Tuesday, April25, 2017 L-36.com

Marine Weather and Tides
Merchantville, NJ

Version 3.4
What's New / NOTES
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.
3/12/2015 - Added section for Gulf current for users in the GMZ marine zones.
This was requested by a user. If you have requests, please let me know.

Sunrise 6:05AMSunset 7:50PM Tuesday April 25, 2017 2:27 PM EDT (18:27 UTC) Moonrise 4:52AMMoonset 5:57PM 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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ANZ430 Delaware Bay Waters North Of East Point Nj To Slaughter Beach De- 1210 Pm Edt Tue Apr 25 2017
.small craft advisory in effect until 9 pm edt this evening...
This afternoon..NE winds 20 to 25 kt with gusts up to 30 kt... Diminishing to 15 to 20 kt with gusts up to 25 kt late. Seas 2 to 4 ft. Periods of rain. Patchy fog. Isolated tstms late. Vsby 1 to 3 nm.
Tonight..NE winds 10 to 15 kt with gusts up to 20 kt... Diminishing to 5 to 10 kt late. Seas 2 to 4 ft until early morning...then 1 foot or less. Rain likely early in the evening... Then a chance of rain in the late evening and overnight. Patchy fog. Vsby 1 to 3 nm.
Wed..NW winds 5 to 10 kt. Seas 1 to 2 ft. Patchy fog early in the morning. A chance of showers in the morning. Vsby 1 to 3 nm early in the morning.
Wed night..N winds around 5 kt...becoming se around 5 kt late. Seas 1 to 2 ft early in the evening...then 1 foot or less. Patchy fog after midnight.
Thu..SE winds 5 to 10 kt. Seas 1 to 2 ft. Patchy fog in the morning.
Thu night..S winds around 10 kt. Seas 1 to 2 ft.
Fri..SW winds 5 to 10 kt. Seas 1 to 2 ft.
Fri night..S winds 5 to 10 kt. Seas 1 to 2 ft.
Sat..SW winds around 10 kt. Seas 1 to 2 ft.
Sat night..SW winds 10 to 15 kt. Seas 2 to 3 ft. Winds and waves higher in and near tstms.
ANZ400 1210 Pm Edt Tue Apr 25 2017
Synopsis for the coastal waters from sandy hook nj to fenwick island de and for delaware bay.. Low pressure along the coast of the carolinas will slowly progress northward along the eastern seaboard through Wednesday before progressing eastward into the northwest atlantic late this week. A strong subtropical high develops in the western atlantic Thursday through the weekend. A front will attempt to approach the area late this week but will likely stall in the northern mid-atlantic this weekend. A strong cold front will sweep through the eastern u.s. Early next week.

7 Day Forecast for Marine Location Near Merchantville , NJ
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location: 39.98, -75.08     debug

Area Discussion for - Philadelphia/Mount Holly, PA
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Fxus61 kphi 251730
area forecast discussion
national weather service mount holly nj
130 pm edt Tue apr 25 2017

Low pressure along the coast of the carolinas will slowly progress
northward along the eastern seaboard through Wednesday before
progressing eastward into the northwest atlantic late this week. A
strong subtropical high develops in the western atlantic Thursday
through the weekend. A front will attempt to approach the area late
this week but will likely stall in the northern mid-atlantic
this weekend. A strong cold front will sweep through the eastern
u.S. Early next week.

Near term /until 6 pm this evening/
Nearly vertically stacked 1000 mb surface low remains
positioned near CAPE hatteras, and will slowly drift to the
north today.

The first bands of precip are spreading from southwest to
northeast into de, southern nj, and southeast pa. Expect the
leading edge of the more steady precip will reach the delmarva
zones by late morning, phila area around midday and i-78/i-80
corridors in northeastern pa/northwestern nj mid to late
afternoon. Models have been in very good agreement with this
timing. Kept a slight chance for thunderstorms s/e of i-95,
where hi-res cam guidance was highlighting a tongue of modest
elevated instability mainly this afternoon.

There is a risk for locally heavy rainfall. A heavy rain band
that was occurring upstream over nc was juxtaposed with the
trowal and easterly low-level jet on the northern side of the
low as well as an inverted surface trough that extends
northwestward from the surface low. Accordingly, these features
were used to prognosticate the timing and location of the
heaviest rain for our area later today. These features appear to
provide a favorable setup for heavy rainfall mainly this
afternoon in the coastal plain. Model spread for QPF has also
narrowed with the latest iteration of guidance, adding to
forecast confidence. Official rainfall forecast was a blend
between wpc and the wetter nam/hrrr/gem to take into account the
potential for convection to enhance rates this afternoon in
eastern portions of de and nj. The highest amounts in these
locations were 1.5-2.0".

