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Statistical characteristics of Arctic forecast busts and their relationship to Arctic weather patterns in summer
  • Akio Yamagami,
  • Mio Matsueda
Akio Yamagami
University of Tsukuba

Corresponding Author:[email protected]

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Mio Matsueda
University of Tsukuba & University of Oxford
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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.