What Will Fire Season Bring?

Alaska's wildfire season traditionally gets under way in June, and it's an interesting question as to what this year will bring.  Two years ago the fire season was very active (3.1 million acres) despite an entrenched La Niña, and that was an unusual combination; see my early season comments from 2022:

https://ak-wx.blogspot.com/2022/06/wildfire-outlook.html

In contrast, last year we had a strongly developing El Niño, and Canada had its worst fire season on record, but remarkably Alaska's fire acreage was less than 300,000 acres (and most of that was in August).  The 1979-2023 statewide annual median acreage is 482,000 acres.

https://ak-wx.blogspot.com/2023/06/almost-zero-fire.html

The chart below highlights that a majority of very active years have occurred with a warm tropical Pacific phase (positive ENSO or El Niño) in recent decades, but the last two years illustrate how fragile the statistical connection is.

In previous comments on this topic, I suggested that the unusual ocean warmth close to Alaska probably had a lot to do with the 2022 season: this too was highly unusual for La Niña.  If we look at conditions in May leading into the 10 most active fire seasons (since 1979), we see a strong connection to unusual warmth across the Bering Sea and western Alaska - see below.  Bear in mind that fires in May rarely contribute significant acreage to the season's total, so this warm signal is a precursor to the vast majority of the total fire activity in big years.

In years with very low fire acreage, May tends to be cool and damp, with a notable cold signal over the Chukchi Sea, no doubt partly related to higher sea ice in the 1980s.

May 2023 was indeed a lot cooler over the Bering Sea and western Alaska than May 2022.

And how are we looking this year?  May 2024 has been quite cool in Alaska, and notably so in western and southern areas, so it seems there may be a good chance of another subdued fire season like last year.  This would also be quite consistent with the CPC's summer forecast, which points to an elevated probability of significantly above-normal rainfall across interior Alaska, albeit with above-normal temperatures for central and eastern regions:

The May 1 wildfire outlook from NIFC called for "normal wildfire potential statewide from May through August", but given how May has unfolded, I wouldn't be surprised to see an adjustment toward below-normal risk in the upcoming June 1 outlook.