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2009/10 Winter Weather Forecast |
The overall winter weather forecast (09/10) for the high country of Rocky Mountain National Park,
Colorado. Researched and written weekly by professional meteorologist
and avid mountaineer, Dan "the weather man" Gottas.
Oct. 29 weather
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Thursday, October 29th ,
2009
Rocky
Mountain National Park Weather Forecast for 2009/10 Season
Winter
conditions came early to the mountains of RMNP during
the month of October.
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Long
Range Winter Weather Forecast
Several
snowfall events occurred, as an active wave train of
mid-latitude energy cruised over the region on a northwesterly storm
track.
These
conditions remarkably resembled the La-Nina storm-track
pattern of the past two winters, despite the current El-Nino conditions
developing over the tropical Pacific (the warm phase of the Southern
Oscillation).
The
final wave in the train turned out to be the granddaddy
of them all, with anywhere from 1 - 2.5 feet of new snow falling along
the
higher terrain east of the Divide from Indian Peaks to RMNP.
Currently,
medium and long-range forecast model predictions
are converging on a shift in the storm track pattern over the next
couple of
weeks that would increase storminess over the eastern Pacific and along
the
west coast of the US.
It remains to be
seen whether CO will be the recipient of these leftovers.
As we move into November and the winter season, the long-reaching
effects of
the Southern Oscillation on mid-latitude weather patterns over the US
will
become stronger and more apparent.
The
strength of this year’s El-Nino event is expected to be
moderate, as many of
the dynamic and statistical models currently indicate.
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At noon on October 28th, we had received 31cm of snow in 24 hrs. on the
deck at the Helmuth homestead. An additional 4cm fell later
that day for a total of about 14 inches total new snowfall in what has
turned out to be a record breaking storm for this time of year in
Colorado.
Density for this new snow was measured at approx. 6% at this location
at 8,700', 10 miles east of RMNP. Bonding in this new layer was very
good (our clothesline had 6' of snow sitting on a 1cm wide surface)
which indicates high probability of slab formation. More avalanche and ice information will be forthcoming in this week's conditions report.
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Typically during
the winter season
of El-Nino events, the subtropical jet stream strengthens over the
eastern
Pacific Ocean. This often initiates and
guides moist storms along the southern tier of US states.
In addition, the
polar jet stream typically
retreats northward of the northern Rockies which results in warmer than
normal
conditions in that region. These two
conditions combined are often referred to as a split flow.
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In the mean, northeast CO has
equal chances for wetter or drier conditions and a > 40%
probability for
warmer than normal conditions.
However,
these base-state conditions can change dramatically over shorter
periods of
time when other transient atmospheric forcing phenomena (both local and
global)
occur.
Lastly,
extreme precipitation
events are also historically known to occur during the winter months of
El-Nino. The wetter of these events are
concentrated along the mean southern subtropical branch of the jet
stream.
For
northeast CO, many of these storms force
local east-side (of the Divide) upslope events, as deep cyclonic
circulations
move eastward out of AZ and NM.
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Click on chart to expand.
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Detailed
7-Day
Forecast
The
link above will take you to the National Weather Service
forecast for the
12,000 foot level near Longs Peak.
These
forecasts are derived from computer-generated numerical forecasts, and
are
updated shortly after 3:30 am, 9:30 am, 3:30 pm, and 9:30 pm local
time.
In the lower right-hand corner of the page, one can view forecasts for
other
locations in the Park by clicking on the desired location in the
terrain map.
Do-It-Yourself
Weather Forecast
Links
The
link above provides a list
of web links to various sites
containing a variety of meteorological data and information.
Collectively,
these resources can be used to monitor and study current weather
conditions, as
well short-term, medium-range, and climate forecasts
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