Stormy Weather

As expected, the active weather pattern and strong west/southwest flow is producing a stormy end to climatological summer, with lots of rain and wind, for much of western and northern Alaska.  Here are rainfall totals reported from automated sites in the last 72 hours (click to enlarge, and ignore zero values which are mostly false):

The 3.39" of rain at Coldfoot is consistent with a substantial response in the local river gauge, which reached a record high level:

This gauge apparently has a decades-long period of record, so it's quite remarkable to see an all-time record crest.  The list of historic crests includes both spring meltout and late summer flood events:

River gauges in Fairbanks-land are high but don't yet indicate flooding, despite some impressive rain totals in the vicinity.  Here's a list of totals as of yesterday evening, courtesy of the NWS.

The Fairbanks airport's rainfall occurred mostly on Sunday, when the daily total of 1.30" was the highest in August since 1990.  It's also worth noting that the vigorous flow aloft produced strong winds in Fairbanks on Saturday afternoon, reaching 49mph at the airport and causing power outages.

Looking ahead, it's a bit disconcerting to see more of the same: the 15-day ECMWF precipitation forecasts are wetter now than they were a week ago for the same areas of the west and north.  Both models show another 6+ inches of rain across the southern slopes of the Brooks Range, as a powerful ridge redevelops near the northern Panhandle and keeps the flow locked in from the southwest across mainland Alaska.

Heat and Floods

There's an autumn chill in the air for much of Alaska this morning, but summer had a record-breaking last gasp in the eastern interior at the weekend.  Chinook flow from the south produced extraordinary downslope warming for southeastern locations, including 89°F at both Northway and Eagle on Sunday (the 90°F in the map below is a rounding error):

It's hard to overstate how anomalous this kind of heat is at this point on the calendar.  Northway, at 1700 feet above sea level, has only ever reached 89°F or higher in June, with data back to 1943.  The record highs for both July and August are 88°F, and of course the August record was set early in the month.  The previous highest temperature in the second half of August was only 84°F.

As for Eagle, with data (some gaps) back to 1902, the latest in the year for 89°F was August 15, 1982.   It also reached 90°F on August 12, 2013.

This is the second time this month with record-breaking heat for these communities: just two weeks ago, Northway saw its latest measurement of 87°F, on the 6th of the month.  Eagle was 90°F then too.

Here's the 500mb flow (as of 4pm AKDT on Sunday) that produced the downslope warming: notice the strong southwesterly winds between the major North Pacific ridge and the strong trough near the Bering Strait.

The Bering Sea trough and associated storminess has been causing havoc for the Kuskokwim Delta coast, with major flooding reported:

https://alaskapublic.org/2024/08/18/bering-sea-storm-brings-erosion-and-flooding-to-western-alaska-communities/

Two strong and very similar storms moved up the Bering Sea into the Seward Peninsula in the past several days: here are MSLP analyses from Friday morning (top) and Sunday afternoon (bottom):

Next up is the remnant circulation of Typhoon Ampil, which affected northern Japan last week.  The now-extratropical storm moved through the western Aleutians yesterday, and will near the Bering Strait late tomorrow.  Wind and flood warnings are in place for most of Alaska's west coast.

Wet Pattern

Except for Southeast Alaska, much of the state is stuck in a wet and stormy pattern, and minor flooding is occurring on the Tanana River near Fairbanks.  The next round of stormy weather has prompted wind advisories and warnings to be issued for tomorrow in the Alaska Range as well as higher elevations to the north of Fairbanks.

The high water in the Tanana is coming mainly from excessive rains to the south - the Alaska Range - rather than the Yukon-Tanana uplands to the north, and it seems the Chena River isn't running particularly high.  However, the Snotel sites to the east of Fairbanks have also reported quite a lot of rain in recent weeks, for example 9 inches of rain at Upper Nome Creek in the last 3 weeks.

