Monday, August21, 2017 L-36.com


Marine Weather and Tides
Elkton, 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 6:20AMSunset 7:51PM Monday August 21, 2017 12:00 PM EDT (16:00 UTC) Moonrise 5:04AMMoonset 6:56PM 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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ANZ530 Chesapeake Bay North Of Pooles Island- 1031 Am Edt Mon Aug 21 2017
.small craft advisory in effect from Tuesday afternoon through Tuesday evening...
Rest of today..SE winds 5 to 10 kt. Waves 1 ft or less. A chance of showers and tstms this afternoon.
Tonight..S winds 5 to 10 kt. Waves 1 ft. A chance of showers and tstms.
Tue..S winds 10 to 15 kt with gusts to 20 kt. Waves 1 ft or less.
Tue night..SW winds 10 to 15 kt. Gusts up to 20 kt in the evening. Waves 1 to 2 ft. A chance of showers and tstms.
Wed..NW winds 5 to 10 kt. Waves 1 ft or less.
Wed night..N winds around 5 kt. Waves 1 ft or less.
Thu..N winds 5 kt. Waves less than 1 ft.
Fri..N winds 5 kt. Waves less than 1 ft. Winds and waves higher and visibilities lower in and near tstms.
ANZ500 1031 Am Edt Mon Aug 21 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure will move offshore today. A cold front will cross the waters late Tuesday night into early Wednesday. High pressure will return for the second half of the week.

7 Day Forecast for Marine Location Near Elkton, MD
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location: 39.57, -75.85     debug


Area Discussion for - Philadelphia/Mount Holly, PA
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Fxus61 kphi 211315
afdphi
area forecast discussion
national weather service mount holly nj
915 am edt Mon aug 21 2017

Synopsis
High pressure centered over the coastal mid atlantic will begin
to move offshore today. The high will shift farther out to sea
on Tuesday while a cold front approaches from the midwest. The
cold front is expected to move through the region early
Wednesday and then stall nearby to our south Wednesday afternoon
and evening. Canadian high pressure building into the region on
Thursday will continue to influence our weather through the
upcoming weekend.

Near term until 6 pm this evening
Only minor updates needed to reflect current temperature and sky
cover trends.

All eyes on the sky today (but hopefully not directly at the sun). A
colleague here said that this was the most important sky cover
forecast of my career. So of course it would not be an easy one.

There are three issues that complicate the forecast of clouds today.

The first, and probably most important, is the developing cumulus
field with diabatic heating. Model soundings and cross sections
indicate increasing low-level moisture through the day and are
strongly suggestive of at least scattered to possibly broken cumulus
by afternoon, especially from the delaware river westward.

Forecasting the extent of this deck of clouds is a challenge (and
unfortunately, rather low-skill, even in the short range). The
latest high-resolution guidance points to a somewhat slower onset of
these clouds, which is obviously good, but has also trended somewhat
denser with the clouds (given somewhat higher moisture content in
the 900-700 mb layer).

In the larger-scale, a low-amplitude vort MAX will be progressing
into pennsylvania today (issue #2), and there will be attendant
ascent just downstream. With smaller-scale lift associated with
orographic effects and differential heating (via sky cover
gradients, e.G.), convection is expected to develop to our west this
afternoon. The timing of convective initiation looks to be early
afternoon, but the placement should be comfortably west of the cwa
(at least at onset). However, with large-scale ascent present, this
may further aid the development of a thicker low-cloud deck, and the
anvils from developing convection may advect rapidly eastward into
eastern pennsylvania. General thinking is that the greatest area of
concern is in the poconos and near reading. There are also some
convection-allowing models (cams) that develop a couple showers this
morning in delmarva, and residual clouds from any showers that
develop here may be a hindrance to eclipse viewing.

Upper-level moisture will also be available, and high cirrus may be
result (issue #3). However, latest model progs suggest a rather thin
layer would be present, and this may be dwindling with time (at
least during the day) given a departing jet streak.

With all of the above in mind, the current sky cover forecast is
fairly optimistic east of the delaware river (generally mostly
sunny), somewhat more pessimistic from the lehigh valley west and
northwest (increasing cloudiness this afternoon) and in between in
delmarva (partly to mostly sunny). Enjoy the show.

