East Tennessee Weather II

[norrislakevol]

I agree. I think the Cumberland Plateau and northern East Tennessee could see some decent snow totals around 4" from this. Wouldn't want to be out driving early Saturday morning in these heavy snow rates.

My favorite thing about heavy bursts of wet snow like this is when you see the big 2 and 3 inch snowflakes that twirl when they fall to the ground!

 

[headhunter15]

Yeah, sadly, the chances of that are pretty low. Snow has a hard time sticking around this time of year with the increasing sun angle each day.

The only thing I have going for me is I teach in Cocke Co. If Cosby or Hartford get hit good, it shuts the county down!

 

[MetVol]

The 0z model updates continue to nudge totals up slightly. The big difference in accumulation with each model is whether you're looking at 10:1, Kuchera ratios, or a model derived depth change that accounts for melting. If you're looking at model guidance, just make sure you're comparing apples to apples. It can get confusing.

The big difference between the GFS/NAM and ECMWF is that the ECMWF has much lower QPF. I'm not buying that. Looks like QPF will be around 1" across much of the area. If this were January with colder surface temperatures, we could be getting a huge snow. Still looking like some decent totals, and it should be one of those heavy, wet snowfall events with the big snowflakes.



Will be interesting to see how this all starting trending tomorrow as we get some better observations ingested into the models for this developing system.

 

[Vol knight]

Update:

Everyone except NE TN has been upgraded to a Winter Storm Warning. NE TN is under a Winter Weather Advisory.

Snowfall amounts according to Morristown:

Southern Valley 1-3 inches
Central Valley 2-3 inches
Northern Plateau 3-6 inches
Mountains 3-7+ inches
Northeast TN 1-3 inches

Another thing to keep in mind is that we could see wind gusts from 35-40 mph during the storm, which could create blizzard like conditions. Be very careful if you have to travel Saturday morning.

 

[Vol knight]

To add to my last post, people might notice that even though the Central and Southern Valleys, and Northeast TN have the same amounts predicted, the former areas are under a WSW while the latter is under a WWA. The reason for that is because the Winter Storm Warning criteria is different based on your location. Below is a map that shows the different criteria needed for a WSW to be issued for an area.

 

[Matt2496]

This system is already starting to wreak havoc on roads in NW Arkansas. Multiple accidents reported.

 

[Velo Vol]

Can't get over the fact that it's 65F today and tomorrow there will be snow and it will get down to ~14F.

When was the last time we had snow when it was in the 60s the day before?

 

[davethevol]

Can't get over the fact that it's 65F today and tomorrow there will be snow and it will get down to ~14F.

When was the last time we had snow when it was in the 60s the day before?

Blizzard of 93?

 

[MetVol]

Can't get over the fact that it's 65F today and tomorrow there will be snow and it will get down to ~14F.

When was the last time we had snow when it was in the 60s the day before?

It doesn't always happen this way, but it can with these very strong systems with anomalous temperatures on either side. The system in early January actually occurred this way, so it's not been too long ago. Had highs in the 60s and 70s the day and two days prior to that event.

The impressive thing about this system is how much snow will fall vs what will accumulate. May only have 2-4" accumulate but could have 6-8" actually fall with a lot of it melting.

 

[hUTch2002]

It doesn't always happen this way, but it can with these very strong systems with anomalous temperatures on either side. The system in early January actually occurred this way, so it's not been too long ago. Had highs in the 60s and 70s the day and two days prior to that event.

The impressive thing about this system is how much snow will fall vs what will accumulate. May only have 2-4" accumulate but could have 6-8" actually fall with a lot of it melting.

Do you think West Knox will see 2-4?

 

[MetVol]

Do you think West Knox will see 2-4?

I do. May be higher than that if stuff sets up just right. This is setting up to be the biggest March snowstorm since '93.

 

[Matt2496]

MRX has upped totals for Knoxville on their forecast



Also, the high Saturday was 33 now it's down to 29.

 

[MetVol]

MRX has upped totals for Knoxville on their forecast

View attachment 438545

Also, the high Saturday was 33 now it's down to 29.

It's going to be nearly 30 deg below average. MAV and MET values are 32 and 29, and we'll likely be on the low end of statistical guidance. I'll be able to look at some more data here in a bit.

 

[Velo Vol]

It doesn't always happen this way, but it can with these very strong systems with anomalous temperatures on either side. The system in early January actually occurred this way, so it's not been too long ago. Had highs in the 60s and 70s the day and two days prior to that event.

This what you're referring to? It was over two days, not one.



I know this kind of abrupt temperature drop isn't too unusual in western states, but it is here.

 

[hUTch2002]

MRX has upped totals for Knoxville on their forecast

View attachment 438545

Also, the high Saturday was 33 now it's down to 29.

Is that partially because of the cooling from more snowfall?

 

[headhunter15]

This is shaping up to be something special.

 

[headhunter15]

This is shaping up to be something special.

Dang. The post was from David Aldrich showing snow models between 4-7 inches area-wide.

 

[Matt2496]

Is that partially because of the cooling from more snowfall?

If you're referring to the temp drop, yes that is a factor

 

[Matt2496]

The WSW has been extended to include NE Tennessee.

 

[Matt2496]

Latest MRX totals map

 

[hUTch2002]

Wow. The latest warning I saw is updated to 4-6 inches for Knoxville. That’s crazy.

 

[Matt2496]

Just a heads up, there is also the potential for 35+ mph winds, which meets blizzard criteria.

It's going to be a nightmare on the roads tomorrow morning.

 

[MetVol]

This what you're referring to? It was over two days, not one.

View attachment 438550

I know this kind of abrupt temperature drop isn't too unusual in western states, but it is here.

You're correct that it is unusual. The January event was unusual, or out of the ordinary, for how things usually occur. That was an abrupt drop that happened within a few hours with temperatures in the 60s dropping into the 30s. Across the plains, a lot of low-level cold airmasses will move across an area dropping temperatures by 30+ deg, and yes, we don't see much of that here. The terrain of the eastern U.S. does a lot to slow the progression of those cold airmasses. The situation we're seeing tonight usually happens with very dynamic systems where the temperature drop is aided by very strong ascent and dynamic cooling.

This is definitely an unusual event we're about to see, and it's going to be the largest March snow event since 1993 for East TN.

 

[MetVol]

Latest models continue to push the snow totals up. Stronger system, cooler air, and more snow accumulating. Going to be a band of very heavy snow somewhere along the valley near the I-75 corridor that sets up along the mid-level frontogenesis/instability axis.

The ECMWF is still the outlier with lower QPF than any other the other guidance.

The images below account for melting and surface temperatures. If you actually look at the pure snowfall totals that are falling, it's pretty crazy high numbers.

 

[Vol knight]

Just to emphasize my earlier post, it is best to treat this storm as a blizzard if you are going to be traveling tomorrow morning.