Saturday, November18, 2017

Marine Weather and Tides
Big Sky, MT

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 7:27AMSunset 4:51PM Saturday November 18, 2017 3:25 AM MST (10:25 UTC) Moonrise 7:23AMMoonset 5:31PM 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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7 Day Forecast for Marine Location Near Big Sky, MT
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location: 45.26, -111.31     debug

Area Discussion for - Great Falls, MT
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Fxus65 ktfx 180545
area forecast discussion
national weather service great falls mt
1045 pm mst Fri nov 17 2017
updated aviation discussion

Main updates this evening were to increase the snow blowing snow
along the continental divide south into jefferson county to
reflect the persistent snow and strong wind gusts there. Have been
addressing this with special weather statements, and will keep an
eye on it for a possible winter weather advisory. Gusts of 40 to
50 mph have been common through favored passes, including marias
pass and macdonald pass. The montana department of transportation
even has an ALERT for severe driving conditions from marias pass
to near browning. Overall, am expecting the snow and winds along
the divide to decrease somewhat overnight to at least lessen the
impacts from blowing snow. Again, will monitor the situation.

Remainder of the forecast appears to be on track.


Drier conditions move into the region this weekend with
temperatures near average through Saturday. Temperatures trend
warmer with increasing winds Sunday.

Updated 0545z.

Upper level ridge of high pressure building east into the northern
rockies and mt tonight will spread drier and more stable air into
the region with any lingering snow showers along the continental
divide diminishing by Saturday morning.VFR conditions will prevail
at area terminals with scattered to broken mid level cloud cover
over SW mt gradually diminishing late tonight through Saturday
morning. Gusty surface winds will continue along the rocky mtn front
tonight and increase at all area terminals Saturday afternoon.


Prev discussion
Issued 445 pm mst Fri nov 17 2017
tonight through Sunday... Model analyses and water vapor satellite
reveal a synoptic trough axis is now moving east of our forecast
area. Weak instability persists due to cooling aloft. However,
any remaining rain or snow showers are expected to clear this
evening as pressure rises at the surface and aloft. Single digit
temperatures are expected tonight in southwest valleys under
clearing skies. Breezy conditions continue tonight across much of
north central montana with a strong pressure gradient persisting
over the region. The mid-level westerly flow increases on Saturday
for windy conditions across the north-central mt plains, then
increases further by late Sunday as the upper level ridge de-
amplifies. The lee-side trough of low pressure deepens further
Sunday as well, for increasing potential of strong winds,
initially along the rocky mtn front, and possibly extending east
into adjacent western portions of north-central mt by late Sunday.

A high wind watch has been posted to cover this potential hazard.

Sunday night through Friday... A progressive pattern is still
expected during this period. High pressure ridging aloft looks to
exit the CWA to the east Sunday night and be followed by the passage
of a shortwave trough and canadian cold front Monday. High pressure
ridging aloft should then become re-established over the region
Tuesday through Wednesday. However, multiple and subtle weather
disturbances may traverse the ridge during this period. This ridge
may then be broken-down by a shortwave trough and pacific cold
frontal passage on thanksgiving. Another high pressure ridge aloft
should then build-in from the west on Friday, but model guidance
differs on how quickly this will happen. During this progressive
pattern, atmospheric profiles look to be favorable for periods of
strong, gusty downslope winds. This may especially be the case along
the rocky mountain front and during Sunday night, as well as

The aforementioned pattern will be conducive to periods of upslope
precipitation, mainly in the form of snow, along the continental
divide and the southwest mt mountains. Elsewhere, the best potential
for precipitation looks to be on Monday, courtesy of the canadian
cold frontal passage, and on thanksgiving into Friday, along and
behind the aforementioned pacific cold front. Overall, high and low
temperatures will tend to be near or above-normal during the period.

However, some slightly below-normal readings are possible Monday and
Friday, courtesy of the previously-mentioned cold frontal passages.


Preliminary point temps pops
Gtf 29 41 31 48 0 0 0 0
ctb 23 38 26 44 0 0 0 0
hln 22 40 21 43 10 0 0 0
bzn 15 35 15 39 10 0 0 0
wey 5 27 7 30 20 10 10 0
dln 16 34 17 39 0 0 0 0
hvr 18 39 23 46 0 0 0 0
lwt 23 39 25 46 0 0 0 0

Tfx watches warnings advisories
High wind watch from Sunday morning through late Sunday night
cascade... Central and southern lewis and clark... Eastern
pondera... Eastern teton... Judith basin... Toole.

High wind watch from late Saturday night through late Sunday
night eastern glacier... Northern rocky mountain front... Southern
rocky mountain front.


Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Bozeman, Gallatin Field, MT38 mi30 minSE 610.00 miPartly Cloudy19°F10°F71%1027.1 hPa

Wind History from BZN (wind in knots)
Last 24hrS4SW4CalmN5S4SE4NW3E4E7NW7W9W10NW18NW5S4SW4W9W8W8NE3CalmS5SE3SE6
1 day agoSE7S6CalmSE44CalmCalmS8SW9W12
2 days agoCalmSE4SE7S7CalmE6CalmCalmNW3SE3NE4NE3CalmNW4CalmCalmCalmCalmCalmN3NE5W3CalmCalm

Tide / Current Tables for
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Tide / Current Tables for
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Weather Map and Satellite Images
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Weather Map
IR Satellite Image from GEOS

GOES Local Image of NorthernPlains    EDIT

Wind Forecast for Great Falls, MT (5,6,7,8)
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Ground Weather Radar Station Billings, MT
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weather_mapweather_map weather_map

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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.