The weekly
weather forecast 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.
Thursday,
January 1st, 2009
The Weeks in Review
Over the last 2-3 weeks, an active weather pattern over the western US
brought cold, windy, and snowy conditions to the high mountains of RMNP.
The amplification and westward shift and a large-scale anticyclonic
circulation over the eastern Pacific Ocean produced this prolonged
period of unsettled winter weather over the western US.
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The
current global oceanic and
atmospheric circulation patterns continue to reflect La-Nina
conditions. Holding true to climatological form, these
conditions are
often correlated with windy and conditions over the northern mountains
of CO.
Over the last week, a period of orographically-forced snowfall occurred
on Friday. For the days that followed, persistently windy
conditions from the west occurred.
These strong winds again acted to increased lee-side snow deposition
and formed new slab in these lee pocket with many of the most
potentially dangerous slabs forming in the treeline transition
zone.
While some settlement and stabilization in the snowpack has occurred
below treeline associated with warming temperatures, the colder
temperatures and wind activity above treeline continue to maintain
elevated avalanche risks. |
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With
the recent increase in snowfall activity, the snowpack in RMNP has
recovered to near normal levels for this time of year.
While the greatest aerial coverage of snow depth and snow water content
is currently found over the western portions of the Park, localized
areas over the eastern sections of the Park near and above treeline are
likely hosting equivalent conditions (~7.5 – 10 inches of
SWE- snow water equivalent).
However, visual observations from a recent airplane flight over the
Park indicated significant and widespread wind-scouring pillage in
locals susceptible to the mountain-wave barrage (e.g., the Longs/
Meeker area). |
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Numerical
weather forecast skill continues to be quite good over the past month,
as strong and latitudinally-extensive westerly flow and longer
wavelength wave activity continues to dominate the weather patterns
across the US.
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The
Upcoming Week
More weather is on the way for this weekend, as another wave of
disturbed weather moves in on a northwesterly storm track.
Southwesterly through northwesterly winds are expected to remain at
elevated level both prior and during the wave passage, so continued
drifting and slab formation can be expected.
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Precipitation
amounts are not expected to be heavy, as general amounts near 0.25
inches of water equivalency are currently forecast.
Locally heavier
amounts (up to 1.5 – 2 times as much) may occur in
orographically favored zones.
Medium
and long-range models have been trending towards an eastern shift on
the mean ridge position over the eastern Pacific. |
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If
and when this pattern evolves over the next couple weeks, expect the
northwesterly storm track over CO to slowly migrate eastward in its
mean position.
A general trend of decreasing storm activity will ensue, as the
southern extent of passing systems brush over the northern part of the
state.
Even though the precipitation chances may decrease, the winds may
persist under the favorably windy southwest side of the jet stream and
stable northwesterly flow near mountain top. |
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Detailed 7-Day Forecast
NWS
Forecast for the 12,000 foot level near Longs Peak
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
Weather
Observations and Forecasts
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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