Meteorologist Paul Dorian of Vencore Weather here presents an analysis of the just now ending winter of 2017. It’s nothing you’d expect from a world that is supposedly warming.
As the following Environment Canada chart shows, snow is running at well above normal levels across the Northern Hemisphere”
Europe had an extended period of colder-than-normal weather in April accompanied by lots of snow.
Now much of the US is experiencing an extended period of colder-than-normal weather as we transition from early-to-mid May.
Snowfall has been running at above normal levels this winter across the Northern Hemisphere and continues at those higher-than-normal levels as we head towards the middle of May.
Arctic now cooler than normal
In addition, temperatures in the Arctic region – which have been generally running at above-normal levels in recent weeks – have actually dropped to below-normal in recent days and, if this trend continues, it should prevent any chance for sea ice extent to reach record lows up there this summer.
Temperatures in the Arctic region (>80 degrees N) have fallen to below-normal levels (circled area) in recent days following several weeks at generally above-normal levels; map courtesy Weather Bell Analytics/Dr. Ryan Maue
The upper-level pattern across the Northern Hemisphere is playing a big role in this late season cold. Indeed, blocking is now well established over Greenland/Iceland as indicated by the latest 500 millibar height anomalies (red region) and this type of pattern can force cold air southward from northern latitudes into land mass areas on both sides of the Atlantic Ocean.
Two indices that meteorologists can track in order to monitor the pressure patterns over the northern latitudes are the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO). When these indices drop into negative territory for extended periods this time of year, the result is often an upper-level blocking pattern across the northern latitudes.
There is some hope that later this month this blocking pattern will fall apart and the computer model forecasts of the AO and NAO indices (shown in red) do suggest a return to positive territory in the near future.
Text by Meteorologist Paul Dorian, with some editing by NTZ.