Snow and Convection


Image compliments of the National Weather Service. 








Introduction

Thundersnow IS the ultimate winter experience. I am fortunate to have experienced it twice in Columbia, MO, twice in Topeka, KS, and numerous times in Duluth, MN, including cloud-to-ground lightning twice. The "Favorite Storms" page of this website documents some of the snowstorms during which thunder was heard and/or lighting was seen. Understand that primarily personal observations are recorded in the storm summaries. Thunder may not have been officially reported in every case. Also note that convective elements in a snowstorm do not have to produce thunder.






Where Does Thundersnow Occur?

To get thundersnow you obviously have to get snow. Locations that don't get much snow are a lot less likely to experience thundersnow. 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 Portland Oregon with thundersnow producing two inch per hour snowfall rates late evening into overnight January 10 to January 11, 2017. 






The Central United States

More specifically for the central United States, the same study showed 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 occurred 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 can also occur in storms with a weak surface low pressure system if atmospheric processes still produce a condition where instability and 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.





References

Jeff Haby's discussion from   theweatherprediction.com




The "Research on Convective Snows" project at the University of Missouri-Columbia




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, 1290�1295. 




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.