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The developing weather pattern for December, (the first month of meteorological winter) continues to be a fascinating challenge to unravel. The U.S. based GFS and the EURO are at odds with their respective MJO forecasts, the GFS going to cold phases while the EURO goes full bore into warm ones.

The EURO is usually my bread and butter but as I've mentioned here recently that model has not handled cold in the pattern recently as well as the GEFS. For that reason I've been leaning more on the GEFS with it's consistent depiction of the MJO and the EPO (eastern Pacific Oscillation) in cold phases.

In an interesting development today (and this could swing back the other way) the EURO EPS went from a positive early December phase Thursday, to a negative one Friday. Here's the reversal.

That puts it in the camp of the GFS which Friday had an EPO forecast that looked like this.

That makes me feel much better about the prospects of December cold (especially the first 10 days of the month). something I've been touting here recently. At least for now, both models are showing it. With that in mind, the EURO ensemble temperature departure forecast for days 10-15 (December 2nd-7th) came in this way.

The GEFS ensemble for the same period. It's even more widespread with the cold.

It's no wonder we see such a chilly trend with an upper air pattern at 500mb that looks like this December 3rd. There is going ti be a big cool down in early December but I'm still seeing conflicting signals if this is just a short term trend or one that sticks around the whole month. Some data shows the cold lifting out quickly after the 7th. I'll have more on where this is headed in coming days.

On the topic of winter cold. I thought this was interesting. Just 11 days ago the U.S. climate model the CFSv2, showed temperatures for the month of December at blow torch levels, similar to last year.

Thursday the upgraded outlook for December came in like this. Getting colder but still off the mark in my opinion.

Today the daily CFSv2 showed a big reversal as it indicated a 30 day December departure like this for the period Nov. 28-Dec. 28

Wow, that model got off the steroids in a big way! If that's not enough (if you trust it after that) it has this for departures the rest of meteorological winter. Actually I think the general idea has merit, just now sure if readings will be this extreme.



If the CFSv2 is on the right track a long cold winter would be ahead of us. On the other hand, this models track record leaves a lot to be desired.

So what about snow? The model does show precipitation December-February (0.50 to 1.5 inches) below normal. I'm sure the reason for that is the amount of cold air that's shown in the pattern. Cold air holds less moisture and the predominate NW flow would overall keep that to a minimum. However, snowfall could very well end up above normal with what precipitation occurs coming mainly in the form of white gold! I'm very intrigued to see how we fair out come March. Maybe another winter to remember!

That brings me to the potential snow system next Tuesday. The first thing that comes to mind in my area is that this is going to be a tough forecast with the rain snow line cutting right through some part of my region. The latest trends are for a stronger system and that has inched the track and rain snow line further northwest. I did mention Friday that a stronger storm would lead to such a result. Now the question is does this thing deepen even more the next couple days and go even further northwest. In my mind that is indeed a very real possibility. Excluding the potential of the NW shift in the next 24 hours, these are what we have for snowfall forecasts Friday night.

The GFS:

The EURO ensemble control


Personally, with cold air lacking ahead of the deepening system, I like the northernmost solutions for the placement of the snow band. In fact, I think there's a very good chance future runs will be even further northwest. If so, most of the travel issues Tuesday would bypass the majority of my area with much of the precipitation falling as a cold rain as opposed to snow. This is not set in stone yet but I think any shift southeast in coming days is very unlikely if the system phases as expected. Saturday's data will be telling. Stay tuned and roll weather.

By the way, if you want to learn the fine art of forecasting snow and winter weather, you should consider WEATHER SCHOOL which I will be presiding over January 25th. We'll get into the hard core nuts and bolts of forecasting in a way that makes it understandable and doable for you. Space is limited and we are over half way to capacity so get off the fence and sign up. Here's all the details! is offering a very special and unique opportunity for you to learn first-hand the ins and outs of weather forecasting with one of the best meteorologists in the country along with his team of expert meteorologists.

