Saturday, November18, 2017 L-36.com


Marine Weather and Tides
West Chatham, MA

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 6:33AMSunset 4:19PM Saturday November 18, 2017 12:25 PM EST (17:25 UTC) Moonrise 7:23AMMoonset 5:50PM 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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ANZ254 Coastal Waters From Provincetown Ma To Chatham Ma To Nantucket Ma Out 20 Nm- 1104 Am Est Sat Nov 18 2017
.gale warning in effect from 7 pm est this evening through late Sunday night...
This afternoon..SW winds 5 to 10 kt, increasing to 10 to 15 kt with gusts up to 25 kt. Seas 2 to 4 ft.
Tonight..S winds 10 to 15 kt, increasing to 15 to 20 kt after midnight. Gusts up to 30 kt. Seas 5 to 8 ft. A chance of rain.
Sun..SW winds 20 to 25 kt. Gusts up to 30 kt, increasing to 45 kt in the afternoon. Seas 7 to 10 ft, except 9 to 14 ft S and E of nantucket. Patchy fog. Showers likely. Vsby 1 nm or less.
Sun night..W winds 20 to 25 kt with gusts up to 35 kt. Seas 6 to 9 ft.
Mon..W winds 20 to 25 kt with gusts up to 35 kt. Seas 5 to 8 ft.
Mon night..W winds 20 to 25 kt with gusts up to 35 kt. Seas 4 to 7 ft.
Tue..SW winds 15 to 20 kt with gusts up to 30 kt. Seas 3 to 5 ft.
Tue night..SW winds 15 to 20 kt with gusts up to 30 kt. Seas 4 to 6 ft.
Wed..W winds 10 to 15 kt with gusts up to 20 kt. Seas 3 to 5 ft. A chance of showers.
Wed night..N winds 10 to 15 kt with gusts up to 25 kt. Seas 2 to 4 ft. A chance of showers. Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height.
ANZ200 1104 Am Est Sat Nov 18 2017
Synopsis for massachusetts and rhode island coastal waters.. High pressure over the waters this morning gives way to intensifying low pres tracking across the saint lawrence river valley Sat night and Sun, with its attending strong cold front sweeping across the new england waters Sun afternoon. Ssw gales ahead of the front and wnw gales behind the front Sun night into Monday. High pres then builds into the waters Tue followed by another cold front moving across new england Wed. For information on possible hazardous weather beyond the 24-36 hour forecast period, please visit www.weather.gov/boston and follow the current hazards link above the map on the left.

7 Day Forecast for Marine Location Near West Chatham, MA
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location: 41.73, -69.97     debug


Area Discussion for - Boston, MA
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Fxus61 kbox 181456
afdbox
area forecast discussion
national weather service taunton ma
956 am est Sat nov 18 2017

Synopsis
High pressure and dry weather much of today. A warm front
approaches the region late with rain overspreading the area
toward sunset into evening. Strengthening low pressure moves
across W ny state tonight with warm air, strong winds and
showers impacting southern new england. The attending cold front
sweeps across the area midday Sunday with strong winds ahead
and behind the front. Dry and cold conditions move across the
region Sunday night and Monday. Mild and dry weather Tuesday
ahead of a cold front which brings a risk for showers Tuesday
night and Wednesday, followed by dry and colder weather
thanksgiving day.

Near term until 6 pm this evening
10 am update...

dry weather with increasing clouds. If the 12z soundings are any
indication, there is still a lot of dry air in place with both
albany, upton, and chatham observing precipitable waters, the
total amount of moisture throughout the column if it were
squeezed out, around 0.22 inches. SW isentropic ascent ongoing
along the 290-310k surfaces over the oh river valley as initial
mid-level energy pushes E against the retreating ridge of high
pressure over new england, it'll take some time for the column
to moisten allowing precipitation to reach the surface. Clouds
gradually lowering and thickening with time, looking at rain
moving in closer to sunset and overspreading the region into
evening. S winds on the increase as surface low pressure deepens
across the E great lakes towards a model consensus of 985 mb by
7 pm.

Filtered sunshine along with warm S flow, looking at highs
rebounding into the mid to upper 40s, low 50s along the S se
coast, from widespread overnight lows around the 20s with spot
locations in the upper teens. Coolest conditions across the N w
high terrain. Increasing surface dewpoints into the 40s will
give somewhat a more mild feel to the air.

Short term 6 pm this evening through 6 pm Sunday
Early am update...

