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.
Nov. 20th weather
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Friday, November 20th,
2009
Rocky
Mountain National Park Weather Forecast
A
brief round of winter weather settled over RMNP last
weekend, before warmer and milder conditions returned this week.
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The Week in Review
Last
weekend’s storm system was stronger and slower than
earlier forecasts had advertised. That
system brought another beneficial round of precipitation to the region,
with
the mountains east of the Divide being the main beneficiary (~1 foot of
new
snow).
As
is often not the case around these windy parts, the winds
were relatively low both during and after the storm event.
This
provided a lower avalanche risk compared
to what we typically encounter during and following storms of this
magnitude.
The
new snow also helped to replenish the available water
supply for new water-ice growth. The
warming trend for the days that followed the storm brought daytime peak
temperatures above the freezing mark, while clear and dry skies brought
hard freezes
during the night; a favorable temperature cycle for diurnal ice growth.
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click
chart to enlarge
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Dave
Tomasula getting the goods on the lower angled slopes of the east face
of Flattop Mountain in RMNP on Nov. 15th, 2009. Photo
courtesy of Dan Bowers. Dan reported that on steeper slopes
they found poor bonding between old and new snow layers and thus chose
to stick to <30 degrees on this beautful
day.
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The Upcoming Week
Very
stormy weather has focused on the Pacific Northwest
over recent days, and this stream of energy will provide
CO with its next chance for cooler/wetter weather this weekend.
Alpine
temperatures will cool by 5-12 C beginning on late
Saturday, and will last for several days.
Moisture will also be
on the increase, and, when combined with a couple
of weather disturbances, will increase the threat of snow through
Monday.
The
first system will move across as a low-amplitude wave on
late Saturday, which will limit the precipitation to light snow showers.
The
second system will move in on Sunday night, and is
forecast to be stronger than Saturday’s system by all
forecast models.
The European model has
a more favorable
forecast position for precipitation over RMNP.
The European model
continues to out perform all of the forecast models
over the past month.
In
the post-frontal environment, winds are forecast to be
strong out of the northwest, which will transport new snow into east-
through
southeast-facing aspects and will likely form sensitive new slabs.
Another
weather system may clip the northeast part of the
state on Wednesday (11/25).
This may
also bring increased northwesterly winds.
After a brief warm up,
more disturbed weather may stream into the area
by late Friday (11/27).
With currently a
large degree of variability in the model-forecast output, the jury is
still out
on both of these systems.
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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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