Category: Ensemble Discussion

We know the upcoming (10) day period is going to feature a continuation of above average rainfall, but what lies beyond that? Ensemble data is entirely in two different camps once we get to the Day 10-15 period.

GEFS:

EPS:

Talk about a night and day difference. This would result in widespread 70s and 80s should the GEFS prove accurate (and put our May outlook in jeopardy) versus 50s and 60s should the European turn out to be correct (more in line with our monthly outlook). Unfortunately, from a precipitation perspective, wetter than normal times are expected to continue for the balance of the month of May and the data is in more agreement from that perspective- despite the vast differences at 500mb.

When we look at the latest CFSv2, it’s more in line with the European camp, including rather widespread chilly, damp weather for the mid-to-late May time period.

The combination of a negative NAO and AO, though not nearly to the extent of chill found in late winter/ early spring, do continue to hint at cooler than normal times in May. Eventually I would expect the GEFS to trend cooler, as well.

Furthermore, the PNA (currently negative) is forecast to trend positive by mid-May and that supports the cooler anomalies returning to our immediate region.

We’ll also have to keep close tabs on the MJO and see if it wants to propagate through Phases 5-8, or go back in the “wheelhouse” and really not be a factor. (More to come there).

To sum things up, we don’t see an end in sight to the overall wetter than average pattern as we progress into the middle of May. We’re less confident on the overall temperature pattern, but lean towards the EPS and CFSv2 “winning” over the warm GEFS solution in the end.