We've talked about the TNI (Trans-Nino Index) here a few times. For those of you that are wondering how it is calculated, here is the simple formula:
(ENSO Region 1+2) - (ENSO Region 4) = TNI
You can use that to keep up with it weekly as the CPC ENSO readings come out each week for the week before. You can also keep watch on it daily via the daily readings available on TropicalTidbits.com to at least get a rough idea. However, we know that the data on there often has a slight inconsistency compared with the officially released numbers. For instance, last week's Region 4 value was -1.2C. Tidbits has shown steadily daily cooling in Region 4 for the last two weeks at least, as you would expect, but in that whole period, the daily values have not been as low as -1.2C yet. They are just now approaching -1.18C. So, the Tidbits data requires a little caution, but it's usually not too terribly far off.