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Turkey day is fast approaching and the Pilgrims are bringing in a welcome harvest of mild weather. Since Sunday temperatures have been steadily increasing and Wednesday has the ability to bring 50 degree highs, at least to my southern counties. I think we can all gobble that up, especially after the recent brush with winter.

It's easy to see why we've moderated so much when looking at the position of the 500mb jet stream. Last Friday it was aimed from the North Pole directly into the heartland.

Now the flow looks like this. Notice the wind component has veered to the west in what's know to weather buffs as "zonal" flow. The connection to Arctic air is cut-off and replaced by air originating off the Pacific.

This air mass is significantly warmer resulting in temperatures that are above normal over much a north America. A far cry from what we experienced just a few days ago. So take a walk (or a drive) on the "mild" side Wednesday. Sunshine and highs in the upper 40s to low 50s (maybe 55 far south), will all make for a fine late November day.

Thanksgiving day itself will still be mild but the addition of clouds and some scattered light showers will change the overall complexion of the day. The system bringing the change is centered well to the southeast so nothing more than a glancing blow is expected. Any rain will be light, not much more than drizzle, and most likely confined to the southeast half of my area. Morning looks to be the primary window for what rain ends up falling. The EURO indicates totals less than .04" where measurable amounts occur. Highs are generally in the mid to upper 40s across the board.

Friday, conditions improve again with a weak ridge of high pressure and subsidence leading to a dry day. Expect at least partial sunshine with highs remaining mainly in the 40s.

Saturday, a strong southern stream system sweeps northeast towards the northern Ohio Valley. This disturbance has good upper air support and better moisture. A wave of deformation showers is expected to pivot towards the region Saturday afternoon and night. The concern here is with the track. The EURO is further NW and gives most of my area southeast of a line from Cedar Rapids to Dubuque measurable amounts. The GFS is less amplified producing a track that keeps all of my area dry. Here's a comparison of the two solutions.



The national model blend mirrors the EURO making the GFS and its dry solution an outlier. The NBM is a decent compromise for now.

Personally, I will wait for better data to get into the grids before I render a hard opinion. Wherever the rains fall, they depart by early Sunday only to be followed by a blustery cool day with highs in the low to mid 40s.

By all account temperatures will likely remain seasonal into the middle of next week as another storm heads for the Midwest Tuesday night or Wednesday with the threat of some additional rain. I'm not going to get into that right now.

What I will get into is the EURO ensemble showing the EPO (eastern Pacific Oscillation) going deeply negative around December 4th. In fact, the ensemble mean control actually exceeds the boundaries of its phase forecast, more than 7 standard deviations negative. That's even lower than what we just went through with our recent cold snap.

Along with that, the AO (Arctic Oscillation) and NAO (North Atlantic Oscillation) are also in cold phases. Now you add in a phase 7 MJO and you have the makings of a big time cold wave.

Teleconnections such as these are valuable because of their ability to see evolving temperature patterns before guidance. Modeling is still grappling with the idea but showing hints of the cold coming somewhere in the second week of December. The EURO control was pegging it yesterday showing 46 day temperature departures of 12-13 degrees below normal, that's per day. I would be stunned if something like that verified over any given 46 day period. But the fact it's on the table, along with strong support from teleconnections, has me really perked up for a December cold shot. The potential will be closely monitored over the next 6-10 days.

All right, it's Thanksgiving Eve. Nearly time to take in some calories, watch some football, and kick it with family and friends. I'm ready to go. Here's hoping you are too! Roll weather...TS


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