Giving Thanks for the NCAR Ensemble

For nearly three years, the National Center for Atmospheric Research (NCAR) has produced a daily, 10-member, cloud permitting ensemble at 3-km grid spacing known as the "NCAR Ensemble". 

For those of us in the western U.S., the NCAR Ensemble forecasts, available from web sites hosted by NCAR and the University of Utah, attempted to do something that no current operational forecast system could three years ago — capture the extreme spatial contrasts and quantify the inherent uncertainty of precipitation over the western United States. 

Last night's forecast, for example, shows the major deluge expected to affect the Pacific Northwest through Thanksgiving.  At 3-km grid spacing, the NCAR ensemble accounts for many regional and local topographic influences and, with 10-members, one can derive statistics related to the range of possible forecast outcomes and the likelihood of precipitation above certain thresholds (our standard 1" and 2" thresholds work well for the Wasatch, but not the Cascades!). 

Plume diagrams allow one to examine precipitation at various locations, including Mt. Baker Ski Area below.  Such a pity that nearly all of that water will fall in the form of rain.

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Recently, NCAR announced that the NCAR Ensemble will sunset at the end of the calendar year.  More information is below. 

Although I'm sad to see it go, I believe this move makes sense.  NCAR is a research lab, not an operational center.  They need to be unshackled from routine forecasting and free to explore creative ideas and pursue modeling breakthroughs.  The NCAR Ensemble did this for three years.  It has allowed us to learn a great deal about cloud-permitting ensembles.  For example, we have a paper examining the performance of the NCAR Ensemble that may be the subject of a future post.   

Given that tomorrow is Thanksgiving, it seems fitting to toast the NCAR Ensemble team that includes Kate Fossell, Glen Romine, Craig Schwartz, and Ryan Sobash.  Thanks so much! We look forward to a few more weeks of NCAR Ensemble forecasts, and hope that Mother Nature shifts this damn pattern so that we can actually use them for powder hunting in Utah!