Feb 28th - March 2nd Storm System

[Tom]

All NAM models are consistent with a phased/strong storm. I think since the energy is onshore today near CA, as well as the northern piece, models digesting better data.

[jaster220]

Def phased this run but I’m not agreeing or denying anything at this point. If we do get snow, then give me a phased/strong system with sick snowfall rates. Other than that, wind and heavy rain is alright with me.

 

  me no likey!

[Snowshoe]

All NAM models are consistent with a phased/strong storm. I think since the energy is in shore today near CA, as well as the northern piece, models digesting better data.

 

Just give me that 0z NAM from yesterday. That would match my snowfall year to date in 24 hours. 

[Tony]

Definitely some very strong dynamics on the Nam run. Thundersnow would not be out of the question for those closer to the low.

[Tom]

Definitely some very strong dynamics on the Nam run. Thundersnow would not be out of the question for those closer to the low.

Agree, heavy precipitation accompanied with 30-40mph sustained winds near the shore would be quite the scene.

[jaster220]

Definitely some very strong dynamics on the Nam run. Thundersnow would not be out of the question for those closer to the low.

 

Agree, heavy precipitation accompanied with 30-40mph sustained winds near the shore would be quite the scene.

 

Them's some deep, deep blues in SWMI - wowzers

 

[jaster220]

For my Chi-town bro's 

 

Pound-town! Verbatim, a Thursday evening thumper over my way..

 

[jaster220]

@ Tom

 

12km loop = Thurs evening thumper (993mb SLP kinda hesitates in NIN before shooting east) 

 

Iirc, this system in the LRC back in Oct (10/11) did the same thing!

 

[jaster220]

Agree, heavy precipitation accompanied with 30-40mph sustained winds near the shore would be quite the scene.

 

3km snowfall

 

[Tom]

3km snowfall

 

20180227 12z NAM-3km snow map.png

Weenie run right there!

[gosaints]

Kuchera is probably still over done verbatim.  take a look at thermals

 

http://maps3.pivotalweather.com/maps/models/nam4km/2018022712/060/snku_acc.us_mw.png

[Hawkeye]

NAM, ICON, and GFS, this morning, are at least bringing back a light to moderate rain event around here, plus wind.  The northern wave just won't be digging enough, early enough, to wind up a biggie this far west.

[jaster220]

Kuchera is probably still over done verbatim.  take a look at thermals

 

http://maps3.pivotalweather.com/maps/models/nam4km/2018022712/060/snku_acc.us_mw.png

 

Kuchy fails me more in the colder set-ups when it insists on fluffing up totals via ratios while not taking into account tiny flake size/poor dendrites. It seems to do much better imho with low-ratio events. Verbatim as depicted, this would end up similar to the 11-29-11 thumper that hit mby with 8.5" in just over 4 hrs. Concrete stuff that caused a ton of power outages in the greater Marshall area

[gosaints]

Kuchy fails me more in the colder set-ups when it insists on fluffing up totals via ratios while not taking into account tiny flake size/poor dendrites. It seems to do much better imho with low-ratio events. Verbatim as depicted, this would end up similar to the 11-29-11 thumper that hit mby with 8.5" in just over 4 hrs. Concrete stuff that caused a ton of power outages in the greater Marshall area

Look at thermals.  There is pinging

[Hawkeye]

12z UK is the weakest, yet, showing almost no precip at all along I-80 from Iowa to Chicago.

[jaster220]

Look at thermals.  There is pinging

 

Shoulda just said P-type issues, then I woulda understood what you meant.     On something with a classic RN->SN via dynamic cooling, at least over here, we either get-er-done, or we don't. Rarely is a mix-fest in the cards on the margins of winter (front or back). We save all that mix stuff for prime winter months. I'd call it the Lakes Affect. You guys further west that don't deal with the moderating effects of the GL's have a different scenario for better or worse

[jaster220]

12z UK is the weakest, yet, showing almost no precip at all along I-80 from Iowa to Chicago.

 

Does that model ever get amped? Seems to be the least likely of all to do so. It's like a watered-down Euro

 

EDIT- and by that, I'm not saying it's wrong, but it tends to balance the often over-amped NAM imho

[Hawkeye]

12z Euro

 

[jaster220]

Euro's in love with CLE to Erie - dang

 

Nice hit for Tom's place as well. Me, I'm looking for 1.6" and that can be +SLOP on my deck ftw 

[Money]

Nam crushes Chicago into MI

 

http://www.pivotalweather.com/model.php?m=nam&p=snku_acc&rh=2018022718&fh=51&r=us_mw&dpdt=

[gosaints]

Nam crushes Chicago into MI

 

http://www.pivotalweather.com/model.php?m=nam&p=snku_acc&rh=2018022718&fh=51&r=us_mw&dpdt=

Inside of two days either the biggest coup ever or biggest troll job ever. Little more phasing make a huge difference with this one

[Money]

Inside of two days either the biggest coup ever or biggest troll job ever. Little more phasing make a huge difference with this one

When will this fully be sampled?

[gosaints]

When will this fully be sampled?

