January 2026 Short/Medium Range Thread

[GBOVolz]

Supposedly the Euro AI has been trained on 80 years of ERA 5 data 

I haven’t read much about the AI mods… what calibrations did they make to the euro AI for it to show a different scenario from the original euro? Do we know?


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[Bigbald]

I have noticed some mets getting on board for upper east tn, fairly unusual this far out.

[Weatheriscool]

It is amazing that the Weather Channel literally has their forecasts pegged to the GFS; last night it had snow for my area Friday night Saturday and Saturday night, now, maybe an inch Friday night where before it was 1 - 3 for Friday night; 5 - 8 for Saturday, 1 - 3 for Saturday night 

[tnweathernut]

Next 24-48 hours of model runs will be pivotal in determining what this looks like coming out. (i.e. one system vs. several smaller waves of overrunning moisture- Miller A/Miller B and what the orientation the incoming high will take on). Pretty confident a nice winter storm will scoot across, but in the mid-south there's always a chance the warm air across the gulf surges further north than modeled.

[1234snow]

6z Euro was just a thing of beauty (except for the ice). How it unrolls the Baja low is almost perfect with how it has the shortwave moving through the Dakotas.

There is going to be ice somewhere though. I think that is unavoidable with an overrunning setup.

[tnweathernut]

37 minutes ago, Holston_River_Rambler said:

Supposedly the Euro AI has been trained on 80 years of ERA 5 data 

This would actually make sense.  I've been watching winter storms forecast across the mid-south turn into Kentucky maulers (80% of the time) for over 50 years now.  

[Wurbus]

6z GEFS was a beauty. Most of northern East TN in the 6+ mean. Some huge dogs showing 20"+ skewing it some though. 

[Carvers Gap]

So, I have been digging through lots of verification for the AIFS.  The one thing I notice over and over is that the EPS scores equal or better than the AIFS at days 4-5.  At days 4-5 all deterministic models and AI models are fallible...sometimes very fallible in regards to dew point, windspeed, and temp-C.  I Most papers that I have read this morning strongly recommend using a blend of models - EPS, Euro IFS, and AIFS.   I have provided a link to one paper below.  If you favor ensembles, NWP, or AI...there is probably something in that article for you.

This will be a good test, but by no means is it the final test.  Modeling is only as good as its programming and quality/quantity of data input.  All modeling is much better inside of d4.  If I was going to rank models...it would still be pretty much the following at d5....EPS, Euro AIFS EPS, Euro or AIFS.  I would feel much better about the AIFS if it wasn't in the same camp as the UKMET which has low verification scores at this range and also with the AIGFS.  But again, this will be an interesting comparison for sure!  

Right now, the AIFS is on the north side of guidance w/ the GFS suspiciously on the south side.  My guess would be the solution is somewhere in between.  However, I am reminded that most folks were skeptical that a chess bot(not AI) could defeat a grand master.  The chess bot is now better.  But in this case...pretty much all numerical modeling is a chess bot.  We are just trying to see which chess bot is better.

Here is the article I found out of Australia in regards to comparing AIFS vs IFS from AMETSOC.

https://journals.ametsoc.org/view/journals/aies/4/4/AIES-D-25-0037.1.pdf

Interesting quote...

However, as with NWP models, the autoregressive nature of AIFS means that small errors are amplified over the forecast period, which causes AIFS (and HRES) to fall behind ENS in accuracy as the lead time increases.

It is well established that blending models generally im- proves the accuracy relative to the best individual forecast [see e.g., Vannitsem et al. (2021)], and therefore, it is a common approach in operational weather forecasts. 

 

 

 

[tnweathernut]

2 minutes ago, Carvers Gap said:

So, I have been digging through lots of verification for the AIFS.  The one thing I notice over and over is that the EPS scores equal or better than the AIFS at days 4-5.  At days 4-5 all deterministic models and AI models are fallible...sometimes very fallible in regards to dew point, windspeed, and temp-C.  I Most papers that I have read this morning strongly recommend using a blend of models - EPS, Euro IFS, and AIFS.   I have provided a link to one paper below.  If you favor ensembles, NWP, or AI...there is probably something in that article for you.