That’s right… You want to forecast right along with Terry Swails, well now you can. He’s teaching weather with TSwails newest program called WEATHER SCHOOL. The opening bell rings this January and you can be a member of the very first graduating class. The one-day forecasting seminar for weather enthusiasts will be held at his home in January. It’s not your typical run-of-the-mill school. There will be no tests, but Terry, Rebecca, and Nick will cram your head with so much knowledge, it’ll be spinning like a tornado before the day is over

You want to know the essential online sites to use for models, radar, and the basic weather tools? DONE! You want to understand the structure of models and the role they play? DONE! You want to be able to construct forecasts from the ground up? DONE!

WEATHER SCHOOL will be presented in a seminar-type format where you'll have the ability to ask questions and dig deep. You’ll get the scoop on data acquisition, model analysis, severe weather, and actual forecasting from the big dog himself, T. Swails. With 43 years of experience and an uncanny ability to break the science down, you’ll open the door to forecasting like never before.

Along with the head master T. Swails himself, meteorologists Rebecca Kopelman and Nick Stewart of KGAN TV will be there to lend their knowledge and experience to the discussion. It will be fun, informative, and factual! This is the day for you to see, feel, and experience what it’s like to be in the hot seat of a meteorologist.

The seminar will be held January 25th and will last from noon until 5:00pm. We have limited seating and the cost is $ 99 dollars per person. A catered lunch will be provided. Again..not a lot of seats so reservations with a pre-payment are required. Sorry, no refunds. If there’s enough interest, a second session will be added in early February. To register or get additional information send an email to

GIVE THE GIFT OF WEATHER. This might be the perfect gift for that hard to buy for person this Christmas. Along with a WEATHER SCHOOL admittance voucher, TSwails will send a special holiday greeting to your weather enthusiast if you give the gift of weather with the TSwails touch!



Purpose: To help weather enthusiasts understand the basics of forecasting and apply the knowledge and techniques learned to construct personal forecasts.


The essential on-line sites for models, observations, satellite and radar images, and general weather data.

Session 2: ANALYSIS:

Determining your objective goals. Short term, intermediate, or long-term. Understanding the process of analysis and its relationship to forecasting.

Model options and choices. What to use and when!

The GFS, EURO, NAM 3k, NAM 12K, Canadian, HRRR, MJO, ensembles, teleconnections, etc.

Locating, learning, and knowing what’s essential to make a reliable forecast.

The art and science of model interpretation: Using and understanding model output. Its called guidance for a reason!

Learn how to analyze key parameters such as:

Surface and upper air data

Vorticity and energy

Precipitation output

Wind and pressure


A simulation of the basic process using model output.

BREAK: A 25-30 minute recess to enjoy a catered lunch…


Thunderstorms, tornadoes, derechoes, and squall lines.

Soundings. What are they and why should I care?

Instability (CAPE) vs (CIN) Critical interaction involving moisture, heating, and forcing.

Uncovering the ingredients of a severe weather set-up.

TVS signatures. What to look for on radar.

Role of SPC vs NWS, and your local TV station regarding the warning process.

Simulated model driven forecast of a severe weather event/tornado outbreak


The key ingredients required for significant winter storm:

How to forecast the rain snow line.

How to forecast snow totals from QPF

Determining totals from snow ratios.

What to look for at the surface and at upper levels (500 and 850mb)

Model bias and determining the storm track

Simulated model driven forecast of a significant Midwest winter storm


An open period for attendees to ask questions regarding relevant topics or issues discussed during the day.


Some final words of inspiration from the events headliners

Once again, to reserve a spot or ask questions send an email to See you when the bell rings! T. Swails

ALSO, PLEASE CONSIDER WHAT YOU'RE GETTING...I hope you are aware of how far ahead of the competition TSwails has been in catching the trends of our extreme weather the past few weeks. It takes a heck of a lot of commitment, passion, and knowledge to do that. This is now my job and that's why I'm asking for a voluntary subscription fee of $12 dollars a year, one dollar a month to keep TSwails going. Together we can create one of the best, most unique, and reliable weather sites in the Midwest. Your contribution of 3 cents a day, allows me to stay free of the corporate world and pour my energy into doing what I do best, forecasting the weather! We hope you see the value and hard work that goes into the site everyday. You support in any way is sincerely appreciated. Thanks and roll weather. To donate click on the secure green box below.

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