Short term /6 pm this evening through 6 am Wednesday/
Low pressure near the outer banks late this afternoon will
track north-northeastward and just off the DELMARVA coast
tonight. The widespread rain should exit the region toward
sunset as both the low-level jet and trowal will progress
downstream of us. However, the threat of locally heavy rainfall
will persist through the evening in the coastal plain as the
coastal front sets up near the nj coast. Elevated instability
associated with the cold pool aloft under the upper low could
support a few thunderstorms in E nj. Expect showers to end from
sw to NE this evening in E md and overnight elsewhere.

Moisture trapped beneath a low-level inversion will keep stratus
and fog over the area tonight. There is a potential for fog to
become dense in spots, especially near the coast. The combination
of persistent onshore flow and overcast conditions should
prevent temperatures from falling much more than a few degrees
tonight. Lows range from the upper 40s in the poconos to the
upper 50s in S de.

Long term /Wednesday through Monday/
By 12z Wednesday, the slow-moving surface low should be
positioned just off the coast of delaware or new jersey, with
models already showing quite a bit of spread in its placement
and movement thereafter. Fortunately, the implications of these
model differences are relatively minor for our area, as
precipitation will be winding down in our region by this point.

Nevertheless, some residual showers are likely to persist on the
northwest side of the low, potentially aided by a coastal front
that will be slow to dissipate and/or move away from the
northern/central nj coast during the day. As midlevel subsidence
and attendant drying move in during the day, precipitation will
become lighter/spottier, with most of the showers likely out of
the area Wednesday night. Regardless of the coverage of showers,
low-level clouds are likely to stick around for much of the
day, especially north/east of the DELMARVA peninsula. There may
even be some fog on Wednesday morning and again Wednesday night.

Most guidance looked too warm given the expected persistence of
the cloud cover, so went just above the colder met guidance for
max temperatures, though this may still be too warm.

Midlevel ridging will amplify quickly upstream of the weakening
low, as a potent shortwave trough progresses into central north
america. Models are showing a considerable amount of
disagreement with the small-scale phenomena associated with this
feature, with the 00z GFS in particular being problematic owing
to what appears to be a substantial amount of convective
feedback. Placed little or no weight on the GFS solution for the
rest of the long-term forecast as a result. However, confidence
is not much better with the rest of the model suite given the
complex interactions associated with the smaller-scale
perturbations revolving around the larger-scale cyclonic flow.

My suspicion is that the models are likely a bit too progressive
with the system in general, particularly given the retrograding
subtropical ridge in the western atlantic, which will aid in
the amplification of the midlevel east coast ridging. This is a
blocky pattern, and models tend to progress waves too readily in
such a regime.

A surface low is forecast to progress nne from the central u.S.

Into the great lakes/southern canada Wednesday and Thursday.

The associated cold front will struggle to move eastward as
blocky ridging takes hold. Despite weakening large-scale lift as
the surface low and attendant midlevel vort MAX move well north
of the region late this week, frontal ascent in a moistening
warm sector should be enough to generate isolated to scattered
convection along the front as it progresses into the eastern
ohio valley and adjacent appalachians Thursday night. The front
makes its run for the CWA Thursday night through Friday night,
with the highest chances for precipitation generally north of
i-78. There will be sufficient instability for thunderstorms.

Gfs forecast soundings do hint at a somewhat favorable cape-
shear parameter space for severe storms on Friday during peak
heating, but the displacement from the main vort MAX seems to be
a primary limiting factor. Nevertheless, this will be something
to monitor as the end of the week approaches.

The main question in the long-term period is what happens to
this front over the weekend. The strong subtropical ridge in the
western atlantic and the displacement northward of the vort max
into far eastern canada suggests the front will likely stall
somewhere in the northeast. Unfortunately, this could be
relatively close to our region, which sets up this forecast for
major potential for error over the weekend.

For now, it seems that most of the operational mid-range models
place the front north of the area. This would make for a warm
and humid weekend as moist southerly/southeasterly flow
entrenches itself equatorward of the remnant front.

Perturbations in the west-southwesterly midlevel flow would move
generally parallel to this boundary, bringing occasional chances
for convection near it. Because of the uncertainty in the
placement of this boundary, its general proximity to the region,
and added uncertainty associated with the timing of these
perturbations, felt a broadbrush of slight chance to low-end
chance pops were justified through the weekend across the area.

Kept temperatures close to the previous forecast (i.E., on the
warm side) given the higher likelihood of the front not quite
making it through the area. Note that this is not an indication
that it will storm the whole weekend or even very much of it;
instead, it is an indication that there could be some storms at
some point this weekend.

