Friday, January 9th, 2009

The Week in Review

Yep, you guessed it – wind.  After a brief relative respite last weekend, the west-northwesterly wind tunnel cranked up once again over the last several days battering the peaks with 75+ mph gusts. 

Weather disturbances guided by the northwesterly flow also brought deep moisture to the area.  This moisture, when combined with strong orographic forcing and some atmospheric forcing, brought a two-day period of steady snowfall to the northern mountains of CO.

At least one inch of new snow water equivalence (SWE) was measured at several locations from Indian Peaks north to the Medicine Bow Range.  In RMNP, 1-2 inches of SWE accumulated on Tuesday and Wednesday, with Bear Lake reporting 2 new inches.  With the powerful and persistent alpine winds, a significant fraction of the new accumulations near and below treeline are likely the result of snow transport from above treeline.  In addition, significant slab development has likely occurred.

The Upcoming Week

One more snow producer will occur on Friday, before the wicked ridge of the west casts its dry weather spell once again.  For the storm system on Friday, roughly 0.25 inches of SWE are forecast for the higher terrain. 

The next chance for precipitation comes on Monday and Tuesday, but little accumulation is expected.  However, periods of strong northwesterly wind gusts will accompany these weather disturbances, as they brush by the northeastern part of the state.

A strong extended jet stream across the Pacific Ocean will maintain a mammoth ridge of high pressure along the west coast of North America.  Pacific storm systems will make landfall in Alaska, and Canadian storm systems will enter the USGreat Plains. 

If and when the extended Pacific jet retracts, retrogression of the ridge may once again allow storms system to make landfall along the US west coast and bring increased chances for precipitation to CO.  This process may take a couple of weeks to come to fruition.

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.