About ESAC

Our Mission:
To provide quality avalanche and snowpack information to local and visiting backcountry users in the Eastern Sierra Nevada with the goal of helping them make better decisions while travelling in avalanche terrain.


The Eastern Sierra Avalanche Center has a staff of three full-time forecasters - profiled below.
For general information, please email 

Josh Feinberg
Lead Forecaster


Josh moved out to the Eastern Sierra for a winter in 2002 to try out Ski Patrolling, and can’t seem to leave.  Discovering and exploring the winter backcountry soon became a passion as he learned to link more than 2 turns together on those floppy hippy skis with broken heal bindings.  Over the years he’s learned to respect the snow thru experience and education.  He’s had the privilege of being part of the Mammoth Mountain Ski Patrol team for over a dozen years, and it is now his sixth year as part of the Eastern Sierra Avalanche Center’s forecasting team.  He spends summers working for the Forest Service’s Forest Inventory and Analysis program, hugging trees with measuring tapes and collecting data on forest health all over central California.

Chris Engelhardt


The Eastern Sierra has always been a special place to Chris- he grew up skiing at Mammoth and after college returned to ski patrol at Mammoth for four winters. His adventurous nature led him to other mountain ranges, first as a guide/patrol and then snow safety director at Silverton Mountain in the San Juan Mountains of Colorado. He has also forecasted and guided heli-skiing in the Chugach and Kenai Ranges of Alaska, and guided skiing on Hokkaido, Japan. Chris has worked as a ski/snow professional since 1999 and is experienced with both maritime and continental snowpacks. Personal ski trips, especially extended tours in the High Sierra, have solidified his passion for skiing and immersion in the winter environment. Chris lives with his wife Blake in Bishop, CA. He is thrilled to be back in the Range of Light for his 20th winter season!

Steven Mace



Steven grew up in Golden Colorado where he learned to ski at quite a young age.  He began to venture outside the gates in his mid teens and never looked back.  While attending college in Durango CO, he continued to push his skills and knowledge earning his turns in the San Juan Mountains.  He has skied across the globe from Japan to the Himalaya where he helped start a ski school in Gulmarg, Kashmir.  More recently Steve has worked as a Ski guide in the Wallowa Mountains of eastern Oregon as well as a member of the Snow Safety department at Mt Hood Meadows.  When Steve isn’t skiing he spends his time guiding raft trips on the Colorado River through the Grand Canyon. 


The Friends of Eastern Sierra Avalanche Center is a 501(c)3 non-profit organization dedicated to raising funds to ensure staffing for the operation of the avalanche center each year. The organization is overseen by a volunteer Board of Directors, outlined below.  For general information, please email office@esavalanche.org.

Nate Greenberg

Nate Greenberg has called the Eastside his home since 2000. Drawn here by the acess to amazing terrain and quality of skiing, he has spend a considerable amount of time exploring the snowy Sierra. Nate is AAA Level III trained and has worked as a NOLS instructor for climbing and mountaineering. A former competitive telemark skier, Nate now enjoys getting into the backcountry with friends and exploring the endless terrain of the Eastern Sierra.

As his day-job, Nate is the IT Director for Mono County, and as the co-author of Backcountry Skiing California's Eastern Skierra, Nate's interest is in disseminating quality information to the general public. As a result, Nate spends a great deal of time on the Center's website, and helps coordinate the overall operations of the Center.


Scott Quirsfeld
Vice President

Over the past 18 years Scott has been working in the outdoor industry, starting as a rock climbing instructor, part time Ski Patroller and a PSIA certified Ski Instructor. After a winter in New Zealand, Scott moved from Taos, NM to Mammoth in order to pursue longer winters. He has been a Pro Patroller for Mammoth and a passionate Eastern Sierra backcountry skier since 1998.

Scott earned an Engineering degree at The Ohio State University and immediately relocated to the Rockies where he earned an Emergency Medical Technician degree from the University of New Mexico. Since moving to Mammoth he has earned the following certifications: National Avalanche School phases I & II, Avalanche Blaster’s license, AAA Level III, AUNAC Artillery Gunner, Avalanche Rescue Dog Handler. He has continued to challenge himself and fellow patrollers by organizing avalanche rescue scenarios and training new patrollers at Mammoth. He is currently recognized by Recco, Dynastar/Lange, and Hestra as a representative.
When Scott is not working, you can find him backcountry skiing, ski mountaineering, or ski touring with his dogs all over the Eastern Sierra.  

Forrest Cross

Forrest Cross has been visiting the Eastern Sierra for almost 15 years and has lived here for the last 10 years. One of the main reasons he lives here is for the endless backcountry skiing opportunities during the winter months. For the last 20 years he has been backcountry skiing in the mountains of Northern California and the Sierra. He has completed a level 2 AIARE course and has taught avalanche awareness to guides for Outdoor Adventures at UC Davis. When not playing in the hills, Forrest works as an engineer for the Mammoth Community Water District and helps monitor all the runoff that the winter snows produce. Forrest enjoys being involved with ESAC and helping to spread the word of avalanche safety in the Eastern Sierra. As Membership Director he keeps tabs on membership numbers and maintains the member email list-serve.

Howie Schwartz

Howie Schwartz is an AMGA/IFMGA certified ski and mountain guide based in Big Pine, California. Howie guides skiing and mountain climbing trips year round in the Sierra Nevada, the Alps, Alaska and other destinations. He is an instructor/examiner for the American Mountain Guides Association and is on the AMGA Technical Committee. He was a founding member of the American Institute for Avalanche Research and Education and leads AIARE level 1-3 avalanche courses. Howie also trains AIARE instructors. Howie’s skiing relationship with the Sierra started in the spring of 1996 on a basecamp ski trip near Virginia Lakes. Since that time, this love affair has all but ruined his otherwise productive professional life. Howie has still not figured out what “Sierra Cement” is, but he has heard some can be found up near Lake Tahoe.

Allan Pietrasanta

It was almost 25 years ago that Allan Pietrasanta realized the need for an easier to use, more protective case for his Pieps avalanche beacon. The standard yellow thin cloth bag and shoestring necklace just wasn’t cutting it, so he created high-tech padded pouches that he was able to use in trade for payment to complete one the first avalanche courses taught in Mammoth. While the beacon case project helped increase his avalanche awareness, it was also the roots of a sewing manufacturing company, ABCOM/Buttermilk Mountain Works, that Allan owned and operated for over two decades in Bishop. Allan has left ski tracks in the High Sierra and other mountain ranges of the world, and continues to celebrate the joys of backcountry skiing and its contributions to world piste. He combines his interest in business, his past experience as a mountain guide and early Board member of the American Mountain Guides Association to help ensure a bright future for ESAC.

Neil Satterfield


Bio coming soon!

Walter Rosenthal
President in memoriam

Walter Rosenthal was the Snow and Avalanche Analyst for Mammoth Mountain, a remote sensing expert for the U.S. Army Cold Regions Research and Engineering Laboratory and a researcher at the Institute of Computational Earth System Science, University of California, Santa Barbara. He specialized in remote sensing of snow and snowpack processes related to sintering and avalanches. As a private consultant he provided operational subresolution snow mapping algorithms and programs to the U.S. Army Cold Regions Research and Engineering Laboratory from 1995 through 2002. Both the Army and the National Weather Service’s National Operational Hydrologic Remote Sensing Center employ his algorithms and are expanding their use to daily operational snow cover maps over North America.

Walter tragically lost his life while trying to save the lives of others in 2006. He was a vital force in the development of the Center and is dearly missed.

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ESAC receives significant financial support from ...