Jet Stream and Low Level Jets (LLJ)

Jet Stream

•Polar Front Jet Stream (midlatitudes)

•Subtropical Jet Stream

–Warm ENSO event à amplitude of polar jet stream increases (Rohli 77)

•Warm ENSO event à amplitude of polar jet stream increases

–Jet amplitude dictates where storms form and where they will travel (Rohli, 77)

•Troughs may induce greater precipitation in the southern and central US (78)

•N. American Jet during wet (dry) years is southward (northward) shifted and intensified (weakened) (Ting)

(click to enlarge)

•Flood (drought) years may be associated with increase (decrease) in frequency and strength of LLJ (Arritt)

•Severe precipitation episodes associated with the incidence of strong LLJs (Arritt)

LLJ pulling moisture into Great Plains

LLJ diverges limiting moisture transport to Southeast US

(configuration during 1930s Dust Bowl)