Was pretty close to at 12z.  Almost fully onshore tonight

[Tony]

Nam crushes Chicago into MI

 

http://www.pivotalweather.com/model.php?m=nam&p=snku_acc&rh=2018022718&fh=51&r=us_mw&dpdt=

Go BIG or go home as they say. If this actually happened with the crazy snowfall rates and the wind then it would be nuts around here. I do expect that that there will be thundersnow with this system as the dynamics are there. Will see what the 0z modeling shows.

[jaster220]

Nam crushes Chicago into MI

 

http://www.pivotalweather.com/model.php?m=nam&p=snku_acc&rh=2018022718&fh=51&r=us_mw&dpdt=

 

Again, the 3km bodes better for those of us on the southern fringe:

 

http://www.pivotalweather.com/model.php?m=nam4km&p=snku_acc&rh=2018022718&fh=51&r=us_mw&dpdt=

[jaster220]

Per Hoosier:

 

"I may be forgetting something, but from a wet snow and wind perspective, the only other storm I can think of in the past 20 years that even remotely resembles what the NAM is advertising in the LOT cwa is 3/9/98.  And that one was more of a city/south storm, with biggest impacts in northwest Indiana.  The 18z NAM would surpass what that 1998 storm did.  This would be an entirely different beast from the GHD storms with major power outage concerns."

[jaster220]

Again, the 3km bodes better for those of us on the southern fringe:

 

http://www.pivotalweather.com/model.php?m=nam4km&p=snku_acc&rh=2018022718&fh=51&r=us_mw&dpdt=

 

Will add here that every time we've had these long warm interludes during this cold season, they've ended very abruptly, and usually with something dynamic and snowy. So, this would continue that theme imho

[Money]

Gfs coming in stronger

[Money]

Actually way stronger

 

995 L in the south side of LM at 45

[Money]

https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=us&pkg=mslp_pcpn_frzn&runtime=2018022718&fh=48

 

990 in SW MI

 

It’s just a tad warmer than the nam so a lot of the precip is rain

[hlcater]

https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=us&pkg=mslp_pcpn_frzn&runtime=2018022718&fh=48

 

990 in SW MI

 

It’s just a tad warmer than the nam so a lot of the precip is rain

The warmth is a GFS bias. RC on Amwx said that the GFS especially tends to not handle dynamic cooling well and as such has rain falling in some places where it would be snow.

[Money]

2.2 QPF in SE WI on the 18z gfs

3.1 qpf on the nam

 

http://www.pivotalweather.com/model.php?m=gfs&p=qpf_acc&rh=2018022718&fh=66&r=us_mw&dpdt=

 

Hopefully 0z runs we start seeing the models come together

 

I also saw that over half the ensembles on the euro had much higher frozen qpf

[gosaints]

GFS will be to warm north and west of the low

[gimmesnow]

This is one hell of a nail biter, specially when the rest of my snowboarding season depends on this. If this dumps some good snow and it cools off, I might make it to St Patrick's Day weekend.

 

GEM 12z completely cut out the snow for me, I thought this was all going downhill pretty fast.

[bud2380]

Silly NAM.  

 

http://maps1.pivotalweather.com/maps/models/nam/2018022718/069/sn10_acc.us_mw.png

[Money]

Not surprising but big shift nw on the gfs ensembles

 

Few take the low into WI (990 or lower)

 

https://www.tropicaltidbits.com/analysis/models/?model=gfs-ens&region=us&pkg=lowlocs&runtime=2018022718&fh=42

 

24 HR precip map

 

https://www.tropicaltidbits.com/analysis/models/?model=gfs-ens&region=us&pkg=apcpn24&runtime=2018022718&fh=54

[BrianJK]

LOT:

 

Several
factors will support less of a snow threat locally on Thursday than
previously had been anticipated as a possibility. These include the
more progressive nature of this system, the track of the 850 low
nearly overhead, and the movement of the surface low just south of
the CWA. Another factor is the later and more downstream deepening
of this system from phasing of energy between the northern and
southern streams, when the left exit region and ageostrophic
divergence aloft become better aligned with the position of the
surface low.

[Craig-OmahaWX]

Kuchera probably isn't the best method to use for a storm that will hover around freezing. the standard is more like it. On another note, the NAM i was surprised to see gives us some snow as well tomorrow and is quite a bit colder. Some gfs ensembles also came back way west over us as well. Definitely think it doesn't turn into much but we shall see

[hlcater]

Kuchera probably isn't the best method to use for a storm that will hover around freezing. the standard is more like it. On another note, the NAM i was surprised to see gives us some snow as well tomorrow and is quite a bit colder. Some gfs ensembles also came back way west over us as well. Definitely think it doesn't turn into much but we shall see

you realize that kuchera is showing less than 10:1 in this case and as such is a better measure? If it were showing 12-15:1 ratios, that'd be one thing.

[indianajohn]

if that Kuchera model comes to fruition I can only imagine the devastation that snow would bring to those parts the sheer weight of that type of snow would be crazy...Power lines snapping roofs caving....its not going to be pretty.