Friday, December15, 2017 L-36.com


Marine Weather and Tides
Butler, 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 7:17AMSunset 4:44PM Friday December 15, 2017 9:09 AM EST (14:09 UTC) Moonrise 4:38AMMoonset 3:22PM Illumination 8% Phase: Waning Crescent; Moon at 27 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- 632 Am Est Fri Dec 15 2017
.small craft advisory in effect from this evening through Saturday evening...
Today..S winds 5 kt. Waves flat. A chance of snow this morning, then snow this afternoon. Vsby 1 to 3 nm.
Tonight..W winds 10 to 15 kt with gusts to 20 kt. Waves 1 to 2 ft. A chance of snow. Vsby 1 to 3 nm.
Sat..W winds 10 to 15 kt. Gusts up to 20 kt... Increasing to 25 kt in the afternoon. Waves 1 to 2 ft.
Sat night..N winds 5 to 10 kt. Waves 1 ft or less.
Sun..S winds 5 kt. Waves less than 1 ft.
Sun night..SW winds around 5 kt. Waves 1 ft or less. A chance of rain.
Mon..SW winds around 5 kt. Waves flat.
Tue..W winds 5 to 10 kt. Waves 1 ft.
ANZ500 632 Am Est Fri Dec 15 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A low pressure system will develop as it moves up the coast today into tonight. High pressure will return on Saturday before weak low pressure possibly impacts the waters early next week.

7 Day Forecast for Marine Location Near Butler, MD
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location: 39.3, -76.17     debug


Area Discussion for - Philadelphia/Mount Holly, PA
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Fxus61 kphi 151112
afdphi
area forecast discussion
national weather service mount holly nj
612 am est Fri dec 15 2017

Synopsis
A surface low will move from the carolinas early this morning to
offshore the mid-atlantic tonight. High pressure will build into
southeast canada, allowing a backdoor cold front to move into or
through the area Saturday night and Sunday. This front will then
stall before lifting northward as a warm front Sunday night and
Monday. A cold front will progress through the region around the
middle of next week. Another system may affect the area near the
close of next week.

Near term until 6 pm this evening
The biggest weather story for our area today is the potential for
snow through the afternoon.

Changes from the previous forecast: based on the latest high
resolution model runs, adjusted the pops primarily west of the
i95 corridor up as it looks like the snow could continue further
west than previously forecast. However, the further west from
the coast, the drier the boundary layer, so still expect snow
totals near or below one inch. Therefore, no plans to expand or
change the winter weather advisory at this time.

Synoptic and mesoscale pattern: in the mid and upper levels, a
positively-tilted short wave trough will be propagating east through
the day at the same time that the low over northwestern mexico
transitions to a cutoff low. At the surface, a low currently over
the carolinas, will lift northeast as it deepens and intensifies (in
response to the approaching mid and upper level trough). At this
point there doesn't appear to be a strong signal for significant
mesoscale banding as the jet in the upper level is off set
significantly to the north from the mid level jet. Additionally, the
theta E ridge and MAX frontogenesis on the north side of the
surface low look to stay well off shore of our region.

Locations: it generally looks like the favored area will still be
along and southeast of the interstate 95 corridor. There will likely
be a sharp drop off in snow along or northwest of 95, but given the
potential timing, have erred on the side of caution with including
delaware and philadelphia counties in the winter weather
advisory.

Precipitation type: mostly snow except along coastal delaware. Some
models indicate that there may not be ice crystals in the clouds to
start the event, but given the satellite trends, it looks like
seeder-feeder high clouds should arrive over our region well before
precipitation begins, leading to a negligible freezing rain threat.

Along the delaware coast, the center of the surface low is expected
to get close enough to the coast to result in a rain snow mix and
periods of all rain.

Temperatures: with the exception of coastal delaware, most of the
area will see high temperatures near or below freezing, which is
about 10 to 15 degrees below normal.

