*A fresh 7-day will be updated late tonight or early Christmas Eve.*
Modeling continues to suggest a colder return looms as we close out 2016 and open 2017. We’ve discussed the implications of a negative EPO and it certainly appears as if, at least initially, the negative EPO will do the “dirty work” to drive a colder regime in the 6-10 day period.
We note ensemble data is suggesting high latitude blocking tries to develop towards Day 10. Recall this was the missing ingredient in the bitterly cold blasts of air that occurred during the first few weeks of December. Both the GEFS and EPS agree on the increasingly blocky look to the pattern by Day 10. This would help drive a cold, stormy pattern by early January. Instead of storms cutting, we would see more suppression. With a “stubborn” southeast ridge, things could get interesting across the Ohio Valley from a wintry perspective….
We don’t want to jump the gun, but it the positives can “hook up” over the pole, we stand the chance of locking into a rather lengthy cold, snowy regime as we rumble deeper into the heart of winter.
Given the look, it’s no surprise we see the 12z teleconnections want to continue the trend of a negative look to the NAO and AO in the medium to longer term.
Summary: A rather mild regime remains as we rumble through Christmas before trending more seasonable next week. From a wintry perspective we need to continue to keep an eye on the period around New Year’s Eve/ Day. Confidence continues to increase on the potential of a return of arctic air come early January.
We won’t bore you with the meteorological ingredients/ lingo that are coming together to lead to an active Wednesday with this post, but please know that nearly all severe weather parameters point to the threat, and even likelihood, of an active day.
The first of multiple storm clusters will likely be moving into central IN Wednesday morning. Here’s an idea of what the radar may look like around 7a.
We think we undergo a “lull” in the action Wednesday afternoon before a potentially more serious complex of storms blows into town during the evening hours. We caution that we’re not as confident on specific timing with the evening round of storms.
Current data would imply a tornado threat for areas from northern IL into northwestern IN with the afternoon/ evening convection before “morphing” into a more widespread damaging wind threat as the line propels southeast into the nighttime hours.