Pre-Christmas (Dec 21-23rd) Winter Storm

[Kaner88]

If I start out expecting 2" of snow and 50 MPH winds here at ORD, I can't possibly be disappointed

 

 

... right?

[Harry Perry]

Don’t throw the towel in yet. This is still 72 hours away. A lot ̶c̶a̶n̶ ̶ WILL change (for better or worse in the next 72 hours) 

[Powerball]

5 minutes ago, Harry Perry said:

Don’t throw the towel in yet. This is still 72 hours away. A lot ̶c̶a̶n̶ ̶ WILL change (for better or worse in the next 72 hours) 

Indeed.

[Malacka11]

There has to be a windshield wiper pattern here because what's the alternative? If the east/weak trend continues for 72 more hours in any capacity there literally will not be a storm

[Powerball]

4 minutes ago, Malacka11 said:

There has to be a windshield wiper pattern here because what's the alternative? If the east/weak trend continues for 72 more hours in any capacity there literally will not be a storm

Same windshield wiper pattern happened with GHD 3 as well.

Seems to be the SOP with potentially major winter storms these days.

[Sciascia]

2 weeks ago, I just wanted a white Christmas. Then I got greedy with all the model runs. Now, I’m back to just wanting a white Christmas. 

[Chicago Storm]

0z ECMWF follows the current trend that the rest of the 0z suite featured.

[Cartier God]

2 hours ago, Natester said:

0z ICON east of 18z.

me returning from my year long hiatus after natester mentions the icon

[hlcater]

Euro is a glorified frontal passage out here. Good lord.

[Sciascia]

11 minutes ago, Chicago Storm said:

0z ECMWF follows the current trend that the rest of the 0z suite featured.

Well, this thread is going to go basically silent until the 12z NAM tomorrow morning.

[HillsdaleMIWeather]

We've had sudden daily shifts every day for three days, models all agree and then suddenly change to something else they all agree on

[Stebo]

2 hours ago, HillsdaleMIWeather said:

@SteboI told you not to punt!

I'm still very hesitant. It can easily keep moving east or move back west. 

[RCNYILWX]

Some perspective is in order I think, and this doesn't apply to all areas and how much snow might fall. The ECMWF did shift in the direction of the other models related to changes over Canada at h5. However, it adjusted less and still shows a 980 mb low over south central lower MI at 12z Friday. That's still a powerhouse low given the very strong high pressure over the Plains.

The changes that have been described here may or will hurt totals depending where you're at. It does not mean storm cancel for everyone or that there can't be adjustments back somewhat as the mid and upper pattern evolves over Canada, and some of the features still over the Gulf of Alaska this evening get sampled by the RAOB network.

24 hours ago there was perhaps some concern based off some of the models and mid and upper evolution they were showing that the system would be more amped and track far enough NW to bring rain even into Chicago. Given that this setup is fairly complex but essentially involves the PV lobe piece and the developing main wave over northwest Canada and not some exotic phase (think the failed Feb 2020 storm).

If the models are a little bit wrong in the interaction between these and changes in 500 mb height fields, the strength of the main wave, the strength of the intensifying upper jet rounding our main wave, etc, there can be adjustments that oppose what we've seen tonight, just as last night it seemed like everything (except the Euro) was going much more amped.

There are valid meteorological reasons why the PV lobe tracking to James Bay might destructively interfere with this setup, but imo it's still too early to feel confident that the changes seen tonight are directional changes that will continue unabated in subsequent model cycles. Even though it is drawing closer and the NWP should have more skill in this part of the forecast, there's still time for meaningful changes. I am not saying that the changes seen tonight won't continue unabated, but that this range before winter storms can and certainly has had shifts back in a positive direction for snow enthusiasts.

Describing what the models are showing isn't the same thing as what will actually happen. I don't think if I was analyzing the data tonight at the office (I'm working the day shift today/Tuesday) that I'd have enough info to be completely confident yet. We can see some of the key features on water vapor imagery, but there's not really much observationally right now that can tell you affirmatively the 00z models are on the right track.

This still looks like a high to very high impact event for the Chicago area and points south and east at this time due to the wind and snow combined with extremely cold temps. Really, anywhere that gets at least 3-4" of snow will have blizzard conditions in open areas.

Finally, as a snow enthusiast myself, hopefully the shifts on Tuesday are back in a positive direction.

[RCNYILWX]

As another note, re. questions about the earlier than usual watch issuance today, a bit of a domino effect took place. That is a challenge we sometimes face in collaborating headlines. In the case of the Monday day shift, most offices we border (and the offices some of our neighboring offices border) preferred to hold off on a watch because we were still well outside the typical 48 hours out before the event issuance timeframe.

However, a few offices preferred to issue the watch Monday PM. So with that, and challenges associated with only including portions of CWAs (ie. only western half of LOT, MKX, ILX), ultimately it was decided by most (except GRR and IWX) to issue the early watch. Plus we had to consider what the perception of public safety and media partners and the public would be if we didn't issue and neighboring offices did, also contributing to my office joining in.