Short term 6 pm this evening through 6 am Saturday
The previously mentioned surface low quickly lifts away from our
region, with snow ending from southwest to northeast. A surface high
is expected to build over the southeastern u.S. As a result
over our region, low and mid level northwesterly flow will
increase. However, through the overnight hours, it does not look
like a favorable fetch for lake effect snow to reach the
southern poconos, so have kept the region dry after midnight.

Temperatures should be higher than what we saw this morning,
thanks to lingering cloud cover. Lows are expected to be in the
teens and 20s across the region.

Long term Saturday through Thursday
The large-scale pattern in the long term will change somewhat
with fairly zonal flow across much of the eastern u.S. Next
week. However, the flow will remain progressive, with numerous
systems passing near or through the region during the period.

This weekend's forecast is a little tricky in a few respects.

Though two surface highs will build into eastern north america
(one in southeast canada and the other in the southeastern
u.S.), a deformation axis will form in between, with onshore
flow equatorward of the canada high allowing for a backdoor cold
front to move into the mid-atlantic Saturday and Saturday night.

The differences among the models are rather pronounced, with
statistical guidance varying between the warmer Saturday cooler
Sunday (ecs) and vice versa (met mav). The warm look of the ecs
on Saturday looks questionable given the antecedent cold near-
surface air and potential for additional snow cover in portions
of the area. Furthermore, the low levels will feature warm-air
advection as a weakening midlevel perturbation rapidly
progresses to the mid-atlantic by Sunday night. Nevertheless,
the source region of the surface flow on Sunday will likely be
onshore, and this makes me hesitant to go with considerably
warmer values this day. I went on the low side of consensus
both days, especially Saturday (with residual effects of snow
cover and heights that do not rise significantly until dark).

With backdoor cold fronts, there is always a worry of
fog stratus, which is not readily apparent in much of the
guidance. The pattern is not overly favorable, with the surface
high a bit west of where it needs to be for more favorable (and
stronger) onshore flow.

Then there is the matter of a northern-stream perturbation
moving through new england on Saturday, which may generate
enough lift (with favorable northwesterly low-level fetch) to
bring some snow showers to the poconos. The 00z ECMWF even
suggests this could spread east-southeast into the lehigh valley
and northern new jersey. For now, kept the pops confined to
mainly carbon, monroe, and sussex (nj) counties with the caveat
that these may need expansion southeastward should the ECMWF be
on to something.

The aforementioned weak perturbation moving into the region
Sunday night may generate some light rain or snow in the area,
especially north of the mason-dixon line. The models are
uniformly unimpressed with the system, which is unsurprising
given its weakening phase. One thing to watch will be its track,
though, which is a little uncertain given the influence of a
northern-stream kicker and the always unknown position of the
backdoor front (typically farther south than progged this far
out). With a slightly southward track (one reason the ECMWF is
colder on Sunday), the isentropically-generated lift precip on
Sunday night spreads over more of the area. Meanwhile, the gfs
looks rather sparse save for areas north of i-78. Plenty of
uncertainty here, so kept fairly low broad pops. The 00z cmc,
notably, is more in agreement with the ecmwf.

A surface low develops and moves through southeast canada Monday
night and Tuesday, but models generally keep the strongest lift
north of the region. The 00z GFS looks suspiciously wet so far
south of the system, though it is noticeably deeper with the
attendant trough. There also appears to be more phasing with a
southern-stream perturbation near the gulf coast. There is a lot
of uncertainty here, given that the southern-stream perturbation
stems from a trailing upper low in the southwest, and the
evolution of these systems is generally of low predictability.

At 18z Tuesday, the 00z ECMWF has two distinct southern-stream
vorticity maxima in association with the southwest upper low,
whereas the GFS has a single (stronger) entity (with typical
long-range timing errors, too), with the disparities between
the two giving me little confidence forecasts will remain like
they are now. With all of this said, I do not have a lot of
confidence to change the forecast from what I inherited until
model agreement improves. Main changes were to bring in a
distinct dry period on Monday (after the first perturbation
passes) and keep low pops in Tuesday with this second system.

Qpf impacts from both of these systems look low minor at this
time.

There should be a distinct warming trend Monday and Tuesday
given the midlevel ridging that develops in advance of the
canada surface low. Temperatures on Tuesday could be around ten
degrees above seasonal averages.

