Temperatures have been consistently above normal, with every month since October falling in the top third of the historical distribution.
As for precipitation, data from SNOTEL sites along the Dalton Highway reveal that the water year ending September 30, 2014, was wetter than the long-term normal. At the Sagwon SNOTEL, about 50 miles south of Deadhorse, 2014 was close to the wettest year on record, although the anomaly was not as great at either Imnaviat Creek (closer to the Brooks Range) or Prudhoe Bay. Note that some years have missing data in the chart below.
Could the weather anomalies explain the massive overflow south of Deadhorse this year? I think it's possible that the combination of high precipitation last year and a very mild winter have allowed the Sag River streamflow to remain higher than normal (under the surface ice and above the permafrost) even at this time of seasonal minimum streamflow. The Sag River streamflow gage near Pump Station 3 hasn't reported in recent months, so I can't confirm this, but it seems physically reasonable. With the winter's cold still being sufficient to freeze the river to the bottom in places and cause backups, the excess volume of water has become apparent in the widespread overflow.
Of course it's also possible that this event is a random occurrence related to an unusual configuration of ice formation. However, if the weather did play a role, then we might see more of this in future years if reduced Arctic sea ice continues to produce a wetter, warmer climate on the North Slope.