Exceptional Alaska Heat Wave Threatens All-Time Records, Notably in Anchorage

[Anta Assamey]

Exceptional Alaska Heat Wave Threatens All-Time Records, Notably in Anchorage

 

The jet stream pattern responsible for what may be a record heat wave in parts of southern Alaska, including Anchorage, from July 4th into the following week. 

At a Glance

• Alaska's largest city may swelter in a record heat wave from July 4th into next week.
• Highs well into the 80s, to near 90 degrees are possible, threatening the city's all-time record high.
• An expansive dome of high pressure aloft is the culprit for this stifling heat.
• Other parts of Alaska have set notable heat records in the past week.
• Ice coverage near Alaska's arctic set a record low in June.

A heat wave will intensify over Alaska from the Fourth of July into next week and threaten all-time record highs in parts of the state, but most notably in the state's largest city, Anchorage.

An unusually strong dome of high pressure aloft will intensify and spread over our 49th state the next several days.

 

According to UCLA climate scientist Daniel Swain, the strength of this high-pressure dome could break all-time records over Alaska. Its intensity mirrors a dome forecast to produce 90 degree temperatures over the central and southern U.S.

 

Daniel Swain

 

✔@Weather_West

 

 

Southern Alaska's ongoing #heatwave is expected to intensify significantly over coming week. Strength of high-pressure ridge at mid-levels of atmosphere may exceed all-time records over much of state. Surface temperatures may also reach all-time records in southern areas. #AKwx

 

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7:32 AM - Jul 2, 2019

 

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Sinking air in this high-pressure dome will suppress rain, leading to plenty of sunshine and record warmth.

This heat dome won't ease off over western Alaska until next week.

A Record Heat Wave?

July highs in the 80s and 90s are the norm in most of the Lower 48 states during the hottest time of the year. 

In Alaska, those highs flirt with daily records in some locations and all-time records in others.

Take Anchorage, for example. 

The record longest streak of days with 80 degree-plus highs at Ted Stevens Anchorage International Airport is just three, in both June 2015 and 1954. Only once since 1953 has the city experienced four 80 degree days in a single year (in 2015). 

But with this heat wave, the city will flirt with their all-time record of 85 degrees at the airport on the city's west side and it could be even warmer in other parts of the city. 

This hot forecast grabbed the attention of Anchorage resident and climatologist Brian Brettschneider, who noted some parts of the metro area could even reach an unprecedented 90 degrees.

It's not just the magnitude of the heat, it's how long it will last.

Our forecast suggests highs may top out in the 80s in Anchorage for six straight days into early next week, before the heat slowly eases a bit later next week. 

 

 

 

Here are some of the locations that could flirt with their all-time records during this heat wave:

-Bethel (current record is 90 degrees on June 17, 1926)

-King Salmon (current record is 88 degrees on June 27, 1953)

-McGrath (current record is 94 degrees on June 17, 2013)

Alaska Fires: An Unexpected Side Effect 

The exceptional heat will combine with dry conditions to make any fires worse and increase risk of new ones.

There are over 30 large fires burning in Alaska, including the Swan Lake fire burning on the Kenai Peninsula southwest of Anchorage, which has occasionally pumped smoke across the city in recent days. 

(MORE: Dozens of Fires Leave Areas Shrouded in Smoke)

Last Saturday, it prompted the first-ever dense smoke advisory for Anchorage, according to Brettschneider.

Tuesday, a brush fire on the city's east side prompted brief evacuations.

View image on Twitter

BLM AK Fire Service@BLM_AFS

 

 

Wildfire in East Anchorage 30 percent contained; evacuations lifted http://akfireinfo.com/2019/07/02/wildfire-in-east-anchorage-30-percent-contained-evacuations-lifted/ …

 

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11:26 PM - Jul 2, 2019

 

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Incredibly, wildfire smoke could hold down high temperatures during this heat wave. Smoke particles scatter and absorb sunlight before it can warm air near the ground, leading to a slight cooling effect.

Latest in a String of Warm Records

This potentially historic heat wave is only the latest chapter in a long saga of Alaskan warmth.

June was both the warmest and driest on record in Anchorage, according to the National Weather Service, continuing a warm June trend this decade.

View image on Twitter

Rick Thoman@AlaskaWx

 

 

Last month was the warmest June of record at Anchorage Airport (also warmer than any June in pre-1952 Merrill Field /downtown era). Four of the five warmest Junes have been since 2013. Something's changed, but what? #akwx @Climatologist49 @dougrbbns @Ch2ktuuWX @MelissaDFrey

 

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10:28 AM - Jul 2, 2019

 

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Kotzebue, Talkeetna and Yakutat also had their record warmest June, according to Rick Thoman, an Alaska-based climatologist. 

Northway, near the border with Canada's Yukon Territory about 280 miles northeast of Anchorage, topped its all-time record high last Sunday, reaching 92 degrees.

Juneau had its warmest five-day period in 83 years, according to Brettschneider, including three days with highs in the 80s.

A few days earlier, Utqiagvik, formerly known as Barrow, set its new all-time June record, soaring into the low 70s. The first six months of 2019 have been the warmest first half of any year on record in America's northernmost town on the Arctic coast, according to the Southeast Regional Climate Center. 

In April, two Alaskan rivers set records for the earliest ice breakup.

March was the state's warmest on record, including Alaska's earliest 70-degree high, one day before the spring equinox. 

Given all this warmth, it's not surprising sea ice extent near Alaska has set record lows. 

Sea ice coverage in the Chukchi Sea was a record low for June and water temperatures in the Bering and Chukchi Seas were running at least 4.5 degrees warmer than average, Thoman noted.

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Rick Thoman@AlaskaWx

 

 

Chukchi Sea average ice extent in June was the lowest of record in 41 years of daily passive microwave data from @NSIDC. That means an additional (compared to normal) area the size of Florida was open water being heated by the sun instead of ice. #akwx #Arctic @Climatologist49

 

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1:24 PM - Jul 1, 2019

 

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Sea ice reflects a large fraction of incoming sunlight, keeping the air above it cooler. 

A lack of sea ice allows the ocean to warm by absorbing incoming sunlight.