Other big concern today is storm chances. The environment is
decently favorable for organized storms capable of isolated strong
to severe wind gusts and hail. MUCAPE will approach exceed 2000 j kg
this afternoon in the far western cwa, and effective shear will be
increasing through the day as the aforementioned vort max
approaches. Cape-shear parameter space will become favorable for
severe storms this afternoon and evening, and cams are suggestive of
scattered, semi-discrete storms developing in the higher terrain of
central pennsylvania moving eastward into the area late this
afternoon. Included mention of gusty winds, hail, and heavy rain
with storms generally west of philadelphia during this period. With
scattered coverage and questions regarding timing, have no more than
chance pops in the grids at the moment.

Forecast temps are a blend of gfs ECMWF nam MOS with a bit of
continuity and cam-based 2-m temperatures added to the blend. It
should feel noticeably more uncomfortable today with increasing
surface moisture.

Short term 6 pm this evening through 6 am Tuesday
Main forecast concerns tonight are precipitation chances and
fog stratus development.

Cams are not overly optimistic in maintaining convection after
sunset, and this makes sense given little in the way of surface
support for smaller-scale lift. Nevertheless, the presence of a
passing vort MAX leaves me concerned, especially since these have
been poorly simulated in general this summer. Notably, another vort
max should be moving through northern pennsylvania late tonight, and
may provide glancing ascent to the northern portions of the cwa
during this time. Global coarser models are keeping precipitation
chances around for much of the night in the area, with cams
generally showing little to nothing after 03z. With such disparity,
i find it difficult to remove pops entirely or to elevate them
beyond slight to low-chance during the period. Notably, met MOS pops
went way up with the 00z package, and I have a hard time trending
the opposite direction of statistical guidance.

Meanwhile, some guidance (notably, the nam, as per usual) develops
low clouds and or fog in portions of the area tonight. I am somewhat
skeptical, given that a shortwave trough will be moving through
during the evening early overnight hours. With attendant lift
associated with this and the aforementioned upstream vort max, cloud
cover may be too prevalent to get more than patchy fog in the usual
valley rural spots. The chance for low stratus seems more pronounced
as warm moist advection will be in full swing during the overnight
hours (downstream of a much more potent vort MAX moving into the
great lakes region). Combined with uncertainty regarding
precipitation forecast, only mentioned fog in the lehigh
valley poconos NW nj region for now, though patchy fog certainly
cannot be ruled out elsewhere.

Low temps were a combination of MOS guidance and should be a few
degrees above seasonal averages across the region. It will be muggy
thanks to increased dew points.

Long term Tuesday through Sunday
On Tuesday, a longwave trough associated with an upper low near
james bay is forecast to amplify over the great lakes region as
shortwave energy digs around the backside of the trough. The
surface low will deepen in response to increasing height falls
as it tracks northeastward across ontario and quebec. The
attendant cold front will progress eastward through the midwest.

Looking farther downstream and closer to our area, models show
development of a pre- frontal lee trough over central pa and
potomac highlands during the afternoon hours.

Tuesday will clearly be the hottest of the next 7 days with
forecast highs in lower 90s (except cooler 80s near the coast
and at higher elevations in NE pa NW nj). The humidity will also
be a factor with dewpoints reaching the mid 70s across delmarva
and southern nj and lower 70s just about everywhere else. Peak
heat indices in the upper 90s to near 100f are likely for the
urban i-95 corridor and points south east.

With the expectation that focused lift will remain to our west
near the pre-frontal trough on Tuesday, convection over the
forecast area will likely be disorganized and generally isolated
in coverage (perhaps widely scattered across NE pa where the
terrain could locally enhance lift) during the afternoon.

Slightly better chances for showers and storms arrive Tuesday
evening as convection along this trough propagates eastward into
our area. Pops are highest in our far western zones (west of
the delaware valley and near the eastern shore of md). Showers
and storm are then expected to move eastward into the delaware
valley and coastal plain at night as the cold front catches up
with the pre-frontal trough and moves into the area. Even though
the environment should be supportive of showers and storms
continuing into the night owing to the arrival of deep synoptic
lift, pops decrease slightly with eastward extent due to some
uncertainty concerning the intensity and coverage of convection
later with the nocturnal boundary layer tending to stabilize
further into the night.

The approach of a low- and mid-level jet ahead of the cold front
will yield increasing shear profiles (0-6 km bulk shear 35-45 kt) by
evening. Additionally, weak to moderate amount of instability
(mlcape 1500 to 2000+ j kg) is forecast to be available to fuel
convective updrafts. Some storms could be strong to severe,
primarily during the afternoon and evening hours, with this
setup. The latest d2 convective outlook from SPC includes the
southern poconos in a slight risk for severe storms with a
marginal risk extending southeastward into the i-95 corridor.

