Dec 29-Jan 2 potential storm event

[A-L-E-K]

The real kick in the balls scenario 

[NEILwxbo]

18z GEFS a step in the right direction. NW of op & more members on board than 12z

 

Subtle, but slightly stronger with the SW ridging compared to 12z pushing the storm NW. Will have to see if 00z continues the trend. 

12z:

18z:

 

 

[Frog Town]

1 hour ago, iluvsnow said:

GFS slowly moving track NW. 18z moves the sweet spot from eastern Ohio to central Indiana to the northwestern half of the Buckeye state. If I were betting.....ORD just might win this one....IF there is enough cold air.

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This is it fella's!  Mide as well  Lock it in.  I've been dreaming of this scenario since I was 5.   

[Radtechwxman]

1 hour ago, Hoosier said:

I am guessing that at least 90% of the time when a surface low comes out of the GOM into Louisiana in winter, you don't have to worry about it raining in Chicago because the track is gonna tend to have a significant enough easterly component to keep it far enough south.

But then there's the other percentage of time, when the track is basically due north into the Quad Cities.

That would be a very 2020 track and perfect scenario to end this whack year

[Hoosier]

24 minutes ago, StormChaser4Life said:

That would be a very 2020 track and perfect scenario to end this whack year

It's a fairly atypical track, but it or some version of it (say, AL to IN) happens from time to time.  The fact that some models are showing such a hard north move suggests there's a greater than usual chance of it occurring.

[CheeselandSkies]

59 minutes ago, StormChaser4Life said:

That would be a very 2020 track and perfect scenario to end this whack year

Again, what happened to these things forming in the Rockies and moving NE?

[purduewx80]

13 hours ago, blizzardof96 said:

One of the main differences between the GFS & ECMWF relates to the confluence zone across Quebec. The ECMWF has a much stronger eastern ridge while the GFS has a weaker ridge and a confluence zone further south which keeps the GFS low track further southeast.

This. Looking at the even bigger picture, a lot of it comes down to both the Pacific pattern (Aleutian low, NE Pac ridge) and how the ridging evolves near New England/Maritimes/Greenland. The latter has not been entirely consistent in the finer details even while the idea of anomalous positive heights in that general area has been persisting. 

Another trend is for more troughing in the western U.S. behind this wave, which in my mind helps to amplify the East Coast ridge and favor a rainer for areas E of the Mississippi and S of WI/MI. Best bet for wave 1 in Chicago, as it stands now, is for a front end thump. The high is in the wrong position initially to avoid turning to a mix/slop/rain, but that confluence will affect where the high trends ahead of the low.

Wild card is the 2nd wave. For now it seems like something similar to the Xmas storm would be favored (Upper Ohio Valley to the Appalachians and northern New England).

Model 500 height anomaly comparison and GFS trends below:

 

[purduewx80]

2 hours ago, Hoosier said:

I am guessing that at least 90% of the time when a surface low comes out of the GOM into Louisiana in winter, you don't have to worry about it raining in Chicago because the track is gonna tend to have a significant enough easterly component to keep it far enough south.

But then there's the other percentage of time, when the track is basically due north into the Quad Cities.

It's possible with a large enough cut-off low and high enough amplitude ridging/blocking pattern, but def agree it's somewhat laughable for now. 

[RCNYILWX]

This. Looking at the even bigger picture, a lot of it comes down to both the Pacific pattern (Aleutian low, NE Pac ridge) and how the ridging evolves near New England/Maritimes/Greenland. The latter has not been entirely consistent in the finer details even while the idea of anomalous positive heights in that general area has been persisting. 
Another trend is for more roughing in the western U.S. behind this wave, which in my mind helps to amplify the East Coast ridge and favor a rainer for areas E of the Mississippi and S of WI/MI. Best bet for wave 1 in Chicago, as it stands now, is for a front end thump. The high is in the wrong position initially to avoid turning to a mix/slop/rain, but that confluence will affect where the high trends ahead of the low.
Wild card is the 2nd wave. For now it seems like something similar to the Xmas storm would be favored (Upper Ohio Valley to the Appalachians and northern New England).
Model 500 height anomaly comparison and GFS trends below:

 

Fwiw, the 18z EPS doesn't have a lot of east outliers with the secondary low, has more tracks that would be too far west for much snow here, with a slight westward adjustment of the mean. It would be nice to get some of the front end snow, but failing that, I think overall best chance (not necessarily a good one yet) to get a 6"+ snow is with the secondary low/wave 2.

While there's been a tendency for weaker/sheared/more east with secondary development, the magnitude of the eastern ridging makes a case for Alek and Hoosier's worry of a more amplified nw track cutter/rainer. I'd still lean toward miss east being a bigger worry, but miss NW is not too far off. I think we're in the game here, but as always need a lot to work out right to get a good event locally.

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[McHenrySnow]

Hard to assume this is wrong considering the season thus far.

[RCNYILWX]

Hard to assume this is wrong considering the season thus far.

Yeah, can't blame the sentiment. But now that the secondary low/southern wave is slowing to not coming up until Friday, that's an eternity in model land, and clearly not the final solution.

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[hawkeye_wx]

We continue to see significant changes from run to run with the southern energy.  The trend is certainly to slow it and dig it farther south.

[McHenrySnow]

I prefer the Canadian models ftr. lol 

 

Desperate times, desperate measures. 

[Cary67]

4 minutes ago, RCNYILWX said:

Yeah, can't blame the sentiment. But now that the secondary low/southern wave is slowing to not coming up until Friday, that's an eternity in model land, and clearly not the final solution.

