon
Tue -- 11:39 PM EST     -1.05 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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

GOES Local Image of Mid-Atlantic    EDIT

Wind Forecast for Philadelphia/Mount Holly, PA (4,6,7,8)
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Ground Weather Radar Station Dover AFB, DE
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weather_mapweather_map weather_map

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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.