*** strong ssw winds south coastal ma and ri ***
*** possible fine line of low convection ***
tonight and Sunday morning...

wind threat...

strong low level jet overspreads the south coast tonight. Good
agreement from models on magnitude of jet 55-60 kt at 925 mb. Model
soundings initially show low level lapse rates favorable this
evening for 35-40 kt transfer in gusts. But as the night progresses
strong WAA steepens low level inversion with gusts becoming less of
a factor and sustained winds becoming the main issue with speeds 25-
30 kt. This will be sufficient to support wind advisory for the
entire south coast including CAPE cod and the islands.

Rain and convective threat...

periods of rain with warm front lifting north across the region.

Impressive warm sector for mid to late nov overspreads the area late
tonight with dew pts surging to 55-60! Thus temps will rise
overnight toward 60 in the coastal plain. This will set the stage
for a potential fine line of low top convection toward daybreak
Sunday from west to east. Short wave energy merges into a negative
tilt trough approaching the region toward 12z Sunday. Also a strong
upper level jet streak of 130 kt approaches from the southwest 12z
Sunday with lfq over southern new england, enhancing QG forcing. In
addition very strong frontal convergence as low pres deepens to 982
mb over ny state. Thus very strong forcing for ascent in a high
shear environment. With dew pts rising to near 60 a few hundred
joules of CAPE advects across the area, anomalous for mid to late
nov. However limiting factor for convection is marginal low and mid
level lapse rates. So question becomes will there be sufficient
instability to yield a strong response at the surface in the form of
fine low of convection. Unfortunately model timeframe here is 36-42
hrs, on edge of our mesoscale guid with hrefv2 only out to 36 hrs.

However the ncar ensembles, arw and nmmb all hint at possible fine
line in simulated reflectivity fields. For now will insert slight
chance thunder with gusty winds and heavy downpours as pwats climb
to 1.5 inches (+2 standard deviations).

Sunday afternoon...

*** strong post frontal winds likely ***
979 mb low traversing northern new england st lawrence river valley
will yield strong pres gradient, post frontal CAA and impressive
pres rise-fall couplet for a period of strong wnw post frontal winds
Sunday afternoon with speeds of 40 to 50 mph possible. Later shifts
will have to evaluate model trends for possible issuance of wind
advisories for Sunday afternoon. Drying trend behind the FROPA along
with temps falling from morning highs near 60.

Long term Sunday night through Friday
Highlights...

* strong w-nw winds linger Sunday night into Monday
* some question whether moisture tries to work up the eastern
seaboard around the Tue night Wed timeframe as cold front passes
* temperatures fluctuate day to day, from mild to cold back to mild
again through most of the work week
overview...

overall mid level steering pattern across the lower 48 remains
progressive through most of the long term periods. However,
noting some members of the 00z model suite try to dig a long
wave h5 trough along the eastern seaboard around the late
Tuesday into Wednesday timeframe, which may try to capture some
southern stream moisture and push it up the eastern seaboard as
a cold front passes across the region. The trough appears to
retreat northward late Wed night or thu, then becomes nearly
zonal in the northern stream by the end of next week while
another northern stream trough starts to dig into the pacific
northwest.

Models and ensembles continue to signal fluctuating temperatures
as progressive short wave troughs and ridges move across the
region. So, will see mild temps ahead of approaching frontal
systems, then a cool down after the systems pass. By the end of
the week, temps may feel more like early winter than late
autumn.

Used a blend of available guidance for the majority of the
forecast, though opted closer to a 00z ggem ECMWF blend for tue
night Wed with possible influx of moisture into the region ahead
and with the approaching cold front.

Details...

Sunday night through Monday night...

h5 short wave digs across into E pa N nj and steadily shifts e
which will bring another shot of cooler air as well as gusty
w-nw winds. As the strong surface low, on order of sub-980 hpa
across N maine into the gulf of st lawrence will exit with a
tight pressure gradient in place. Also, both the GFS and nam
bufkit soundings showing deep momentum transfer, possibly up to
800 hpa across inland areas from Monday morning through early
afternoon. There is also excellent low level lapse rates up to
h85, up to 8-9c km. So, could see gusts up to 35 to 45 mph,
possibly higher across the higher inland terrain and along the
coast at times. Have kept mention of the potential of strong
gusts in the hwo for this timeframe.

Expect dry conditions during this time, but some question
whether any lake effect snow bands may reach into western areas
during Monday on the strong w-nw winds. At this point, kept a
dry forecast going.

Strong cold air advection continues behind the departing low,
with h85 temps down to -10c to -12c overnight into Monday
morning and not changing much during the day Monday. So, expect
highs possibly holding in the lower-mod 30s across the higher
terrain of N central and NW mass, ranging to 40-45 across the
coastal plain. With the gusty winds, it will feel more like the
upper teens to mid 20s inland to 30-35 along the shore.