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The only certainty is those qpf snow numbers will undoubtedly diminish significantly as time progresses

[Malacka11]

There's actually been a lot of concurrence between the ICON, GFS, and CMC so far tonight. What I don't like now tho is that they all show a relatively narrow band of snow with the second low and a lot of energy streaming by. Yeah Chicago is in the right area perhaps to get some snow, but once again we went from forecasting a swath the size of two states to one that's maybe 100 miles wide tops. Would like to see things look a bit... more widespread in future runs

[Hoosier]

9 minutes ago, RCNYILWX said:

Yeah, can't blame the sentiment. But now that the secondary low/southern wave is slowing to not coming up until Friday, that's an eternity in model land, and clearly not the final solution.

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For anyone concerned that the GFS has suddenly locked into a solution, I'd encourage them to loop the runs just from today.  There has been a monstrous trend toward a slower solution, and also west.

[Radtechwxman]

Man if only I could lock in that run of Canadian. Great front end thump and decent 2nd hit from the secondary low

[Cary67]

2 minutes ago, Hoosier said:

For anyone concerned that the GFS has suddenly locked into a solution, I'd encourage them to loop the runs just from today.  There has been a monstrous trend toward a slower solution, and also west.

 

5 minutes ago, Malacka11 said:

There's actually been a lot of concurrence between the ICON, GFS, and CMC so far tonight. What I don't like now tho is that they all show a relatively narrow band of snow with the second low and a lot of energy streaming by. Yeah Chicago is in the right area perhaps to get some snow, but once again we went from forecasting a swath of snow the side of two states to one that's maybe 100 miles wide tops. Would like to see things look a bit... more widespread in future runs

Concerned the phrase "thread the needle"is the norm for every system that develops this winter and far too many other winters recently. 

[Hoosier]

Last 5 runs of the GFS, all valid at the same time

[McHenrySnow]

1 minute ago, Hoosier said:

Last 5 runs of the GFS, all valid at the same time

No one actually thinks the GFS has it locked in. 

[CoachLB]

30 minutes ago, StormChaser4Life said:

Man if only I could lock in that run of Canadian. Great front end thump and decent 2nd hit from the secondary low

That would be an incredible Ice storm for some.

[hawkeye_wx]

The Euro has now joined the other models, showing the northern wave clearing out and leaving the southern wave behind.  The southern wave then cuts north and wraps up.

[sbnwx85]

1 minute ago, hawkeye_wx said:

The Euro has now joined the other models, showing the northern wave clearing out and leaving the southern wave behind.  The southern wave then cuts north and wraps up.

Monster ice then rain. 

[Hoosier]

Holy ice batman, especially on Euro and GEM.  It's a pretty wide area that gets clocked with it too.

[hawkeye_wx]

This thing is going to change so much over the next few days.  My area could easily get 10 inches or nothing.

[RCNYILWX]

Holy ice batman, especially on Euro and GEM.  It's a pretty wide area that gets clocked with it too.

Just with respect to the 00z ECMWF operational run, I think there would probably be a much larger zone of sleet. Valid 12z Friday when both Pivotal and WeatherBell algorithms are showing primarily freezing rain, I'd guess those 925 mb and 850 mb temps would be supportive of sleet, especially north of I-80. Don't have access to forecast soundings to confirm though.

 

Also looked at the GEM for Tuesday night into early Wednesday and it appears the algorithm is accumulating ice when the soundings for at least a portion of the icing zone with northward extent would favor sleet. Does appear there would be a freezing rain zone south of the sleet zone.

 

Regarding the overall 00z suite, focusing on wave 2 alone, all we can say is that the potential for a high impact event is there, but lots of moving parts. Going to take a while to sort this one out.

 

Wave 1 looks to produce a swath of advisory to low to mid range warning snows, with a mixing zone south, and even wave 1 has a good deal of uncertainty associated with it.

 

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[Hoosier]

14 minutes ago, RCNYILWX said:

Just with respect to the 00z ECMWF operational run, I think there would probably be a much larger zone of sleet. Valid 12z Friday when both Pivotal and WeatherBell algorithms are showing primarily freezing rain, I'd guess those 925 mb and 850 mb temps would be supportive of sleet, especially north of I-80. Don't have access to forecast soundings to confirm though.

 

Also looked at the GEM for Tuesday night into early Wednesday and it appears the algorithm is accumulating ice when the soundings for at least a portion of the icing zone with northward extent would favor sleet. Does appear there would be a freezing rain zone south of the sleet zone.

 

Regarding the overall 00z suite, focusing on wave 2 alone, all we can say is that the potential for a high impact event is there, but lots of moving parts. Going to take a while to sort this one out.

 

Wave 1 looks to produce a swath of advisory to low to mid range warning snows, with a mixing zone south, and even wave 1 has a good deal of uncertainty associated with it.

 

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Great point about sleet.  Seems a little strange that the output isn't depicting more sleet in the area you mentioned.  Where 850 mb temps are around 1-2C and 925 mb temps are around -4C, that is often highly suggestive of sleet unless the warm layer is obscenely thick, but chances are it's not.

Edit:  I checked 700 mb temps and they are below 0C along/north of the Kankakee River at that time.

[RCNYILWX]

Great point about sleet.  Seems a little strange that the output isn't depicting more sleet in the area you mentioned.  Where 850 mb temps are around 1-2C and 925 mb temps are around -4C, that is often highly suggestive of sleet unless the warm layer is obscenely thick, but chances are it's not.
Edit:  I checked 700 mb temps and they are below 0C along/north of the Kankakee River at that time.

Red flag for me was seeing 925 mb wind speeds being at 40-50 out of the east-northeast. When combined with the progged h8 and h9 temps, that's a strong signal for cold/dry air damming. Sleet will be something to watch for in this setup if we get a wound up low like on the 00z ECMWF.

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[A-L-E-K]

Rainer and obv toss any ice solutions lakeside 

[Baum]

Going to be a fun week. And right on cue.