Saturday, June24, 2017 L-36.com


Marine Weather and Tides
Chelsea, MA

Version 3.4
What's New / NOTES
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 5:06AMSunset 8:26PM Saturday June 24, 2017 1:29 AM EDT (05:29 UTC) Moonrise 5:50AMMoonset 8:55PM Illumination 0% Phase: New Moon; Moon at 0 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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ANZ230 Boston Harbor- 116 Am Edt Sat Jun 24 2017
Rest of tonight..SW winds 10 to 15 kt with gusts up to 20 kt. Seas around 2 ft. A slight chance of showers and tstms. Some tstms may produce heavy rainfall.
Sat..SW winds 10 to 15 kt with gusts up to 20 kt, becoming W 5 to 10 kt in the afternoon. Seas around 2 ft. Showers likely with a chance of tstms. Some tstms may produce heavy rainfall.
Sat night..W winds 5 to 10 kt. Gusts up to 20 kt in the evening. Seas around 2 ft.
Sun..SW winds 5 to 10 kt. Seas around 2 ft.
Sun night..W winds 5 to 10 kt. Gusts up to 20 kt in the evening. Seas around 2 ft.
Mon..SW winds 5 to 10 kt with gusts up to 20 kt. Seas around 2 ft.
Mon night..SW winds around 5 kt. Seas around 2 ft.
Tue..SW winds around 5 kt. Seas 1 foot or less. A chance of showers.
Tue night..W winds around 5 kt. Seas 1 foot or less.
Wed..W winds around 5 kt. Seas 1 foot or less.
Wed night..SW winds around 5 kt. Seas 1 foot or less. Winds and seas higher in and near tstms. 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 116 Am Edt Sat Jun 24 2017
Synopsis for massachusetts and rhode island coastal waters.. A cold front will approach the waters from the west tonight while the remnants of tropical storm cindy approach from the southwest. The cold front will sweep across the waters Saturday afternoon and behind it drier and less humid air will follow into 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 Chelsea, MA
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location: 42.37, -71.06     debug


Area Discussion for - Boston, MA
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Fxus61 kbox 240217
afdbox
area forecast discussion
national weather service taunton ma
1017 pm edt Fri jun 23 2017

Synopsis
Mild, humid air continues tonight out ahead of the remnants of
cindy which will bring the threat of showers and thunderstorms
through the first part of Saturday. A cold front will sweep the
remnants of cindy out to sea through late Saturday, improving
overnight. Seasonably warm and less humid conditions Sunday will
be followed by cooler weather and few diurnally driven showers
and isolated thunderstorms Monday and Tuesday. A return to
summer-like warmth and humidity is expected by the end of the
work week.

Near term until midnight tonight
10 pm update...

let's keep it simple. Scattered showers and thunderstorms are
expected tonight given the broad tropical moist plume and the
remnants of cindy out ahead of a mean long-wave mid-level trough
axis digging S E out of the great lakes.

Particular focus is on any forcing mechanisms, and broadly
speaking there are two of focus: 1.) convergent forcing and
subsequent frontogenesis along the nose of h925-85 winds which
are starting to amplify with the tightening baroclinic zone
between the aforementioned trough axis and NW atlantic high
pressure. Exacerbating theta-e convergence beneath favorable
venting per westerly flow aloft. And 2.) along and ahead of a
cold front sweeping S E parent with the mid-level trough.

Expecting overnight clusters of showers and thunderstorms that
may pose an isolated, localized threat of nuisance flooding.

None of the forecast guidance is quite locking in on one area.

Just given the general synoptics and the sultry, tropical air-
mass, the upstream activity over the mid-atlantic should
maintain with the absence of dry air downstream as observed from
latest 0z soundings. There aren't any clear indications as to
why scattered wet-weather will not continue overnight. So chance
pops continue accordingly.

The much stronger signal comes towards morning as the remnants
of cindy are flushed N E with the mean wind out ahead of the
sweeping cold front which acts as a lifting mechanism. Ahead of
the mid-level long-wave trough axis and parent elongated vortmax,
indications of forced ascent beneath falling heights and an
accompanying jet streak. It is these sharp dynamics that strongly
indicate the likelihood of outcomes, especially across SE new
england where there is the possibility of marginal instability
that could aid in the invigoration of cindy remnants, yielding
the development of strong thunderstorms, possible severe weather.

Then again it may just end up benign.

The simple takeaway here is to keep our heads up, maintain an
awareness, and be prepared for anything. As the previous
forecaster alluded to, this is a tricky forecast. We are dealing
with an anomalous setup with very high atmospheric moisture
content, and with any squeeze put on the environment, and the
stronger that squeeze, there is the threat for some measure of
flooding, and incorporating instability and shear as was observed
upstream earlier today, there is the possibility of strong to
severe weather.

We'll keep analyzing it through the night, especially as 0z
guidance becomes available. Please see the discussion below
which touches on Saturday interpreted from earlier forecast
guidance.

Previous discussion...

overnight lows will remain mild, dropping into the upper 60s to
low 70s. This may result in another round of fog and stratus
with the highest confidence across the south coast once again.

