Monday, June25, 2018

Marine Weather and Tides
Siasconset, MA

Version 3.4
What's New / NOTES
5/20/2018 -- NOAA is having problems with the data feed that I use to draw the graphs. They are aware of the issue and working to resolve it. Sometimes changing the location by about a mile will give a correct graph. 3/3/2018 - There is a new GOES Satellite for the east coast that required rewriting that part of the code. Please report any issues.

Sunrise 5:11AMSunset 8:24PM Monday June 25, 2018 3:43 AM EDT (07:43 UTC) Moonrise 5:55PMMoonset 3:34AM Illumination 90% Phase: Waxing Gibbous; Moon at 12 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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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 250307
area forecast discussion
national weather service boston norton ma
1107 pm edt Sun jun 24 2018

A cold front will move across the region overnight and will be
accompanied by scattered showers and a thunderstorm or two.

Another disturbance will result in a continued risk of a shower
or isolated t-storm across eastern ma and ri on Monday. High
pressure and seasonably warm conditions follow for Tuesday and
Wednesday, then a weak front will bring a chance of showers and
t-storms for Thursday. There is a signal for a prolonged heat
wave next weekend into early next week with the potential for
dangerous heat and humidity.

Near term until 6 am Monday morning
1040 pm update...

a line of showers and scattered thunderstorms moving slowly se
along the S coasts of mass and ri as seen on latest kbox and ne
regional 88d radar imagery. The islands will see the brunt of
the thunderstorms, with some locally heavy downpours as well as
c g lightning. The line of thunderstorms should weaken as it
moves over the cooler ocean waters after about 04z or so.

Noting a second line of showers lies across the nh mass border,
extending SE across southern franklin and northern hampshire
counties into the berkshires at 0240z. This appears to be
associated with the approaching cold front moving se, especially
on its western extent. May also see a few brief, heavy
downpours with this front, though the instability has pushed se
with the leading area of precip along the S coast.

Areas of dense fog also continue along the S coast and across
the southern coastal waters, with a report of zero visibility
from the vineyard ferry during its crossing at 01z. As the cold
front moves across from 06z-07z or so, should see improving
visibility as winds shift to light w-nw bringing the drier air

Dewpoints remain very high, mainly in the mid-upper 60s
regionwide except a bit lower across the CAPE and islands with
the onshore wind off the cooler waters. So, expect the areas of
dense fog to linger there as well as across the islands until
the cold front crosses during the early morning hours.

Have updated near term to bring conditions current.

Short term 6 am Monday morning through Monday night

fairly robust mid level trough and shortwave rotates south
across sne with -22c cold pool at 500 mb. Coldest air aloft and
pocket of higher ki and tt focused across eastern half new eng
where best chance for a few showers developing and possibly an
isold t-storm as models indicate a few hundred joules of cape.

Certainly not a washout, but a few showers will be possible and
given cold air aloft can't rule out some small hail. A mix of
sun and clouds expected with most sunshine in the ct valley.

Temps ranging from upper 60s 70 degrees east coastal ma with ne
flow to upper 70s near 80 degrees ct valley. A bit breezy with
northerly winds gusting to 20-25 mph at times.

Monday night...

high pres builds into sne from the west with clearing skies and
diminishing wind. Decent radiational cooling will result in a
chilly night with lows down into the 40s in the colder outlying
areas, except 50s urban centers and milder coastal locations.

Long term Tuesday through Sunday

* seasonable temperatures through Thu with chance of showers
wed night thu
* heat wave potential beginning next Friday weekend

surface high pressure passes overhead bringing sunny skies, low
humidity, and highs in the 70s. Mainly clear skies Tuesday night.

However some increase in clouds is possible towards daybreak as the
high moves offshore, and a low pressure system moves into the great
lakes region. Lows mainly in the 50s.


our region is in SW flow and eventual increasing moisture as the low
pressure system continues pushing eastward thru the great lakes
region. Mainly dry weather is expected in our area during the day,
with a slight chance of showers late across far western ma. Highs
once again in the 70s.

