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Feb 16-17th Winter Storm


Chicago Storm
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1 hour ago, Baum said:

"IT IS A SYSTEM   
WORTH KEEPING AN EYE ON.   "- Gino Izzi.

I agree could be interesting this thread will blow up more tomorrow night into Monday. After being shafted last time depending on where you were people not getting hopes up. I’m in that same boat a more I’ll believe it when I see more. 10:1 ratios look pretty decent thru a good chunk of the forum region. A potential footer one more good snow and I’ll be happy and ready for spring and severe wx season

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This storm has a similar look and feel to one that affected the region back in 2010.  Here in SE Michigan the forecast was for 50 degree temps rain just days prior.  It ended up turning into an ice storm that crippled the region with heavy snow just in mid Michigan and NW.  Anyone else remember that one?? It was Presidents Day weekend.  

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11 minutes ago, Frog Town said:

This storm has a similar look and feel to one that affected the region back in 2010.  Here in SE Michigan the forecast was for 50 degree temps rain just days prior.  It ended up turning into an ice storm that crippled the region with heavy snow just in mid Michigan and NW.  Anyone else remember that one?? It was Presidents Day weekend.  

I totally remember that one. Was suppose to get 2-5" followed by freezing rain. Ended up with 11" of snow and zero freezing rain as it was south of 94. 

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*Longer post with some explanation of ensemble analysis for this event*

Things to consider regarding sensitivity of the setup to key features:

- Obvious one being strength of southern stream/main short-wave, also entailing whether wave is negative, neutral, or positively tilted. Most recent ECMWF and GFS solutions favor neutral to negative tilt in southwest trending to neutral to pos tilt in Midwest.

- If there is phasing with the northern stream or at least constructive interference/interaction between northern stream and main wave.

- Strength of downstream positive height anomalies.

One of the things you've probably seen referenced in LOT AFDs over the past year is ensemble cluster analysis. WPC has an experimental page for this:
https://origin.wpc.ncep.noaa.gov/hmt/wk2/day_3_7/view.php?type=day_5_&field=cluster_qpf&reg=_central&regstr=CENTRAL
(linked to day 5/24h period ending valid 00z Friday)

Abbreviations to note on the attached images:
C: Canadian ensemble members
E: ECMWF/EPS members
G: GEFS members
T: I believe UKMET members but not 100% sure

I'll focus first on clusters 2 and 3, which are wetter farther northwest Wednesday night and Thursday, our time frame of interest.

Cluster 2 has the highest % of GEFS members at 37%. Cluster 3 has the highest % of EPS members at 36%. The drier clusters farther NW, 1 and 4, have the highest % of Canadian members, but note that cluster 1 has a noteworthy minority of GEFS, EPS, and T (UKMET?) members.

You can then see the ensemble cluster mean 500 mb height anomalies vs the multi-model ensemble (MME) and the 500 mb height differences between the clusters and the MME.

My interpretation of h5 w.r.t the cluster precip difference vs the MME is that the favorable clusters either have stronger downstream positive height anomalies (cluster 3) or better northern stream interaction (cluster 2) with the main wave via phasing or constructive interference. This is kind of an obvious point, but in light of the 06z GEFS and EPS, what I'm seeing is that:

Of the members with heavy (6"+) snow swaths, a distinct majority of these are farther northwest with the swath. There are only a few that are solidly farther southeast/ie. congrats IND.

My take from the above is that the more likely way to get a heavy snow swath out of this is represented by ensemble cluster 2 or 3, or a combination of those. I'm not sold that there will be a warning worthy snow swath in a flatter/more progressive/farther southeast scenario, which is essentially what most recent GEM runs have shown.

A flatter solution will have much narrower deformation area cold sector precip and will contend with being undercut by encroaching dry Arctic air mass from the NW.

As far as which scenario I'm currently leaning toward at this point, I'd say *slightly* toward a decent (warning worthy) event within the LOT CWA and parts of surrounding CWAs, given the EPS and GEFS lean toward this. I'm certainly worried about the GEM like solution however.

We'll see here shortly if the various clusters diverge much with the 12z cycle today. 555ba2622bae0ccbcd451de67fbb3a58.jpg08a3a2db5b5588fb7bbff866c851e1cf.jpgcbcb624c6187bb36c2b752dfab7b8c59.jpg











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Just now, ILSNOW said:

 

I'd argue this is only the second SW Low event(provided that happens) or moisture laden over running event of the season.  Still, a more strung out solution seems like it has been the way to go for quite sometime. However, that does not preclude a 4"-8" event as we just saw. Or a heavy rain to freezing rain to back end 3" thump. Tis the season.  No meteorology here just a amateur take.

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1 minute ago, Baum said:

I'd argue this is only the second SW Low event(provided that happens) or moisture laden over running event of the season.  Still, a more strung out solution seems like it has been the way to go for quite sometime. However, that does not preclude a 4"-8" event as we just saw. Or a heavy rain to freezing rain to back end 3" thump. Tis the season.  No meteorology here just a amateur take.

Last nights 0z GFS had it coming out in piece the 6z and 12z now show a break in between. I really dont recall a heavy rain event going over to warning level snow. I also think that there is going to be a significant area of freezing rain some where in the Chicago metro area. Long way to go !!!  An amateur snowlover take here.

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care to share your thoughts on this potential storm?

While not a carbon copy, there are a lot of similarities to the early Feb winter storm (GHD3). Many of the same moving pieces will be in place and a factor, and how they interact will obviously dictate how things progress.

Based on how things look at face value on guidance as of now, it would not be surprising if this ended up close to where GHD3 hit. Shall see how things evolve over the coming days though.

Really wouldn’t get invested in things until tomorrow or more-so Monday.


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This one is about gone for Iowa.  It's a repeat of the last storm.  It looks good early, but then the energy tracking eastward along the Canada border trends stronger and stronger and ends up sweeping everything south and east of the upper midwest.  Two days ago the Euro and GFS both had widespread 2+" of precip across Nebraska and Iowa.  Now, not even a flake or sprinkle in Nebraska and nothing outside of far se Iowa.

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An observation if you will.  It's one thing when a bunch of us weenies are discussing and dissecting the possibilities with these storms a week out.  But when local mets starting showing something 7 days out saying a snow storm is on the horizon, you end up with a skeptic public when two days later the forecast has made a 180 turn.  They really should wait till 3-4 days out to even show a graphic.  i.e. the 12Z Euro

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