Tuesday, March19, 2019 L-36.com

Marine Weather and Tides
Big Sky, MT

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 7:27AMSunset 7:36PM Tuesday March 19, 2019 2:07 AM MDT (08:07 UTC) Moonrise 5:04PMMoonset 6:08AM Illumination 97% Phase: Waxing Gibbous; Moon at 13 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 190514
area forecast discussion
national weather service great falls mt
1115 pm mdt Mon mar 18 2019
aviation section updated.

No updates needed to current forecast this evening. Temperatures
and winds are trending close to what is in the forecast. Should
remain dry overnight, as only scattered high cloudiness is moving
south out of canada down the east side of a high pressure ridge
over the pacific northwest southwest canada. Mostly clear skies
and light winds should allow patchy fog to form once again in
river valleys of north central montana and in some southwest
valleys. If the trend from the last two mornings holds, fog in the
helena valley may become dense at times again later tonight.


High temperatures will continue to warm through the remainder of
the work week, with Thursday and Friday likely being the warmest
days. Patchy fog may once again develop in the milk river valley
and the valleys of southwest montana tonight. Otherwise a quiet
and pleasant work week is in store for the region.

Updated 1115 pm mdt Mon mar 18 2019
vfr conditions will continue over the forecast area at least
through the day on Tuesday. High clouds will likely move over the
area with high pressure over the pacific northwest. Otherwise,
patchy fog has formed in river valleys and low lying areas the
past few mornings, so with little change in the atmospheric
conditions, will continue mention of fog in these same areas
between 10z and 17z. Some of these areas (including khln, khvr,
kbzn) may fall to MVFR ifr conditions, with khln possibly having
lifr conditions at times. Coulston

Forecast temperatures trend toward above normal readings by the
middle of the week, resulting in an increase in snowmelt at lower
elevations. Overnight temperatures should fall just below freezing
in most areas, helping to mitigate the runoff that occurs from
melting during the daytime periods. With the ground still frozen,
any melting could cause water to accumulate in low lying areas and
the additional runoff into creeks and streams could increase the
potential for ice jams.

Expect the snow melt runoff to begin to increase by Thursday and
Friday, after a few days of warmer afternoon temperatures over the
region and overnight low temperatures not getting quite as cold.

Prev discussion
Issued 530 pm mdt Mon mar 18 2019
rest of this afternoon through through Thursday night... Primary
forecast concern through the period will be temperatures and how
much the on-going (but shrinking) snow pack will affect both highs
and lows.

Upper level ridge centered over british columbia this afternoon
(but with the ridge axis extending well north into the yukon and
northwest territories) will drift east southeast across the
northern rockies through Tuesday night before moving into the
northern and central high plains on Thursday. As the upper level
high transitions eastward, 1000-500mb thicknesses will climb from
from ~5400m this evening to around ~5500m by Thursday
afternoon evening. This combined with sunshine and light southerly
to southwesterly winds should allow for temperatures to warm into
the 40s and 50s across the CWA on Tuesday, Wednesday, and
Thursday (coolest temperatures in the valleys of southwest
montana). Some guidance is suggesting that widespread 60s are even
possible to end the work week over the plains of north central
montana, but given the widespread snowpack and lack of a
significant downslope wind event I believe that this guidance is
being to aggressive. Otherwise, expect patchy to areas of fog to
once again develop in locations that saw fog this morning,
however, some increasing mid- to upper level clouds moving in from
north to south could limit the development of fog (especially
over the plains of north central montana). - moldan
Friday through next Monday... Model discrepancies and forecast
uncertainty grow during this period. In general, the western flank
of the departing ridge aloft should be broken-down by multiple
disturbances from the south and west Thursday night and through
Saturday. High pressure aloft may then rebound over our CWA Sunday
night into Monday, but the potential exists for additional
disturbances to ripple generally eastward through this ridge.

Accordingly, a cooling trend occurs to start the following work
week, with temperatures expected to fall to near or slightly
below-normal values by next Monday. As for precipitation, a few
snow and or rain showers are possible over far-southwest mt on
Friday. Periods of precipitation may then affect most of our cwa
Saturday through next week Monday, with the better potential
existing over the southern two- thirds of the forecast area and
along the continental divide. As for precipitation type, primarily
rain (snow) should fall at lower elevations during the day
(night), while the mountains should mainly receive snow. However,
it may be warm enough for some rain to mix with the mountain snow,
especially during the late morning through afternoon hours.

- jaszka moldan

Preliminary point temps pops
Gtf 18 50 23 54 0 0 0 0
ctb 17 54 22 56 0 0 0 0
hln 13 45 15 51 0 0 0 0
bzn 11 44 16 51 0 0 0 0
wey 5 46 9 53 0 0 0 0
dln 14 45 19 49 0 0 0 0
hvr 13 45 18 50 0 0 0 0
lwt 17 47 21 54 0 0 0 0

Tfx watches warnings advisories


Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Bozeman, Gallatin Field, MT38 mi71 minN 04.00 miFog/Mist21°F17°F85%1031.4 hPa

Wind History from BZN (wind in knots)
Last 24hrCalmCalmCalmCalmSE4CalmCalmCalmNE3CalmCalmE3N5CalmN3CalmCalmCalmE4S4CalmS4CalmS3
1 day agoSE5SE5S4CalmCalmCalmCalmCalmCalmNE4N3CalmN3N4NE3NE3CalmCalmSW3SE4SE4S3SW3Calm
2 days agoCalmE4CalmCalmSE3CalmE4SE4NW4CalmCalmNE3CalmCalmNE3N4CalmCalmCalmS3CalmSE3S8Calm

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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GOES Local Image of    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 Great Falls, MT (4,6,7,8)
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Ground Weather Radar Station Billings, MT
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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 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.