January 24-26: Miracle or Mirage Thread 2

[osfan24]

NAM is definitely a warning sign with midlevel warming but nothing to panic over yet. If its similar tomorrow, then it’s a red flag and might be doing its usual thing of sniffing that out better than other models.

[psuhoffman]

1 minute ago, MN Transplant said:

On the upside, this will be the most impressive sleet event since at least 2017, if not 2007.

I really thought we had a cushion (the thermal boundary is starting out so far south this time compared to those two events you just cited) that DC had at the minimum like 6" of snow before a flip.  But the NAM is bothering me...it just blasts the h75 warm later up faster than the precip is advancing once the trough starts to approach and the SW flow hits us...such that it's implying despite how far south the boundary is ahead of this...DC might barely have any snow before the sleet...the "thump" might just be mostly sleet.  You buy that?  

[LP08]

My take away as it took a step towards wetter.  Maximizing 0z-12z is so critical.  

[clskinsfan]

The NAM is much warmer at the surface at onset than the other Meso models for some reason. 

[TSSN+]

Definitely starting to get more of that gfs look. Just needs to cool off/shift se a little more.

 

[NorthArlington101]

FV3 is sexy and I can tell it's at least trying to filter out pure freezing rain. Dunno how it treats sleet. I'll pretend this was the NAM.

[baltosquid]

Tbh I think roll with the better synoptics and see how it looks at 18z. If it keeps trending like that I feel like at some point the 850s and 700s will respond and we’ll get a better mix line outcome. It may not be a linear process to translate incremental synoptic changes to surface result.

[DDweatherman]

1 minute ago, TSSN+ said:

Definitely starting to get more of that gfs look. Just needs to cool off/shift se a little more.

 

I agree, it’s a product of the shifts that @psuhoffman shared. Again; there were positives for sure. 

[MN Transplant]

1 minute ago, psuhoffman said:

I really thought we had a cushion (the thermal boundary is starting out so far south this time compared to those two events you just cited) that DC had at the minimum like 6" of snow before a flip.  But the NAM is bothering me...it just blasts the h75 warm later up faster than the precip is advancing once the trough starts to approach and the SW flow hits us...such that it's implying despite how far south the boundary is ahead of this...DC might barely have any snow before the sleet...the "thump" might just be mostly sleet.  You buy that?  

I guess it depends on your definition of "barely any snow".  I think a <4" snowfall is still an outlier possibility for DC.  Even on the 3k NAM the sounding is perfectly fine up until 15z (12z for reference below). 

 

[psuhoffman]

6 minutes ago, Buddy1987 said:

FV3 looks much nicer than the Nam's. Good bit colder though, although idk if that's a bias it has or not.

FV3 was based on the GFS physics I think, and often is pretty close to the GFS so there is that. 

[MN Transplant]

2 minutes ago, NorthArlington101 said:

FV3 is sexy and I can tell it's at least trying to filter out pure freezing rain. Dunno how it treats sleet. I'll pretend this was the NAM.

Yeah, the FV3 is a better scenario.  Flip isn't until 21z and 1" QPF falls by then in DC.  I just don't buy it.

[LP08]

Just now, MN Transplant said:

Yeah, the FV3 is a better scenario.  Flip isn't until 21z and 1" QPF falls by then in DC.  I just don't buy it.

It’s obviously too late with the flip but hopefully not far off on qpf?  0.6” pre flip is the goal for the metros I think.

[DDweatherman]

Just now, MN Transplant said:

Yeah, the FV3 is a better scenario.  Flip isn't until 21z and 1" QPF falls by then in DC.  I just don't buy it.

I think somewhere in between for now sounds the “most” accurate. Nam definitely was closer to keeping the sleet lines SE especially towards the back half of the storm. If it didn’t shoot the ML warm nose northward so quickly this run, the totals would have looked similar to the FV or at the very least a lot closer. 

