Thursday,  March 5th, 2009

The Week in Review

After a brief couple of days of winter weather, unseasonably warm conditions returned to the mountains of RMNP over the past week.

A weather system tracking southeastward across northeast CO at the end of last week brought a few inches of new snow, relatively low winds, and cold temperatures. 

With pressure building rapidly from the west in the wake of that system, strong westerly down-sloping flow developed late Friday and into Saturday over eastern sections of the Park.  Winds gusting above 50 mph during that time acted to transform the new snow into hard slab and lee-side drifts.

Persistent storminess along the west coast forced continued amplification of the ridge over CO through Tuesday.  During that time, temperatures warmed well above freezing near and below treeline, and the winds remained occasionally gusty.  Significant settlement and stabilization in the near-surface layers of the snowpack occurred.

Pressure and winds have decreased over the past couple of days in response to the beginnings of large-scale shift in the weather pattern.

The prolonged stormy weather pattern off the California coast has begun its forecasted eastward shift.  Winter weather will return to the mountains of RMNP this weekend, as two weather disturbances affect the area on Friday through Monday.  Winter-like temperature and snow are expected.

Frontal and jet-stream dynamics and steep lapse rates will produce widespread snowfall.  Pre-frontal precipitation will be accompanied by southwesterly winds, and post-frontal precipitation (mostly orographically induced) will occur with westerly winds. 

The combination of stable lapse rates and westerly component flow in the post frontal environment will favor stronger lee-side accelerations on Sunday morning and again on Tuesday.  Significant lee-slope drifting and soft and hard slab formation is probable during these times.

The NWS numerical forecast for the mountains of RMNP over the upcoming weekend is as follows:

Click chart to enlarge

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