A few days ago, some of the weather models were forecasting a cool period next week. If you believed them, you would think highs in the 60s would be a safe bet. Now, however, these same guidance products are suggesting a return to the 70s at least — above normal temperatures once again — as early as Tuesday.

Why the change? Well, the model that was gunning for a cool week just happens to have comparatively little skill at predicting weather in tropics. Yep, that’s right, the tropics. It turns out that a relatively sizeable part of our week-to-week weather pattern shifts are driven by changes in the tropical circulation. And if a model doesn’t get those tropical changes right, it just might do the old flip flop on our weather forecast in its day 6 (and beyond) prediction.

This may well be what we are observing now in the GFS forecast model. Until recently, it figured the MJO (a large tropical weather system called the Madden-Julian Oscillation) would quickly move across the Atlantic Ocean next week. More skillful predictors of the MJO, however, have been consistent in returning it to roughly the same Southeast Asian corridor that it has so often been in since late March – a period during which Kansas has seen some really warm weather. One might reasonably suspect, then, that our climate system just might get pushed a bit by the MJO in a way that would favor a return to/continuation of the warmth later next week.

Of course there are lots of moving pieces to the weather puzzle (some of which are unrelated to the tropics), and we’ll see how quickly things warm up after our brush with cooler temperatures this weekend. But a return to 80F late next week, which looked impossible through the lens of the GFS model in recent days, is not a bad bet.