1-30/2-1-26 Arctic Blast, ULL Snow Event

[Daniel Boone]

5 minutes ago, John1122 said:

The 0z NBM was pretty much a repeat of the 18z. Gonna see what models they used. It literally has 1/2 inch for me. 

Ugh. Is there even a Model showing that low ?

[John1122]

2 minutes ago, Daniel Boone said:

Ugh. Is there even a Model showing that low ?

Maybe the UKIE. 

It looks like for snowfall they use individual ensemble members from the GEFS and Euro, the Rap, the HRRR, the SREF, all the CAMs from the NAM nest, and a few others like that. It's amazing really, because to me, not using the OP Euro is mind blowing. 

[GBOVolz]

The SREF is up to 4.5 for TYS. It started today at 2”


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[Daniel Boone]

1 minute ago, John1122 said:

Maybe the UKIE. 

It looks like for snowfall they use individual ensemble members from the GEFS and Euro, the Rap, the HRRR, the SREF, all the CAMs from the NAM nest, and a few others like that. It's amazing really, because to me, not using the OP Euro is mind blowing. 

I agree. The Euro track record is great at this Range. If the 0Z NBM is still showing the same they'll keep showing what they are. It's what they use. I don't know who decides which Models to implement in it. 

[Vol4Life]

1 minute ago, GBOVolz said:

The SREF is up to 4.5 for TYS. It started today at 2”


.

Good call out and info! Thanks

[TellicoWx]

Nice jump by the RGEM

[Vol4Life]

2 minutes ago, TellicoWx said:

Nice jump by the RGEM

Was just coming to post the same.  On my phone, but from what I could tell it did increase totals from 18z in most locations in ETN

[WintryMixmaster]

18 minutes ago, John1122 said:

Maybe the UKIE. 

It looks like for snowfall they use individual ensemble members from the GEFS and Euro, the Rap, the HRRR, the SREF, all the CAMs from the NAM nest, and a few others like that. It's amazing really, because to me, not using the OP Euro is mind blowing. 

The NBM also seemed to significantly lag the trends with the last storm... when Morristown put out that first call snowfall map with 7" for Knoxville despite the fact that other than the GFS, no model had shown that in multiple suites, I realized they probably just copy/pasted the NBM

[TellicoWx]

0z RGEM

[ShawnEastTN]

I think it was 2014 or 2015, but there was a storm very similar to this one that happened in February followed by an ice storm like 4 days later (central valley).  I remember the storm really well because MRX forecast 1-2" south of 40 and east of the plateau, and forecast 2-4" north of 40, and mountains 6".  This was their forecast 24 hours before.  The next day they bumped everyone by an inch or so, then the storm began. It kept snowing and snowing high ratio snows they kept increasing the forecast through the evening even bumping folks in advisory up to warning.  After all was said and done Chattanooga north across the whole great valley and western plateau got around 10".  It was a near carbon copy storm track and type.  These storms have high potential to bust high.

[John1122]

So far, the RGEM and Canadian have shown that outcome, the longest, then the GFS, but the GFS faltered some earlier today. All modeling has folded towards the Canadian suite as we approach the event. 

[TellicoWx]

While I would cash out now in a heart beat, there is enough support in the soundings (omega, low dgz but still thick enough for crystals to grow, and just enough pwat left) that there could possibly be another inch or two the models are not picking up (basically snow that wouldn't show on radar).

[Math/Met]

The 00z trend so far seems to be a little bit of improvement at 500mb. 

[Math/Met]

4 minutes ago, TellicoWx said:

While I would cash out now in a heart beat, there is enough support in the soundings (omega, low dgz but still thick enough for crystals to grow, and just enough pwat left) that there could possibly be another inch or two the models are not picking up (basically snow that wouldn't show on radar).

I agree with this. Think some of the models have it moving out too quickly. That is often the case in northern areas of East TN and along the foothills in these super cold airmasses.

[Vol4Life]

1 minute ago, Math/Met said:

The 00z trend so far seems to be a little bit of improvement at 500mb. 

It looks to me like it’s been a tad further west with the ULL.

[WintryMixmaster]

3 minutes ago, John1122 said:

So far, the RGEM and Canadian have shown that outcome, the longest, then the GFS, but the GFS faltered some earlier today. All modeling has folded towards the Canadian suite as we approach the event. 

It seems kind of like the RGEM/Canadian have come down a bit from their highs, but the other models have met them like 80% of the way there. I feel like the main inconsistent thing is how sharp is the gradient on and west/south of Knoxville. Some models like the RGEM have 3-6" back to the plateau, others like the NAM seem to have a much sharper cutoff with low totals on the Plateau and really shafting that Oak Ridge-Harriman area

[TellicoWx]

2 minutes ago, Math/Met said:

I agree with this. Think some of the models have it moving out too quickly. That is often the case in northern areas of East TN and along the foothills in these super cold airmasses.

