National Weather Service forecast for extremely intense storm in the North Pacific on Saturday morning ET (NWS Ocean Prediction Center)

Typhoon Nuri, a once great but now weakening storm east of Japan over the open Pacific, is on the brink of an explosive transformation and rejuvenation unlike anything I’ve seen in all my years of storm watching.

Right now, it’s nothing special.  Its central pressure is probably in the neighborhood of 987 mb and its peak winds are around 80 mph – equivalent to a category 1 hurricane. It is forecast to hold at that level for another day or so. But then, as this tropical storm transitions into an extratropical (or temperate) storm, it is literally going to go haywire.

A storm is considered a meteorological bomb when its pressure drops 24 millibars in 24 hours. The GFS weather model predicts this storm’s central pressure will free fall an astounding 58 millibars (mb) in 24 hours – from 976 mb at 8 p.m. (ET) Thursday to 918 mb at 8 p.m. Friday (ET). This is so-called “bombogenesis” to the extreme.


Surface pressure simulation of North Pacific storm between 8 p.m. ET Thursday and 8 p.m. ET Friday via GFS model (WeatherBell.com)

As CWG’s Angela Fritz wrote Tuesday, a non-tropical storm that attains a central pressure this low is extremely rare.  This one is projected to achieve the lowest pressure ever recorded in the Bering Sea. “It would also come very close to the lowest extratropical pressure on record for any location, which is 913 mb, set in the North Atlantic in 1993,” she said.

 

At its previously-reached pinnacle as a super typhoon, Nuri maintained category 5-intensity for an incredible 24-hour stretch.  Extremely warm waters in the tropical central and western Pacific fueled the storm, which challenged Super Typhoon Vongfong for the crown of Earth’s strongest storm in 2014.


Infrared satellite image of Super Typhoon Nuri on Sunday. (NOAA/NASA and RAMMB/CIRA)

 

In its upcoming phase,  rather than ocean heat, the temperature contrast between the tropics and the Arctic will power this storm’s evolution and turn it into a veritable superstorm as it charges towards the Bering Sea.

The strength of high altitude jet stream winds flanking the storm offer an indicator of this temperature contrast. The GFS model shows winds at 30,000 feet rip-roaring across the northern Pacific at a mind-boggling 205+ mph (or 180 knots).


High altitude winds (or the jet stream) at 8 p.m. Thursday ET in the northern Pacific, as simulated by the GFS model (WeatherBell.com)

You can also get a sense of the temperature contrast driving the storm’s growth by looking at the GFS model simulation of temperatures at an altitude of around 5,000 feet.  Over a relatively small distance, the temperature drops the equivalent of 40 degrees F in the vicinity of the storm.


Temperatures at an altitude of 5,000 feet at 1 a.m. Friday as simulated by the GFS model (WeatherBell.com)

As the beastly storm encounters the Bering Sea and the Aleutians, hurricane-force winds and humongous waves to 50 feet are forecast, as Mashable’s Andrew Freedman discusses:

The storm will likely bring howling winds to the Aleutian island and to the western part of the Alaskan mainland. It will affect flights between North America and Asia, in part by rendering alternate airports in Alaska useless, as they are buffeted by hurricane force winds of nearly 80 miles per hour or greater. Seas are forecast to build to at least 50 feet in the southwest Aleutians, and potentially higher in the Bering Strait.

The National Weather Service’s Ocean Prediction Center warns of an “extremely dangerous” storm with “phenomenal waves” in its Facebook updates.

The storm is likely to set off a chain reaction that eventually steers Arctic air into the central and eastern U.S. next week, as CWG’s Fritz discussed Tuesday.

We’ll have more information on this spectacular storm it as evolves in the next two days.