The
weekend weather forecast for the high country of Rocky Mountain
National Park, Colorado. Researched and written by professional
meteorologist and avid mountaineer, Dan "the weather man" Gottas.
March 4weather
|
Friday, March 5th,
2010
Rocky
Mountain National Park Weather Forecast
The
first weather signs of the upcoming spring season
arrived over the past week, with warm afternoon surface temperatures
(near
freezing) between storms and convectively enhanced precipitation during
storms.
|
|
The Week in Review
The
two stormy periods occurred on 2/25-2/26 and
2/28-3/1.
The first storm was a
dud for
new snowfall over the higher terrain, while the second storm produced
about
4-6” of new snow above Bear
Lake.
The
first storm was a ‘no go for snow’ owing to the
shallow
depth of the easterly upslope flow, which only extended up to ~9500
feet.
This orographically
forced the airmass along
the eastern slope to rise and produce precipitation east of the ~9000
foot
level.
As
depicted by the green areas in the radar image, snowfall
rates were locally enhanced due to convective instability.
During
the spring, convective instability and
resulting enhanced precipitation rates often result when cold air aloft
(associated
with storm circulations) phase with warming temperatures near the
surface
during the afternoon hours.
Convectively
enhanced precipitation also occurred with the
second storm on 2/28-3/1, with very brief periods of 1-2 inch-per-hour
snowfall
rates near Bear
Lake.
More
consistently enhanced rates
were observed near Berthoud
Pass
(to the south of
RMNP), where orographically favorable northerly winds combined with the
instability to produce over a foot of new snow.
|
Mike Arnold hitting the fresh powder below Hallett on March 5th, 2010.
We found sensitive slab conditions in
this new snow which combined with strong winds was setting-up soft slab
conditions at and above treeline today in the Tyndall Gorge.
|
|
The Upcoming Week
Three
storm systems will affect the weather over RMNP over
the next week.
The
first system will track across the state of CO on Friday,
3/5. After pre-frontal southerly winds and a dry frontal passage in the
early
morning, westerly winds will develop in the post-frontal environment.
Orographically
induced snows will occur during
the day in this post frontal environment, and the formation of new
drifts and
slabs is expected with sustained winds in the 30-40 mph range.
The
next system is expected on late Sunday 3/7. Current
forecasts indicate both weak
dynamical and orographic forcing, as most of the system’s
energy is forecast to
remain the south.
A change in the forecast
track will be necessary to produce more than the currently forecasted
meager
snowfall.
The
third system is forecast to clip CO from the northwest
on Wednesday 3/10.
The current forecast
track
and strength is not conducive for a significant snow producer.
|
Dan
Gottas taking
the time to do a couple of column tests in the middle of the 40 degree
steep Otis Redding Couloir on a Feb. 28th, Avalanche Field Seminar.
We found strong over weak layering in the top meter and an easy
failure under a 15cm pencil hard slab on one out of three, side by side columns with no other failures
occuring within this single profile.
|
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
|
|
