Ty Dickinson - May 5

Weather and Climate Systems Seminar

Subseasonal to Seasonal Extreme Precipitation Events in the Contiguous United States: Generation of a Database and Climatology

Ty Dickinson

Wednesday, May 5^th

2:00pm

Join Google Meet:

https://meet.google.com/jdv-kpfr-gnu

Extreme precipitation across multiple timescales is a natural hazard that creates a significant risk to life, with a commensurately large cost through property loss. We devise a method to create 14-day extreme event windows that characterize precipitation events in the contiguous United States (CONUS) for the years 1915 through 2018. Our algorithm imposes thresholds for both total precipitation and the duration of the precipitation to identify events with sufficient length to accentuate the synoptic and longer time scale contribution to the precipitation event. Kernel density estimation is employed to create extreme event polygons which are formed into a database spanning from 1915 through 2018. Using the developed database, we clustered events into regions using a k-means algorithm. We define the “Hybrid Index”, a weighted composite of silhouette score and number of clustered events, to show the optimal number of clusters is 14. We also show that 14-day extreme precipitation events are increasing in the CONUS, specifically in the Dakotas and much of New England. Connections to large-scale modes of variability and regional characteristics will also be discussed. Overall, our algorithm can be extended to any desired number of days on the subseasonal-to-seasonal (S2S) timescale and the databases will serve as focal points in extending predictability of S2S extreme precipitation events in the CONUS.