April 9, 2021 archive

Updated 04.09.21 @ 6:45a

Month-to-date, April has opened up quite warm (little more than 5° above normal) and dry (half inch below normal) across central Indiana.

There are changes on the horizon that will at least result in significantly cooler times ahead. While the transition will be accompanied by an unsettled, wetter stretch, the long range pattern appears to continue the overall recent dry theme.

The drivers behind the cooler shift ahead have to do with the EPO and NAO going negative.

Additionally, the MJO is going to rumble through Phase 7. This is the interesting driver as a stall in Phase 7 would allow for an extended period of colder weather, whereas if things remain amplified and we blow right into Phase 8, the cooler period will be brief. As it is, it appears the latter is more likely from this distance.

That would produce an 8-10 day stretch of cooler conditions (centered on mid-month) before a modifying trend as we close April. Within this cooler stretch a late season frost threat is present towards the middle to latter part of next week.

To reiterate, after the wet period in the short-term, this is still an overall dry pattern (relative to normal) through mid month.

We’ll keep a close eye on the MJO for any potential delay in bringing back the warmth, but the idea here is the look of getting into Phase 8, combined with the NAO and EPO returning to neutral/ positive, milder times should return towards late month.