Importantly, the weekend forecast is low confidence. If the
front ends up being closer to or even through the region,
temperatures will be considerably colder than forecast. However,
the trend has been to position this boundary farther north
(i.E., the amplified ridging has been forecast to be stronger)
with time, which makes sense given the blocky nature of the
pattern, so this seems like a fairly low probability outcome at
this point. One other caveat - the closer this boundary is to
the area - the better the chances for more precipitation this

By early next week, a deep, negatively-tilted trough approaches
the eastern u.S. With an attendant strong cold front moving
through the region. Widespread/strong convection will likely
develop along the front as it sweeps through the northeast on
Monday (if the timing of the model guidance is to be believed).

Pattern recognition suggests the potential for a more pronounced
severe threat as this boundary moves through. However, given the
large spread in simulations by this point, too early to get into
the finer details.

Aviation /18z Tuesday through Sunday/
The following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.

Widespread ifr conditions in place across the TAF sites for the
rest of today, and moderate to heavy rain will continue to
spread across the terminals from south to north through this
afternoon. Local/temporary lifr restrictions likely in the
heaviest rain. E-ne winds 10-15 kt with gusts to 20 kt expected
at most terminals today. Stronger winds will affect kilg, kacy,
kphl, kmiv where gusts to 30 kt are possible into this

Steady rain ends from SW to NE between 22-03z. However, do not
anticipate much improvement in the CIGS behind it with low
clouds trapped over the region. Expect ifr to lifr conditions
for most of tonight. Some of the guidance is indicating dense
fog tonight but this may be a bit overdone. Nonetheless,
restrictions from vsby are also expected.


Wednesday... Scattered showers, especially in nj. Residual low
clouds/fog possible in the morning, but conditions should
primarily beVFR by afternoon. Winds north or northeast 5 to 15
kts. Confidence below average.

Wednesday night... Low clouds and fog (MVFR/ifr) again possible
with light winds. Confidence below average.

Thursday... Winds becoming southeast and increasing to 5 to 15
kts. Potential for some gusts near the coast. Slight chance for
thunderstorms late, mainly north/west of kphl. GenerallyVFR,
except locally sub-vfr conditions near any storms. Confidence

Thursday night through Saturday... GenerallyVFR with
south/southwest winds 5 to 15 kts. Locally sub-vfr conditions
with isolated/scattered storms, especially Thursday night and
Friday. Best chances for storms near/north of kphl. Confidence

A gale warning remains in effect for the coastal waters and the
lower delaware bay today. Do not expect a long duration of
gales today with the period generally confined to 2-4 hours
(longer in the de coastal waters). It looks to be an
increasingly marginal setup the farther north you go along the
coast with it being highly uncertain if winds get to gale force
in our northern coastal waters of nj. Seas will quickly build to
7-10 ft today in concert with the surge of gale-force winds.

A SCA remains in effect for the upper de bay though the ending time
of the SCA was pushed ahead to this evening with winds quickly
ramping down as the coastal low approaches.

A SCA will be needed for the coastal waters for tonight after the
glw expires this evening or is cancelled beforehand.

A marine dense fog advisory may be needed for tonight with a
very moist airmass advecting over the relatively cool waters.

The potential for dense fog would be favored after the rain ends
this evening.


Wednesday through Friday... Sub-advisory level winds expected.

However, seas will likely remain near or above 5 feet through
the period. A chance of showers on Wednesday, and a chance of
storms late Thursday night through Friday. There may be some
restrictions to visibility Wednesday and Wednesday night from
patchy fog.

Friday night... Sub-advisory conditions expected. A chance of
thunderstorms persists, with locally gusty/erratic winds near
any storms.

Saturday... Some potential for advisory-level winds by afternoon.

A low chance of storms.

Tides/coastal flooding
A coastal flood advisory was issued for tonight for coastal
zones with minor tidal flooding expected along the de and nj
shores, in the de bay and on the far lower part of the de river.

The minor flooding should also affect the back bays and the
estuaries. This tidal flooding episode is a result of the
cumulative effects of onshore flow and the approaching new moon.

Overwhelming majority of guidance (estofs, etss and ensembles
from stevens institute) continues to predict widespread minor
coastal flooding at all of our tidal forecast points this
evening along oceanfront and de bay. The surge on top of the
base astronomical tides is expected to be a foot to a foot and a
half at that time.

With all that said, we will have to monitor the potential need
to upgrade to a warning if estofs verifies, which predicts cape
may, atlantic city and lewes will reach moderate flooding. This
appears to be an outlier solution with the setup not particularly
primed for a moderate coastal flood event.

It appears as though the tidal delaware river above the commodore
barry bridge area may just reach the minor flooding threshold.

However, the impacts should not be widespread enough there to
warrant a coastal flood advisory.

