Thursday, July18, 2019 L-36.com


Marine Weather and Tides
Chelsea, MA

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Sunrise 5:21AMSunset 8:19PM Thursday July 18, 2019 1:46 PM EDT (17:46 UTC) Moonrise 9:40PMMoonset 6:50AM Illumination 97% Phase: Waning Gibbous; Moon at 16 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 Pm Edt Thu Jul 18 2019
This afternoon..NE winds 5 to 10 kt with gusts up to 20 kt. Waves around 2 ft. A chance of showers.
Tonight..NE winds 5 to 10 kt. Waves 1 foot or less. A chance of showers.
Fri..NE winds around 5 kt, becoming S around 5 kt in the afternoon. Waves 1 foot or less.
Fri night..SW winds 5 to 10 kt. Waves 1 foot or less.
Sat..SW winds around 5 kt. Gusts up to 20 kt in the afternoon. Waves 1 foot or less.
Sat night..W winds around 5 kt. Waves 1 foot or less.
Sun..SW winds around 5 kt. Waves 1 foot or less.
Sun night..W winds around 5 kt. Waves 1 foot or less. A chance of showers. Vsby 1 to 3 nm.
Mon..N winds around 5 kt. Waves 1 foot or less. A chance of showers. Vsby 1 to 3 nm.
Mon night..W winds around 5 kt. Waves 1 foot or less. A chance of showers. Vsby 1 to 3 nm. 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 Pm Edt Thu Jul 18 2019
Synopsis for massachusetts and rhode island coastal waters.. The remnants of barry will pass across the waters today, then will head offshore this evening. High pres builds across northern new england today, bringing e-ne winds across the waters. The high will move E across nova scotia tonight. South to southwest winds will bring increasing heat and humidity Fri and Sat. A cold front will slowly approach on Sunday, bringing a chance for showers and Thunderstorms which may linger into Mon. 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 181426
afdbox
area forecast discussion
national weather service boston norton ma
1026 am edt Thu jul 18 2019

Synopsis
Today will feature plenty of clouds with a few showers, perhaps
briefly heavy along the south coast. The showers will push
offshore tonight. A warm front will push across late Friday into
Friday evening, ushering in hot and humid conditions through
Sunday with heat related headlines likely. Will also be watching
for a some possible thunderstorm activity. A sweeping cold
front Monday with a scattered line of showers and thunderstorm
Monday behind which relief in the form of seasonable
temperatures, lower humidity is on tap into late july.

Near term until 6 pm this evening
1025 am update...

weak low pressure over long island sound (basically the remnants
of "barry") is moving east and will be offshore by later today.

Low level winds have turned northeast across most of the region
in response to the low, bringing in some cooler air. Lots of low
level moisture, so plenty of clouds and some showers scattered
about. For the most part expect the higher chance for rain to be
across ri south coast of ma CAPE & islands closer to the track
of the low. Instability is lacking, so I did take out mention of
t-storms today, though with the high precipitable water values
(2.16" from 12z chatham sounding and 2.43" from 12z okx
sounding) brief heavy downpours are not out of the question.

Hi-res models do show scattered showers continuing through the
day, but primarily across the south. That said, some pesky
showers have also formed around boston, but thinking those
should fade away in the next few hours as the best forcing is
farther south.

Made some tweaks to the pop forecast, but at this point have
left the temperature and wind forecasts as is. Should start to
see a few breaks in the clouds, especially north and west, as
the afternoon progresses.

Short term 6 pm this evening through 6 pm Friday
Tonight...

showers and a few thunderstorms linger across mainly from
central mass NE ct eastward this evening. May see some localized
flooding in any heavy downpours especially across ri SE mass
where the higher pwat values (around 2.3 inches) will be
located, as well as a slow moving front.

The convection should end by around midnight, but showers will
linger into the early morning hours before shifting slowly e.

Patchy fog will also develop in the humid airmass.

Expect readings to bottom out in the lower-mid 60s across most
areas as the precip pushes offshore.