Another deep trough enters the western u.S. Near the end of next
week, which should regenerate zonal flow or even slight ridging
east of the rockies during this period. This will bring a
period of dry and seasonable weather (cooling after frontal
passage midweek, with warm advection returning thereafter). A
potentially strong surface low looks to develop in the central
plains during this period and will move east or northeast via a
strong southwesterly jet streak. The models are all over the
place with effects to the mid-atlantic, with potential for
plenty of warm-sector precip near the end of the week (gfs) or
frontolysis limiting the precipitation generated in our area
(ecmwf) or a frontal wave developing and generating a low that
crosses much closer to the area (cmc).

At this point, kept Wednesday and Thursday fairly dry, but
there may be another chance for some precip near the end of the
week.

Aviation 11z Friday through Tuesday
The following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.

Today... StartingVFR through much of the morning, but MVFR ceilings
are expected to move in around 18z. In addition, snow is expected,
primarily along and east of the delaware valley which will result in
MVFR, and localized ifr, visibility. Confidence is moderate on both
flight categories and timing.

Tonight... Conditions should improve back toVFR between 00 and 03z.

Northwesterly wind gusts up to 20 kt will be possible at kacy. For
the rest of the TAF sites, northwesterly winds will generally be
near or below 10 kt.

Outlook...

Saturday: generallyVFR, with snow showers possible in the poconos
and vicinity. West winds 10 to 15 kts with gusts around 20 kts or
so. High confidence.

Saturday night: generallyVFR with light and variable winds. There
is a low chance of sub-vfr CIGS vsbys if stronger onshore flow
develops. Medium confidence.

Sunday: generallyVFR, with increasing cloudiness late. Light east
or southeast winds. Medium confidence.

Sunday night and Monday: generallyVFR, though brief sub-vfr
conditions are possible with light rain or snow, especially north of
phl. Light winds generally transitioning from southeast to southwest
during the period. Low confidence.

Monday night and Tuesday: sub-vfr conditions possible, with
scattered showers during the period, especially on Tuesday. Winds
primarily between south and west at 5 to 15 kts. Medium
confidence.

Marine
Today... Winds and seas should stay below small craft advisory
criteria.

Tonight... Northwesterly winds will increase, primarily after
midnight. On the atlantic coastal waters, wind gusts right around
gale force are possible, but still uncertain. Therefore, have issued
a gale watch for these locations. On the delaware bay, small craft
advisory conditions are likely.

Outlook...

Saturday: westerly gales possible in the morning, with advisory-
level winds likely during the afternoon. Fair weather.

Saturday night: residual advisory-level northwest winds in the
evening will diminish overnight. Seas below criteria. Fair weather.

Sunday and Sunday night: no headlines anticipated. There may be some
light rain off the new jersey coast, with potential for some
visibility restrictions.

Monday and Monday night: no headlines anticipated. Mainly fair
weather, but there could be some showers off the new jersey coast at
times during the period.

Tuesday: southwest winds increasing to near or above advisory levels
by afternoon, with seas also building. A chance of showers and
attendant visibility restrictions.

Phi watches warnings advisories
Pa... Winter weather advisory from 1 pm this afternoon to 9 pm est
this evening for paz070-071.

Nj... Winter weather advisory from 1 pm this afternoon to 9 pm est
this evening for njz016>027.

De... Winter weather advisory from 1 pm this afternoon to 9 pm est
this evening for dez001>003.

Md... Winter weather advisory from 1 pm this afternoon to 9 pm est
this evening for mdz008-012-015-020.

Marine... Gale watch from late tonight through Saturday morning for
anz450>455.

Small craft advisory from 1 am to 6 pm est Saturday for anz430-
431.