We are not anticipating any coastal flooding along the upper eastern
shore of chesapeake bay.

Phi watches/warnings/advisories
Pa... None.

Nj... Coastal flood advisory from 6 pm this evening to midnight edt
tonight for njz012>014-020>027.

Coastal flood advisory from 9 pm this evening to 1 am edt
Wednesday for njz016.

De... Coastal flood advisory from 6 pm this evening to midnight edt
tonight for dez002>004.

Coastal flood advisory from 9 pm this evening to 1 am edt
Wednesday for dez001.

Md... None.

Marine... Gale warning until 6 pm edt this evening for anz431-450>455.

Small craft advisory until 9 pm edt this evening for anz430.

Synopsis... Cms
near term... Klein/mps
short term... Klein
long term... Cms/klein
aviation... Cms/klein/mps
marine... Cms/klein/mps
tides/coastal flooding...

Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BDSP1 0 mi40 min 56°F 1013.2 hPa
PHBP1 - 8545240 - Philadelphia, PA 5 mi40 min 56°F 59°F1012.1 hPa
BDRN4 - 8539094 - Burlington, Delaware River, NJ 13 mi52 min 55°F 56°F1013.3 hPa
NBLP1 - 8548989 - Newbold, PA 20 mi40 min E 11 G 19 56°F 55°F1014.3 hPa
MRCP1 - 8540433 - Marcus Hook, PA 21 mi46 min 56°F 1011.3 hPa
RDYD1 - 8551910 - Reedy Point, DE 39 mi40 min 56°F 58°F1010.3 hPa
DELD1 - 8551762 - Delaware City, DE 39 mi40 min SSW 4.1 G 8 57°F 57°F1010.6 hPa
JCRN4 - Jacques Cousteau Reserve, NJ 45 mi58 min NE 18 55°F 1012 hPa55°F
SJSN4 - 8537121 - Ship John Shoal, NJ 49 mi40 min ENE 27 G 32 57°F 57°F1008.4 hPa

Wind History for Philadelphia, PA
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1 day
2 days

Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Philadelphia, Northeast Philadelphia Airport, PA8 mi34 minENE 146.00 miLight Rain Fog/Mist57°F55°F93%1013.9 hPa
Philadelphia, Philadelphia International Airport, PA11 mi34 minNE 15 G 244.00 miLight Rain Fog/Mist57°F54°F90%1012.4 hPa
Mount Holly, South Jersey Regional Airport, NJ13 mi34 minENE 11 G 202.00 miLight Rain Fog/Mist55°F53°F93%1013 hPa
Philadelphia - Wings Field Airport, PA15 mi53 minENE 10 G 171.50 miOvercast54°F53°F100%1014.2 hPa
Doylestown, Doylestown Airport, PA24 mi34 minVar 510.00 miOvercast54°F54°F100%1014.1 hPa

Wind History from PNE (wind in knots)
Last 24hrE11--E12E14E7E10E10E11E11NE10E9E10NE10NE10
1 day agoSE5SE5SE3CalmSE6S5S4SE3S53CalmCalmCalmE3E4NE5NE4NE5E7NE6E6E9NE9E11
2 days agoNW8NW5NW5N6W5N3NW3N13

Tide / Current Tables for Bridesburg, Philadelphia, Pennsylvania
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Tue -- 01:37 AM EDT     7.50 feet High Tide
Tue -- 05:51 AM EDT     Moonrise
Tue -- 06:07 AM EDT     Sunrise
Tue -- 08:50 AM EDT     0.30 feet Low Tide
Tue -- 01:58 PM EDT     7.23 feet High Tide
Tue -- 06:56 PM EDT     Moonset
Tue -- 07:49 PM EDT     Sunset
Tue -- 09:10 PM EDT     0.40 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Tide / Current Tables for Philadelphia, Pennsylvania Current
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Tue -- 02:02 AM EDT     -0.00 knots Slack
Tue -- 05:34 AM EDT     -2.25 knots Max Ebb
Tue -- 05:52 AM EDT     Moonrise
Tue -- 06:08 AM EDT     Sunrise
Tue -- 09:09 AM EDT     0.00 knots Slack
Tue -- 11:09 AM EDT     2.07 knots Max Flood
Tue -- 02:24 PM EDT     -0.01 knots Slack
Tue -- 05:45 PM EDT     -2.22 knots Max Ebb
Tue -- 06:56 PM EDT     Moonset
Tue -- 07:49 PM EDT     Sunset
Tue -- 09:29 PM EDT     0.00 knots Slack
Tue -- 11:32 PM EDT     2.20 knots Max Flood
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 (14,3,4,5)
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Ground Weather Radar Station Philadelphia, PA
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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.