The Tanana gauge near Fairbanks shows the water level about a foot above flood stage, i.e. enough for nuisance flooding of low-lying areas.

Here's a before-and-after comparison of webcam views from Nenana: one week ago versus today.  Click to enlarge.

And here's a simple animation of the latest 10-day forecast from the ECMWF's deterministic model, showing a very active weather pattern with several troughs affecting Alaska in the next week.

Ice and Fire

Extensive breakup-related flooding continues for certain unfortunate locations, including Buckland in the northwest, and along a lengthy portion of the Yukon between Ruby and Tanana.  In the words of the river forecast center, it's a "very dynamic" breakup, with ice being displaced only reluctantly by pressure from backed-up river flows.

Photos from the NWS in the past few days:

Spring breakup continues across the Yukon River. Our team flew from Stevens Village down past Tanana on Tuesday. There remains a 120 mile long run of ice moving down the Yukon. Pictured here is a part of that run moving past the bridge on the Dalton Highway. #akwx #riverwatch pic.twitter.com/6LxzZGOB4y

— NWS APRFC (@NWSAPRFC) May 17, 2023

We are saddened to see the damages from ice jam flooding in Buckland, and our thoughts go out to the community during this significant flooding event. Here are some photos taken by our River Watch team on Thursday. The threat of further flooding continues for Buckland. pic.twitter.com/HOacQviDkr

— NWS Fairbanks (@NWSFairbanks) May 19, 2023

The jam is causing extensive flooding along the Yukon River for nearly 90 mi upriver from the front of the jam. The Kokrines Bible Camp is in the flooded area and some flooding can be seen in these photos. Tanana is experiencing minor flooding.

📸 Photos: https://t.co/bsq7GOZGme https://t.co/NCTqVtnlSA pic.twitter.com/JBHDCHLh67

— NWS Fairbanks (@NWSFairbanks) May 21, 2023

 

Ned Rozell's latest dispatch recounts the dramatic breakup in Eagle last weekend:

https://www.adn.com/alaska-news/science/2023/05/19/when-river-breakup-came-to-eagle/

But while the weather has remained chilly in western Alaska - indeed there was a bit of accumulating snow in Bethel on Tuesday and Wednesday - things are heating up in eastern and southeastern Alaska.  Sitka rose to a remarkable 82°F on Thursday, and Haines reached 80°F, both the earliest on record for such warmth.

Also very remarkable was Fairbanks' daily minimum temperature of 60°F yesterday.  (The overnight low Saturday morning was actually 61°F, but it then reached 60°F by midnight Saturday evening.)  Only one other year has had a low temperature of 60°F in May, and that was on the 25th (in 1960).  Some years don't see a single night that warm over the whole summer, most recently in 2020.  And prior to the mid-1960s it was an unusual occurrence in any year.

It's also been very dry recently in Fairbanks, with only 0.08" of precipitation since mid-April, and zero measurable precipitation so far this month.  If warm and dry weather persist into next month, then wildfire risk will rise quickly.  Western Canada is already having an extremely active and early fire season, with fire acreage already exceeding 5 million acres nationwide.  Of course Canada is a very big place, but for reference that's already on par with Alaska's largest fire seasons on record (2004 holds the record, at 6.6 million acres).

Interestingly, the two coldest Aprils of the last 30 years in Fairbanks were also fairly active fire seasons for Alaska: 2013 (1.3 million acres burned), and 2002 (2.2 million acres).  The modern average (median) is about 600,000 acres or so.

The emerging El Niño in the tropical Pacific is definitely a risk factor for increased fire acreage this summer.  Here's a chart I've shown before, updated to include last year:

Last year was actually a surprise from this perspective, because La Niña was still very much entrenched in the tropical Pacific, and yet Alaska's fire acreage was much above normal.  I'll have more to say on this in a subsequent post.

Severe Breakup Flooding

Unfortunately the worst-case scenario for ice jam flooding has occurred for some stretches of the Yukon and Kuskokwim rivers in recent days, as a "dynamic" breakup unfolds following the very cold April.

