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Wintry 2/11-2/12 ULL Magic or More Cold Rain

packfan98 said:
I definitely wasn't expecting that from the Euro! Trying to get back to a NW of I-85 deal. I still think any accumulation will be limited to west of I-77, but I'd happily take a burst of snow in the air. Thanks for posting.
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Also looked like it tried to start as snow so take that for what its worth
 
12z MMFS final.. regional 4km followed by local 1km. BTW- These aren't a specific ratio (such as 10:1), it's a explicit model snowfall forecast, based on radiation and land surface model soil/land temperature.
18z run will be starting immediately.


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Here's my theory for why we're trending better in the upstate and Northeast GA:

The clear trend since this morning has been for a slighlty less deepening/bombing low... we assumed that was a concern b/c it means a "warmer" cold pool to work with, which is true, but all the models are showing that even with these weaker solutions... soundings are well below freezing through the column. We've got plenty of wiggle room to work with, even with the weaker solutions.

With the less/slower deepening solutions they aren't turning the corner as fast so we aren't losing the best dynamics to our North and West. Also, the delayed/slower deepening is giving time for the cold pool to catch up to the precip before it fans out to our north.

The less deepening/amping solutions have less WAA at the mid levels out ahead of the cold pool. This is signifcant because we're at the point on modeling now where some people are keeping a snow sounding from start to finish, but even if you have to wait on the cold pool to arrive... it's going to come quicker when the warmer air out ahead of it is closer to freezing due to less WAA.
 
You know what's really crazy? You can point to about anywhere on a map of GA/SC/NC and that spot is sweating a different aspect of the sounding profile for snow it various times and it has near nothing to do with traditional climo.

It's pretty wonky when you factor in the circular nature of the cold pool, the boundary layer issues which are worse in non CAD areas including mountain valleys, time of day is another factor... just a really weird puzzle to put together.

Boone could theoretically stay all rain due to a persistent mid-level temp above freezing while it rips snow in atlanta with a column that's well below freezing all the way to the surface.
 
bouncycorn said:
12z MMFS final.. regional 4km followed by local 1km. BTW- These aren't a specific ratio (such as 10:1), it's a explicit model snowfall forecast, based on radiation and land surface model soil/land temperature.
18z run will be starting immediately.


330051152_952154366163072_835966859090829541_n.png


330360229_730099945172858_3042618836848463024_n.png
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Man that snowfall forecast is so cool! Thanks for the labor running these for us.
 
rburrel2 said:
You know what's really crazy? You can point to about anywhere on a map of GA/SC/NC and that spot is sweating a different aspect of the sounding profile for snow it various times and it has near nothing to do with traditional climo.

It's pretty wonky when you factor in the circular nature of the cold pool, the boundary layer issues which are worse in non CAD areas including mountain valleys, time of day is another factor... just a really weird puzzle to put together.

Boone could theoretically stay all rain due to a persistent mid-level temp above freezing while it rips snow in atlanta with a column that's well below freezing all the way to the surface.
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This is definitely one of the more complicated/difficult forecasts that we see in the SE US. I don't anticipate that we'll have a clear model consensus until <24 hrs in advance.
 
Myfrotho704_ said:
18z euro getting really close again for CLT/85 in general
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It really is. I wouldn’t be suprised if there aren’t still some surprises in store over the next couple days. There’s gonna be a quickly deepening low on the coast and in the past that’s often translated to heavy snow spreading further south and east in the Piedmont from what was thought 72 hours earlier. Even in cases of smaller to localized events. I remember the 4/2/2019 storm that gave southeast CLT metro a quick 1-3”… 24 hours earlier it was looking like that band was going to set up near GSP.
 
bouncycorn said:
12z MMFS final.. regional 4km followed by local 1km. BTW- These aren't a specific ratio (such as 10:1), it's a explicit model snowfall forecast, based on radiation and land surface model soil/land temperature.
18z run will be starting immediately.


330051152_952154366163072_835966859090829541_n.png


330360229_730099945172858_3042618836848463024_n.png
Click to expand...
The level of detail here is amazing. You've nailed the micro-climate battle lines for events like this one in Oconee/Pickens county with that model. You can see the lakes and even less accumulation on the west side from the wind direction blowing over them. It also has the trapped warm pocket in the northern part of my county.(which has happened in the past and pretty much exactly where your model is showing).
 
rburrel2 said:
The level of detail here is amazing. You've nailed the micro-climate battle lines for events like this one in Oconee/Pickens county with that model. You can see the lakes and even less accumulation on the west side from the wind direction blowing over them. It also has the trapped warm pocket in the northern part of my county.(which has happened in the past and pretty much exactly where your model is showing).
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Thanks. That's the benefit of a 1km horizontal resolution w/ an independent land surface model, high vertical resolution in the PBL, and super-res (100m) geography input.
 
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