Even though we are still in the middle of winter and most people are not thinking about hurricanes, there are important large scale signals to track and one of those is the ENSO or El Nino Southern Oscillation.
As most people who are in to tracking hurricanes know, the abnormal warming of the Tropical Pacific, also known as El Nino, typically reduces the numbers and intensities of Atlantic hurricanes. It was thought at about this time last year, and going in to the hurricane season, that an El Nino would develop and keep the Atlantic activity to a more average or even below average level. As we know, that El Nino failed to materialize and we almost ran out of names in 2012.
So how do things look now? Take a peek at the current sea surface temperature anomaly map for the Atlantic and Pacific. You’ll notice quite easily that a large ribbon of blue stretches across the Pacific along the Equator. That is a plume of lower than average sea surface temperatures. In fact, comparing the Pacific to the Atlantic as a whole, you can see that overall the Pacific is colder than the Atlantic. This is part of another set of phenomenon that would be a useful discussion in a future blog post, not really related to El Nino directly.
Considering how cool the tropical Pacific is now, it begs the question: will it last in to the 2013 hurricane season? Or, will conditions change and a warm up of the tropical Pacific commences at some point? This time of year, it is very difficult to gauge what will happen 3 to 6 months down the road but there are efforts to do just that. Check out the IRI/CPC graph from mid-January depicting the forecasts from the various computer models going out well in to the Atlantic hurricane season time frame. The red bar represents El Nino conditions. Once we get in to the summer months, the models generally indicate less than a 20% chance of El Nino conditions being reached in the central tropical Pacific. On the other hand, looking at the green bar, which represents neutral conditions, we see that a greater than 50% probability exists for the heart of the hurricane season. It also worth noting that the blue, which represents La Nina, or cooler than average conditions, creeps up throughout the coming months.
The state of the ENSO is only one of the larger puzzle pieces that we keep watch over coming in to any hurricane season. Other factors such as steering currents and instability over the deep tropics are also very important. However, it seems that sea surface temperatures and how they deviate from the average across the tropical Pacific play a large role in setting the stage for overall activity in the Atlantic. Right now, indications are that conditions in the Pacific would favor increased hurricane formation in the Atlantic. Of course, there could be 1 hurricane only and if it hits you, it’s potentially a bad season for you. On the other hand, we could have 15 hurricanes and, although unlikely, it is mathematically possible for all 15 to avoid the U.S. completely. Obviously, other nations of the Atlantic Basin might not fare so well but the bottom line is that it appears that the upcoming season could be quite busy. Might as well plan ahead and use that info as perhaps a little bit of a nudge to get your act together and have a plan in place – just in case one of this season’s 21 names has your lat/long in its sights!
Read more about the IRI/CPC ENSO forecasts via this link