This will be a good test, but by no means is it the final test.  Modeling is only as good as its programming and quality/quantity of data input.  All modeling is much better inside of d4.  If I was going to rank models...it would still be pretty much the same at d5....EPS, Euro AIFS EPS, Euro or AIFS.  I would feel much better about the AIFS if it wasn't in the same camp as the UKMET which has low verification scores at this range and also with the AIGFS.  But again, this will be an interesting comparison for sure!  

Right now, the AIFS is on the north side of guidance w/ the GFS suspiciously on the south side.  My guess would be the solution is somewhere in between.  However, I am reminded that most folks were skeptical that a chess bot(not AI) could defeat a grand master.  The chess bot is now better.  But in this case...pretty much all numerical modeling is a chess bot.  We are just trying to see which chess bot is better.

Here is the article I found out of Australia in regards to comparing AIFS vs IFS from AMETSOC.

https://journals.ametsoc.org/view/journals/aies/4/4/AIES-D-25-0037.1.pdf

Interesting quote...

However, as with NWP models, the autoregressive nature of AIFS means that small errors are amplified over the forecast period, which causes AIFS (and HRES) to fall behind ENS in accuracy as the lead time increases.

It is well established that blending models generally im- proves the accuracy relative to the best individual forecast [see e.g., Vannitsem et al. (2021)], and therefore, it is a com- mon approach in operational weather forecasts. 

 

 

 

Good find.  Thanks for your research.

[Carvers Gap]

The fun question is weather the AIFS will outperform its own ensemble at this range.  The ensemble is quite different for our forum area.  One thing that many models have missed over time is that when we have a hp funneling cold down west of the Apps, many models will often miss that the actual surface is below freezing.  Depending on the sequence that this arrives, the scenario exists that cold air could get trapped in the eastern valley.  That is why the model difference below is important.  The AIFS has changed quite a bit since 18z w/ a more amped cutter while the AIFS EPS has remained fairly steady.  The ensemble mean (rightly or wrongly) smooths out that amped look.  If the mean is correct, then the heat transport northward(moisture) will be less and cold air at the surface could be trapped.  If the AIFS is correct....liquid drops for almost everyone but NW TN.

[Weatheriscool]

4 minutes ago, Carvers Gap said:

The fun question is weather the AIFS will outperform its ensemble at this range.  The ensemble is quite different for our forum area.  One thing that many models have missed over time is that when we have a hp funneling cold down west of the Apps, many models will often miss that the actual surface is below freezing.  Depending on the sequence that this arrives, the scenario exists that cold air could get trapped in the eastern valley.  That is why the model difference below is important.  The AIFS has changed quite a bit since 18z w/ a more amped cutter while the AIFS EPS has remained fairly steady.  The ensemble mean (rightly or wrongly) smooths out that amped look.  If the mean is correct, then the heat transport northward(moisture) will be less and cold air at the surface could be trapped.  If the AIFS is correct....liquid drops for almost everyone but NW TN.

That is a huge difference in temps for places such as central and northern Alabama, almost 30 plus difference

[GBOVolz]

So I asked Mike Witcher about the AI mods. He said the euro AI will initiate the same as the euro OG but the AI mod leans heavily on climatology and that’s why we are seeing a cutter from it. He said as of now he feels like this is a snow event for East Tennessee, except for the southern Valley, which might get warm nose a little.


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[Carvers Gap]

I mean when looking at the AI scenarios above...either looks plausible, right?  We have seen both scenarios play out.  I think we need to really watch trends w/ hp to our north and how the Baja slp evolution plays out.  I do think we could see a truncation as the energy involved gets better sampled in the northern stream.  No matter how good programming is...data input quality is just as important at the programming in the model.

[GBOVolz]

I mean when looking at the AI scenarios above...either looks plausible, right?  We have seen both scenarios play out.  I think we need to really watch trends w/ hp to our north and how the Baja slp evolution plays out.  I do think we could see a truncation as the energy involved gets better sampled in the northern stream.  No matter how good programming is...data input quality is just as important at the programming in the model.

I feel pretty confident that as long as we don’t see a cutter,IMO, we should not have temperature issues.


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