[Wetbulbs88]

7 minutes ago, psuhoffman said:

I really thought we had a cushion (the thermal boundary is starting out so far south this time compared to those two events you just cited) that DC had at the minimum like 6" of snow before a flip.  But the NAM is bothering me...it just blasts the h75 warm later up faster than the precip is advancing once the trough starts to approach and the SW flow hits us...such that it's implying despite how far south the boundary is ahead of this...DC might barely have any snow before the sleet...the "thump" might just be mostly sleet.  You buy that?  

I don’t as much until other mesos agree. NAM isn’t the greatest model. 

[Bob Chill]

3k is a good model for tracking mid levels and ptypes but it's prob too early to heavyweight it. Storm is still in formation stage. 12z run tomorrow is a biggie. It could be nailing it today but the globals (imo) are still the most important data points. 

[87storms]

13 minutes ago, NorthArlington101 said:

I mean here is why I'm not happy regardless of whatever anyone says. Seeing the cushion to the SE of DC erode. We've still got like a day for this to fully evaporate. Doesn't work for me

This is giving me Feb 94 vibes, but I hope I’m wrong.

[rjvanals]

2 minutes ago, NorthArlington101 said:

FV3 is sexy and I can tell it's at least trying to filter out pure freezing rain. Dunno how it treats sleet. I'll pretend this was the NAM.

It’s a model I watch, but it definitely has a cold bias. It’s too quick to crash rain over to snow when surface temps drop and tends to underplay the warm nose, so it’s often slow to flip snow over to sleet or freezing rain.

[StormyClearweather]

Good lord. 

[WxUSAF]

Just now, Bob Chill said:

3k is a good model for tracking mid levels and ptypes but it's prob too early to heavyweight it. Storm is still in formation stage. 12z run tomorrow is a biggie. It could be nailing it today but the globals (imo) are still the most important data points. 

This. Blend tomorrow’s 12z 3k with the euro and you’re probably on target. Or just take the snowiest model and assume 15:1 ratios?

[Eskimo Joe]

Big plus on the 12z NAM is that it appears to kill off the primary surface low quick, and further south. 

[Eskimo Joe]

RE: Freezing rain risk. See the response from @wxmvpete

 

 

[adelphi_sky]

I thought we couldn't trust the NAM? Is the NAM like the girlfriend you can't quit? You know she's bad for you, but you keep her number and call her every now and then? 

[rjvanals]

1 minute ago, StormyClearweather said:

Good lord. 

that's one way to get to double digits in the official snowfall records

[Terpeast]

Low end map from LWX

[WinstonSalemArlington]

1 minute ago, adelphi_sky said:

I thought we couldn't trust the NAM? Is the NAM like the girlfriend you can't quit? You know she's bad for you, but you keep her number and call her every now and then? 

It tends to excel at thermal profiles 

[Bob Chill]

4 minutes ago, WxUSAF said:

This. Blend tomorrow’s 12z 3k with the euro and you’re probably on target. Or just take the snowiest model and assume 15:1 ratios?

Other than the last 15 consecutive storms, I can't remember a time when going with the coldest and snowiest model was a mistake. 

Agree 100% with euro/3k blend @ 12z tomorrow. If the 3k is quicker to jack the mid-levels go with that. If they are the same it's safe to assume the solution is correct. I wish I could trust the gfs with fine details at close range but someone will have to remind me of the last time that worked out lol

[MillvilleWx]

My colleagues at LWX are way too high on snow/sleet accums right now imo. NAM Nest is still outside its full useful range, but not exactly a beacon of positivity on that 12z run. We shall see. That front end thump trending later has been a boon to this forecast. That needed to show up between 00-06z and not 06-12z. I’ll have a forecast later today. Fighting a monster headache this morning. 

[DDweatherman]

Does anyone have the total QPF map from the nam?

[Terpeast]

I don't know how reliable 3k is with thermal profiles at 51 hours out, but that warm nose really punches through at 750-800 mb. One hour prior to this, it was still left of the 0C line.

[Eskimo Joe]

FWIW, the 12z HRRR appears colder and holds the sleet line below I-66 through 12z/15z Sunday.