It's a bitter pill to swallow after such a harsh winter, but significantly colder than normal weather is set to return next week for much of Alaska, and there will be snow for many. Breakup will be pushed back, and unfortunately the risk of a dynamic breakup with flooding problems is now on the rise, so to speak.
Here are ensemble-mean temperature forecasts from the latest ECMWF and GEFS models (temperature departure from normal at 850mb) for early next Wednesday:
The very good agreement at a 6-day lead time suggests that confidence is rather high.
Interior river ice thaw still has quite a way to go. In Fairbanks, although temperatures have been above freezing by day for the last two weeks, the accumulation of daily "thaw units" has been minimal, and snowpack depth is still reported at 18".
The Tanana River ice at Nenana doesn't go out until at least 75 thawing degree days have accumulated in Fairbanks, which would equate to (for example) a week of high temperatures in the low 50s Fahrenheit and lows around freezing. (Thawing degree days are calculated by summing the daily differences between daily mean temperatures and 32°F, for positive values only.) And ordinarily a lot more thawing is needed - unless breakup is very late, in which case the sun's strength can get the job done without the same amount of warmth in the air. Here's a chart to illustrate (click to enlarge):
Speaking of the sun's strength, data from the CRN site north of Fairbanks shows it has been cloudier than usual in the last 10 days, so that's another strike against breakup progress. With Nenana ice thickness most recently measured at 51 inches, it's going to be a while.
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