November 17-19th Autumn storm with explosive potential for the GL's

[OKwx2k4]

Track/strength depicted is actually very reminiscent of mid-Dec '00 bliz

Woof woof. Good storm. Good analog year buddy. I like it.

[Niko]

Track/strength depicted is actually very reminiscent of mid-Dec '00 bliz   

Snow knocking on my doorstep Jaster. The NAM might be on to something.

[Tom]

18z NAM flashing a nice “thump” SN for IA...

[jaster220]

18z NAM flashing a nice “thump” SN for IA...

 

with so many NAM's out there, we need to know if that's the over-hyper 3km or the parent 32km cuz it makes huge diff in this very marginal instance..

 

Edit - 32km looks to hit IA (and dare I say) SE Neb..

Edited November 16, 2017 by jaster220

[Madtown]

Gimme some suga...i am your neighbor

[Tom]

with so many NAM's out there, we need to know if that's the over-hyper 3km or the parent 32km cuz it makes huge diff in this very marginal instance..

Both!  I rarely look at the 32km and primarily use the 12km/3km...

[jaster220]

18z NAM flashing a nice “thump” SN for IA...

 

And NEB peeps?? Did I see that right? 

[jaster220]

Both!  I rarely look at the 32km and primarily use the 12km/3km...

 

Is there a reason you "dis" the 32km? Remember, I'm new to the whole following of the model runs..so don't really know

[jaster220]

Gimme some suga...i am your neighbor

 

NAM for President! 

[jaster220]

Snow knocking on my doorstep Jaster. The NAM might be on to something.

 

Fixed..

[bud2380]

I'm posting the 10:1 ratios for dramatic effect.  NAM! NAM! NAM!

 

http://maps3.pivotalweather.com/maps/models/nam4km/2017111618/057/sn10_acc.us_mw.png

 

 

http://maps1.pivotalweather.com/maps/models/nam/2017111618/060/sn10_acc.us_mw.png

[Tom]

18z NAM3km really wraps this storm up...979mb storm in NE OH!

 

 

 

[Tom]

Is there a reason you "dis" the 32km? Remember, I'm new to the whole following of the model runs..so don't really know

Not necessarily, I just don't use it in my daily "model watching" routine...

[Tom]

Good thing is, both NAM models are seeing a better phasing system earlier and the convection showing up on the 3km is something "sweet" about this storm.  I can see big fatty flakes falling from the sky whoever is lucky to get underneath the banding that sets up.  You can see the defo band forming as the storm wraps up.

[jaster220]

Good thing is, both NAM models are seeing a better phasing system earlier and the convection showing up on the 3km is something "sweet" about this storm.  I can see big fatty flakes falling from the sky whoever is lucky to get underneath the banding that sets up.  You can see the defo band forming as the storm wraps up.

 

Guy on the SMI forum who was all-in for the originally forecast severe stuff, posted that the convection indicated by the 18z NAM might "make this interesting after all. Would be a short-duration blizzard for those caught in the cross-hairs"..wow do I love these trends! Remember me posting about how rare it is with today's guidance to get any real surprise storms like happened in my youth?? More of your universe vibes stuff going here..

[Tom]

Guy on the SMI forum who was all-in for the originally forecast severe stuff, posted that the convection indicated by the 18z NAM might "make this interesting after all. Would be a short-duration blizzard for those caught in the cross-hairs"..wow do I love these trends! Remember me posting about how rare it is with today's guidance to get any real surprise storms like happened in my youth?? More of your universe vibes stuff going here..

Love it!  Yup, I agree...certainly a dynamic system and part of the reason why I think the EURO/GFS are not showing a lot of frozen precip.  Systems that rapidly deepen as being advertised tend to create their own cold air from the cooling column.  These details should be ironed out by tomorrow but I wont be surprised to see some lighting even!

[Minny_Weather]

The NAMily has easily been the best model(s) this season so far. Definitely hoping we get the backside snow that they are advertising right now.

[bud2380]

Good read from the DVN AFD

 

 

 

Saturday

Widespread precip is likely Saturday morning, possibly lasting into
part of the afternoon across the eastern CWA. Early morning thermal
parameters support rain as the precip type. But as low-level cold
air advection and the effects of dynamic cooling both increase,
there is potential for a changeover to a rain/snow mix or all snow.
The best chance is along and north of a line from Fairfield, IA
to Freeport, IL. It`s lower to the SE, but still possible.

Time-height sections have a frontogenetic band developing beneath
a coupled jet structure which produces deep layer ascent across
the CWA. The jet feature and Fgen are actually forecast to be
over southern/central Nebraska Friday night, then reach E Iowa/NW
Illinois by Saturday morning. A meteorological setup like this one
is conducive for a period of light to moderate precip, so the
hardest part about the forecast is definitely the precip type.

If snow occurs, antecedent wet ground conditions and marginal sfc
wet-bulb temps above 32 F, will make it difficult to get more than
slushy accumulation on elevated surfaces or the grass. It is still
too early to have any confidence on where, and if, a localized
narrow band of moderate snow would occur. It`s something we`ll
continue to monitor for in subsequent model runs, because it would
increase the potential for brief snow accumulations, and for
visibility restrictions to those traveling.