I actually stopped looking at what the algorithm has been putting out on the snowfall maps starting last night with the 0z runs. Probably sound like a worn out drum on here today, but something hasn't been adding up just going off sounding analysis (think it has something to do with the algo wanting to look at the normal DGZ vs looking at the super low one on the SHARPy). Think HiRes is correcting itself as time moves forward.

[John1122]

The 0z NAM even gives Nashville 1-2 inches of snow. So the mid-state may still be in this one. 

[TellicoWx]

Those streaks in Ark also makes me wonder if there is bodies of water close to the origin of the streak. That is something else models may initially over look (basically lake effect snow except here locally).

[John1122]

3 minutes ago, TellicoWx said:

I actually stopped looking at what the algorithm has been putting out on the snowfall maps starting last night with the 0z runs. Probably sound like a worn out drum on here today, but something hasn't been adding up just going off sounding analysis (think it has something to do with the algo wanting to look at the normal DGZ vs looking at the super low one on the SHARPy). Think HiRes is correcting itself as time moves forward.

I've seen snow here last for 12 hours after models stop showing it in these super cold situations with a saturated low dgz. 

I've seen some analogs to Christmas 2010, that happened here then. I ended up with about 8 inches of powder because it just snowed about 1/4th inch an hour, hour after hour after hour. 

[GBOVolz]

Go ahead and lock her in boys….




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[TellicoWx]

Icon tried to fill more of the valley in..just dont think its resolution is quite built for this setup tho.

[Carvers Gap]

The 0z RGEM is a decently marked increase.  Shift west with short range models at 0z.

[Daniel Boone]

8 minutes ago, GBOVolz said:

Go ahead and lock her in boys….




.

Yep. That settles it . 

[Daniel Boone]

1 minute ago, Carvers Gap said:

The 0z RGEM is a decently marked increase.  Shift west with short range models at 0z.

Yeah, that one is a real confidence booster !

[Vol4Life]

NWS just updated WSW…now says 3-5 inches

Winter Storm Warning

URGENT - WINTER WEATHER MESSAGE
National Weather Service Morristown TN
1036 PM EST Thu Jan 29 2026

TNZ015-038-039-069>071-073-VAZ001-301800-
/O.CON.KMRX.WS.W.0003.260130T1800Z-260201T0600Z/
Hancock-Grainger-Hamblen-Knox-Jefferson-Northwest Blount-North
Sevier-Lee-
Including the cities of Chestnut Hill, Strawberry Plains, Kodak,
Dandridge, Pigeon Forge, McMahan, Happy Valley, Jefferson City,
Knoxville, Alcoa, Sevierville, Sneedville, Kyles Ford, Treadway,
Harrisburg, Morristown, Bearden, Seymour, Rose Hill, Evanston,
Alpha, Maryville, Bean Station, Lake Forest, Russellville, and
White Pine
1036 PM EST Thu Jan 29 2026

...WINTER STORM WARNING REMAINS IN EFFECT FROM 1 PM FRIDAY TO 1 AM
EST SUNDAY...

* WHAT...Heavy snow expected. Total snow accumulations between 3 and
  5 inches.

* WHERE...Portions of east Tennessee and southwest Virginia.

* WHEN...From 1 PM Friday to 1 AM EST Sunday.

* IMPACTS...Travel could be very difficult. The hazardous conditions
  could impact the Friday evening commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. The latest road conditions for
the state you are calling from can be obtained by calling 5 1 1.

&&

[Jed33]

17 minutes ago, GBOVolz said:

Go ahead and lock her in boys….




.

I saw a halo around the moon earlier and thought the same thing.

[Greyhound]

Maybe the UKIE. 
It looks like for snowfall they use individual ensemble members from the GEFS and Euro, the Rap, the HRRR, the SREF, all the CAMs from the NAM nest, and a few others like that. It's amazing really, because to me, not using the OP Euro is mind blowing. 

I don’t know if you saw bouncycorn’s reply, but this is what he said and posted this graphic
:

NBMv4 has these models/weights:

NBMv5 (parallel) is a bit different but the weights haven't been released. Pretty sure they removed SREF and added AI Models (like AIFS). They also do some different bias correction methods in v5 such as probability matched mean to achieve more accurate/unsmoothed outputs.


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[John1122]

8 minutes ago, Greyhound said:

I don’t know if you saw bouncycorn’s reply, but this is what he said and posted this graphic
:

NBMv4 has these models/weights:

NBMv5 (parallel) is a bit different but the weights haven't been released. Pretty sure they removed SREF and added AI Models (like AIFS). They also do some different bias correction methods in v5 such as probability matched mean to achieve more accurate/unsmoothed outputs.


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Yes and it confirmed I was correct. It doesn't use the Euro op. It uses the 50 individual members and it was using old ones for the run. I selected hr 42 6hr snowfall, and it used the hour 60 panels of the ensembles for the forecast. 

[TellicoWx]

Looking at various topo maps..fairly confident the RGEM is developing streamers out west off various bodies of water (ie Lake Barkley/Kentucky Lake)