This is the second installment of the June climate review. See the Alaska June 2023 Sea Ice and Wildfire post for more on those important topics. The lack of wildfire in Alaska in June was easily the most remarkable feature of the Alaska’s climate in June.
Temperatures
Surface air temperatures in the Arctic (poleward of 60°N) in June averaged 0.4°C above the 1991-2020 average. This is the lowest June average temperature since 2018 for the Arctic, but higher than any June prior to 2002. Much of the Canadian Arctic and central Siberia were exceptionally warm, and while not as extreme, Svalbard and Arctic Scandinavia was also warmer than normal. Northeast Canada, western Greenland and Alaska were cooler than normal. Temperatures over the Arctic Ocean hardly ever vary much in early summer because the solar heating goes into melting snow and sea ice and not raising the air temperature (technically, latent heat of fusion).
Zooming into Alaska and vicinity, we see that average temperature departures from normal were mostly not large. However, in some areas especially in mainland Alaska average daily high temperatures were markedly below normal while average low temperatures were near to even slightly above normal. In the summer this is usually a sign of more cloudiness than average. Statewide, the highest reliable temperature in June was 84°(28.9°C) at Eagle Airport. That’s two degrees lower than the statewide May high temperature (86°, 30.0°C at Klawock Airport), but interesting that isn’t too not uncommon, having now occurred five times since 2000. On the other hand, the June low temperature of 13°F (-10.6°C) at the NOAA Climate Reference Station north of Utqiaġvik on June 1 is the lowest reliable June temperature since the Department of Defense’s old automated weather station at Barter Island dipped to 10°F on June 3, 1997.
Ocean surface temperatures were well below normal in June from the central Bering Sea north into the Chukchi Sea, per Fig. 3. This was a result of the slow sea ice melt in May and June. See the post here for more details on sea ice in June. Sea surface temperatures in the deep waters of the Gulf of Alaska were generally a bit below normal except for offshore of southern Southeast Alaska.
Precipitation
Total precipitation in June around Alaska was generally near to above normal, but with eastern Interior more in the near to below normal range (Fig. 4). For Alaska as a whole, 2023 was the sixth wettest June since 1940 in ERA5 reanalysis data. Total rainfall was especially high on the Gulf of Alaska coast and parts of the Bristol Bay region due to repeated storminess. A single rain event late in the month pushed monthly totals way up in parts of the North Slope and northwest Alaska. At Umiat, along the Colville River south of Nuiqsut, 1.85 inches of rain fell in about 27 hours from showers and a thunderstorm June 25 to 26. This is more than a quarter of the 1991-2020 annual average precipitation! The area with below normal precipitation from east of Fairbanks to Whitehorse reflects the persistence southerly flow across the mountains during the month (see the Circulation Aloft section below).
The snow during the first days of June was not well captured by reanalysis or what remains of the conventional climate observation network. But just to keep it from being completely lost to memory, we note that accumulating snow fell on the morning of June 1st along the southern Seward Peninsula coast from Teller to Koyuk. At Nome, based on community reports, there was (conservatively) about 2.5 inches (6.3cm) accumulation, which would be the second highest one day June snowfall in the past 116 years. In the Fairbanks area on June 2nd, mixed rain and snow fell to valley level, accumulating snow fell above about 1600 feet (490 meters) MSL, with 2 to 3 inches above 2700 feet (820 meters) MSL.
Circulation Aloft
June 2023 average mid-atmosphere circulation pattern show in Fig. 5 explains a lot of the observed surface temperature and precipitation because it was rather stable during the month. Low pressure from the central Chukchi Sea south through the Bering Strait to the eastern Aleutians, with south to southeast winds aloft east of the low centers during summer will certainly favor the weather we saw in June.
I saw a press note of above normal Greenland melt. Did that continue through June?