Jan 24-26 Weekend Snow and Sleetfest Model Thread Part Tres

[nj2va]

UK would be fun, flips DC basically at 17/18z Sunday with ~0.9” QPF before that.

[konksw]

Just now, balltermen said:

23/2 here near Braddock Road metro. 

Just saw the 3k NAM.   5" snow followed by 3" sleet.  Would still be quite the storm.  You can't toss it unfortunately.  Too many times we've seen mid level warm air punch its way well north and west than the globals suggested at 36 hours out.  

How many times has that happened with this level of significant cold in place?

[Interstate]

UKMET still looks great 

[Chris78]

Just now, nj2va said:

UK would be fun, flips DC basically at 17/18z Sunday with ~0.9” QPF before that.

Sounds like an improvement?

[WEATHER53]

Big boy cold arrived

3:30 44F

6:30 38F

10:30 22F

This will be fresh cold for next 36 hours  12 noon Sunday onward unknown but 7-9” looks likely first 

[balltermen]

1 minute ago, konksw said:

How many times has that happened with this level of significant cold in place?

a million. You never think a warm nose can find a way through.  But it does. 

That said, the NAM is also wrong a lot and I think it is probably early with the flip time

[EHoffman]

Ukie flips DC to plain rain on Sunday evening lol

[konksw]

19 degrees in NW DC. 

[wxmeddler]

1 hour ago, WxMan1 said:

Typically the degree of the warm air (MaxT aloft) will be proportional to the depth. In other words, the highest the MaxT aloft, the deeper the warm or >0C air.

In many studies I've seen though, no matter how deep or shallow the warm air is, when you hit 3C or 37F, you're completely melting the hydrometeor. Once that happens, there's no going back to sleet or anything "pellety" unless the air somewhere within the subfreezing layer can get down to -13C/8F or lower. Unless that happens, the rain drop does not refreeze. When we see sleet, it's typically associated with an elevated warm layer temp between 0.5C and just below 3.0C. When it's closer to 0.5C, it's probably more of a sleety & rimed snow mix. When the MaxT aloft is closer to 2.5C, it's more like a sleet ball, with little if any evidence of a mangled snowflake. 

We're in for some real sh*t if that's the case. Most guidance gets the fall line and SE at or above +5C as early as 11am tomorrow. Would love to see those studies if you have the links. 

I don't recall ever having a situation where there is a +7 to -8 swing in a single profile in this area. That is some southern high plains ice storm levels of cold air wedging. We do not see this here.

[IUsedToHateCold]

Just now, JenkinsJinkies said:

Now what if NAM stays the course but the other models do not cave to it?

If a model is on an island it's probably wrong unless it's in it's wheelhouse doing something it's proven to excel at. NAM is good at thermals, so it is a wheelhouse, but we've seen the NAM be wrong outside of 24 hours. This is within 24 hours, so we are to assume it could be on to something, but I wouldn't necessarily conclude that verbatim. 

[balltermen]

10 minutes ago, nj2va said:

I'm guessing rimed snow/sleet is like 5:1 and barely sleet like 2:1?  

 

[nj2va]

Just now, Chris78 said:

Sounds like an improvement?

Honestly, I’ve been so busy at work I haven’t paid much attention during the day.  A quick look vs 18z and the flip was  a touch later than 18z.  I honestly don’t really put much confidence in UK thermals but a nice data point for the better lol

[hsq]

Dropping quickly down here in Calvert

 

[Ji]

Canadian at 18z looks pretty good!

[bncho]

Does anybody have the UKIE kuchera?

[T. August]

17/-7 in Havre de Grace

[umdterps29]

Can someone post CMC kuchera?


.

[SnowenOutThere]

6 minutes ago, wxmeddler said:

We're in for some real sh*t if that's the case. Most guidance gets the fall line and SE at or above +5C as early as 11am tomorrow. Would love to see those studies if you have the links. 

I don't recall ever having a situation where there is a +7 to -8 swing in a single profile in this area. That is some southern high plains ice storm levels of cold air wedging. We do not see this here.

Seems like multiple studies disagree with each other. One I read/skimmed said that if we have a freezing layer of 3000+ feet below the elevated warm layer it’ll refreeze to sleet regardless. Just such an extreme setup to where it all breaks down. 

[NorthArlington101]

Ukie flips DC to plain rain on Sunday evening lol

Would be a kick in the nards even though it’s all gonna freeze back over rapidly

[pazzo83]

4 minutes ago, SnowenOutThere said:

Seems like multiple studies disagree with each other. One I read/skimmed said that if we have a freezing layer of 3000+ feet below the elevated warm layer it’ll refreeze to sleet regardless. Just such an extreme setup to where it all breaks down. 

wild to think we'd have a layer of 40+F air when it's around 20F at the surface.  That would seem to produce a catastrophic ice storm if it occurs though.

 

[balltermen]

8 minutes ago, Ji said:

Canadian at 18z looks pretty good!

it flips in DC around 15z probably, but it dumps prodigious amounts of snow before then.  around 10" 

[LordBaltimore]

4 minutes ago, SnowenOutThere said:

Seems like multiple studies disagree with each other. One I read/skimmed said that if we have a freezing layer of 3000+ feet below the elevated warm layer it’ll refreeze to sleet regardless. Just such an extreme setup to where it all breaks down. 

I'd imagine besides the depth of freezing layer there's also variability based on if the drops contain ice nucleating particles which then becomes a matter of if they were homogenously nucleated in the first place. Probably no way to tell

[mattie g]

26 minutes ago, Buddy1987 said:

Anyone got gfs sleet map?

 

24 minutes ago, nj2va said:

[jayyy]

d

It’s gotta be missing some of that mid layer warmth. Or is it a big thump pre flip?

[nj2va]

Unless the NAMs stay stubborn tomorrow, I’m feeling good for a 6” floor for DC based on tonight’s globals.  

[balltermen]

This is 10:1 Canadian through 15z sunday 

 

[jayyy]

Does anybody have the UKIE kuchera?

Not up on pivotal just 10:1

[wxdude64]

3 minutes ago, mattie g said:

 

Coalin'

[caviman2201]

1 minute ago, jayyy said:

Not up on pivotal just 10:1

[hsq]

3 minutes ago, balltermen said:

This is 10:1 Canadian through 15z sunday 

 

Seems a little south-ier than I expected