Wednesday, April 16, 2014
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John Bolaris' winter weather outlook: wicked

The Philadelphia meteorologist looks into his crystal ball to predict a wild winter.

Rob Tornoe / Philly.com

Ever since the historical winter of 2009-2010 when we were crushed with over 71 inches of snow, better known as Snowmageddon, it has been a walk in the park.

With the exception of Superstorm Sandy, which many people don't realize produced two feet of snow in the mountains, we've been basically in a snow drought - eight inches of snow last season, and only three inches the season before.

From my analysis, the winter of 2013-2014 is about to change dramatically. Not so much through the remainder of 2013, but the New Year will bring the onslaught of a wicked second half.

Before I get started let me remind you, long range forecasts are like ticking time bombs, they can blow up at anytime as the atmosphere can swing into unexpected modes. I know this: we are in an extreme weather cycle that will last through our lifetime and beyond. The globe is in a blow-torch state, with the warming of our oceans and atmosphere continuing to lead to unprecedented superstorms. Expansion and rising sea levels will ultimately lead to reconfigurations of our coast lines.

More coverage
  • Snow, cold move into Philly area
  • Latent heat in the oceans and atmosphere is Mother Nature's version of lighter fluid, and will continue to fuel explosive storm formation. Predicting long range forecasts, I believe, has become more difficult as past weather patterns are becoming disruptive as the atmosphere is going through unprecedented warming....yes, I'm talking about global warming.

    Winter forecast, 2013-2014

    There are many atmospheric players in putting together a long-range outlook, I'm going to focus on the top four.

    • ENSO - El Nino southern oscillation.
    • AO - Arctic oscillation.
    • NAO -North Atlantic oscillation.
    • PNA - Pacific North American teleconnection.

    This winter season we are starting out in neutral, meaning no El Nino phase, which normally leads to warmer and more frequent storm cycles across North America.

    La Nina is the opposite, resulting in colder winters and less-frequent precipitation in the Northeast.

    Currently La Nada, or neutral, means the atmosphere is up for grabs, however, computer models are hinting that La Nada should become weak-to-possibly-moderate El Nino by mid-late winter. If this comes to fruition this will lead to additional fuel for storm development along the East Coast.

    PNA, or Pacific North American teleconnection, is in a positive phase (warmer Pacific waters) and this should lead to high pressure ridging in the intermountain region, creating an energized trough to develop in the East sometime by early-mid January. This should lead to enhanced storm development and cold air damming in the East.

    NAO, or North Atlantic oscillation, is the key to storm tracking along the East Coast. If NAO is in a positive phase for the majority of winter, then snow amounts would be limited. But a negative phase domination would lead to nasty East Coast storms. From 1979 through 1995, the negative phase appeared only twice. Since 1996, however, the negative phase of NAO has dominated.

    Above-normal water temperatures in and around Greenland should lead to building heights and a negative phase through the second half of winter. The Greenland Block will keep storms locked in unable to race out to sea.

    AO, or Arctic oscillation, is the biggest player of them all. If AO is in a strong negative phase, the East Coast gets hammered. During the record-setting winter of 2009-2010, AO was in a record negative phase in January and most of February. This led to more than 71 inches of snow. AO is influenced by ice and snow cover across North America. The latest on AO shows snow and ice has steadily increased, and long-range projections are for AO to be in a negative phase, moderate-to-strong by mid-January through February.

    AO and NAO are connected, and a double negative leads to well-above-average snow amounts in the East.

    The winters of 1960-61 and 1978-79 both had neutral phases, transforming into weak El Nino. And both winters were dominated by negative NAO and AO.

    Philly snowfall in 1960-61 totaled 49.1 inches. In 1978-79, the total was 37.7 inches.

    The biggest wild card is the possibility of a major-to-super storm that can dump a winter's total (Philly averages around 20 inches of snow a winter) in one day. The odds of this happening have been increasing over the past two decades.

    My estimated snow total for the winter of 2013-2014 is 30 to 40 inches if AO and NAO become strongly negative by mid-winter.

    And, for right now, that is the way I see it.

    John Bolaris For Philly.com
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