The latest 00z models have trended faster with the cold front as it
moves through eastern pa and nj early Wednesday morning. The front
will then likely slow down when it reaches DELMARVA and perhaps
eventually stall just south of the area across southern va Wednesday
afternoon. Accordingly, it is looking more probable that the
majority of the forecast area dries out on Wednesday, especially
north of the mason-dixon line. While pops were also lowered farther
south, the close proximity to the cold front means that there is
still a chance that showers and storms linger into the day.

Additionally, some of the models (most prominently, the 00z nam)
develop a wave of low pressure along the stationary front in
southeastern va. More organized convection could shift back
northward toward DELMARVA and possible far southern nj by evening.

High pressure over canada and the great lakes region then starts to
build southeastward toward the area on Thursday. This expansive high
will remain in control through the weekend. The end result will be
an extended stretch of pleasant weather Thursday through Sunday.

Highs in the upper 70s lower 80s and and lows ranging from the mid
50s to lower 60s are forecast each day and night, respectively.

While the forecast remains dry for these four days, there looks to
be increasing cloud cover heading into the weekend and potentially a
risk for an isolated shower with 1) the approach of the upper trough
and 2) light onshore flow helping to moisten low-levels over
time.

Aviation 13z Monday through Friday
The following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.

Cumulus field will develop during the day, with bases generally
in the 4-6 kft range. Retained prob30 -tsra to krdg kabe given
somewhat increased confidence that convection will move into
eastern pa late this afternoon into the evening hours. Generally
increasing cloud cover from this afternoon through tonight, and
latest guidance shows at least some potential for sub-vfr
cigs vsbys Monday night. Winds generally light variable through
15z, then becoming mostly southerly 5-10 kts.

Outlook...

Tuesday... Early morning fog should dissipate by mid morning, leading
toVFR for most of the day. Showers and storms develop during the
afternoon but current thinking is coverage should initially be
isolated and mainly confined to western terminals (abe rdg).

Tuesday night... Potential for MVFR or ifr restrictions with
slightly higher chances for showers and storms. This activity
should progress to the east-southeast through the night.

Wednesday... Scattered showers and isolated thunderstorms mainly
for terminals S E of phl and earlier in the day. May start off
MVFR with lower CIGS but improvement toVFR is likely from nw
to SE during the day. A wind shift from SW to NW can be expected
early in the day W fropa.

Wednesday night through Friday...VFR and light winds.

Marine
Generally tranquil conditions on the waters today, though southerly
winds should pick up this afternoon evening. Speeds should attain 5-
15 kts with gusts to 20 kts or so, especially off the new jersey
coast. Seas will generally range from 2 to 3 feet. There may be some
patchy fog early this morning, but this should dissipate rapidly
after sunrise.

Outlook...

Tuesday... SCA was issued for the atlantic coastal waters of nj
and de for late Tuesday afternoon and night. S-sw winds are
expected to strengthen late in the day to 15-25 kt. Isolated
gusts to 30 kt are possible mainly during the evening when the
winds will be strongest. Seas will quickly build in response to
the wind field to 4-6 ft.

Wednesday... A wind shift from SW to w-nw should occur on
Wednesday behind a cold front. Winds will also decrease as well.

There is still a possibility that the SCA may need to be
extended into Wednesday morning if seas take a bit longer to
subside below 5 ft.

Thursday and Friday... Winds and seas below SCA criteria.

Rip currents...

the rip current risk has been upgraded to moderate for today,
mainly from late this afternoon through this evening, when a
longer-period swell develops (around 9-10 seconds), seas begin
to increase, and southerly winds increase to around 15 kts with
higher gusts. The combination of the above factors and the
presence of a new moon suggests the rip current risk will be
increasing through the day. As such, felt best to raise the risk
to moderate.

Tides coastal flooding
Based on observations yesterday evening and current projections
for the high tide this evening, will hold off on issuing a
coastal flood advisory this morning. Current model projections
continue to indicate levels reaching near minor flood thresholds
but consistently below advisory thresholds. Spotty minor
flooding is probable this evening, but confidence is too low at
this point to issue an advisory. Nonetheless, there is some
concern that a more onshore component of the wind (south to
possibly south-southeast) may contribute to somewhat higher
levels than guidance suggests this evening. Should this be
observed during the day, the threat for minor flooding would
increase.

Phi watches warnings advisories
Pa... None.

Nj... None.

De... None.

Md... None.