Friday...

a weak high pres ridge builds across early Friday, so should
see mainly dry conditions weather wise through the day. However,
dewpoints will slowly rise to the lower 70s during the
afternoon. Light northerly winds will shift to s-sw during the
midday and afternoon hours.

H85 temps will rise to 16c to 18c, possibly reaching 20c by
midday across the ct valley. This translates to temps rising to
upper 80s to lower 90s away from the S coast. The combination of
high temperatures and dewpoints means heat indices could reach
the mid to upper 90s across the ct valley and interior E mass.

Long term Friday night through Wednesday
Big picture...

zonal flow continues across the northern half of the usa
Saturday while subtropical high pressure controls the southern
half. The subtropical high builds north over the western usa
Sunday through Wednesday. Meanwhile, shortwave energy ejects
from a closed low over the north pacific and races east. This
shortwave eventually merges with a closed upper low over hudsons
bay, and the combined system digs over the northeast usa as the
western upper ridge builds.

Normal 500-mb heights for mid july are 580 to 582 dm. Forecast
heights build to 591 dm over the weekend, then trend lower from
late Sunday through Wednesday as the upper trough digs in. From
this, we expect above-normal temperatures Friday night through
Sunday, then a trend to near normal temperatures early next
week.

General agreement among the model mass and thermal fields
through the weekend. The fields early next week show a similar
general pattern with small differences. Overall forecast
confidence is moderate-high, but confidence in timing of the
cold fronts early next week is low-moderate.

Concerns...

Friday night through Sunday...

high pressure surface and aloft builds over southern new
england. Plenty of hot air with this high, which should keep
the airmass rain free for much of the weekend. The best chance
for any showers will be late Sunday as the high diminishes.

High pressure and subsidence should give us a period of rain-
free weather. The airmass in place will have pw values around 2
inches through the weekend, and is also expected to have
surface dew points 70 to 75. Mixing to 850 mb will tap
temperatures of 21c-23c, which would support MAX sfc temps of
96f-101f. This is at or near record territory. We continue to
list high temp records and high min temp records in our climate
section below. The combination of these factors leads to heat
index values of 100 to 110, except 90s on the south coast. At a
minimum, much of the area will require a heat advisory... Some
places may eventually need an excessive heat warning. In
anticipation, we will be issuing an excessive heat watch for
Saturday with this package.

Model precipitation fields continue to show measurable showers
to our north and to our south on Saturday. Surface-based cape
values in our area Saturday range from 2000 to 4000 j kg, totals
are 50-55, LI is -6 to -9. That's a lot of instability
available for convection. But how tough will it be to break
through the hot air into the deeper atmosphere? Temperatures at
700 mb on Saturday continue to be forecast at 13c. It would take
a surface temperature near 110f to support dry adiabatic lift
past that level. How about moist adiabatic lift from 850 mb to
700 mb? Well, that might do it except that the forecast
soundings for Saturday are quite dry aloft, leaving little
moisture for cloud or rain development which would be needed for
a moist adiabatic trace. Because of that, we are forecasting
pops below 15 pct Saturday and Saturday night.

The ridge will diminish Sunday, but the effects from Saturday
should linger into at least part of Sunday. Temperatures at 850
mb will be 20-23c supporting high sfc temps of 95 to 100. Dew
points will be in the upper 60s and lower 70s, so another muggy
day. The 700 mb temps will relax below 10c late in the day,
especially north of a bos-hfd line. Higher moisture amounts will
move into the mixed layer, associated with an approaching weak
cold front. Expect a hot and humid day with a chance of
thunderstorms... Best chance north of the mass pike. Leftovers
from the thunder could affect southern areas Sunday night before
they fade away.

Monday through Wednesday...

a more substantial cold front moves south through our area
Monday. This front will have better dynamic support as the upper
jet shifts south into ny and northern new england. Expect
scattered showers thunderstorms with the frontal passage.

As the upper trough digs more over the northeast usa, it is
possible the Monday cold front stalls south of new england.

Shortwaves moving through the trough could then generate waves
along the front which could bring a chance of showers Tuesday.

