Snow and Convection


Image compliments of the National Weather Service.


Introduction

Thundersnow is the ultimate winter weather experience. This observer is fortunate to have experienced it quite a few times, most recently the evening of February 20th, 2014 and twice in April 2013. Even observed cloud-to-ground lighting in storms on April 5th, 2008 and about a week later on April 11th, 2008. Lucky me!

The "Favorite Storms" page of this website documents some (but not all) additional observations. To emphasize, these are personal local observations. Thunder was not necessarily reported at the official observation location.

Where Does Thundersnow Occur?

First of all you have to get snow. Locations that don't get much snow are obviously a lot less likely to experience thunder with snow reaching the surface. Climatological studies done for the "Research on Convective Snows" project at the University of Missouri-Columbia indicate that thundersnow is most common in the central United States as well as areas downwind of the Great Lakes that experience single-banded lake effect snow squalls and parts of the intermountain region of the western U.S. Utah showed one of the highest concentrations. An example of thundersnow occurring in a much less likely location is Port Oregon with thundersnow producing two inch per hour snowfall rates late evening into overnight January 10th to 11th, 2017.

The Central United States

More specifically for the central United States, a higher concentration of thunder reports extended from the central High Plains and the Texas Panhandle, east and northeast through the middle and upper Mississippi Valley. The observations typically occur from northeast to northwest of a strong surface low pressure center where instability can exist without being surface-based. Thundersnow does still occur with surfaced based convection along cold fronts. Thundersnow also still occurs in storms with a weak low pressure system if atmospheric processes produce a condition where instability and strong vertical motion overlap. The occurrence of thundersnow in mountain ranges is aided by orographic lift helping to initiate thunderstorm development and the fact that the high elevations poke up into air cold enough for snow to reach the ground.


General Discussions

Jeff Haby's brief discussion from theweatherprediction.com

Research and Case Studies

Morales,R. F., 2008: The Historic Christmas 2004 South Texas Snow Event: Diagnosis of the Heavy Snow Band. Bull. Amer. Meteor. Soc., 2, 135-152.

Market, P. S., C. E. Halcomb, and R. L. Ebert, 2002: A Climatology of Thundersnow Events over the Contiguous United States. Wea. Forecasting, 17, 12901295.

Market, P. S., A. M. Oravetz, D. Gaede, E. Bookbinder, B. Pettegrew, and R. Thomas, 2004: Proximity sounding composites of Midwestern thundersnow events. 20th Conference on Weather Analysis and Forecasting, Seattle, WA, Amer. Meteor. Soc., p4.2.