The question comes up frequently, and it's a good one. "How could this winter be so radically different than last?" Polar opposites. But we've been living thru some amazing extremes in recent years: 145 tornadoes in Minnesota in 2010 (most in the USA), a 7 month flood on the Missouri River ni 2011, followed one year later by the warmest year on record and the worst drought since the mid-50s. One extreme to the next.
A warmer, wetter atmosphere worldwide is flavoring all weather now, allowing weather to get "stuck": longer, deeper drought, floods, record heat, even prolonged chill and snow.
A 2012 paper published at Cornell links record Arctic melting last fall with changes in the "polar vortex", reducing the winds that swirl around the North Pole. "What goes on in the Arctic remotely forces our weather patterns here" said Dr. Charles Green.
The Arctic is the canary in the coal mine - a 75% drop in ice volume in 40 years may be having a domino effect at more southerly latitudes, including Minnesota and the northern tier of the USA this "spring".
"What’s happening now is that we are changing the climate system, especially in the Arctic, and that’s increasing the odds for the negative "AO" (Arctic Oscillation) conditions that favor cold air invasions and severe winter weather outbreaks."
Global warming implies steady warming, worldwide. Global Weirding better describes what we are seeing.
The next storm soaks us with rain Wednesday, maybe ending as wet snow Thursday, but not as much drama as last week.
50s return next week; a few 60s last week of April. Hurry up spring.
- Global warming has increased the loss of summer sea ice in the Arctic, which has altered atmospheric conditions that influence winter weather in the U.S. and Europe.
- The changes lead to invasions of Arctic air into the middle latitudes, increasing the likelihood of severe winter outbreaks, which occurred in the eastern U.S. and northern Europe in 2010 and 2011 and in eastern Europe in January 2012.
- The deck may be stacked for harsh outbreaks during the 2012–2013 winter in North America and Europe.
Graphic above: This winter has seen a very negative phase of the AO, as low as -5, meaning unusually weak westerlies at far northern latitudes, allowing polar air to become entrenched over Canada and the northern USA. Last winter: a strongly positive phase; meaning strong west to east winds, keeping the coldest air of winter well north of Minnesota. What changed from year to year? Record melting of the Arctic in September, 2012. Graphic: Greene/Scientific American.
"How much precipitation has Twin Cities area gotten so far in April (and can you break out snow vs. non-snow forms) of this year? What is normal for April precipitation. And for God's sake, please make it stop. Thanks."
Kris - I share your sense of angst, along with pretty much every other Minnesotan out there. Maybe there are a handful of snowmobilers amused they can ride their sleds in mid-April, but I'm not one of them.
April Rainfall (MSP): 2.63" (normal rainfall is 1.11", to date. Last year only .70" rain fell as of April 14).
April Snowfall (MSP): 6.8" (normal is 1.5" - only a trace of snow fell in April, 2012).