And today’s 12z euro is starting pick up on the system Fred already next week.It's been showing up in the Euro ensembles and the operational GFS off and on since 300+ hrs out, but now we are getting into the range where all the main operational globals have the time period in range. We are getting hints between the Euro and GFS, but there is naturally some inconsistencies. The GFS ensembles, Euro ensembles, Canadian ensembles, however, all are consistently showing a large-scale pattern over the CONUS with a low amplitude trough over the middle of the nation and low-latitude/low-amplitude downstream ridging that would potentially support a significant/large-scale type severe weather threat east of the Plains in the general next Thursday-Friday timeframe. All of that would be dependent on exact shortwave and surface low evolution from the main large-scale trough, as well as quality of the boundary layer moisture. However, this is a large-scale pattern that is typically associated with large-scale/significant severe weather events when those things evolve favorably.
Given what we have already seen this fall, with October being the second most active on record for tornadoes since 1950 (and would've been #1 without the little bit of help that Hurricane Michael gave it in 2018, since this October had no tropical influence), and how that speaks of the background being primed with the strongly negative PDO and the intensifying La Nina in place, it would be prudent to keep all heads on a swivel as this approaches next week, just in case.
We're not at the stage yet where we can determine how an embedded shortwave in the large scale trough like that will evolve. Just last night's 00z Euro run had the parent surface low in southeast Missouri. If the operational models today are right and the surface low is way north and the low-level jet is pulling away, the threat isn't as significant. I will caution though, that on November 10, 2002, the main surface low was pulling into southern Canada that morning... and the main event was from a low amplitude trough left behind and surface pressure falls ahead of the advancing cold front backing the low-level winds the same way a surface low would. And that event looked similar to this in the models a week to 10 days out. There was a time 8-12 days out when even 4/27/2011 looked similar to this with an upper low over the Upper Midwest and a surface low pulling away over the Great Lakes. We know the models eventually caught on to energy in the base of the trough and trended differently with time. These longwave low-amplitude troughs are tough to figure out the specific shortwaves embedded within in advance because of how subtle everything starts. We're too far out to write off or hype up anything. It's all about watching for trends in the data and looking at large scale pattern recognition at this phase.
This is the biggest reason why I haven't gotten any more excited about it yet. Trough evolution can work itself out of what is depicted right now. Just looking like we're probably about 36-48 hrs too short on time for quality moisture to return as it needs to.
I thought dewpoints in the low to upper 60s was more than sufficient for this time of year. I could be wrong though.