Best of all, lower dew point air works down from the north and
should overspread the region Tuesday and Wednesday.

Aviation 14z Thursday through Monday
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Friday ... Moderate confidence.

Today...

fairly widespread MVFR conditions, with a few locations briefly
ifr (either due to visibilty reductions in showers, or lower
ceilings primarily ri southeast ma and CAPE islands). Expect
those conditions to more or less continue through the day. Could
be someVFR across northern ct and western ma as we get into the
afternoon as ceilings lift and perhaps scatter out some.

Tonight...

areas of ifr-lifr CIGS will continue across central and eastern
areas, withVFR to local MVFR CIGS across N central and NW mass
through most of the night. Vsbys will be mainlyVFR, but lower
to ifr across ri SE mass and to lifr at times across the outer
cape and nantucket. Sct showers and a few thunderstorms may
linger across central and eastern areas this evening but should
push offshore during the night.

Friday...

areas of ifr-lifr CIGS early Fri morning will improve toVFR by
mid to late morning from w-e. MVFR CIGS may linger through
midday across CAPE cod and the islands.

Kbos terminal... Moderate confidence in taf.

Kbdl terminal... Moderate confidence in taf.

Outlook Friday night through Monday ... High confidence.

Friday night: mainlyVFR, with local ifr possible in patchy br.

Saturday:VFR. Breezy.

Saturday night:VFR.

Sunday: mainlyVFR, with local MVFR possible late. Slight
chance shra, isolated tsra.

Sunday night: mainlyVFR, with local ifr possible. Chance shra,
slight chance tsra, patchy br.

Monday: mainly MVFR, with areasVFR possible. Chance shra,
slight chance tsra.

Marine
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Friday ... High confidence.

Today... Showers will continue along the southern waters. Areas
of fog will also reduce visibility mainly across the waters
from CAPE cod southward. Will see a brief period of NE wind
gusts of 20 to 25 knots across the waters E of CAPE ann to
boston harbor, where a small craft advisory has been posted
through midday. Seas 4 ft or less.

Tonight...

showers will linger through around midnight, along with
isolated thunderstorms, then should push slowly offshore
overnight. Patchy fog will also linger. Light e-ne winds will
shift to N overnight. Seas 4 ft or less, highest on the southern
waters.

Friday...

leftover showers near CAPE cod and the island will push
offshore by mid morning. Expect good visibility. Light N winds
shift to SW up to 10-15 kt during the day. Gusts up to 20 kt
during the afternoon. Seas 4 ft or less, highest across the
southern waters.

Outlook Friday night through Monday ... High confidence.

Friday night through Saturday night: winds less than 25 kt.

Seas locally approaching 5 ft.

Sunday: winds less than 25 kt. Slight chance of rain showers,
isolated thunderstorms.

Sunday night through Monday: winds less than 25 kt. Seas
locally approaching 5 ft. Chance of rain showers, slight chance
of thunderstorms.

Climate
Record highest min temps for Saturday july 20:
bos: 75 in 2016
bdl: 73 in 1975
pvd: 77 in 1983
orh: 72 in 2013
record highs for Saturday july 20:
bos: 99 in 1991
bdl: 100 in 1991
pvd: 101 in 1991
orh: 92 in 1901
record highest min temps for Sunday july 21:
bos: 81 in 1991
bdl: 74 in 1977
pvd: 77 in 1980
orh: 73 in 1991
record highest MAX temps for Sunday july 21
bos: 102 in 1977
bdl: 101 in 1991
pvd: 102 in 1991
orh: 95 in 1926

Box watches warnings advisories
Ct... Excessive heat watch from Saturday morning through Saturday
evening for ctz002>004.

Ma... Excessive heat watch from Saturday morning through Saturday
evening for maz002>021-026.

Ri... Excessive heat watch from Saturday morning through Saturday
evening for riz001>007.

Marine... Small craft advisory until 2 pm edt this afternoon for anz250-
251.

