Thursday, February 28th, 2013

Rocky Mountain National Park Weather Forecast

Researched and written by professional meteorologist and avid mountaineer, Dan The Weather Man Gottas.

Week in Review

Two storm systems on 2/24 and 2/26 produced about 0.5” of new snow water equivalent (SWE) at several subalpine SNOTEL sites across RMNP. A third system, in progress on 2/28, is expected to produce an additional 0.1-0.15” of SWE. During a Level-1 AIARE Course over the weekend, a ClimbingLife Guides group found a foot of new snow near Dream and Emerald Lakes in the Tyndall Gorge, with up to an additional 8-10 inches in lee-loaded wind deposition zones.

Last week’s model forecast had these first two disturbances passing over as open cyclonic waves, with enhanced precip production by post-frontal northwesterly flow. Instead, these systems spun up into closed circulations as they passed east of the mountains, which brought easterly-component wrap-around flow to locations east of the Divide in the vicinity of RMNP.

The closed-circulation structure also dramatically changed the snow transport and deposition patterns, with scouring/transport originating on east-facing terrain features and lee/cross-loading deposition on west-facing terrain features.

With high pressure building across the western US on 3/1-2, mountain snow showers will taper off by late 3/1 and drier and warmer conditions will prevail over the weekend across RMNP. Moderate northwesterly flow aloft on 3/1-2 will keep the downslpoing breezes going east of the Divide.

The next winter system will track across the northern Rockies late on 3/3 and 3/4. This will place RMNP on the windy south side of a cyclonic wave, where a mid-level jet and stable westerly flow at mountain-top will force a healthy lee-side mountain wave response. Current model guidance suggests another 0.25” of SWE, however much greater deposition (particularly on east-facing aspects below treeline) can be expected if the wind forecast verifies.

Another much larger scale storm system making landfall in CA on 3/6 will bring the next threat of winter weather to CO and RMNP on 3/7.

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.

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