Tuesday...

high pressure builds across the mid atlantic and SE states,
with northern ridging passing across the region. Winds will back
to SW by Tue afternoon as the high pushes off the coast. Could
see gusts up to 25-30 kt along the immediate S coast, CAPE cod
and the islands late in the day. May see some mid and high
clouds work into western areas Tue afternoon. Will likely see
the mildest temps of the week during this time as highs are
forecast to be in the 45-50 degree range inland and the mid 50s
across N ct to the coastal plain.

Tuesday night and Wednesday...

cold front approaches, so will see clouds increase. Associated
low pressure will shift across southern ontario and quebec in
the fast flow aloft. There are some questions as to the
evolution of the eastern u.S. Pattern during this timeframe, as
there is wide model solution spread handling the h5 pattern.

Some models trying to dig an h5 trough to the mid atlantic or se
u.S. While one model member actually cuts off h5 low across s
ga fl.

At this point, the front should push offshore, but the big
question will be whether the timing of the front and a weakness
in the h5 pattern may be enough to allow some southern stream
moisture to work NE along the eastern seaboard across the
region. At this point, have introduced chc pops Tue night into
wed, then shift E late Wed into Wed night. Have lower confidence
due to wide solution spread.

Expect highs on Wed to run close to or just above seasonal
normals, though temps will start to fall as NW winds take over
later wed.

Thanksgiving and Friday...

at this point, looks like dry conditions will be in place at
the end of next week as high pressure ridge builds in from the
west as the northern stream steering flow becomes nearly zonal.

Some clouds may push in across the CAPE and islands on Friday as
low pressure passes well SE of the region.

Looks to be a chilly thanksgiving day with highs only in the
mid 30s to around 40 inland and the lower-mid 40s at the shore.

It may be a bit milder on Friday, with highs mainly in the 40s,
but some upper 30s may linger across the higher inland terrain.

Aviation 15z Saturday through Wednesday
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Sunday ...

1145z update...

today... High confidence.

ExpectVFR with dry conditions. The exception will be across
western ma N central ct where MVFR conditions in light rain
will increase between 21z-00z. Light winds this morning
increase sharply this afternoon from the s-sw with gusts
approaching 30 kts by sunset (22z). Elsewhere s-sw winds
increasing to 10-15 kt.

Tonight... High confidence.

Vfr-MVFR to start in areas of light rain but trending toward
ifr-MVFR after midnight. Strong s-sw 20-25g45kt winds along the
south coast including CAPE cod and islands. Elsewhere winds not
as strong and this results in llws across much of ri and
eastern ma including bos.

Sunday... Moderate confidence.

Some uncertainty on probability of -tsra and areal coverage
along and ahead of strong cold front.

MVFR-ifr with widespread showers, some with locally heavy
downpours. Could be a fine line of low top showers with embedded
thunder roughly 15z-18z. Gusty winds may accompany this
convection. Strong ssw winds 20-25g45kt continue along the south
coast including CAPE cod and islands. Away from the south coast
expect llws to continue thru the morning across ri and eastern
ma. Then a strong cold front sweeps across the area late morning
into the early afternoon, with improving conditions behind the
front and a wind shift to the west.

Kbos terminal... High confidence in TAF thru 00z, then some
timing issues on arrival of lower CIGS and rain. Period of
rough weather tonight into midday Sunday with llws along with
+shra. Isolated thunder possible 15z-18z Sunday, then strong
cold front sweeps across the area with improving conditions
after 18z Sunday.

Kbdl terminal... High confidence in TAF thru 21z, then some
timing issues on arrival of lower CIGS and rain. Unsettled
weather tonight into Sunday morning with +shra and possible
isolated thunder.

Outlook Sunday night through Wednesday ...

Sunday: mainlyVFR, with local ifr possible. Strong winds with
gusts to 45 kt. Shra likely, patchy br.

Sunday night through Monday:VFR. Windy with gusts to 35 kt.

Monday night:VFR. Windy with gusts to 30 kt.

Tuesday:VFR. Breezy.

Tuesday night: mainlyVFR, with local MVFR possible. Breezy.

Chance shra, slight chance fzra.

Wednesday: mainly MVFR, with areasVFR possible. Breezy. Chance
shra.

Marine
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Sunday ... High confidence.

Today...

light winds this morning with high pressure overhead. S-sw
winds increase this afternoon and approach gale force by late in
the day.

Tonight...

s-sw gales along with poor vsby in showers and fog.

Sunday...

strong cold front sweeps across the region late morning and early
afternoon, with ssw prefrontal gales and wnw gales behind the front.

Showers, locally heavy in the morning along with fog but improving
with the wind shift.

Outlook Sunday night through Wednesday ...

Sunday: moderate risk for gale force winds with gusts up to
45 kt. Rough seas up to 17 ft. Rain showers likely, slight
chance of thunderstorms, patchy fog. Local visibility 1 to
3 nm.

