There are premature signs that this year's winter could be particularly harsh in the Northeast.
- Baltimore, holla! Snow in Charm City in Feb. 2010, as captured by Flickr user patrickjoust.
Predicting the 2011 winter's weather when the clock hasn't yet chimed on the fall equinox is a hard and sure a bit uncertain thing to attempt. But it's fun, so here goes!
The meteorologists over at WSI, the Weather Channel-owned company that I cited in yesterday's post about more Atlantic hurricanes, have released their outlook for the fall and winter months of 2011. They see the fall developing as slightly warmer than usual, but then temperatures plunging below average until the year ends.
The WSI people believe that across the U.S. the winter will start early, much like the winters of the past few years. They predict that temperatures chillier than the norm will be widespread across the northern U.S. by December. The outlook specifically states that in November the Northeast and Southeast will likely be colder than average (except for Maine), while the rest of the country could be warmer.
For December, the forecast has it that all of the nation will be shivering more than usual, save for the Southwest, Texas and Florida. Said WSI's chief meteorologist Todd Crawford: “The combination of the newly-emerging La Nina event and the continued trend towards North Atlantic atmospheric blocking support both support this hypothesis.”
Crawford et al.'s outlook is geared toward energy traders and others interested in the vagaries of the high-$$$ heating-fuel market, so one would expect the utmost care to be poured into it. But how does it stack up against the U.S. government's own winter forecast?
Kind of like a square peg into a round hole, to judge from the 90-day discussion from NOAA's Climate Prediction Center. The feds see October, November and December featuring above-average temperatures from the Southwest to the central U.S. to parts of the Great Lakes. Plus northern Alaska. Florida could be colder than usual.
However, the CPC does see a greater chance of cold snaps striking in the Northeast, as well as in the West Coast and southern Alaska. Rain will fall in greater quantities in the Pacific Northwest, but drought could still grip a sizable portion of the South, according to the government's analysis.
Sure, but what does Bob Ryan, senior ABC7 meteorologist, think?
The "superwinter" of 2009-2010 was greatly affected by the way the recurring weather pattern El Niño sucked in moisture from the south while a strongly negative Arctic Oscillation brought persistent cold from the north, Ryan says, which makes the perfect recipe for massive snowfalls. But La Nina is manning the wheel right now, and that pattern "typically has a neutral impact here."
So let's turn to that Arctic Oscillation, an alternating pattern of high and low pressure encircling the northern latitudes. One of the big drivers of fiercely cold weather in the Northeast (like in 2010/2011) is the Arctic Oscillation going negative, allowing polar air to seep deeper into the U.S. The AO has been positive for a while, and may be due for a negative phase soon, says Ryan. "Going into October and November, we may be in for a cool pattern."
For kicks, here's the CPC's winter temperature and precipitation forecasts: