New Years Winter Storm

[Natester]

18z GFS looking juicy and slightly north, in line with the NAM.

[ChiTownSnow]

Secondary wave playing catch up.  Maybe similar to what EURO was showing earlier

[Natester]

1 minute ago, ChiTownSnow said:

Secondary wave playing catch up.  Maybe similar to what EURO was showing earlier

Which run? 0z or 12z?

[ChiTownSnow]

2 minutes ago, ChiTownSnow said:

Secondary wave playing catch up.  Maybe similar to what EURO was showing earlier

Wait. Didn't really materialize

[Snowstorms]

4 hours ago, blizzardof96 said:

Yep, the rain/snow transition time will be key. That will be dictated by the track of the surface low. A spatial mean of the 12z GFS/GDPS/RDPS/UKMET/6z ECMWF supports a general 5-10cm south of the 401 and 10-15cm north of the 401. Will see if that holds and whether model consensus starts to build over the next 24-36hrs. I think your forecast is a pretty good starting point with some room to increase if consensus builds.

I agree. 18z runs were much cooler and much snowier for us (10-15cm). Let's hope that holds serve for 00z tonight.  Nice overrunning event. The blocking doing a number on keeping this storm from amping up more but it'll do. I'd assume models are playing catch up with those cold NNE winds? Thermals should cool pretty quick so I'd imagine snow ratios would become better and better as the precip continues to fall. 

[Natester]

21z RAP still wants to ramp the system up.  Toss.

[ChiTownSnow]

LOT mentions the below caveats In their discussion

 

1). The leading and secondary troughs phase more than currently

anticipated, leading to the surface low path much further northwest

than advertised. In this scenario, a much larger portion of area

would end up with a cold, wet rain with the southern edge of the

snow roughly along a line from Dixon to Waukegan. While displayed by

NAM/SREF guidance, we (as well as WPC) believe this outcome is

unlikely.

 

2). Convective episodes across the Lower Mississippi River Valley

muddy the surface low pressure pattern leading to a more "sheared"

out wave and less forcing overall. While this would not necessarily

shift the zone of anticipated accumulating snow, eventual amounts

would end up lower than in our forecast (more in the range of 3-5"

instead of 6"+). We saw this occur with a similar-looking storm

system in February 2020. Of the two possible failure modes, this

appears more realistic.

[Natester]

18z GEFS at hour 48.

 

[Chicago Storm]

LOT mentions the below caveats In their discussion
 
1). The leading and secondary troughs phase more than currently
anticipated, leading to the surface low path much further northwest
than advertised. In this scenario, a much larger portion of area
would end up with a cold, wet rain with the southern edge of the
snow roughly along a line from Dixon to Waukegan. While displayed by
NAM/SREF guidance, we (as well as WPC) believe this outcome is
unlikely.
 
2). Convective episodes across the Lower Mississippi River Valley
muddy the surface low pressure pattern leading to a more "sheared"
out wave and less forcing overall. While this would not necessarily
shift the zone of anticipated accumulating snow, eventual amounts
would end up lower than in our forecast (more in the range of 3-5"
instead of 6"+). We saw this occur with a similar-looking storm
system in February 2020. Of the two possible failure modes, this
appears more realistic.

Makes sense, and would agree the latter option would be the concern.

[Baum]

did I miss the GFS snow maps? Feel I didn't see either a 12Z or 18Z.

[blizzardof96]

35 minutes ago, Snowstorms said:

I agree. 18z runs were much cooler and much snowier for us (10-15cm). Let's hope that holds serve for 00z tonight.  Nice overrunning event. The blocking doing a number on keeping this storm from amping up more but it'll do. I'd assume models are playing catch up with those cold NNE winds? Thermals should cool pretty quick so I'd imagine snow ratios would become better and better as the precip continues to fall. 

Ya, I agree with the bolded. We may start off as a bit of light rain. What will probably happen is that as the main deformation band moves through on Saturday evening, precip rates should be heavy enough to cause low level temps to fall below freezing rather quickly. Once that happens, temps won't recover as winds are locked in a NE direction.

[sbnwx85]

2 minutes ago, Baum said:

did I miss the GFS snow maps? Feel I didn't see either a 12Z or 18Z.

They weren't juiced enough to post. 

[sbnwx85]

Here's the 18z GFS map for inquiring minds. Lock it in.

[Baum]

7 minutes ago, sbnwx85 said:

They weren't juiced enough to post. 

Thank you. 

[Hoosier]

21z RAP is pretty sweet around here.  Approaching double digits and still snowing at end of run.

[Harry Perry]

This is about the time the 00z model suite comes in with weenie amounts, just to trickle back down to reality just before the event begins. One can wish.. right?

[Sciascia]

14 minutes ago, Hoosier said:

21z RAP is pretty sweet around here.  Approaching double digits and still snowing at end of run.

Riding the RAP for major snowfall 42hrs out is not the position I want to be in. Yet here I am!

[cyclone77]

Feeling pretty good about our location with this.  It's far from a lock, but 6"+ looks pretty likely for the QCA. 

[Natester]

2 minutes ago, cyclone77 said:

Feeling pretty good about our location with this.  It's far from a lock, but 6"+ looks pretty likely for the QCA. 

On the bright side you don't have to deal with any mixing issues.

[Sciascia]

18z Euro should be interesting after the deflating balloon that was 12z.

[ILSNOW]

[Natester]

1 minute ago, ILSNOW said:

Better than the 12z run which only gave Cedar Rapids 3 inches of snow.

[IllinoisWedges]

2 minutes ago, ILSNOW said:

Comatose 

[Cary67]

10 minutes ago, IllinoisWedges said:

Comatose 

Stumbling to the finish

[mimillman]

10 minutes ago, Cary67 said:

Stumbling to the finish

It’s an improvement from 12z at least. Would rather go the right direction and stop the bleed 

[Baum]

looking good still. Seems were on track for a 4-8 or perhaps a 6-10 event. Hoping we don't land in the 3-5 advisory level category in the western burbs.  Tonight's runs should really begin to tell the tale.

[CheeselandSkies]

first and final call of 1" here.   look to just be on the northern fringes of this.   Congrats to all to the south on significant snows

A good number of model runs within the last few days had 6"+ in Madison but didn't seem anyone was really buying it.

Sent from my Pixel 4a using Tapatalk

[ChiTownSnow]

Plumes for ORD back up to 0.67 mean qpf.  Not all snow verbatim but that can be argued a bit 

IF all snow, figure mean 7 inches at 10:1.  Add in better ratio per LOT at 20:1 for a bit, and can easily argue the 6-10

[Nelson]

I will take whatever SREF is smoking for MSN (grasping at straws on the northern fringe)

 

[Cary67]

1 hour ago, mimillman said:

It’s an improvement from 12z at least. Would rather go the right direction and stop the bleed 

True. Wish it would trend back to a bit stronger solution.