HOW THE TURKEY TUMBLES

If you like your Thanksgiving weather cold without the trimmings of rain or snow, this is the year for you. The door was opened for colder air Monday with the passage of a cold front. Now that's its east, a progressively colder weather pattern is on the burner, reaching its peak Friday when Black Friday deals and leftovers are on the table.

Here's the 500mb jet stream Friday. A nice bowl of cold air is oozing into the center of the nation.

By Friday afternoon, temperatures up to 15 degrees below normal will have temperatures struggling to get out of the mid 20s.

The hysplit backward trajectory model based on the GFS shows the air mass coming off Siberia, taking a hard right west of Hudson Bay before arriving in the Midwest. The chill has a serious road to travel.

Despite some vorticity in the 500mb flow, there is no organized phasing or lift for what could be snow. Instead, aside from a few flurries, the air mass is just cold and brutally dry. Available water vapor necessary for precipitation Friday evening is .08 inches in Dubuque.

That's just 20 percent of what the typical norms would support. Bone dry to be sure!

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Looking at the MJO oscillation, both the GEFS and EURO extended models indicate a good week or so of phase 5 conditions through December 7th or 8th. The numbers represent the daily dates of the cycle going back to October 15th, ending Christmas day.

The EURO.

The GEFS, slightly slower with more amplitude than the EURO.

In phase 5 of the MJO, 500mb height anomalies equate to a western ridge, eastern trough with plenty of blocking over the top in northern Canada.

That screams NW flow here in the Midwest with a strong tendency for near to below normal temperatures through the next 6–10 days. Here's the mean 5 day 500mb heights shown by the EURO December 2nd-5th. That sinks up nicely with the phase 5 MJO anomalies.

NW flow means severely restricted moisture, arguing for dry weather to accompany the chill. That's why CPC shows below normal temperatures and precipitation in its 6-10 day outlook out to December 5th.

Here's the total precipitation shown on the GFS the next 2 weeks. Back to dry conditions.

If you like snow for Christmas and the cold that goes with it, my concern is what comes after December 8th. If you return to the MJO cycles above, both the GFS and EURO send it out of phase 5 into phase 6. Generally, that is the kiss of death for cold and snow, with a trough over the west and ridge over the east. A complete flip in the 500mb flow that is void of polar air masses.

That's essentially what is shown happening with the MJO in phase 6 from December 9th to the 24th. For snow lovers, that is the worst possible scenario from an MJO standpoint. Take a look at the phase 6 temperature correlations in December. Good Grief. That does not look good.

Right around Christmas it appears a shift takes place to colder MJO phases of 7, 8, and 1, but most likely it won't be in time to save a white Christmas. Having said that, other factors can off-set the MJO for a few days, but phase 6 makes it really hard to get snow and keep it long in December. This is one of those times I hope I'm reading the tea leafs wrong. I like snow at Christmas.

Getting back to the short term. There's little to be concerned about in terms of storminess through Thanksgiving weekend, maybe a few flurries. Temperatures however are a different story, Here's what the meteograms of the EURO and GFS show through next Monday. You can see the coldest air doesn't make itself known until Thanksgiving and beyond.

The EURO

The GFS

By the way, if you have tickets to the Iowa football game Friday night, you better bring the mukluks. The temperature at University of Iowa's Kinnick Stadium on Saturday evening will be one of the coldest ever when the Hawkeye's kick-off against Nebraska at 6:30pm. Currently, temperatures look to be around 25-26 to start, with readings slipping into the lower 20s by the conclusion of the game. Wind chills could be as low as 14–16 degrees! How fun. Just five home games in UI football history have had highs in the 20s. Myself, I'll be nice and comfortable on the couch. Husk those huskers!

That is all for now. Enjoy a crisp but mostly sunny day as the countdown to Thanksgiving continues. Roll weather...TS