Thursday January 29, 2009

The Week in Review

An active week of weather brought significant snows and wind to the mountains of RMNP.

Last Thursday through Sunday, a cyclonic circulation off the coast of Californiatransported a deep plume of warm, moist air over Colorado. The plume had moisture characteristics of a spring-time airmass, with vertically integrated water vapor values exceeding twice their winter-time climatological levels.  

Despite weak dynamical forcing and only modest orographic forcing, efficient high-density snowfall processes were sustained by the warm, moist, and thermodynamically unstable airmass.  

The Park Range, west of RMNP, was the big precipitation winner with 4-6 inches of new snow water equivalence (SWE) in four days, while the mountains of RMNP received around 2 inches of SWE during the same period. 

Winds during the storm were from the south through west, and produced drifting on north- through east-facing aspects.  

Deep, stable northwesterly flow developed once again on Tuesday through Thursday, which induced mountain-wave accelerations east of the Divide.  As a result, strong down-sloping westerly winds have been continuously cranking over the Park. 

Alpine terrain with western exposure was once again scoured, and significant transport produced healthy snow drifts in the sub-alpine regions (see Eli’s conditions report). 

A cold disturbance in the northwesterly flow produced additional low-density snows on Wednesday and Thursday, supplying more available mass for the drifting machine.

The Sharkstooth emerges from a winter windstorm near the Continental Divide.

The Upcoming Week

In terms of new precipitation, the next week will be quiet.  Some light mountain snow may accompany a weather system on Sunday, but accumulations are expected to be minimal.  Stable northwesterly flow will persist over the region for most of the week.  This will maintain an accelerated wind pattern east of the Divide.  The strongest winds of the week may occur in the post-frontal environment following the passage of Sunday’s weather system.

Low pressure and storminess will develop off the coast of California by Wednesday.  This energy is currently forecast to move into the southwestern US by Friday.  Southwesterly flow will develop over CO, with the threat of precipitation increasing and favoring the southwestern and central mountains.

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

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