Wednesday night and Thursday...

low pressure center tracks into southern quebec, while associated
cold front tracks towards and thru southern new england. Showers and
scattered thunderstorms expected over the course of Wed night into
thu. Moisture-rich airmass ahead of the front with surface dewpoints
climbing into the 60s and possibly low 70s, so locally heavy
downpours are possible. Cold front should push east of the region
thu night.

Friday thru Sunday...

cold front moves offshore but increasing heat and humidity not far
behind it, as models show a mid level ridge building into our
region. Ensembles continue to indicate well above normal
temperatures at 925 mb and 850 mb. This should mean well above
normal temperatures at the surface as well, except for perhaps the
cape and islands where SW flow off the water will keep temperatures
lower. The heat and humidity may persist into early in the following
week. Heat advisories will likely be needed, especially by Saturday.

Also of note, in cpc's risk of hazardous temperatures outlook
(experimental), southern new england is highlighted as having a
moderate (40%) risk of excessive heat during 6 30 thru 7 3. For this
cpc outlook, excessive heat is considered to include MAX temps of 95-
100 deg f with a MAX heat index of 105 deg f or greater.

Aviation 03z Monday through Friday
Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Monday night ...

overnight... Moderate confidence.

Mainly MVFR-ifr CIGS with mainlyVFR vsbys except briefly
lowering to MVFR in heavy showers across most areas. Will see
improving conditions as the cold front passes, with winds
shifting to light w-nw. Along the S coast, CAPE cod and the
islands, expect mainly lifr in areas of dense fog. Showers and
sct tstms will move across through 05z or so, then a brief break
before another line of showers moves across during the early
morning hours. Lifr will continue until the cold front passes
around 09z or so. Winds will shift to w-nw overnight as cold
front swings around 11z-12z.

Monday... High confidence.

MainlyVFR. Bkn CIGS across eastern half new eng where a few
showers possible. Ifr along the CAPE and islands gradually
improves toVFR during the afternoon. Northerly wind gusts to 20
kt, and up to 25 kt CAPE islands.

Monday night... High confidence.VFR. Light winds.

Kbos terminal... Moderate confidence in taf.

Kbdl terminal... Moderate confidence in taf.

Outlook Tuesday through Friday ... Moderate confidence.

Tuesday through Tuesday night:VFR.

Wednesday: mainlyVFR, with local MVFR possible. Breezy.

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

Slight chance shra, slight chance tsra.

Thursday: MVFR. Breezy. Chance shra, slight chance tsra.

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

Chance shra, slight chance tsra.


Forecaster confidence levels...

low - less than 30 percent.

Moderate - 30 to 60 percent.

High - greater than 60 percent.

Short term through Monday night ... High confidence.

Light SW winds tonight becoming NW late. Increasing northerly
winds Mon with a few gusts to 25 kt possible across eastern
waters where seas may approach 5 ft. SCA may eventually be
needed here. Diminishing wind seas Mon night as high pres builds
into the region.

Poor vsbys tonight in developing fog south coastal waters.

Scattered showers and possibly an isold t-storm this evening.

Outlook Tuesday through Friday ...

Tuesday through Wednesday: winds less than 25 kt.

Wednesday night: winds less than 25 kt. Seas locally
approaching 5 ft. Chance of rain showers.

Thursday: moderate risk for small craft advisory winds with
gusts up to 25 kt. Areas of rough seas. Chance of rain showers,
slight chance of thunderstorms.

Thursday night: winds less than 25 kt. Areas of rough seas.

Chance of rain showers, slight chance of thunderstorms.

Friday: winds less than 25 kt. Local rough seas.

Box watches warnings advisories
Ct... None.

Ma... None.

Ri... None.

Marine... None.

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

Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Nantucket, Nantucket Memorial Airport, MA168 mi51 minSW 51.75 miFog/Mist63°F63°F100%1006.9 hPa

Wind History from ACK (wind in knots)
Last 24hrNW7N5N4CalmS4SW5SW9SW10SW11SW9SW11S9S8S7S7S6SW8S6S7S5S9S8SW5SW5
1 day agoE12E11E12
2 days agoN4NE5NE6NE7NE7NE8E10E9E9E10E10SE13E12E11E11E8E8E9E7E7E10E8E8E9

Tide / Current Tables for
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Weather Map and Satellite Images
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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 (3,6,7,8)
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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.