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Aug 21

Winter 2016-2017: Preliminary Outlook

Another year is more than halfway in the books and as we have a month left until we reach the autumnal equinox, this is the time of the year I shed some insight as to what the upcoming winter could spell for us. Now keep in mind, as with any long-range outlook that spans the course of several months, there will always be margin for adjustment and tweaking. While my goal is to always present the big picture in a manner in which major outlook overhauls are not needed, I do plan on making adjustments and tweaks as needed, if new data comes out that would change my overall thinking.

As we finally begin cutting ties with the one of the strongest El Nino signals we’ve seen in history, we’ve begun to transition into its counterpart, La Nina. As strong as long-range model output had forecast the El Nino signal we were entrenched in this year, and while a vigorous El Nino indeed developed, model output actually had overdone its strength, to a point. Similarly, model output appears to be handling a La Nina phase in the same light. Recently, long-range model guidance has suggested a moderate to weak La Nina signal heading into Winter and Spring 2017, as oppose to its premature aggression illustrating a strong, vigorous La Nina. All considered, we are indeed moving from an El Nino signal into a La Nina signal.

As I talked about in last year’s winter outlook, while climate signals (i.e., El Nino, La Nina) do have impacts on the manner in which our winters develop and play out, they are not the only factors that drive out winter. Our winters are driven by how the ocean behaves as well, in fact, our weather and climate is driven by the “motion of the ocean” …. Sorry, I had to…

WHAT IS LA NINA: La Nina is a phenomenon that involves the interaction between ocean and the atmosphere and is the positive counterpart of El Nino as part of the ENSO (El Nino-Southern Oscillation) climate pattern. During a La Nina cycle, there is a cooling of the sea surface temperatures across the East Central Pacific Ocean, usually ranging from 3 to 5°C below normal.

Now, given a typical La Nina, especially a moderate to strong one, we’d see much cooler than normal temperatures across the East Central Pacific, even stretching as far north as the Alaskan Gulf in many cases. But this is not the case at all as warmer than average sea surface temperatures continue to dominate across the Northeast Pacific, an anomaly that would prevent a La Nina signal to achieve a strong phase, but rather a weaker version of the climate signal. Because of this, I suspect that the we are in for an entirely different version of winter, compared to last winter and the winter prior, although, it is very possible we could see stretches of cold temperatures rivaling the dangerous cold we saw two winters ago.

Here is a look at present sea surface temperature anomalies or departures from normal. The reds and the browns illustrate temperature above or well above normal.

alaska_cdas1_anom

Here are projected sea surface temperature anomalies or departures through meteorological winter (December, January and February) and we note that the northeast Pacific continues to exhibit sea surface temperature milder than normal. This is all indicative of a “weaker” La Nina.

ssta.glob.DJF2017.1aug2016

As far as climate signals playing a role in how the winter will shape up, this winter I suspect, will be influenced again by other, critical drivers in addition to the effects that a projected “weaker” La Nina phase might have, similar to how the last two winters have played out, in correlation to the dominant climate signal that year.

KEY IMPACTS THIS WINTER: With everything considered from the discussions above, noted below are several focus points explaining the manner in which I suspect that the upcoming winter will play out.

2016-08-20_22-41-46

2016-2017 Graphic Winter Outlook

 

As we head into the Fall months, it appears that milder air will remain in place, especially from the Southeast and up the Eastern Seaboard. As we progress deeper into the winter months, though, I suspect that these regions will see much colder temperature values and good chance at a number of systems that will deliver snow and ice, but do not be alarmed if the start of winter activity is a bit tardy.

Early on it appears that the bullseye for much of the winter activity, focusing on cold, snow and ice prospects will be from the Central and Southern Plains to the Great Lakes, just to the west of Appalachia. Focusing in on the Great Lakes region, I suspect this winter will ramp up another episode in the series of the Lake Effect Snow Machine. I could see a very active winter in terms of Lake Effect Snow events throughout much of the winter for the Great Lakes as a whole.

Throughout the High Plains and Upper Midwest, particularly from Montana into the Dakotas and the upper and western Great Lakes, a winter reminiscent to two years ago may develop for these regions in terms of magnitude of cold. Depending on the exact setup of the jet stream, if a deep, persistent trough sets up over the central and eastern part of the country, there will be a good chance for several episodes of Arctic air to funnel into and across the aforementioned regions. With prospect for colder air comes the threat for pattern of winter activity with the prospects for snow and ice.

As noted previously, parts of the eastern US will likely begin on the milder side of things, transitioning from a mild Fall into a colder winter. Because of this, the Northeast may begin on the milder side as we head into winter, but as we move further into winter, the mild air will subside and give way to much colder temperatures, particularly for the areas across the Northeast east of the Appalachian Mountains. West of the Appalachian Mountains, I see a more abrupt transition to a colder, active winter pattern.

The Northwest region of the US always seems to present the most challenges for long-range forecasting and this year, it will be no different. Early on, it appears that the Northwest is in line for cooler than normal temperatures values and above to well above normal precipitation. On the contrary, unfortunately, the Southwest looks to remain mired in drought conditions, overall, with few exceptions.

All considered, early on it appears that the brunt of winter will be felt most across the heart of the nation; from the Rockies to the Eastern Seaboard. Keep in mind, this does not mean everyone east of the Rockies will have a snowmaggedon this winter, rather that anyone East of the Rockies, with few exceptions, could see a number of chances for very cold air and several snow and ice chances.

As I noted previously, this outlook covers the span of 3 months, and while I am confident in my outlook, over, things can easily change over such a haul, especially when an outlook is produced using a number of factors and variables that can and usually do change over time. As time moves forward, heading into Fall and winter, if I find it necessary to adjust this outlook any degree, I will do so, but only if thoroughly convinced that any new data that comes in will have a drastic impact or cause a drastic change in my overall thoughts. Please do no take this outlook as gospel truth, but more as a guide and a tool, using this to get an idea of the kind of winter we may be in store for. This is an imperfect science, as is why any outlook should be used as a guide.

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