Category: Ensemble Discussion

Updated 10.20.22 @ 5:48p

It’s been a chilly October. Officially, IND is running more than 4° below average month-to-date. It’s also been dry. We’re running close to 2″ below normal in the rainfall department.

When we look at the pattern drivers, it’s hard to see a way for there to be any sort of prolonged chill (compared to normal) over the next couple of weeks. That’s not to say there won’t be “pops” of cooler air here and there, but given the EPO and PNA state below, the upper pattern should favor more persistent ridging across the eastern portion of the country as opposed to the troughiness of late.

The MJO (likely a major driver this upcoming winter) is forecast to move out of Phase 6 into Phase 7 late October.

Phase 7 favors a western trough and associated cooler temperatures compared to average across the western portion of the country.

To no surprise, modeling sees the ‘mean’ trough and ridge placement in exact positions that we’d expect given the primary pattern drivers laid out above.

Week 1 500mb

Week 2 500mb

It’s also a continued overall drier than normal pattern, locally, over the next couple of weeks (in the face of a midweek storm system that should at least provide some unsettled weather the middle of next week- more on this in our short-term products).

As we look ahead towards November, there are potential changes with respect to the primary pattern drivers that could shift a colder regime back east. Note we think the month opens warmer than normal, but that things begin to take a turn towards the colder towards mid-month. Interestingly, the longer range teleconnection forecasts see the EPO heading negative by mid-Nov and the PNA heading neutral to positive. These are encouraging signs our idea is on the right path and perhaps that a colder pattern emerges during the lead-up to the holidays this year.

The NEW European Weeklies develop a 500mb look that features plenty of high latitude blocking by mid-November and should this be correct (we think it is), we should see the model trend colder across the East during this time period. Needless to say, this is the period we’ll continue to keep close tabs on…