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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.
april28weather
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Thursday, April 28th, 2011
Rocky Mountain National Park Weather Forecast
In what has already been a banner year for snowfall across RMNP, April has so far been the winner for the greatest monthly snowfall accumulations across the Park.
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Week in Review
This winter’s La-Nina conditions were the strongest observed since 1975. During La-Nina events, the circulation response over the western US often produces snowier than average conditions across the northern ranges of CO. This correlation verified and was further strengthened this year, as record snows have fallen across much of the northern mountains including RMNP.
The propensity for frequent storms to track across CO from the northwest to the southeast produced the greatest snowfall accumulations west of and near the Divide, owing greatly to enhanced orographic lift. The stable, northwesterly flow also forced strong winds, which produced monstrous cornices and very deep drifts (10’s of feet deep) in the lee of the Divide, and warmed on its down-sloping trek to keep the lower eastern slope and high plains anomalously dry.
The northwesterly racetrack reestablished itself in full force in April. This guided relatively weak weather systems directly across the northern ranges of CO on a very frequent basis (every 1-3 days). The combination of a warming and moistening spring atmosphere produced higher-water content snows and greater snowfall rates, thus providing a good coating on alpine terrain features that were otherwise scoured by the colder and drier winds of winter. On average, about 10 inches of new snow water equivalent (SWE) fell across the Park in April.
As the annual peak in SWE draws very near, we are currently seeing some of the greatest snowpack water content observed in years across the Park. In the subalpine locations, the SWE is between 138% and 208% of average. At 174% of average, the SWE at Willow Park (the southern end of the Mummies) is the greatest observed since measurements began in 1980.
The 167% of average SWE at Never Summer is also the greatest observed on record there, but measurements only recently began in 2003. However since 1981 at Bear Lake, there have been three other years with greater peak SWE than 2011, namely 1986, 1996 and 1997 (all in the 30-35” range). Those years were aided by easterly-upslope snow events, which were essentially absent this past year.
Needless to say, the rest of this spring and early summer is shaping up to be one of the finest mountaineering seasons in recent memory.
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A graphed summary of the winter's weather snowfall depths in Rocky Mountain National Park, Colorado.
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The weather forecast for April 28-May 5th , 2011 over the skies of RMNP, Colorado.
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The Upcoming Week
Winter-like storms are still forecast to track across northern CO over the coming two weeks. However, owing to the larger spatial scale of these upcoming systems, there are likely to be warmer and longer periods (2-3 days) of spring weather between systems.
The main system for the week will occur over the weekend on 4/30-5/1. Temperatures will plummet back to winter levels, and an extended period of snowfall is possible with the passage of the cold front, post-frontal orographics, and possibly even an east-side upslope event to follow. Unstable lapse rates will produce heavy snowfall rates and spatially-variable accumulations.
If the temperature rapidly rebounds on 5/3-4 as forecast, there is a strong likelihood for shedding of the new snow on aspects exposed to the sun.
The next weather system is currently forecast to affect the Park at the end of next week.
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Horacio sliding back to camp on our recent Ski Mountaineering Expedition to the Pika Glacier area of the great Alaska Range.
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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.
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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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