Case Study of Wintertime Thundersnow in the Lake Tahoe Region
Authors
Korotkin, Mikhail
Issue Date
2021
Type
Thesis
Language
Keywords
Convective Snowfall , Jet Streak , Lightning , NCFR's , Sierra Nevada , Thundersnow
Alternative Title
Abstract
On February 14, 2019 over 1,000 lightning strikes were recorded in the Sierra Nevada and western Nevada. This was part of an atmospheric river that impacted the entire state of California and produced substantial precipitation and snowfall totals. A substantial portion of lightning strikes were coincident with snowfall and thus, this was a large-scale instance of thundersnow. Thundersnow has the potential to impact transportation and safety of life and property through heavy snow loading and lightning. This study employs the Weather Research & Forecasting Model (WRF) to recreate this event and study the synoptic and mesoscale mechanisms. By using an ingredients-based methodology the postmortem analysis of the WRF data revealed that a combination of factors contributed to this event. An upper-level jet streak was present, and the left exit region was overhead which promoted upward vertical motion over the region. A strong cold front was passing into the region which ushered in cold air and destabilized the region. Observational radar analysis revealed Narrow Cold Frontal Rainbands (NCFR’s) which were the associated lightning producing bands. The WRF model also produced NCFR’s during the time period of greatest lighting strikes. The sounding analysis revealed substantial instability for wintertime, but on par with previous studies on thundersnow. This analysis revealed mechanisms for a large scale thundersnow event in mountainous terrain which would help increase accuracy in predicting events like this in the future.