Sunday night: moderate risk for gale force winds with gusts up
to 35 kt. Rough seas up to 13 ft.

Monday: moderate risk for gale force winds with gusts up to
35 kt. Rough seas up to 11 ft.

Monday night: low risk for gale force winds with gusts up to
35 kt. Areas of rough seas.

Tuesday: moderate risk for small craft advisory winds with
gusts up to 30 kt. Local rough seas.

Tuesday night: moderate risk for small craft advisory winds
with local gusts up to 30 kt. Areas of rough seas. Chance of
rain showers.

Wednesday: winds less than 25 kt. Local rough seas. Chance of
rain showers.

Box watches warnings advisories
Ct... None.

Ma... Wind advisory from 10 pm this evening to 5 pm est Sunday for
maz020>024.

Ri... Wind advisory from 10 pm this evening to 5 pm est Sunday for
riz005>008.

Marine... Gale warning from 5 pm this afternoon to 6 am est Monday for
anz232>234.

Gale warning from noon to 11 pm est Sunday for anz230.

Gale warning from 1 am Sunday to 6 am est Monday for anz231-
251.

Gale warning from 7 pm this evening to 7 pm est Sunday for
anz236.

Gale warning from 3 pm this afternoon to 6 am est Monday for
anz235-237-255-256.

Gale warning from 7 pm this evening to 6 am est Monday for
anz250-254.

Synopsis... Nocera evt
near term... Nocera sipprell evt
short term... Nocera
long term... Evt
aviation... Nocera evt
marine... Nocera evt


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
44090 20 mi26 min 51°F1 ft
44020 - NANTUCKET SOUND 23 mi36 min SSW 3.9 G 3.9 46°F 50°F1 ft1012.3 hPa (-2.6)37°F
WAXM3 - Waquoit Bay Reserve, MA 31 mi101 min 1 45°F 1014 hPa31°F

Wind History for Nantucket Island, MA
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Last
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chatham, Chatham Municipal Airport, MA2 mi34 minVar 310.00 miFair46°F30°F56%1012.8 hPa
Hyannis, Barnstable Municipal-Boardman Airport, MA17 mi30 minSW 410.00 miFair45°F32°F61%1011.8 hPa
Provincetown Municipal Airport, MA23 mi30 minSSW 710.00 miFair45°F21°F39%1012.1 hPa

Wind History from CQX (wind in knots)
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Last 24hrNW9
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NW74SW3SW4W4W3CalmW3CalmCalmSW43
1 day agoSE9
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5W76
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2 days agoNE7NE8NE5N3N3CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmE5E3E3SE5SE8SE10
G18
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Tide / Current Tables for Pleasant Bay, Quonset Pont, Massachusetts
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Pleasant Bay
Click for Map
Sat -- 01:06 AM EST     3.10 feet High Tide
Sat -- 06:22 AM EST     Moonrise
Sat -- 06:33 AM EST     Sunrise
Sat -- 06:42 AM EST     New Moon
Sat -- 07:57 AM EST     0.08 feet Low Tide
Sat -- 01:17 PM EST     3.44 feet High Tide
Sat -- 04:16 PM EST     Sunset
Sat -- 04:50 PM EST     Moonset
Sat -- 08:27 PM EST     -0.19 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
2.83.132.72.31.810.30.10.41.12.133.43.332.521.20.4-0.1-0.10.41.3

Tide / Current Tables for Pollock Rip Channel, Massachusetts Current
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Pollock Rip Channel
Click for Map
Sat -- 02:53 AM EST     0.00 knots Slack
Sat -- 06:21 AM EST     2.07 knots Max Flood
Sat -- 06:22 AM EST     Moonrise
Sat -- 06:32 AM EST     Sunrise
Sat -- 06:42 AM EST     New Moon
Sat -- 09:11 AM EST     -0.00 knots Slack
Sat -- 12:07 PM EST     -1.83 knots Max Ebb
Sat -- 03:09 PM EST     0.00 knots Slack
Sat -- 04:17 PM EST     Sunset
Sat -- 04:50 PM EST     Moonset
Sat -- 06:43 PM EST     2.23 knots Max Flood
Sat -- 09:41 PM EST     -0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
-1.8-1.5-0.80.111.7221.30.2-0.9-1.6-1.8-1.7-1.1-0.20.81.62.12.21.80.8-0.3-1.2

Weather Map and Satellite Images
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Weather Map
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IR Satellite Image from GEOS
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GOES Local Image of Northeast    EDIT
Geos

Wind Forecast for Boston, MA (12,3,4,5)
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Ground Weather Radar Station Boston, MA
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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.