Ideally we would have waited, because we were gonna hit the messaging hard anyway, and beyond 48 hours, there can be pretty big changes still.

[Stebo]

Yeah I dont blame you guys for going with a watch given the time of year the travel impacts and the high impact potential. Plus it is a watch not a warning anyways. 

[Harry]

40 minutes ago, Stebo said:

Yeah I dont blame you guys for going with a watch given the time of year the travel impacts and the high impact potential. Plus it is a watch not a warning anyways. 

 

Yep. Agree. And I don't blame GRR for waiting either. I admit I would be hesitant to issue one with the morning update. If they do go with one I wouldn't blame them either. I just am not trusting anything yet. Alot can change with this sort of thing still 72hours out as we have all seen before. 

 

[Roger Smith]

06z NAM has the center steadily deepening to 970 mb tracking up western L Huron to near APN MI by end of run 18z Friday and would give sw MI possible 2-3 feet of lake effect snow with 60 mph wind gusts. From that track I think ORD would see 5-8" and that would increase around southern L Mich to 24 inches by Benton Harbor, probably about 18" for SBN mostly lake effect. Storm pulls in Atlantic moisture but probably too late if this model verified, heavy snow for ne ON. Lake Erie squall potential looks high after fropa and could give BUF another heavy fall late 23rd into 24th. Could all change on later guidance of course, but there seems to be no plausible track that would fail to dump very heavy snow in sw MI and n IN. Given the likely temps and wind speeds, long-lead warnings were certainly justified and even 1-3 inches of snow blowing around in those conditions would be very dangerous. 

[Harry]

4 minutes ago, Roger Smith said:

06z NAM has the center steadily deepening to 970 mb tracking up western L Huron to near APN MI by end of run 18z Friday and would give sw MI possible 2-3 feet of lake effect snow with 60 mph wind gusts. From that track I think ORD would see 5-8" and that would increase around southern L Mich to 24 inches by Benton Harbor, probably about 18" for SBN mostly lake effect. Storm pulls in Atlantic moisture but probably too late if this model verified, heavy snow for ne ON. Lake Erie squall potential looks high after fropa and could give BUF another heavy fall late 23rd into 24th. Could all change on later guidance of course, but there seems to be no plausible track that would fail to dump very heavy snow in sw MI and n IN. Given the likely temps and wind speeds, long-lead warnings were certainly justified and even 1-3 inches of snow blowing around in those conditions would be very dangerous. 

 

Well for GRR atleast they have passed on issuing a watch with this mornings package. Strong wording in afd but that's it. I would have waited for the 12z runs so yeah I am guessing that is what they may be doing?.

Btw.. With the stronger winds the heavier Les should be inland a bit like we saw in November. I love the snow but those damn winds. Have lucked out with the wind part so I guess my luck may have run out on that atleast.. 

[HillsdaleMIWeather]

IWX has hoisted a watch 

[A-L-E-K]

Gonna bust high 

[Baum]

7 minutes ago, A-L-E-K said:

Gonna bust high 

I tend to think you'll be spot on or bust badly low. Either way,

 

[HillsdaleMIWeather]

06Z GFS is about the same, not a shocker, onwards to 12Z!

[A-L-E-K]

1 hour ago, Baum said:

I tend to think you'll be spot on or bust badly low. Either way,

 

 

Lost the one feature that made the event interesting, pre xmas mood dust+ is nice but will be a letdown after the what the euro teased in mid range

[Chicago WX]

12 minutes ago, A-L-E-K said:

Lost the one feature that made the event interesting, pre xmas modd dust+ is nice but will be a letdown after the what the euro teased in mid range

DAB that all blows away into the Lake leaving you with bare ground on Christmas  

[Chicago WX]

Majority of the 0z EPS members are leaning left at 0z Friday, alas still a shift east from previous runs.

 

[The Ole Bucket]

14 minutes ago, Chicago WX said:

Majority of the 0z EPS members are leaning left at 0z Friday, alas still a shift east from previous runs.

 

There may yet be another swing left with this thing once the upper level feature actually descends into the lower 48..

[Baum]

LOT with another nice write up. If you get bummed with the  back and forth of the model hugger crowd it provides a nice reality check when deciphering all the information used to hone in on a forecast with an event like this. 

[Chicago WX]

GEFS tend to play follow the leader, but holy crap versus what was projected a day ago...to this below off the current 6z run.  And no not saying storm cancel at all, just posting the run. 

 

[mimillman]

On the bright side, I don’t have to go to Dubuque 

[Baum]

17 minutes ago, Chicago WX said:

GEFS tend to play follow the leader, but holy crap versus what was projected a day ago...to this below off the current 6z run.  And no not saying storm cancel at all, just posting the run. 

 

that's ugly.