Flooding and damage has been particularly severe in Circle and Crooked Creek, located on those two rivers respectively.  Apparently the flood was equal to or worse than the record 1945 flood in Circle, and was worse than the benchmark 2011 flood in Crooked Creek.

https://www.adn.com/alaska-news/2023/05/15/record-flooding-destroys-homes-and-prompts-evacuations-in-southwest-and-interior-alaska/

As noted in this article, the risk of serious breakup problems was flagged ahead of time, with the combination of a cold April and deep snow pack being major contributing factors.  Rick Thoman highlighted historical examples of breakup flooding in his latest Substack post:

https://alaskaclimate.substack.com/p/spring-break-up-flooding

Courtesy of UAF's GINA group, here's a satellite-estimated view of severe flooding downstream of Circle on Sunday, after the breakup front moved downstream from the village.

On Saturday the village of Circle on the Yukon River saw extreme flooding due to an ice jam between Circle and Fort Yukon, with reports of a 10-foot rise in 30 minutes. This image displays the VIIRS River Flood product, showing the overbank flood water in warm colors. #akwx pic.twitter.com/yC0lW7x2G7

— GINA (@uafgina) May 15, 2023

 

Here are some NWS photos of the aftermath:

We are saddened to see the damages from the ice jam flooding in Circle over the weekend. Our thoughts go out to those that have lost their homes or property during this devastating flood. Here are photos take by our River Watch team on Sun after the water receded. #akwx pic.twitter.com/5omf6xERmM

— NWS Fairbanks (@NWSFairbanks) May 15, 2023

 

And Crooked Creek:

After major flooding in Crooked Creek, our thoughts are with those that have lost their homes or property in this devastating flood. Our Riverwatch team captured these images on Sunday as water receded. For the latest on breakup, please see: https://t.co/hcRq2g2mDP #akwx #flood pic.twitter.com/MLO5aXsJ4X

— NWS APRFC (@NWSAPRFC) May 15, 2023

With very cold Aprils occurring with surprising frequency in recent decades, it seems that ice jam flooding will unfortunately remain a big problem for communities along Alaska's largest rivers for the foreseeable future.

 

Flooding and June Climate Data

First, weather news today from the southeastern interior: flooding has damaged the Richardson Highway in a number of locations near the crossing of the Alaska Range to the south of Delta Junction.  Damage looks considerable:

UPDATE: 4:00 p.m. ⚠️Richardson Highway⚠️ REMAINS #CLOSED fMP 218 to MP 234 due to washouts from flash flooding. We anticipate this closure will continue THROUGH THE WEEKEND, depending on weather. Photo: Alyeska Pipeline Service Company of the Bear Creek washout. pic.twitter.com/InKkO7SuEY

— Alaska DOT&PF (@AlaskaDOTPF) July 13, 2022

 

A combination of big snowmelt from the higher elevations and heavy rain are to blame.  The latest 3-day precipitation analysis shows 1-2" of rain in a number of places, but of course amounts may have been much higher in mountainous areas.

 

A similar washout happened on the Alaska Highway in northern British Columbia less than two weeks ago.  Here's a photo of the remarkable damage there, obtained at the time from Twitter, although regrettably I can't remember the exact source:

On another note, June climate data finally came in from NOAA/NCEI, who confirmed that (based on the limited available data) it was the driest June on record for Alaska as a whole.  Compared to the prior 30 years (see below), June was the driest or second-driest across a wide area, and the Bristol Bay, Cook Inlet, and Northwest Gulf divisions were extremely warm: Kodiak had its second warmest June on record, and King Salmon was third warmest.

Gridded ERA5 data adds more detail to the picture and fills out some additional variables that help explain why the fire season has become so bad:

 

And here's an interesting result: June average dewpoints were much above normal across southern Alaska, but much lower than normal in the western and northern interior.