Extratropical Hurricane Force Low Centers in the North Pacific Ocean

Forecasters at NOAA's Ocean Prediction Center (OPC) routinely analyze extratropical low pressure systems on the North Pacific surface analysis.  Official wind warnings are issued for each system if the winds associated with the respective low center meet or exceed the minimum threshold for a particular warning category.  There are currently 3 categories for extratropical wind warnings that the OPC issues.  The first category, gale, is assigned to extratropical systems that have winds from 34 to 47 knots.  The second category, storm, designates low pressure systems that have winds from 48 to 63 knots.  The last category, hurricane force, denotes an extratopical or post-tropical system that has winds of 64 knots or greater.  OPC forecasters started issuing hurricane force wind warnings in late 2000 when QuikSCAT data became routinely available.  Up to that point, they were unable to reliably identify hurricane force systems due to insufficient data.  The QuikSCAT mission ended on November 23, 2009, and the OPC forecasters began relying on data from the ASCAT scatterometers on the European METOP-A and METOP-B polar orbiting satellites for guidance with determining wind warnings.  Buoy and ship data are also used for this purpose.  Hurricane force wind warning data have been collected from January 2005 for extratropical and post-tropical systems as determined from the OPC's North Pacific surface analyses.  This Story Map presentation is a summary of the extratropical hurricane force low centers over the North Pacific Ocean from 2005 through 2016 with an emphasis on the 2015/2016 cold weather season.  An overview presents general information on the topic along with a comparison to tropical cyclones.  A comparison between the distribution of hurricane force low centers from January 2005 through May 2016 to the individual centers is then shown.  It highlights the area with the highest density.  A similar comparison is then displayed for the 2015/2016 cold weather season, and it is the first of four pages that provide a statistical analysis of the recently concluded 2015/2016 cold weather season.  In the last section, "A Tale of 2 Cyclones", a comparison between two intense systems that occurred over the course of the last two cold weather seasons is presented.