Marine... Small craft advisory from 3 pm Tuesday to 6 am edt Wednesday
for anz450>455.

Synopsis... Klein
near term... Cms di spigna
short term... Cms
long term... Klein
aviation... Cms klein
marine... Cms klein tides coastal
flooding...



Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
CHCM2 - 8573927 - Chesapeake City, MD 4 mi43 min SSW 5.1 G 5.1 81°F 83°F1023.4 hPa
44057 - Susquehanna, MD 12 mi31 min S 5.8 G 5.8 81°F 1022.8 hPa
DELD1 - 8551762 - Delaware City, DE 14 mi43 min S 6 G 8 82°F 77°F1023.2 hPa
RDYD1 - 8551910 - Reedy Point, DE 15 mi43 min 85°F 81°F1022.9 hPa
MRCP1 - 8540433 - Marcus Hook, PA 28 mi43 min 80°F 1022.8 hPa
SJSN4 - 8537121 - Ship John Shoal, NJ 31 mi43 min SSE 12 G 12 78°F 80°F1022.9 hPa
TCBM2 - 8573364 - Tolchester Beach, MD 32 mi43 min S 6 G 13 81°F 81°F1023.1 hPa
44043 - Patapsco, MD 41 mi31 min S 12 G 14 80°F 1023.1 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 43 mi43 min SE 8 G 9.9 81°F 1022.3 hPa
BLTM2 - 8574680 - Baltimore, MD 44 mi43 min S 4.1 G 8.9 83°F 83°F1022 hPa
PHBP1 - 8545240 - Philadelphia, PA 45 mi43 min 88°F 78°F1022.5 hPa
CPVM2 49 mi43 min 81°F 76°F

Wind History for Chesapeake City, MD
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Wilmington, New Castle County Airport, DE15 mi70 minSSE 710.00 miPartly Cloudy81°F66°F61%1023.2 hPa
Phillips Army Air Field / Aberdeen, MD18 mi63 minSSW 87.00 miMostly Cloudy82°F69°F66%1023.6 hPa

Wind History from ILG (wind in knots)
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Last 24hr4N45W8W10NW7NW5NW3CalmCalmCalmNW3NW4CalmNW3NW4CalmCalmCalmCalmCalmSE7S7SE9
1 day agoNW6
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W6NW7SW3SW5W5W7NW9NW8W5NW5N5N4--4
2 days agoSW7SW4SW8S11
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Tide / Current Tables for Old Frenchtown Wharf, Maryland
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Old Frenchtown Wharf
Click for Map
Mon -- 03:20 AM EDT     0.65 feet Low Tide
Mon -- 06:03 AM EDT     Moonrise
Mon -- 06:21 AM EDT     Sunrise
Mon -- 09:57 AM EDT     4.25 feet High Tide
Mon -- 02:31 PM EDT     New Moon
Mon -- 04:51 PM EDT     0.93 feet Low Tide
Mon -- 07:50 PM EDT     Sunset
Mon -- 07:56 PM EDT     Moonset
Mon -- 10:12 PM EDT     3.18 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
21.40.90.70.71.11.82.73.54.14.34.13.62.92.21.51.10.91.21.72.42.93.23.1

Tide / Current Tables for Chesapeake and Delaware Canal, Maryland/Delaware Current
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Chesapeake and Delaware Canal
Click for Map
Mon -- 12:46 AM EDT     -2.36 knots Max Ebb
Mon -- 04:38 AM EDT     0.03 knots Slack
Mon -- 06:03 AM EDT     Moonrise
Mon -- 06:21 AM EDT     Sunrise
Mon -- 07:26 AM EDT     2.37 knots Max Flood
Mon -- 11:04 AM EDT     -0.09 knots Slack
Mon -- 01:30 PM EDT     -1.76 knots Max Ebb
Mon -- 02:31 PM EDT     New Moon
Mon -- 04:51 PM EDT     0.01 knots Slack
Mon -- 07:34 PM EDT     2.08 knots Max Flood
Mon -- 07:50 PM EDT     Sunset
Mon -- 07:56 PM EDT     Moonset
Mon -- 10:17 PM EDT     -0.08 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
-2.3-2.4-2.2-1.8-1.211.92.32.321.50.4-1.3-1.7-1.7-1.5-1.10.51.5221.70.8-1.2

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

GOES Local Image of Mid-Atlantic    EDIT
Geos

Wind Forecast for Philadelphia/Mount Holly, PA (12,3,4,5)
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Ground Weather Radar Station Dover AFB, DE
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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.