Climate Watch
By Rick Thoman Alaska Climate Specialist Alaska Center for Climate Assessment and Policy International Arctic Research Center University of Alaska Fairbanks
NOAA’s Climate Prediction Center has released the outlook for October and it calls for slightly increased chances of above normal temperatures for the Seward Peninsula and St. Lawrence Island but no tilt to favor above or below normal temperatures for eastern Norton Sound. The precipitation (rain plus melted snow) outlook favors neither above or below normal anywhere in western Alaska. For reference at Nome, the average October temperature is 30.4°F. The drop in temperature in October is greater than any other month: on the first, the average temperature is 37°F, but falls to 24°F on Halloween. Temperatures during the month over the past 115 years have ranged from 59°F in 1954 and again in 2016 to a low of -10°F in 1966.
October marks the month when the typical temperature difference across western Alaska flips directions. During the spring and summer, the Bering Strait and St. Lawrence are cooler than areas farther to the east. In October that reverses so that areas from Nome eastward are typically cooler than further to the west. Average precipitation in October of 1.84 inches is lower than in September but still about that of May and June combined. Because of the moderating influence of the ocean, October snowfall in Nome is rarely heavy. Over the past 50 years the average October snowfall is 4.7 inches and, in the past, snowfall exceeds 12 inches in October less than once a decade. However, in the Nome area as well as across nearly all of Alaska, during the past 50 years the trend is for significantly less snow in October as more precipitation falls as rain.
Sea ice often starts to form in Norton Bay and in the brackish waters near the Yukon Delta during the last week of the month. Historically, the threat of storms producing coastal flooding is higher during October than any other month. This does not change just because we’ve already had a severe storm.
Since the construction of the sea wall after World War II, there has not been an autumn with two significant coastal flooding storms in Nome proper, but if all the pieces fall into place it could happen again, so it pays to stay up to date to weather forecasts at this time of year.