Subseasonal prediction of the state and evolution of the North Pacific jet stream Journal Article uri icon

Overview

abstract

  • The state and evolution of the North Pacific jet (NPJ) stream strongly; influences the character of the downstream synoptic-scale flow pattern; over North America. This study employs data from nine models within the; Subseasonal-to-Seasonal Reforecast Database hosted by the European; Centre for Medium-Range Weather Forecasts to examine the subseasonal (2; weeks–1 month) predictability of the NPJ through the lens of an NPJ; phase diagram. The NPJ phase diagram provides a visual representation of; the state and evolution of the NPJ with respect to the two leading modes; of NPJ variability. The first mode of NPJ variability corresponds to a; zonal extension or retraction of the climatological jet-exit region,; whereas the second mode corresponds to a poleward or equatorward shift; of the climatological jet-exit region. The analysis reveals that; ensemble forecasts of the prevailing NPJ regime, as determined from the; NPJ phase diagram, are skillful into week 3 of the forecast period.; Forecasts initialized during a jet retraction, or verifying during a jet; retraction and equatorward shift, generally feature the largest errors; during the forecast period. Examination of the worst-performing 21-day; forecasts from each model demonstrates that the worst-performing; forecasts are uniformly associated with development, maintenance, and; decay of upper-tropospheric ridges over the high-latitude North Pacific.; These results demonstrate that bias-corrected NPJ phase diagram; forecasts have the potential to identify periods that may exhibit; enhanced forecast skill at subseasonal lead times based on the; anticipated NPJ evolution.

publication date

  • August 10, 2021

has restriction

  • hybrid

Date in CU Experts

  • August 17, 2021 12:41 PM

Full Author List

  • Winters A

author count

  • 1

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