More On Ex-Merbok

Following up on the meteorology of the Bering Sea storm (formerly Typhoon Merbok), Rick Thoman penned some comments that are well worth reading:

https://theconversation.com/typhoon-merbok-fueled-by-unusually-warm-pacific-ocean-pounded-alaskas-vulnerable-coastal-communities-at-a-critical-time-190898

To Rick's point about unusually warm SSTs, the map below demonstrates that the storm did indeed pass over very unusually warm water in the northwestern Pacific as it was undergoing its transition from tropical to extratropical cyclone.  An SST anomaly of +4°C is extremely large, but it's been like this on and off since mid-summer in various parts of the northern and northwestern Pacific.

 

I don't think we can say with absolute certainty without doing modeling experiments, but I agree with Rick that the unusual warmth and moisture were very likely significant factors in the unseasonably extreme intensification of ex-Merbok as it moved into the Bering Sea.  As noted in yesterday's post, however, the mid-latitude jet features clearly also played an important role, with their strength and timing being "just right" to facilitate an extreme outcome.

In terms of impacts, flooding was the big story, and it was devastating for some communities.  This article documents many of the events in sad detail:

https://alaskapublic.org/2022/09/17/powerful-storm-slams-western-alaska/

Some of the most dramatic pictures were before and after shots from FAA webcams, such as these posted by NWS Fairbanks:

Images from the FAA airport webcam in Unalakleet. One image shows a normal day, the other shows water inundating the area around the airport as of 8am this morning. Water levels will continue to rise another foot by this afternoon. #akwx pic.twitter.com/0tVjXy3dLv

— NWS Fairbanks (@NWSFairbanks) September 17, 2022

 

The news from Golovin at first light on Saturday was overwhelming:

Major flooding in Golovin this morning. Water is still expected to rise 1-2 feet by this afternoon Our thoughts are with the community. (photos courtesy C. Lewis) #akwx pic.twitter.com/BO63uN8dGL

— NWS Fairbanks (@NWSFairbanks) September 17, 2022

 

A fact I saw frequently mentioned is that this was the worst storm in nearly 50 years, and that refers back to the benchmark November 1974 storm.  The late Ted Fathauer wrote about that event, but I don't have access to the article (perhaps someone can help):

https://www.tandfonline.com/doi/abs/10.1080/00431672.1975.9931740

More recently, November 2011 saw a tremendous Bering Sea storm, as mentioned on this blog at the time (beginning with the following post and several thereafter):

http://ak-wx.blogspot.com/2011/11/bering-sea-superstorm.html

As for this weekend's flooding, Rick Thoman showed that Nome's peak water level was higher than 2011 but not as bad as 1974:

Observed ocean water levels from the NOAA/National Ocean Service gauges at Nome and Unalakleet across the Bering Sea storm. Exact levels not available but at Unalakleet the Oct 1960 and Nov 1974 storm levels were likely higher than this event. #akwx #superstorm @knomradio pic.twitter.com/fe6fqFdD5p

— Rick Thoman (@AlaskaWx) September 19, 2022

Flooding in Nome on Saturday pic.twitter.com/CgXO2i2Hk9

— KNOM (@knomradio) September 18, 2022

 

Here are a couple of photos I grabbed from the Nome Visitor Center webcam on Saturday, showing an extremely threatening sea, and waves running up beside the building:

Let's hope many, many years pass before a storm like this returns to the long-suffering communities of western Alaska.