Statistical characteristics of Arctic forecast busts and their
relationship to Arctic weather patterns in summer
Abstract
Operational numerical weather predictions (NWPs) have been improved
considerably over recent decades; however, they still occasionally
generate large forecast errors referred to as “forecast busts”. This
study investigates forecast busts over the Arctic between 2008 and 2019
using operational forecasts from five NWP centers. Forecasts with an
anomaly correlation coefficient below the climatological 10th
percentile, and a root-mean-square error above the 90th percentile, are
regarded as “busts”. The percentage of forecast busts decreased from
2008 (7% to 13%) to 2012, and was between 2% and 6% for the period
2012-2019. The seasonal cycle of the forecast busts shows peaks in May
and July-September. The forecast bust occurred more frequently when the
initial pattern was the Greenland Blocking (GB) or Arctic Cyclone (AC)
pattern rather than one of the other patterns. These results help users
to be careful when they use the forecasts initialized on GB and AC
patterns.