At the end of March, I wrote an outlook for Spring that predicted a very active severe weather season in this part of the country. Unfortunately for many, this prediction was spot-on. In fact, even more so than I expected. From Minneapolis, to Joplin, to Birmingham...severe weather ripped the nation apart. Right here in Kentucky we recorded dozens of tornadoes and set new records for rainfall and flooding. The tornado in Joplin, MO set a new record for most lives taken by a single tornado in U.S. history. Just two weeks ago we saw Kentucky’s two largest cities, Louisville and Lexington, both go under tornado warnings within a 24 hour period. Spring was a wild season and we probably won’t see anything quite like it in many years to come.
I’m running about a month late, because hurricane season technically began on June 1st, and astronomical Summer began on June 21st, but I’m going to give this a whirl anyway seeing as how we are just now getting into the real pattern of Summer. The question is, after the kind of Spring we just had where does Summer go from here?
I think that Summer in Kentucky this year will be slightly different than what we’ve seen in recent years. For the same reasons that Spring was so wild, Summer will likely stay a little wetter and a little cooler on average than what we’re used to lately. During a La Nina cycle, the jet stream generally moves northward. Rather than hanging out along the Gulf coast, it will tend to spend a lot of time flowing across the Midwest and into the Great Lakes. This alters the storm track and pulls moisture northward into the Ohio Valley and also steers the storm systems our way. This resulted in a terribly active severe weather season in our part of the world. We are now seeing the La Nina (cooling waters of the Pacific equatorial region) start to weaken a little and we’re going back toward neutral. But coming off a La Nina cycle I still think that the overall storm track may continue to bring occasional rainfall to Kentucky through the Summer. This is not to say that we won’t have dry periods or hot days. I do think though that the average temperatures will stay in check, and we won’t see a severe drought this Summer. Remember 2007? That was a horribly dry and hot Summer with almost zero rainfall for several months. Summer 2010 wasn’t very fun either. We saw many days in August last year with heat index readings in the 120s. I’ve never seen heat index readings that high in Kentucky before in my life. I do not think we will see a repeat of this in 2011. I think that overall, Summer 2011 will be a very average Summer statistically and the really intense heat and drought will stay away.
Another consideration is the hurricane season. Coming off a La Nina cycle, it is very possible that the upper level high that we saw in place last year will not establish itself as persistently this year. Last year we saw no hurricanes strike the U.S. coastline. Most storms that tried to invade the Caribbean and threaten the U.S. coast were sheared apart by the intense high pressure aloft that hung out in the Caribbean all Summer and Fall. With the general location of the jet stream retreated slightly northward, and the historical removal of this upper level high in the Gulf region that we see with La Nina, I think it’s very possible that this year we could have more hurricanes. Not only this, but those hurricanes will be able to penetrate into the Gulf region and grow stronger as they move into a position where they could threaten the U.S. coast. I doubt that it’ll be a 2005 type season all over again, but it should shape up to be more active than average in the Atlantic. How does this relate to Kentucky? Well, much of the rainfall we receive in September and October comes from the remnants of tropical systems. The same storms that devastate the Gulf coast are the ones that provide relief and rainfall to the southeastern states during what is typically the driest season of the year. If we do indeed see a more active hurricane season this year, that could also translate into additional rainfall for Kentucky as some of these systems will pass their remnants over or near the Commonwealth.
So there you have it...if everything comes together as expected I think Summer will be less extreme and more normal for what we should see this time of year. There will be days in the 70s to go along with those days in the 90s. There’ll be rain here and there to keep the ground from drying out too bad. And we’ll see a lot of Jim Cantore on The Weather Channel. I hope this forecast works out well, for the farmers’ sake.
Just for kicks, I looked up the official Summer outlook put together by the Climate Prediction Center. They are expecting "climatology" to be the rule... which basically means that Summer will be very average in their opinion. Neither drier than normal nor wetter than normal, neither hotter nor cooler than normal. Just a very typical KY Summer. Not too far from what I'm expecting. Here are their charts:
Temperature:
Precipitation:
-Shawn