Model Trends:

The ECMWF is the warmest model and would be mainly rain. Other
models, NAM/GFS/CMC, are colder and indicate a higher probability
for a period of snow. The 3km NAM nest is the most aggressive model
with dynamic cooling resulting in a quick changeover to snow, which
eventually reaches all the way to the eastern CWA toward late
Saturday morning. Went colder than the model blend sfc temps, but
not as cold/aggressive with the changeover as the 3km NAM. Model
consensus QPF is on the order of 0.10 to 0.30 inches for Saturday,
but could locally be higher within narrow bands. There is still
time to trend toward a more significant/prolonged period of all
snow if models, like the NAM, are consistent over the next few
runs.

[bud2380]

The RGEM also starting to pull in some back side snows for Saturday.  

 

http://maps3.pivotalweather.com/maps/models/rgem/2017111618/048/sn10_acc.us_mw.png

[jaster220]

The RGEM also starting to pull in some back side snows for Saturday.  

 

http://maps3.pivotalweather.com/maps/models/rgem/2017111618/048/sn10_acc.us_mw.png

Very nice! Goes with that DVN write-up as well.

[jaster220]

GRR's pm AFD didn't even mention the NAM. Going with rain then a chance of some SHSN Sat night. Not so much as a potential change-over.

[jaster220]

APX - expecting quite a long duration wind event

 

 

.SHORT TERM...(Friday night through Sunday)

Issued at 318 PM EST Thu Nov 16 2017

 

...Rain transitions to snow this weekend...

 

High Impact Weather Potential: Gusty winds will develop Saturday and

persist through Sunday night. Rain will transition to snow Saturday,

with a round of lake effect snow Sunday.

[Minny_Weather]

GRR's pm AFD didn't even mention the NAM. Going with rain then a chance of some SHSN Sat night. Not so much as a potential change-over.

Yeah our local office is ignoring the NAMily like usual too. Not a smart move imo.

[St Paul Storm]

GRR's pm AFD didn't even mention the NAM. Going with rain then a chance of some SHSN Sat night. Not so much as a potential change-over.

They’re smart for not getting sucked into the NAM at this point. Cold-biased and it’s the only model showing any decent snow. Not saying it can’t score a coup but can you really trust it?

[bud2380]

00z nam backed off on the depth of the cold air. Still showing some snow but not as widespread and looks to be shorter duration than previous runs. 3k nam a little stronger but also weaker than the last couple runs

[Niko]

Something to keep an eye on.

[Tom]

RPM model is showing snow across IA/S WI/N IL...primarily over S WI

[Minny_Weather]

Every single NWS and TV met here is still refusing to acknowledge even the possibility of a snowflake falling. I know it's inconsistent, but c'mon. Worst case scenario, it'll be a few wet snowflakes mixing in.

[GDR]

Same here just calling for drizzle

[Niko]

Rain will end as a few flurries and turning sharply colder as the low departs. Winds will be a big factor as they will gusts to as high as 40mph. WCF will be quite cold, into the teens.

[Niko]

In an avg autumn/winter, mid-December climo would still favor NMI to get the storm. We're way outside our normal climo for storms. That finally shifts down our way about Christmas. Truth be known, if I see a tenth of an inch I've prolly beat climo on Nov 18 in Marshall. But, early cold is in vogue this year so it ups the ante for earlier shot at it tho, I'll give ya that

I have always believed that true Winter conditions usually start after Christmas and last into late Feb.

[Niko]

with so many NAM's out there, we need to know if that's the over-hyper 3km or the parent 32km cuz it makes huge diff in this very marginal instance..

 

Edit - 32km looks to hit IA (and dare I say) SE Neb..

[Niko]

Fixed..

[Minny_Weather]

with so many NAM's out there, we need to know if that's the over-hyper 3km or the parent 32km cuz it makes huge diff in this very marginal instance..

 

Edit - 32km looks to hit IA (and dare I say) SE Neb..

I've just started calling it the NAMily.

[Tom]

RPM keeping the accumulating snow chances up north into S WI...

 

[St Paul Storm]

Light rain falling here now associated with the northern piece of energy. Might change over to light snow or flurries tonight but the main precip associated with the southern piece will be well east southeast of here. Good luck to everyone with the precip and wind. Let’s hope the next storm thread is about snow.

[Niko]

Rain, Rain, and Rain...still forecasted w this system in SEMI. Now, they are not mentioning at all about any mixing, not even snowshowers on the backend. Wow. Looks like the cold air will not get in on time. By the time it does, all the moisture will have left my area.

[Minny_Weather]

Precipitation is stupid anyway. It's all dumb and wet.

 

(We're in the process of getting screwed again)

[OKwx2k4]

Precipitation is stupid anyway. It's all dumb and wet.

 

(We're in the process of getting screwed again)

If you're like me, just start planning outdoor activities every day. Ended a six week drought in no time. Haven't gotten very many of the things done that I've needed to though the last few weeks.

[jaster220]

In an avg autumn/winter, mid-December climo would still favor NMI to get the storm. We're way outside our normal climo for storms. That finally shifts down our way about Christmas. Truth be known, if I see a tenth of an inch I've prolly beat climo on Nov 18 in Marshall. But, early cold is in vogue this year so it ups the ante for earlier shot at it tho, I'll give ya that

 

 

RPM keeping the accumulating snow chances up north into S WI...

 

 

RPM chucks me my 0.1" over in Marshall that I was half-joking about in that prior post    This was never a snowstorm for us (this go-around), but the "NAM-fake" was intense there for about 12 hrs, lol