Wednesday, May22, 2019

Marine Weather and Tides
Siasconset, MA

Version 3.4
What's New / NOTES
10/6/2018 Colors of tide XTide graphs changed to emphasize that they were upgraded. See next note. Comments welcome.
10/4/2018 I have fixed XTide and updated the harmonic files. There were some name changes so you might have to click EDIT to find the new station name.

Sunrise 5:18AMSunset 8:05PM Wednesday May 22, 2019 8:55 AM EDT (12:55 UTC) Moonrise 11:33PMMoonset 8:27AM Illumination 87% Phase: Waning Gibbous; Moon at 18 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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ANZ005 627 Am Edt Wed May 22 2019
Synopsis for eastport me to stonington me out 25 nm.. Low pres tracks E across the maritimes through Wed. High pressure will build over the waters Wed night. Low pres will track across the waters late Thu night into Fri with high pressure building in on Sat.

7 Day Forecast for Marine Location Near Siasconset, MA
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location: 38.84, -69.85     debug

Area Discussion for - Boston, MA
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Fxus61 kbox 221059
area forecast discussion
national weather service boston norton ma
659 am edt Wed may 22 2019

High pressure brings dry and seasonably mild conditions today
with less wind. A few showers are possible late tonight into
early Thursday as a warm front approaches. Low pressure will
push across northern new england late Thursday, bringing showers
and scattered thunderstorms into early Friday morning. Another
brief dry period moves in Friday night into Saturday morning.

Fast moving weather systems move across late Saturday into
Sunday morning, then again Monday into Monday evening, bringing
chances for showers. Cooler weather returns next Tuesday behind
a cold front.

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

skies were mainly clear across the region as seen on the goes-
east visible satellite loop since sunrise. Noting a patch of
high clouds moving e-se in the flow aloft moving across the mid
and lower ct valley into the mid hudson valley to near ksyr.

Noting NW winds running at about 10-15 kt mainly across higher
terrain and along the coast, which have begun to veer to n-nw
and diminish across the ct valley into W mass on the 10z
observations. N-s oriented high pressure ridge extending from
western quebec to W ny W pa to the mid appalachians will shift e
during the day. Latest goes-east air mass rgb satellite imagery
showing thicker high clouds across the eastern great lakes to
the eastern ohio valley shifting e-ne.

Should see mainly clear skies through at least early afternoon,
then some high thin clouds may begin to push across the region.

Near term forecast on track. Have updated to bring conditions

Previous discussion...

high pres builds in from the west with gradually diminishing
wind through the morning which will lead to sea-breezes
developing this afternoon. Lots of sunshine with highs mostly in
the lower 70s, except 60s along the coast and over the higher

Short term 6 pm this evening through 6 pm Thursday

high pres shifts south of new eng with developing warm advection
pattern bringing an increase in cloud cover. A mid level warm
front approaches from the west late tonight with deepening
moisture and weak 850 mb frontogenesis developing along the
boundary. This may lead to sct showers along the leading edge
of higher theta-e air, with focus across western ma and northern
ct late tonight.


a few showers may linger early in the day, mainly south of the
pike, otherwise mainly dry weather for much of the day with
limited sunshine developing. However, a cold front will be
approaching from the west late in the day as fairly robust mid
level shortwave moves into the gt lakes. There is no surface-
based instability as soundings indicate a pronounced low level
inversion, but models indicating a few hundred j kg of MUCAPE in
the afternoon. Surface instability axis will remain to the west
across pa ny where strong t-storms are expected to develop.

Convection should weaken as it approaches new eng given less
favorable environment, but sct showers and isold t-storm may
move into western new eng late in the day.

High temps upper 60s to around 70, but cooler south coast with
gusty SW flow. Developing low level jet will result in gusts to
30 mph across ri and SE ma.

Long term Thursday night through Tuesday

* cold front pushes across with showers and scattered
thunderstorms Thursday night into early Friday
* should be dry and seasonable late Friday into Friday night
* fast moving systems may bring scattered showers from time to
time through the holiday weekend
* dry and seasonable conditions may return by Tuesday

continue to see active weather pattern across the lower 48,
along with a fast moving mid level steering flow across the
northern tier states, especially from the great lakes to the
northeast. Looks like h5 short waves in this fast flow will
shift eastward, bringing batches of showers from time to time
through the holiday weekend. Can not rule out a few thunderstorms
with one or two more energetic h5 short waves into the holiday

Rather good model agreement amongst the 00z members into
Saturday, then solutions diverge with the fast mid level
steering flow in place. Above average confidence early in the
forecast period, then decreases from the weekend onward.


Thursday night through Saturday...

low pressure shifts E out of southern quebec Thursday evening,
with its associated cold front bringing a round of showers. 00z
models continue to signal good instability with this system, as
slis run from zero to -1, k indices in the lower 30s and total
totals in the lower 50s. So, have mentioned scattered
thunderstorms through Thu night. Also noting pwats up to around
1.5 inches, running 1-2 sd above seasonal levels, though this
pushes through by around midnight so will limit the amount of
precip. At this point, looks like 0.2 to 0.4 inches of QPF are

Back edge of precip should push E as the cold front moves
across early Friday morning. Should see generally dry conditions
Friday into Saturday as high pressure ridge builds across.

