NOAA Visual Satellite image of Monster North Pacific Storm
As 2020 transitioned into 2021, a rapidly deepening and intense hurricane-force storm over the western North Pacific has set an all-time record low central pressure of 921 mb breaking the previous record of 924 mb recorded on Nov 8th, 2014 over the Bering and tied in Dec 2015.
High Seas Forecast
The NOAA NWS High Seas Forecast earlier today was predicting winds of 60-95 knots within 300 south of the low center with significant wave heights up to 60 feet(18.3 meters). I cannot remember ever seeing a forecast up to 95 knots wind for an extratropical storm.
NOAA OPC North Pacific Surface Analysis 18Z 31 Dec 2020
Hurricane-force Storms
These winter storms are extratopical cyclones, storm systems that get energy from horizontal temperature gradients and are often associated with frontal zones. Tropical cyclones, in contrast, are generated by the energy released as clouds and rain form in warm, moist, tropical air masses.
Extratropical cyclones occur throughout the year and can vary widely in size from under 100 nautical miles to over 2500 nautical miles. On average, extra-tropical cyclones last about 5 days, however, hurricane-force wind events associated with these systems typically occur during the rapidly deepening phase of the cyclone and that hurricane force conditions were short lived, on average lasting less than 24 hours in duration.
During the cold weather season Arctic air masses will move out over both the North Pacific and North Atlantic Oceans and interact with low latitude tropical air to produce large temperature gradients and strong frontal boundaries. Low pressure centers will then intensify using the temperature contrast as one of the main ingredients for development. When surface winds reach 64 knots the system is classified as “hurricane force”.
Warm ocean currents like the Gulf Stream in the Atlantic and the Kuroshio current in the North Pacific enhance the temperature contrast and thus add significant energy to these developing storm systems.
NOAA OPC Significant Wave Height 00Z 01 Jan 2021