Synopsis... Wtb nash
near term... Nash
short term... Evt
long term... Wtb
aviation... Wtb evt nash
marine... Wtb evt nash
climate... Team box


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
BHBM3 - 8443970 - Boston, MA 1 mi47 min 69°F 1016.3 hPa (-0.0)
44013 - BOSTON 16 NM East of Boston, MA 22 mi57 min NE 18 G 19 66°F 69°F4 ft1014.4 hPa (-0.0)62°F
44029 - Buoy A0102 - Mass. Bay/Stellwagen 28 mi103 min NE 16 G 18 65°F 64°F5 ft1015.2 hPa
FOXR1 - 8454000 - Providence, RI 43 mi47 min NE 8.9 G 15 69°F 74°F1014.8 hPa (+0.6)
BLTM3 - 8447387 - Borden Flats Light at Fall River, MA 46 mi47 min NNE 11 G 13 70°F 1015.2 hPa (+1.4)
FRVM3 - 8447386 - Fall River, MA 46 mi47 min 70°F 80°F1015.5 hPa (+1.2)
FRXM3 47 mi53 min 69°F 66°F
IOSN3 - Isle of Shoals, NH 47 mi47 min NE 15 G 17 65°F 1015.5 hPa (-0.4)55°F
CPTR1 - 8452944 - Conimicut Light, RI 48 mi47 min NNE 8.9 G 11 69°F 76°F1015.4 hPa (+1.3)
BGXN3 - Great Bay Reserve, NH 49 mi62 min ENE 6 75°F 1016 hPa57°F

Wind History for Providence, RI
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Boston, Logan International Airport, MA2 mi53 minENE 1210.00 miOvercast70°F57°F66%1016.3 hPa
East Milton, MA11 mi51 minENE 10 G 17 mi64°F59°F84%1016.7 hPa
Norwood, Norwood Memorial Airport, MA14 mi54 minENE 10 G 1510.00 miOvercast71°F59°F66%1015.7 hPa
Laurence G Hanscom Field Airport, MA14 mi51 minENE 810.00 miOvercast73°F57°F59%1016.9 hPa
Beverly, Beverly Municipal Airport, MA16 mi54 minNE 710.00 miOvercast68°F57°F68%1015.5 hPa

Wind History from BOS (wind in knots)
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Tide / Current Tables for Charlestown Bridge, Charles River, Massachusetts
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Charlestown Bridge
Click for Map
Thu -- 12:45 AM EDT     10.50 feet High Tide
Thu -- 05:23 AM EDT     Sunrise
Thu -- 06:50 AM EDT     Moonset
Thu -- 07:07 AM EDT     -0.04 feet Low Tide
Thu -- 01:22 PM EDT     9.23 feet High Tide
Thu -- 07:13 PM EDT     1.00 feet Low Tide
Thu -- 08:17 PM EDT     Sunset
Thu -- 09:39 PM EDT     Moonrise
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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10.110.59.685.73.10.9-00.41.83.86.18.19.297.96.24.12.111.42.84.87

Tide / Current Tables for Boston Harbor, Massachusetts Current
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Boston Harbor
Click for Map
Thu -- 12:26 AM EDT     -0.00 knots Slack
Thu -- 04:47 AM EDT     -1.34 knots Max Ebb
Thu -- 05:22 AM EDT     Sunrise
Thu -- 06:49 AM EDT     Moonset
Thu -- 06:58 AM EDT     0.00 knots Slack
Thu -- 10:18 AM EDT     1.18 knots Max Flood
Thu -- 01:00 PM EDT     -0.00 knots Slack
Thu -- 05:12 PM EDT     -1.18 knots Max Ebb
Thu -- 07:15 PM EDT     0.00 knots Slack
Thu -- 08:16 PM EDT     Sunset
Thu -- 09:38 PM EDT     Moonrise
Thu -- 10:33 PM EDT     1.12 knots Max Flood
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.2-0.3-0.7-1-1.3-1.3-0.900.711.21.10.60-0.4-0.8-1-1.2-1-0.20.611.11.1

Weather Map and Satellite Images
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GOES Local Image of Northeast    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
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Wind Forecast for Boston, MA (13,3,4,5)
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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.