Wednesday, March 17th, 2010

Rocky Mountain National Park Weather Forecast
 

The battle between winter and spring continued over RMNP, with spring weather taking the upper hand during most of the past week.

The Week in Review

The battle between winter and spring continued over RMNP, with spring weather taking the upper hand during most of the past week.

The strong northwesterly winds of nearly a week ago produced widespread hard slab on exposed snow slopes above treeline, as observed in the Longs-Meeker cirque.  Wind speeds have since dropped to lower levels, with little in the way of additional drifting and slab formation.

The storm system on the 3/14 dropped some new snow over RMNP (with 2-3 inches measured at BearLake), but most of the precipitation action remained south of the Park as the storm circulation took a southeastward trek across the southern Rockies.

Sunny, warm, calm spring conditions graced the Park over the past three days.  With this, diurnal melt/freeze cycles have returned to elevations near and below treeline.

Near-surface snow in these regions settled and strengthened (e.g., the snow depth decreased 4 inches near Bear Lake), and sun crusts developed on aspects exposed to solar radiation.

The Upcoming Week

After one more day of spring-like conditions, winter will make a roaring comeback on Friday,  3/19.  Powder days are on the way.

Strong atmospheric dynamics will accompany a strengthening winter cold front, which is forecast to move into the region from the north during the overnight and early morning hours on Thu/Fri. 

Strong rising motion will produce moderate to heavy snowfall rates that will quickly increase the avalanche risk, with rapidly accumulating new loads and possible bonding issues with the old snow surface.

Snowfall is expected to continue during the afternoon hours in the post-frontal environment, as moist easterly-component upslope flow is forecast up to mountain-top level and atmospheric lapse rates become increasingly unstable during the latter part of the day.

Potential snowfall totals by the end of Fri. may be in the 1-1.5 foot range across the higher elevations.  Any drifting and new slab formation will occur under moderate northeast flow.

When the storm system moves east of the area on late Fri into Sat, winds will turn around from a west through northwest direction.  Mountain wave accelerations can be expected east of the Divide, and significant snow transport and new slab formation are probable on the more climatologically typical lee- and cross-loaded terrain features.

Winds will begin to turn around from the southwest on Mon 3/22 in advance of the next winter storm system. Current forecast model projections indicate another round of snowfall on Tue and Wed.

As is often the case with forecasting storm position and strength beyond 5 days, particularly during the transition seasons, there is currently too much variability in the forecast solutions to detail how this next storm will pan out for RMNP.  Stay tuned.

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