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November 16, 2015

John Bolaris' weekly snow outlook

For the winter ahead, I will present my weekly snow outlook on Mondays on PhillyVoice. Hopefully you had the chance to read my long-range winter outlook for 2015-16, which posted here last Monday. I feel very fortunate that my last two long-range winter outlooks were the most accurate in the Delaware Valley.

Winter 2013-14: My prediction was 40+ inches of snow / Actual total 68 inches.

Winter 2014-15: My prediction 30+ inches of snow / Actual 27.3 inches

The weather gods always require some educated luck in forecasting snow amounts, but I am most proud of my overall outcome and timing of winter episodes. Predicting exact amounts are beyond a forecasting skill and the ones that attempt to do this are either drunk on meteorological punch or suffering from short-term memory loss on just how many 48-72 hour snow prediction forecasts go bust. The margin of error is too big, leading to irresponsible outlooks.

Scanning the week ahead, I look at two major players and see they are are NOT in position to favor snow.

The North Atlantic Oscillation (NAO) will remain in the positive position until Nov. 22nd. You need a negative phase for the best chance of snow. That will not happen this week.

The Arctic Oscillation (AO) will remain in a positive phase through Nov. 22 as well. We'll need more of a negative phase to enhance snow chances.

Looking out a bit further, there are signals that both NAO and AO will start to slide more into a negative phasing around Nov. 23-24. This should lead to a brief, modified Arctic shot between the 23rd and 25th, and possible snow showers and or flurries can't be ruled out.

The outlook for the week of Nov. 16-22: No significant snow.