May need to watch for a possible dense fog advisory as surface
dewpoints will be in the 70s. Muggy to start the day tomorrow
but depending on how quickly the front will push through, the
later half of the day will begin to improve. Highs will remain
in the mid 80s.

Short term midnight through 6 pm Saturday
Into Saturday...

* increasing localized flood potential for southern new england
active weather pattern for the first half of tomorrow as S new
england remains in the warm sector for this period.

Biggest focus is on precipitation potential. Increasing moisture
will begin to pool into the area with pwat values increasing to
above 2.5 inches. This tropical moisture from cindy will push
pwat near 3 to 4 std above normal. In fact, moisture flux values
at 850 mb during this timeframe is nearing 4 std above normal.

Thus within any heavy shower, the potential for flooding rains
is possible.

Models are struggling with the placement of the axis of heavy
precipitation as there are several features to note. Aside from the
approaching front out west, a LLJ will be across the southeast
portion of the area. However, the higher instability values will be
across the western half of the area. If both of these features
could align, then we could see widespread heavy rainfall. But
because there is some separation, believe that the threat is more
localized. Again the heavy rainfall axis amongst the guidance are
in different locations, but there is agreement that the potential
for over 1.5 to 2 inches. If this falls in just a few hours, then
flash flooding is possible. Best timing for this to occur will be
after midnight and into Saturday morning.

Cold front sweeping through the region. Latest hi-res guidance
is a lot slower than synoptic models so have blended the forecast
down the middle. More widespread showers and embedded thunderstorms
are anticipated along the frontal passage. Convection along the
front continues to be a possibility especially across eastern
ma during the late morning hours. CAPE values will be near 1000
j kg with 40 kts of 0-6 km shear. The caveat is poor lapse rates
and the bulk of the moisture will be pushing offshore. One thing
to watch for is the potential for a quick spin-up thanks to the
tropical airmass with 70f dewpoints and lower lcls. Hodographs
do show some helicity and good 0-1 km shear. The frontal system
should push through by Saturday afternoon resulting in clearing
skies and drier air as westerly flow takes hold.

Long term Saturday night through Friday
Highlights...

* seasonably warm less humid Sun with a spot shower t-storm possible
* a few showers iso t-storms possible Mon Tue but not a washout
* below normal temps Mon Tue return to summerlike readings Thu fri
details...

Saturday night...

dry and a much less humid airmass will work into the region behind
Saturday's cold front. This should allow low temps to fall into the
50s across many outlying locations, to between 60 and 65 in some of
the urban centers.

Sunday...

a pleasant end to the weekend across southern new england. 850
temps between +11c and +12c should allow highs to reach into the
lower to middle 80s in most locations, but dewpoints in the 50s will
make it feel much more comfortable outside. Mainly dry weather
anticipated, but approaching shortwave may be enough to trigger an
isolated shower t-storm or two by mid-late afternoon across the
interior.

Monday and Tuesday...

anomalous upper trough cold pool aloft overhead will result in
slightly below normal temps with comfortable humidity levels. Highs
mainly in the 70s are expected both days. The cold pool
aloft shortwave energy will result in the potential for a few
diurnally driven showers isolated thunderstorms both days. Not
expecting a washout by any means, but the main risk for any activity
will be during the afternoon early evening hours.

Wednesday...

axis of upper trough will probably have shifted to the east of the
region. This should allow temps to warm a few more degrees than
mon Tue and result in mainly dry weather. However, if trough ends up
slower than currently expected there would be the risk for a few
more showers isolated thunderstorms.

Thursday and Friday...

upper trough lifts northeast of the region with rising height
fields. This should result in a warming trend for the end of the
work week, with a return to summerlike warmth and humidity.

Aviation 02z Saturday through Wednesday
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Saturday ... Moderate confidence.

Tonight into Saturday... Moderate confidence. MVFR to ifr
conditions expected into Saturday morning. Low risk of lifr
conditions along the south coast in fog, but enough wind in the
boundary layer may prevent that from happening. Scattered
showers and thunderstorms mainly late tonight into early sat
afternoon.

Improving conditions from west to east around midday ahead of a
wind shift from the w. Prior to the wind shift will continue to
see SW winds with potential gusts 25 to 30 kts llws possible
for SE coastal terminals as is some embedded tsra. Improving
towards evening to low-endVFR skc.

Kbos terminal... Moderate confidence in taf.

Kbdl terminal... Moderate confidence in taf.

Outlook Saturday night through Wednesday ...

Saturday night through Wednesday... High confidence. MainlyVFR
conditions other than a few mainly diurnally driven showers and
perhaps isolated t-storms.

Marine
Sw gusts up to 25 to 30 kts through early Saturday prior to a
cool frontal passage. Waves building around 5 to 7 feet on the
waters as the remnants of cindy are advected NE around the
morning hours. Prior to and during this time, likely to be
either a combination of low clouds and fog with visibility down
to a quarter mile or less possible. Improving late Saturday as
winds become westerly while beginning to diminish along with
wave action.

Outlook Saturday night through Wednesday ...

Saturday night through Wednesday... Moderate to high confidence.