Might see a few spotty showers linger into midday Friday across
n mass as the low shifts off the maine coast. Another question
about the timing of the next system that bring scattered showers
into areas near and N of the mass pike during Saturday

Note increasing low level northerly jet moves across along with
very good low level mixing on Friday. So, may see n-ne wind
gusts up to 25-35 mph, possibly a bit higher through early
afternoon. Winds should diminish as the high moves in.

Temperatures on Friday will be close to seasonal levels with highs
in the mid 60s across the higher terrain and along the coast,
ranging to the lower-mid 70s. Readings may be a few degrees cooler
as clouds move in during Saturday. Winds shift to s-sw Saturday
afternoon and become gusty along the immediate S coast.

Saturday night through Tuesday...

another energetic short wave moves across Saturday night, so
could see scattered showers with a few thunderstorms during the
night. Precip should shift E by midday Sunday, with another
quick period of dry conditions. Mild temps move in as well, with
forecasted highs in the 70s with a few spots possibly reaching

May see another round of showers move across with yet another
system late Sunday night through memorial day. For now, should
see dry, seasonable conditions on Tuesday, but rather low
confidence for this timeframe due to wide model solution spread.

Aviation 12z Wednesday through Sunday
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Thursday ... High confidence.


vfr. Occasional N NW gusts to 20+ kt east coastal ma and higher
terrain through mid morning, then diminishing with sea breezes
developing around midday into the afternoon.


vfr with gradually lowering cigs. A few showers possible western
half ma and northern ct toward daybreak.


mainlyVFR cigs. A few showers possible early south of the pike,
then sct showers and possible t-storm may move into western new
eng late afternoon. SW gusts to 25 kt developing in ri SE ma
during the afternoon.

Kbos terminal... High confidence in taf. Sea breeze developing
around 17z.

Kbdl terminal... High confidence in taf.

Outlook Thursday night through Sunday ...

Thursday night: mainly MVFR, with areasVFR possible. Breezy.

Shra likely, chance tsra.

Friday: mainlyVFR, with local MVFR possible. Windy with areas
of gusts up to 30 kt. Slight chance shra.

Friday night:VFR. Windy with local gusts up to 30 kt.

Saturday: mainlyVFR, with local MVFR possible. Chance shra.

Saturday night: mainly MVFR, with local ifr possible. Breezy.

Chance shra, isolated tsra, patchy br.

Sunday: mainlyVFR, with local MVFR possible. Breezy. Slight
chance shra.

Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Thursday ... High confidence.

Today... Northerly wind gusts to 25 kt, especially eastern
waters will diminish by late morning, becoming light this
afternoon with sea breezes developing over nearshore waters.

Tonight... High pres over the waters with light winds and seas.

Thursday... Developing low level jet and shallow boundary layer
mixing will lead to SW gusts to 25 kt developing over nearshore
south coastal waters. Less wind expected over outer waters due
to less mixing.

Outlook Thursday night through Sunday ...

Thursday night: moderate risk for small craft advisory winds
with local gusts up to 30 kt. Seas up to 5 ft. Rain showers
likely, chance of thunderstorms.

Friday: moderate risk for small craft advisory winds with gusts
up to 30 kt. Seas up to 5 ft. Slight chance of rain showers.

Friday night: low risk for small craft advisory winds with
local gusts up to 30 kt. Local rough seas.

Saturday: winds less than 25 kt. Seas locally approaching 5 ft.

Slight chance of rain showers.

Saturday night: low risk for small craft advisory winds with
gusts up to 25 kt. Areas of seas approaching 5 ft. Rain showers

Sunday: winds less than 25 kt. Areas of seas approaching 5 ft.

Slight chance of rain showers.

Box watches warnings advisories
Ct... None.

Ma... None.

Ri... None.

Marine... Small craft advisory until noon edt today for anz231-232-250-

Small craft advisory until 10 am edt this morning for anz230-

Small craft advisory until 2 pm edt this afternoon for anz254.

Synopsis... Kjc evt
near term... Kjc evt
short term... Kjc
long term... Evt
aviation... Kjc evt
marine... Kjc evt

Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Nantucket, Nantucket Memorial Airport, MA168 mi63 minN 18 G 2410.00 miFair and Breezy56°F41°F57%1019 hPa

Wind History from ACK (wind in knots)
Last 24hrNW20
1 day agoSW9SW12SW13SW14
2 days agoS13S13S12SE14S16S14S16S13S15S13S13S11S8S10S11S13S11S10SW8SW8W10S10S7S12

Tide / Current Tables for
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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 (8,2,3,4)
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Ground Weather Radar Station Upton, NY
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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 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 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.