Winter 2015-2016: Pre-season Forecast

9/20/2015 9:45PM Update
Might as well add a table showing how I feel the winter will be like:

	Overall	December	January	Febuary
Temperatures	Below Average	well above average	below average	well below average
Precipitation:	Well above average	above average	above average	well above average
Snowfall:	Above average	well below average	normal	well above average

The overall feeling is that of a backloaded winter as the El-Niño weakens and temperatures start cooling. Precipitation should remain above average for the duration of the winter. If we get snow, which is what I'm betting on, it will likely be the wet and heavy kind, with a chance of mixing. Remember, it only needs to be cold during 1 storm out of many rainstorms for us to get decent snowstorm.

I will actually take a close look at some data-sets during this week to hopefully tweak the chart and come up with some numerical values to the anomalies.

ORIGINAL TEXT:
To all the snowlovers out there: Do not write off the winter before it even starts. But do not get upset that we don;t have a month straight of snowcover this winter. We'll need a bit of luck to realize the full potential of this El-Niño Winter.

An El-Niño is generally defined as the presence persistent warmer than normal pool of water in the Central and East Pacific Ocean near the equator averaging.Typically, El-Niño result in a strengthened subtropical jet stream, which will bring pacific moisture laden storms across the southeast while the . In addition, during the winter, the northern parts of the country normally average on the warm side while the southeast stays cooler than normal due to all the storms. For us Mid-Atlantic peeps, we usually manage to stay around normal in temperatures while cashing in on increased precipitation. So we have a higher than normal chance of heavy snow right? If we can time storms with cold air.

Sea Surface Temperature Anomalies (red being positive) of the Pacific Ocean through late August

Computer model plume forecasts

A record breaking El-Niño is expected this winter. Our previous strongest El-Niño was in 1998. For the snow weenie's sake, let's not mention it. Following 1998's example we should expect to see is a good number of juicy southern jet storms.  The past couple of years, we've had the cold but not the moisture, which leads to the next factor, temperatures. Models have been hinting at a warm December, cooling down through January and February although they disagree on how much the cool-down will be. We need a few well timed cold shots to coincide with storms. We can't just blunder into storms like last year (we had a storm last year where we got 6 inches of snow while essentially sitting in the warm sector). This is where the 1998 example comes in (sorry snow lovers). That year, Pacific air flooded the southeast, resulting in washout after washout. DC recorded a total of 0.1 inches of snow. There was never any cold air. Of course this is just one example but it goes to say that luck is needed and some help from some other atmospheric events.

1998 Winter Temperatures and Precipitation Rankings (Shaded states are ones that had top 10s)

What gave us such amazing storms in 2009-2010 was the presence of extreme atmospheric blocking. Think about the jet stream as a highway, carrying storms along it. If it's straight, storms travel smoothly and quickly, AKA zonal flow, which is what has been dominating our winter for the past two years. Storms zip in and out within a day, dropping no more than a couple inches. To get blockbuster storms that crawl up the coast, one needs to induce kinks in the jet stream, bending it from Canada all the way to the Gulf Coast and back up again. This would be the result if a blocking High Pressure sets up near Greenland. When this happens, an index ( just a number based off of some calculations) call the North Atlantic Oscillation (NAO) will go negative. The more negative, the better. 09-10 was one of the most negative winters. Last year it was always positive. Blocking is somewhat correlated to El-Niños and already, the index and it's larger scale cousin, the Arctic Oscillation (AO) is forecasted to go negative soon, which is a welcome change. It will be something to watch this winter. More blocking=better chance at big snowstorms.

The AO forecast (red being all the individual forecasts of the ensemble)

The main takeaway is that we should be quite wet but temperatures and everything else remains to be seen since we are entering uncharted territory in terms of El-Niño effects. Do not expect a winter of frigid cold and many small snow events and we're going to be staring very closely at the AO and the NAO, looking for blocking. More likely than not, we will get big juicy storms where we're riding on the rain/snow line. We're going to go back to the old I-95 split unless we're as unlucky this year as 1998. Then I'm moving to New England.

I hope what I wrote made sense to those who are not as into this as me. I will probably update this post as I find time to cram in little details and explanations as well as hashing out all the factors and possible scenarios more thoroughly. If you have any questions, please ask.

Thanks for reading,
-Alex