Real Time North Pacific Jet Forecasts
An effective way to examine the state and evolution of the upper-tropospheric flow pattern over the North Pacific Ocean is to consider the two leading modes of 250-hPa zonal wind variability during the cool season (Sept–May). The first mode corresponds to a zonal extension or retraction of the climatological exit region of the North Pacific jet (NPJ) stream, while the second mode corresponds to a poleward or equatorward shift of the climatological exit region of the NPJ. The projection of 250-hPa zonal wind anomalies at any one or multiple times onto the two leading modes of 250-hPa zonal wind variability provides an objective characterization of the state or evolution of the upper-tropospheric flow pattern over the North Pacific, which can be represented on a NPJ Phase Diagram.
Recent work suggests that each mode of variability can influence the character of the downstream flow pattern over North America and that each mode is characterized by different degrees of forecast skill. Motivated by these results, we have collaborated with personnel at the NCEP Weather Prediction Center to develop real time NPJ Phase Diagram forecasts using daily GFS and GEFS ensemble forecasts during the cool season. These forecasts, as well as the composite flow pattern associated with each phase of the NPJ, can be accessed by clicking the images below.
Recent work suggests that each mode of variability can influence the character of the downstream flow pattern over North America and that each mode is characterized by different degrees of forecast skill. Motivated by these results, we have collaborated with personnel at the NCEP Weather Prediction Center to develop real time NPJ Phase Diagram forecasts using daily GFS and GEFS ensemble forecasts during the cool season. These forecasts, as well as the composite flow pattern associated with each phase of the NPJ, can be accessed by clicking the images below.
This work was supported by the National Oceanic and Atmospheric Administration via Grant NA15NWS4680006