Tuesday, December18, 2018 L-36.com

Marine Weather and Tides
Bozeman, 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 7:58AMSunset 4:43PM Tuesday December 18, 2018 3:25 AM MST (10:25 UTC) Moonrise 2:22PMMoonset 3:03AM Illumination 83% Phase: Waxing Gibbous; Moon at 11 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 Bozeman, MT
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location: 45.71, -110.99     debug

Area Discussion for - Billings, MT
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Fxus65 kbyz 181008
area forecast discussion
national weather service billings mt
308 am mst Tue dec 18 2018

Short term Valid for tdy and wed...

morning satellite imagery shows a weak dry shortwave exiting
eastern mt and a strong westerly jet pushing into the pacnw, with
the latest 300mb analysis showing 130 kts along the or coast. At
the surface, pressure falls are beginning to increase in the lee
of the rockies. Wind gusts in the gap areas have picked up a bit,
with gusts near 50 mph at livingston and 60 mph near nye as of
300 am.

Confidence continues to increase in a strong wind event today
through Wednesday. Will make no changes to the high wind warnings
already in effect for livingston, nye, big timber and harlowton.

Gap areas should peak this afternoon and evening, while the other
locations will be as the front moves thru tonight and Wednesday.

Attention will then turn to areas east of the foothills behind the
front on Wednesday. Descent will arrive early tomorrow, with 700mb
winds somewhere between 50-60 kts (gfs continues to run hottest,
but even the ec shows 55 kts). The kicker here is the very steep
low level lapse rates that develop as mid levels cool quickly,
with sfc-700mb values of 7.5-8.5 c km. Believe the strongest winds
will be along the axis of greatest mid level flow and steepest low
level lapse rates, which at this time is expected to set up from
roughly harlowton to sheridan. Have issued a high wind watch for
areas as far east as musselshell-yellowstone-big horn-southern
rosebud-sheridan counties, from 12z-04z Wednesday, with potential
for 50-60 mph gusts. Travel and outdoor activities will be
impacted by strong and gusty w-nw winds. Areas further east will
become windy but not quite as strong, with gusts of 30-50 mph.

Winds will decrease after sunset Wednesday evening.

Otherwise, pacific shortwave will bring some mountain snow and a
few lower elevation rain showers late this afternoon and tonight.

The beartooth absarokas should see something on the order of 4-8
inches on west aspects. Any lower elevation precip will be
insignificant. Temperatures will remain above normal with highs
mostly in the 50s today, then 40s to around 50 on a post-frontal


Long term Valid for thu... Fri... Sat... Sun... Mon...

ecmwf ensembles showed uncertainty with the pattern for Thursday
through Friday. This was reflected in the ECMWF deterministic
model for Friday, which was now dry with the cold frontal passage,
and had a much weaker shortwave than the gfs. In addition, the
ecmwf was much warmer at 850 mb than the GFS on Friday. Also model
pressure gradients on the GFS were no longer as supportive for
strong winds in klvm as they were last night. Model blends brought
a low chance of precipitation to the area on Friday in the form
of rain and snow. Friday still looked windy behind the cold
front. Going back in time to Thursday... Models still showed a high
amplitude upper ridge with mainly dry weather. Advisory strength
winds were likely for the gap areas through thu. Night. High
temperatures will be in the 40s to lower 50s both days.

Weak disturbances will move through the area fri. Night through
Saturday night, with weak ridging on Sunday. Had spotty
precipitation forecast through this time frame. Saturday and
Sunday will be cooler, with temperatures closer to normal. Had
sub-advisory winds sat. Night through sun. Night in the gap flow
areas based on the pressure gradient. Models were in poor
agreement starting sun. Night with a trough on the ECMWF and a
ridge on the gfs. The poor agreement continued into christmas, but
both models did show an approaching trough by late in the day.

Carried mountain pops through Monday night, then had chances for
rain snow showers spreading E into the area on christmas.

Temperatures remained near normal for the rest of the period.


Wsw surface winds will be very strong at klvm today into tonight.

Expect gusts to 50 kt this morning, increasing to 60-65 kt this
afternoon through this evening. The winds will turn W late
tonight and remain strong with gusts in the 50s. Winds will also
be gusty from big timber to judith gap with gusts of 45 to 55 kt
this afternoon through tonight. Expect llws over kmls and kshr
tonight.VFR will prevail today and tonight, with MVFR possible
at klvm late tonight. Obscurations will increase over the western
mountains through this evening, and obscurations will spread into
the NE bighorns late tonight. Arthur

Preliminary point temp pops
Tdy Wed Thu Fri Sat Sun mon
bil 054 039 050 030 048 034 048 026 040 024 040 026 041
0 N 21 N 01 b 11 N 01 b 10 b 11 e
lvm 053 034 044 029 046 033 043 023 036 021 037 024 038
2 W 62 W 01 N 13 W 21 b 12 W 21 n
hdn 055 035 052 025 049 028 050 022 041 019 041 021 042
0 b 21 N 01 b 11 b 00 b 10 b 11 e
mls 048 034 045 026 042 026 043 022 037 017 035 020 035
0 b 11 N 01 u 02 W 11 u 10 u 11 e
4bq 050 033 045 026 043 028 044 023 037 019 036 021 037
0 b 21 N 01 u 02 W 21 b 10 u 11 e
bhk 050 034 045 027 042 026 043 023 037 017 035 019 035
0 u 21 N 00 u 02 W 11 u 11 b 11 e
shr 058 032 046 023 048 026 049 021 039 017 041 019 041
0 b 22 W 00 u 02 W 12 j 00 u 11 b

Byz watches warnings advisories
Mt... High wind warning in effect from noon today to 9 pm mst
Wednesday for zones 28-41-63.

High wind watch in effect from late tonight through Wednesday
evening for zones 29-34-35-38-42-57-58.

High wind warning in effect until noon mst Wednesday for
zones 65-66.

Wy... High wind watch in effect from late tonight through Wednesday
evening for zone 99.

Weather.Gov billings

Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Bozeman, Gallatin Field, MT10 mi30 minSE 710.00 miFair32°F24°F73%1015.5 hPa

Wind History from BZN (wind in knots)
Last 24hrSE5S6SE5S6SE7S5SE3E3CalmE3CalmSW10
1 day agoSE4SE4SE5SE5NW3CalmS3CalmSW3CalmCalmN3SE3S3S6SE10N4S4SW5SE9CalmCalmCalmSE8
2 days agoSW22

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 Billings, MT (5,6,7,8)
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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.