Thursday,  September 24th, 2009

Rocky Mountain National Park Weather Forecast
 

Another taste of winter marked the official end of summer in the mountains of RMNP over the past week.

The Week in Review

After a period of pleasant late-summer weather conditions (on Thu. 9/17 through Sat. 9/19), a trough of low pressure set up camp just east of the state for several days.

Since the colder airmass moved over the region on late Sun. (9/20), temperatures near and above treeline have remained below freezing.

As is usually the case with closed low-pressure circulations that form just to the east of the Front Range, mountain-precipitation forecasts are often a make or break proposition. 

This week’s storm system was no exception.  The official 12-16” mountain snowfall forecast was a bust owing to a ~100 mile westward error in the forecast storm position. 

The observed eastward position of the storm center forced down-sloping winds along much of the eastern slope, which greatly suppressed precipitation production.

Nevertheless, with wrap-around moisture and some upslope flow over the higher elevations, we were able to squeak out a few inches of snow over the alpine region.

Eli 'French-freeing' the first pitch of 'Ladyback Crack'-  an M7 iced up fisure on the South Face of Mt. Lady Washington, directly above Chasm Lake.  Photo taken by CLG Apprentice Guide Mike Arnold on Sept. 24th, 2009- a cold, blizzardy day at these elevations.

The Upcoming Week

The current storm system will continue to wobble around just east of the eastern border through Friday

Afternoon instability will force another round of snow showers on Thursday over the mountains of RMNP, where a couple more inches of accumulation are possible.  Weather conditions should improve on Friday., as the system finally begins its eastward trek.

click to enlarge forecast map

Drier, warmer, and stable weather conditions will return to RMNP over the weekend.  Daytime snowmelt combined with hard nighttime freezes should contribute to water-ice development in favorable alpine locations.

Also, under stable northwesterly flow, winds will be picking up over the high peaks through the weekend, and may be strongest on Monday as a system clips the northeast part of the state.

Pleasant fall weather is forecast for next Tuesday through Thursday, before another winter-like system possibly affects the area near the end of the week.

The NWS numerical forecast for the mountains of RMNP over the upcoming weekend

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