Chicago Storm

11 minutes ago, Angrysummons said:

When you look at the 12z GFS today and yesterdays 18z GFS, you can see the difference. The vort isn't as robust and the phasing is slower, creating a disorganized northern stream "look". With a single vort phase, you need the move from positive-neutral-negative tilt to happen robustly. This is where the Vort being over no mans land is a problem.

That's not the issue at all.

This loop shows what the changes have been...

6 minutes ago, Chicago Storm said:

12z ECMWF will likely bump north.

It started that way, then actually ended up further south.

In the end, the southern stream trough ended up further south and is more positive tilt. The northern stream too a big jump east too.

12z ECMWF will likely bump north.

1 hour ago, michaelmantis said:

Sure this is a question with a lot of unknowns given the models, but for N IL does this look to be more of a matter of timing (i.e. starting later) or amounts? I get both are related, just trying to figure out how bad Saturday morning could potentially be in NE IL. Have to make a decision if I'm going to stay overnight or try to drive home in what seems to be like the middle of the storm Saturday morning. Appreciate any crystal ball reads given the latest models!

Long time no see...Still down the road in Elgin I see as well.

I think either way right now, start time should be Friday evening/early Friday night as the FGEN snows move in. 

6 minutes ago, mimillman said:

I don’t recall seeing any LE headlines in Cook for a couple years. Wonder if this weekend changes that.

It has been a while, but I'd say it's unlikely given synoptic snows will be heavily involved.

This is the last winter LE headlines are in play too, with winter headline simplification coming soon.

The 12z GFS was south of the 6z up until hour 66, at which point SLP was northeast of the 6z run. 

Southern stream faster at H5. 12z GFS should come south.
Edit: Ends up in a similar spot at 6z at hour 66 though slightly faster.

12z NAM with a decent jump north.

Northern stream was slower, and southern stream trough didn’t dig as deep, along with the wave rounding the base much more this run.

Additionally, waves ejecting out ahead of the main southern wave were stronger, and bridged the gap between the southern and northern waves, allowing for some slight phasing.


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11 minutes ago, HillsdaleMIWeather said:

Euro south and weaker 

It's well south of 12z.

The northern stream ended up further west and really dug into MI/WI/MI, which is good for phasing. However, the southern stream ended up much more positive tilt and just continued on east, before phasing over the SE Coast...instead of pushing NE and phasing over the Ohio Valley.

1 minute ago, mimillman said:

I wouldn’t call it south, rather just weak and progressive

The individual members moved south and weaker overall, no doubt.

3 minutes ago, HillsdaleMIWeather said:

Welp, GEFS is south

0z UKMET stayed south.

0z GFS is literally a further north copy of the weekend storm.

0z GGEM actually came north. Way farther north than any other 0z guidance so far. 

SLP travels through far S. Illinois.

0z GFS going to be terrible everywhere.

12z GFS is coming in further south with the southern wave, and slower with the northern wave. That delays any possible phase till after it's past the region.

In other words, not good for the Chicago crew...as it leads to a further south/weaker solution.

Edit: This run also digs the southern wave into Mexico, but not nearly as far as the NAM.

The RGEM only goes to 48hrs, but it will be well north with the southern wave...especially compared to the NAM. 

This run likely wouldn't dig the southern wave too much, with the jet streak rounding the base of the trough already...compared to the NAM which has the jet streak on the backside of the trough, leading to the further digging.

RGEM vs NAM...Might have to click it for it to loop.

Just now, ChiTownSnow said:

But it's long range NAM .. so its basically garbage  

Very true, but at random times we've seen the NAM hit the correct idea in the extended. We'll see how the rest of the 0z's come in.

If anyone thinks today's 12z UKMET was south, just wait till you see the 0z NAM...

By 84hr, the northern wave is already entering the northern Great Lakes, while the southern wave is digging south into Mexico.

1 minute ago, nwohweather said:

Just not buying these high amounts with such an E-W direction. The Euro seems most realistic with its negative tilt

What? No model goes negative tilt until after it leaves the region, and the ECMWF is fairly E-W overall with the snowfall axis until OH on east.

7 minutes ago, hlcater said:

Shoulda let cyclone start it. He’s on fire with these lately. So if it busts... I’m holding you accountable.

4 minutes ago, Hoosier said:

Had to beat him of course.

GFS definitely took a step.

Northern wave a bit faster, southern wave a good deal faster and further NE eventually, which lead to earlier phasing.

For those on the north end of the storm looking for a bump north, those looking for a cutter, or the historic-like 0z ECMWF run to occur...

The one big negative I see that I didn't see before is that the main PV over the Hudson actually gets dragged east by a big storm around Greenland...just as the northern stream wave is diving south around the PV...which pulls the wave more the the east as well. One of the big reasons I believe the 0z ECMWF was a huge run is that the northern wave was faster and the PV was centered further west early on. This combination allowed the northern wave to dig more before sliding more easterly, allowing for some phasing earlier.

Placement of the southern wave is key as well. There is good agreement on it coming onshore in N. CA and diving SE, with the base of the trough down into El Paso eventually. After that what is needed is key timing, as well as the wave closing off further north. The 0z ECMWF also had this occur and what was aforementioned with the northern wave, which helped lead to the big run.

The lead minor wave on Wed/Thur will be fully sampled for this evenings runs. The south and northern wave will be well sampled by Thur evenings runs, and even more so after.

26 minutes ago, AppsRunner said:

Ensembles are very similar to last night. Very tight clustering of tracks across the Ohio river, will post when I’m home

4 minutes ago, RobertSul said:

24"+ for both storms combined or just for the 2nd big dog?

Just off of the second storm alone.