The TUTT is almost always present throughout the season. It's usually at its strongest during late spring-early summer (right now), but fades by the peak. It'll likely still be there even around the peak, just in a much weakened form and too weak to really have a negative influence on development/intensification. During periods when the TUTT is not present at all, it'd be replaced by its opposite...an upper level ridge. Now the strength of the TUTT does vary in different seasons. For example, in 2000 it remained strong through Aug and Sep...which is one of the main reasons why we saw so many named storms fizzle out around the islands that year (Chris, Debby, Ernesto, Joyce). In most cases, you'll see a stronger TUTT in years with easterly QBO and El Nino...though 2000 actually had weak La Nina so it can be argued that the strong TUTT that year was highly unusual. On the subject of this season, we have WEST QBO and NO El Nino (if we do somehow see any weak El Nino form, it'll be after the peak of the season). So I doubt the TUTT will be much problem for storms in the peak this year.