Quiet boating weather overall during this time period. A few hours
of near shore lower 20 knot wind gusts and choppy seas are possible
on both Sun and Mon afternoons.

Tides coastal flooding
Astronomical tides are rather high through this weekend during the
night time cycles. Boston has a 12.3 ft tide just before midnight
tonight, a 12.4 ft high tide around midnight Sat night and 12.2 ft
just after midnight Sun night. While, offshore winds are forecast
current conditions suggest a 0.4 surge which will result in
minor splashover. Thus will go ahead an issue a coastal flood
statement for tonight's high tide.

Box watches warnings advisories
Ct... None.

Ma... None.

Ri... None.

Marine... Small craft advisory until 3 pm edt Saturday for anz231>234.

Small craft advisory until 8 pm edt Saturday for anz235-237-
250-254>256.

Synopsis... Frank dunten
near term... Frank sipprell
short term... Dunten
long term... Frank
aviation... Frank dunten
marine... Frank dunten
tides coastal flooding... WFO box staff


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BHBM3 - 8443970 - Boston, MA 1 mi41 min 74°F 1000.5 hPa
44013 - BOSTON 16 NM East of Boston, MA 22 mi39 min SSE 9.7 G 12 64°F 58°F2 ft1001.8 hPa (-0.9)
44029 - Buoy A0102 - Mass. Bay/Stellwagen 28 mi85 min S 12 G 14 64°F 60°F3 ft1001.3 hPa
FOXR1 - 8454000 - Providence, RI 43 mi41 min SW 6 G 13
PVDR1 44 mi41 min SSW 8.9 G 12 75°F 1002.3 hPa71°F
FRVM3 - 8447386 - Fall River, MA 46 mi41 min 71°F 72°F1003.5 hPa
BLTM3 - 8447387 - Borden Flats Light at Fall River, MA 46 mi41 min SSW 13 G 19 71°F 1002.1 hPa
FRXM3 47 mi41 min 71°F 69°F
IOSN3 - Isle of Shoals, NH 47 mi29 min S 19 G 19 68°F 1000.4 hPa (-1.0)67°F
CPTR1 - 8452944 - Conimicut Light, RI 48 mi41 min SSW 15 G 18 73°F 73°F1002.9 hPa
BGXN3 - Great Bay Reserve, NH 49 mi104 min SW 5.1 76°F 1002 hPa71°F

Wind History for Providence, RI
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Boston, Logan International Airport, MA2 mi35 minS 1010.00 miMostly Cloudy73°F70°F90%1001.2 hPa
East Milton, MA11 mi33 minS 11 mi70°F68°F93%1002.6 hPa
Norwood, Norwood Memorial Airport, MA14 mi36 minS 69.00 miPartly Cloudy73°F71°F94%1001.6 hPa
Bedford, Hanscom Field, MA14 mi33 minSSW 610.00 miPartly Cloudy74°F69°F85%1001.7 hPa
Beverly, Beverly Municipal Airport, MA16 mi36 minSW 910.00 miMostly Cloudy76°F72°F88%1000.4 hPa

Wind History from BOS (wind in knots)
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1 day agoW9W10W8--W7W4W7W7CalmSE7E7SE8W115CalmNW9W9NW9W8W7S9S6SW9SW9
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Tide / Current Tables for Charlestown Bridge, Charles River, Massachusetts
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Charlestown Bridge
Click for Map
Sat -- 05:08 AM EDT     Sunrise
Sat -- 05:50 AM EDT     Moonrise
Sat -- 05:53 AM EDT     -1.87 feet Low Tide
Sat -- 12:06 PM EDT     10.73 feet High Tide
Sat -- 06:07 PM EDT     -0.76 feet Low Tide
Sat -- 08:25 PM EDT     Sunset
Sat -- 08:55 PM EDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1210.47.84.71.5-1.1-1.9-0.71.64.47.49.810.710.28.45.830.5-0.702.35.28.310.9

Tide / Current Tables for Boston Harbor, Massachusetts Current
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Boston Harbor
Click for Map
Sat -- 02:46 AM EDT     -1.48 knots Max Ebb
Sat -- 05:08 AM EDT     Sunrise
Sat -- 05:44 AM EDT     0.00 knots Slack
Sat -- 05:50 AM EDT     Moonrise
Sat -- 08:40 AM EDT     1.44 knots Max Flood
Sat -- 11:34 AM EDT     -0.00 knots Slack
Sat -- 03:14 PM EDT     -1.33 knots Max Ebb
Sat -- 06:03 PM EDT     0.00 knots Slack
Sat -- 08:24 PM EDT     Sunset
Sat -- 08:46 PM EDT     1.47 knots Max Flood
Sat -- 08:54 PM EDT     Moonset
Sat -- 11:54 PM EDT     -0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
-0.7-1.2-1.4-1.5-1.4-0.80.31.21.41.41.20.5-0.3-0.9-1.2-1.3-1.3-1-0.111.41.51.30.8

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

GOES Local Image of Northeast    EDIT
Geos

Wind Forecast for Boston, MA (1,6,7,8)
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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.