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January 2026 Medium/Long Range Discussion

snowfan

By snowfan,
in Mid Atlantic

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stormtracker
stormtracker
stormtracker
stormtracker

Shut the fuck up

csnavywx
csnavywx

Really cool triple phaser. However, it's a triple phaser. Powerful but delicate setup, so your expectations should be very guarded as there's quite a bit of dprog/dt even 3 days out right now. He

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Jebman

Jebman

Posted
Posted
1 hour ago, wasnow215 said:

Temps teens and low 20's Sat could be 20:1 ratios no?

2m temps means something but it is much more about what goes on upstairs. Need Bob Chill or one of the Mets to explain this better than I could, lol. It's something about the DGZ, Dendritic Growth Zone or something like that.

 

Remember the last storm in Virginia? Ground temps in the low teens? Sleet falling in 13 degree temperatures and people saying this is so ridiculous? It was all about what was happening upstairs. I think it was because of a strong warm layer at about 700mb or something like that over top of the incredibly frigid airmass over the Mid Atlantic that caused the warm layer to dump rainfall that froze into sleet pellets because it was so damn COLD in the boundary layer.

Or something like that. I really should leave this to degreed Mets or qualified hobbyists like bncho or Bob Chill or PSU or even SnowinOutThere. He needs a red tag stat. I sure don't. All I am, is an old man, all played out, can't even dig snow anymore, can hardly walk on ice down here in Texas without falling and smashing my low back to smithereens, snow weenie lmao.

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bncho

bncho

Posted
Posted
35 minutes ago, Jebman said:

2m temps means something but it is much more about what goes on upstairs. Need Bob Chill or one of the Mets to explain this better than I could, lol. It's something about the DGZ, Dendritic Growth Zone or something like that.

 

Remember the last storm in Virginia? Ground temps in the low teens? Sleet falling in 13 degree temperatures and people saying this is so ridiculous? It was all about what was happening upstairs. I think it was because of a strong warm layer at about 700mb or something like that over top of the incredibly frigid airmass over the Mid Atlantic that caused the warm layer to dump rainfall that froze into sleet pellets because it was so damn COLD in the boundary layer.

Or something like that. I really should leave this to degreed Mets or qualified hobbyists like Bob Chill or PSU or even SnowinOutThere. He needs a red tag stat. I sure don't. All I am, is an old man, all played out, can't even dig snow anymore, can hardly walk on ice down here in Texas without falling and smashing my low back to smithereens, snow weenie lmao.

Here's my two cents.

Yes, the storm two days ago featured sleet falling at 13 degrees due to the warm nose at ~750-800mb. Snow formed high up in the atmosphere and fell out of it, but when those falling snowflakes ran into that warm nose, they melted and turned into raindrops. After they exited that warm nose, they eventually refroze into sleet pellets.

I'm actually not entirely sure how a snowflake forms, but what I do know is that snowfall efficiency is determined by two things: temperature (amount of cold) and lift (which brings in the moisture and determines where snow grows). These two things are linked. Moist air is lifted high up into the atmosphere, and the cold temperature allows moist air to grow onto ice crystals (I think this is called deposition?). We don't want too little cold air where the lift sets up (-5 to -10°C) where snow forms because everything about snow growth is generally slower. The moist air doesn't grow onto the ice crystals quickly enough to turn into snowflakes. This causes a domino effect: ice crystal growth is slower so the "snowflakes" don't have time to really grow before they fall out of the snow growth zone, which also makes it harder for them to stick together, and what you see is usually more needle like. No dendrites. We also don't want too much cold air where the lift sets up (-20 to -25°C) because that'll mean there won't be enough moisture to grow snowflakes efficiently, so you'll see pixie dust. If, however, if lift sets up at the DGZ (-12 to -18°C), for some reason ice crystal formation is quickest (I have no idea why). This leads to bigger snowflakes in a shorter amount of time, which induces dendritic growth, or where snowflakes start clinging together. That's why you see those baseball sized beauties fall from the sky.

So generally, where lift sets up is where the snow growth zone sets up. Where lift sets up is where the temperature matters most for snow growth. Afterwards, temps below the snow growth zone shouldn't matter much unless it's above freezing (then we might talk about sleet/freezing rain). Hoped this helps. And if I'm wrong anywhere, let me know!

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Roger Smith

Roger Smith

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This has explosive potential as a major energy peak tries to shift a big cold high leaning hard on it from the north and west. The Euro (00z) said expect a heavy snowfall in s.e. VA and some snow north into s.e. PA and s NJ but the low would then head due east, skunking NY, LI, NE etc. 

Other models share the wealth more widely, or hint that everyone will miss out. 

Would not expect a fast trend to model consensus on this. One thing is fairly obvious, there won't be a warm nose for NAM to bring in from the woods. Extreme cold is returning with that high. And this time there is no primary inland to deal with, the coastal is all or nothing. 

Given the fact that at least one model depiction looks like the twin brother of 3-12-1888, it would be an understatement to say this has potential. But we've used that term more often than actual. 

The 06z NAM looks like it is getting ready at 84h to carve out a trough near 75W and would probably evolve more like GEM than Euro. But how often does one see the 498 dm thickness contour dropping south towards TN? Models won't have a lot of analogues to consult on this. I am coming to belief that Euro is currently too weak in development and a storm will move up the coast. As long as it isn't pushed a bit too far east things will be ripe for a large to very large storm impacting land.

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