Halong vs Merbok

Now that ERA5 data is in from last week, we can compare ex-Typhoon Halong with other historical storms on a level playing field, i.e. with the same model reanalysis.  The most obvious comparison to begin is with ex-Typhoon Merbok from September 2022.  First, here are the ERA5 tracks and minimum MSLP of the two storms, at 3-hour intervals:

Merbok tracked much farther west but was much bigger, with more total energy, and it moved much more slowly as it reached the northern Bering Sea, prolonging the period of high wind and flooding for western Alaska.  Here's a comparison of ERA5 wind gusts at a grid point near Hooper Bay, on the far western end of the Y-K Delta, where the peak wind was almost the same in both storms (according to the model).  Notice how quickly the winds dropped off in Halong, versus the prolonged period of high winds during Merbok.

A map comparison of peak wind gust shows that Halong was worse in terms of wind across the Y-K Delta and up to Norton Sound and the western interior; but Merbok was worse for most of the southern Seward Peninsula, including of course Nome.

The small size but ferocious wind of Halong made its impacts much more akin to those of a landfalling hurricane (or typhoon), although both storms were thoroughly extratropical by the time they impacted western mainland Alaska.

Halong was so intense that ERA5 indicates all-time record high wind gusts along a fairly lengthy swath extending northeastward from Nunivak Island.

Here are storm tracks and ERA5 peak wind gusts for a couple of other historic autumn storms in the Bering Sea (but in these cases having no relation to pre-existing typhoons, as far as I know).  First, the 2011 Bering Sea "Superstorm", a really massive storm:

And the infamous storm of 1974, which was catastrophic for Nome:

It is very interesting that all four of these storms occurred during La Niña conditions, and not only that, during second-year or third-year La Niña events (i.e. the second or third consecutive La Niña winter after an El Niño).  More on this "coincidence" another time.

Halong Analog

Prompted by a question from Rick Thoman, I looked back at historical data since 1950 to search for past storms with comparable path and strength to ex-Typhoon Halong.  The task was made much easier using the ERA5-based extratropical cyclone track summaries from the University of Manitoba and NSIDC.  I searched for sub-970mb storms that passed within a box between the Y-K Delta and the Seward Peninsula (see below).

The closest analog in terms of path and ferocity of the wind - as estimated by ERA5 - was a February storm in 1951.  Here's the estimated track (a very good match for Halong) and minimum MSLP (about 10mb lower than Halong at the point of closest approach to the Delta):

And here's the model-estimated maximum 10m wind gust:

This 1951 event produced Bethel's highest sustained wind speed measurement on record, 54 knots or 62 mph.  Wind gusts weren't reported back then, but 80+ mph (as indicated by ERA5) seems entirely possible.  Halong's winds peaked at 48 mph (sustained) and 76 mph (gust) in Bethel, although the measurement techniques aren't directly comparable.

The 1951 storm warranted the following comment in the monthly climatological summary for Bethel (click to enlarge).

The big difference with the 1951 storm is that it occurred in February, so it almost certainly wasn't a redeveloping West Pacific typhoon, and the impacts would have been different for coastal areas where ice was present (but I'm not aware of ice extent information from that time).

In just a couple of days we'll have the ERA5 data for Halong, allowing for a direct comparison of the model data for these and other historical events.

Storm Catastrophe

"Absolute devastation... worst-case scenario" - words chosen no doubt carefully by the Coast Guard's Arctic commanding officer in today's briefing on the impacts of ex-Typhoon Halong.

https://www.adn.com/alaska-news/rural-alaska/2025/10/13/dozens-of-people-rescued-at-least-3-still-missing-after-storm-devastates-western-alaska/

The hardest-hit locations turned out to be on the south side of the Y-K delta, between the Kuskokwim estuary and Nunivak Island.  This is where the storm roared ashore in the early hours of yesterday morning, the extreme winds directed perpendicular to the shallow, low-lying coast.  Here's the GFS analysis from 3am.

Here are reported maximum wind gusts in mph, click to enlarge:

The 6-hourly GFS data shows the storm's evolution.

A meteorological and climatological perspective on the causes of the storm will be worthwhile in due course.  For now, here's a link for those with desire and ability to help with relief and recovery costs:

https://www.adn.com/alaska-news/rural-alaska/2025/10/13/how-to-help-residents-and-communities-after-catastrophic-western-alaska-storm/

https://alaskacf.fcsuite.com/erp/donate/create/fund?funit_id=14833