THE ACTION NEWS 2012/’13 WINTER OUTLOOK COMES OUT IN NOVEMBER.
Over the next month and a half you’re going to see and hear all kinds of wonderful explainations and thoughts on the upcoming winter season. You’re going to hear about the PDO, the AMO, the EPO, the PNA, the NAO, the AO, the EL Nino and God only knows how many other hemispheric and ocean patterns and cycles. I’ve actually seen and read about 6 or 7 of them now. Forecasted winter outlooks from big weather corporations as well as individual forecasters who have already put themselves out there so early in the game and have made their predictions. What Im going to do here with this blog is just simply explain to you why these guys are making the predictions that their making. The 2012/’13 Action News, Accuweather Winter Outlook comes out during the month of November.
The simplest way to explain some of the winter ideas that you may have read already is this…. the way that the ocean cycles (PDO & AMO) are set up this winter will force what we call a split flow in the jet stream to develop. You will have a northern branch, which controls the severity of the arctic outbreaks, and you will have a southern branch which supplies most of the moisture. Most of the time here in Philadelphia a split flow jet stream pattern during the winter months usually means some what above to above normal temperatures and dry conditions. So just this pattern alone would not bode well if you’re a winter weather fan. However, a weak El Nino is forecasted to develop this winter. Over the past 50 to 75 years climatology tells us that when a weak El Nino forms during the winter months while the ocean cycles are in the current state that there in, the jet stream comes together or phases frequently along the eastern seaboard. This tends to produce not only big winter storms (Nor’easters), but also big arctic outbreaks that travel southward from the Great Lakes states through the Mid Atlantic and into the deep south.
This is the reason why most forecasters at this point are going with a some what colder and snowier winter than normal around here. Most of the climate models are seeing this very same thing as well. The CFSV2 as well as the NASA model both show that cold look east of the Mississippi River, especially the NASA model. As a matter of fact the NASA model is going nuts and makes it look like Chicago around here. At least as far as the temperatures are concerned. So generally spekaing this is the overall idea out there, the foundation for the upcoming winter season. Your also going to hear about the NAO, the PNA and the AO. These are teleconnections that are used as cold weather indicators. Without getting too technical the three cycles mentioned above tend to give a hint as to what the overall jetstream pattern will do in the short term as well as enhance it. In other words what will happen here is this….let’s suppose it’s the middle of December and the El Nino has formed which has given us a split flow pattern in the jet stream with the northern branch running from west to east across the US/ Canadian border and the southern branch running along the Gulf Coast states. If the NAO goes negative that’s a good indicator that the two jets are getting ready to phase and you better look out for a big storm along the east coast followed by a big arctic outbreak! If the NAO is in it’s positve phase or being forecasted to go positive it will tell us to expect the split flow to continue for another week or two which would give us more of a mild, quiet look.
So this is the general idea that’s out there this winter season. Almost everyone that has already made their predicitons are going with a slightly colder to colder than normal and snowier than normal winter here in the Mid Atlantic. But again this is all dependant upon the development of the El Nino, the same El Nino that was suppose to develop this summer and never did. So if this El Nino doesn’t develop than that colder than normal idea this winter could be in serious jeopardy. The Action News/ Accuweather 2012/’13 winter outlook will have all the answers for you in November. Until then enjoy the weather out there the next month and a half because even though it will be chilly this weekend the climate models show a warmer than normal October and November overall.