The weekly 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. 

Issued Thursday May 15, 2008

The Week in Review

It was a snowy one this last week, with three different storms collectively precipitating over 1.5 – 2.5 inches of water over the mountains of RMNP.  The first two storms, which occurred last Fri./Sat. and Mon./Tue., produced most of the precipitation, with about 16 and 6 inches of snow falling over the alpine regions during each storm respectively.  Another weaker impulse moved into the area yesterday (Wed.), and dropped an additional 2-4 inches of snow over the higher elevations.  As seen in the plot below, relatively mild temperatures accompanied each storm.

These atmospheric conditions produced higher density snow (with higher water content), which provided a sticky coating of snow for the higher terrain.  However, this relatively warmer airmass combined with increased diffuse solar radiation during the day and trapped longwave radiation (by clouds) during the night have prevented a deep freeze of the new and existing snowpack.  As a result, punchy, funky, and unstable snow conditions currently exist (see Eli’s Ice and Current Conditions reports).  Also noted in the plot, the water content of the overall snowpack has once again increased, which has more than compensated for the melt losses from the week prior.

The post storm (frontal) environment (e.g., Sun. May 11th and Wed. May 14th) has continued to be conducive for stronger winds (see plot below), where speeds as high as 50 mph were reached in the higher alpine locations.  However, below treeline the winds have mellowed significantly, with sustained speeds remaining below 15 mph all week.

The Upcoming Week

One more relatively cool and showery day of weather is in store for the mountains of RMNP, as another weak weather disturbance tracks across the northern mountains overnight on Thurs. into early Fri. morning.  By Fri. afternoon, the well advertised giant ridge of high pressure currently along the west coast will gradually shift eastward over the next few days.  With this, the atmosphere will dry and warm up dramatically over the Colorado.  By Sun. and Mon., we will likely see some of the warmest temperatures of the season.  With this increase in airmass temperature, more direct solar radiation during the morning and afternoon, and the existence of unconsolidated high density snow that fell over the past week, the threat of wet snow instability will dramatically increase over the next few days.  A widespread ‘shedding’ cycle is probable, if the forecasted atmospheric conditions verify. 

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The classic precursor ingredients include a short or non-existent overnight freeze of recently fallen snow (up to 1-2 feet in our case), clear skies / maximum direct solar radiation exposure during the morning and afternoon hours, warm air temperatures, and no to low wind speeds.  Terrain with eastern and southern aspects will be the most likely candidates for this activity, especially near and below rock outcropping where the absorption of solar radiation will be maximized.

The next weather system is currently forecast to move into the area next Wednesday.  It will usher in colder temperatures and bring the threat of precipitation with it and maybe another period of good ice conditions in the high country.

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.