Synopsis... Cms
near term... Johnson
short term... Johnson
long term... Cms
aviation... Cms johnson
marine... Cms johnson


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
TCBM2 - 8573364 - Tolchester Beach, MD 7 mi52 min E 2.9 G 6 26°F 38°F1019.6 hPa
FSNM2 20 mi52 min E 7 G 8.9 28°F 1018.5 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 20 mi52 min ENE 7 G 8 28°F 1019.3 hPa
BLTM2 - 8574680 - Baltimore, MD 22 mi52 min ESE 6 G 8 28°F 46°F1018.8 hPa
CPVM2 24 mi52 min 29°F 11°F
CHCM2 - 8573927 - Chesapeake City, MD 25 mi58 min N 1 G 1.9 25°F 37°F1020.2 hPa
APAM2 - 8575512 - Annapolis, MD 27 mi52 min 30°F 1018.7 hPa
TPLM2 - Thomas Point, MD 31 mi70 min ESE 8.9 G 9.9 29°F 44°F
RDYD1 - 8551910 - Reedy Point, DE 36 mi52 min 26°F 41°F1019.6 hPa
DELD1 - 8551762 - Delaware City, DE 36 mi52 min SE 5.1 G 7 27°F 37°F1019.9 hPa
DRSD1 - Delaware Reserve, DE 41 mi160 min Calm 26°F 1020 hPa16°F
SJSN4 - 8537121 - Ship John Shoal, NJ 42 mi52 min ENE 5.1 G 7 26°F 43°F1019.5 hPa
BSLM2 - Chesapeake Bay, MD 46 mi160 min ENE 1.9 28°F 1020 hPa13°F

Wind History for Tolchester Beach, MD
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Baltimore / Martin, MD14 mi85 minN 010.00 miOvercast28°F14°F55%1020.3 hPa
Baltimore, Inner Harbor, MD23 mi76 minno data mi29°F12°F49%1019.5 hPa
Bay Bridge Field, MD24 mi85 minno data10.00 miOvercast28°F10°F47%1020 hPa

Wind History from APG (wind in knots)
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Last 24hrSE3CalmCalmCalmSW5W5W5W8W8NW10
G19
NW8NW7NW8NW9CalmNW8CalmNW4CalmCalmCalmN3N6N4
1 day agoW6W13
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W5CalmCalmCalmSW11SW7CalmSE3
2 days agoS4S7S5SE3S7S5SE6CalmSW6SW5SW3SW7SW7W4NW5
G17
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Tide / Current Tables for Worton Creek entrance, Maryland
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Worton Creek entrance
Click for Map
Fri -- 12:24 AM EST     0.13 feet Low Tide
Fri -- 04:37 AM EST     Moonrise
Fri -- 05:15 AM EST     0.97 feet High Tide
Fri -- 07:17 AM EST     Sunrise
Fri -- 11:40 AM EST     -0.26 feet Low Tide
Fri -- 03:21 PM EST     Moonset
Fri -- 04:42 PM EST     Sunset
Fri -- 06:21 PM EST     1.50 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.10.20.30.60.810.90.70.50.2-0.1-0.2-0.3-0.10.20.611.31.51.51.31.10.80.5

Tide / Current Tables for Baltimore Harbor Approach, Maryland Current
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Baltimore Harbor Approach
Click for Map
Fri -- 12:42 AM EST     0.00 knots Slack
Fri -- 03:06 AM EST     0.48 knots Max Flood
Fri -- 04:38 AM EST     Moonrise
Fri -- 05:36 AM EST     -0.00 knots Slack
Fri -- 07:17 AM EST     Sunrise
Fri -- 08:43 AM EST     -0.69 knots Max Ebb
Fri -- 11:29 AM EST     0.00 knots Slack
Fri -- 03:11 PM EST     1.14 knots Max Flood
Fri -- 03:23 PM EST     Moonset
Fri -- 04:44 PM EST     Sunset
Fri -- 06:42 PM EST     -0.00 knots Slack
Fri -- 09:56 PM EST     -0.99 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
-0.30.10.40.50.40.2-0.1-0.4-0.6-0.7-0.5-0.20.20.711.11.10.80.3-0.1-0.6-0.9-1-0.9

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 (9,2,3,4)
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Ground Weather Radar Station Dover AFB, DE
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weather_mapweather_map weather_map

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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.