New Years Winter Storm

[Sciascia]

1 minute ago, madwx said:

the WWA in wisconsin is for the freezing drizzle/rain threat today, not for tomorrow's storm

Ah, good to know my geographical neighbor. Thanks

[McHenrySnow]

4 minutes ago, Sciascia said:

Given the WWA’s immediately to my north in Wisconsin’s border counties, I’m expecting to lose my “storm watch” status for an advisory. But hopefully anyone here in “Chicagoland” does well.

I figure Winnebago and Boone are probably WWA for sure, McHenry is quite possible as well. 

[blizzardof96]

12 minutes ago, Snowstorms said:

The trend seems to be weaker and further south right now. A large portion of the energy gets wrapped up further south into a potential secondary low. We'll see what tonights runs yield. I agree with the bold, it is ridiculous. Any reason why you feel we are seeing such high volatility among the models?  

5-10cm does seem like a good bet for now. At the very least it should bring us closer to 50cm (20") for the season. 

Edit: Must be tough for meteorologists like yourself to issue a proper forecast right now.

Synoptically speaking, what we have is a weakening vort max ejecting into the plains. As the vort max moves northeast, it is getting elongated/weakened by the confluence zone/upper jet across the Great Lakes region. With the confluence zone in place, the plains energy is quite limited in how far north it can track and how strong it gets. These weak systems can be subtle which the models will rarely handle well. With a better defined low, the models have better legs to stand on from a physics perspective.

Very similar setups with a plains wave ejecting towards Great Lakes confluence zone occurred last winter on a few occasions, and the models similarly performed poorly up to the final moments. Surface low peaks in intensity near the western Ohio river before deformation snow band weakens gradually as it moves east through MI and ON.

In addition to these factors, slight changes in the upstream trough across the four corners region can make a difference in how the vort max ejects/tracks. These differences can also alter the orientation of the leading wave from neutral/positive/negatively tilted. 

[hlcater]

HRRR coming south again. CR will be left out of the good snow this run. Trend never fails. 

[Natester]

5 minutes ago, hlcater said:

HRRR coming south again. CR will be left out of the good snow this run. Trend never fails. 

Lowering my call down to 3.5 inches.

EDIT: Snow axis on the HRRR hasn't changed, but it's significantly drier.  Also, amounts really cut down for Chicago except for right along the lake.  ALEK is going to bust high.

[Chicago Storm]

Synoptically speaking, what we have is a weakening vort max ejecting into the plains. As the vort max moves northeast, it is getting elongated/weakened by the confluence zone/upper jet across the Great Lakes region. With the confluence zone in place, the plains energy is quite limited in how far north it can track and how strong it gets. These weak systems can be subtle which the models will rarely handle well. With a better defined low, the models have better legs to stand on from a physics perspective.
Very similar setups with a plains wave ejecting towards Great Lakes confluence zone occurred last winter on a few occasions, and the models similarly performed poorly up to the final moments. Surface low peaks in intensity near the western Ohio river before deformation snow band weakens gradually as it moves east through MI and ON.
In addition to these factors, slight changes in the upstream trough across the four corners region can make a difference in how the vort max ejects/tracks. These differences can also alter the orientation of the leading wave from neutral/positive/negatively tilted. 

.

[Natester]

The only good thing about this is the long duration light snows.  HRRR predicts 5.5 inches here but I'm skeptical.

[Baum]

where's spartman when you need him?

[sbnwx85]

5 minutes ago, Natester said:

The only good thing about this is the long duration light snows.  HRRR predicts 5.5 inches here but I'm skeptical.

Nice 19" lollipop over the north suburbs.

[Sciascia]

I wouldn’t immediately discredit the LES shown on the hi-res models. Different circumstances, but they did pretty well with the Chicago LES storm last February.

[Hoosier]

6 minutes ago, sbnwx85 said:

Nice 19" lollipop over the north suburbs.

I do remember the HRRR being overzealous with lake contribution in some previous setups.  But even cutting it down would result in isolated 12"+ amounts near the lake. 

[Baum]

see ILX posting warnings suspect in collaboration with LOT. Guessing a call for 4-8 across the board.

[Natester]

The 18z NAM is an easy toss.  Too far north with the heavy snow axis.  Doesn't ramp up the system, though.

[A-L-E-K]

Nice creeper fog all day 

[CANNOTDIVIDEBY0]

13 minutes ago, Hoosier said:

I do remember the HRRR being overzealous with lake contribution in some previous setups.  But even cutting it down would result in isolated 12"+ amounts near the lake. 

I remember HRRR being pretty good for that one. Had 19 IMBY and ended at 18.6 

[hlcater]

Just now, Natester said:

The 18z NAM is an easy toss.  Too far north with the heavy snow axis.

Respectfully, tossing a model simply because it’s too far north isn’t really worthwhile. I agree that it probably is, but the issue arises when you’ve made what is essentially the same post 15 times in the same thread without providing any reasoning as to why other than “too far north”. 
 

For example, you could make the argument that dry NEly flow eats away at low/mid level RH and prevents precip from spreading as far north as some models think it will. This is certainly the case for the models showing heavy snow to the hwy 20 corridor and may well be the case for Cedar Rapids as well, though seems unlikely from preventing us from seeing at least 4.” 

[Natester]

4 minutes ago, hlcater said:

Respectfully, tossing a model simply because it’s too far north isn’t really worthwhile. I agree that it probably is, but the issue arises when you’ve made what is essentially the same post 15 times in the same thread without providing any reasoning as to why other than “too far north”. 
 

For example, you could make the argument that dry NEly flow eats away at low/mid level RH and prevents precip from spreading as far north as some models think it will. This is certainly the case for the models showing heavy snow to the hwy 20 corridor and may well be the case for Cedar Rapids as well, though seems unlikely from preventing us from seeing at least 4.” 

Yeah, I forgot about the dry air.  Although the southern end of the heavy snow axis is in extreme northern Missouri as shown here.

[Chicago Storm]

The reason for the change in the NAM is due to how it handles the wave as it ejects out into and through the Plains. The 18z run went with a slightly more amped and tilted wave. Subtle differences, but they matter greatly.

[sbnwx85]

IWX going Winter Wx Advisory. Highest totals of 4 to 7 in northwestern counties. 

INZ003-004-MIZ077-078-010430-
/O.NEW.KIWX.WW.Y.0012.220101T1800Z-220102T1200Z/
La Porte-St. Joseph-Berrien-Cass-
Including the cities of Michigan City, La Porte, South Bend,
Mishawaka, New Carlisle, Walkerton, Niles, Benton Harbor,
St. Joseph, Fair Plain, Benton Heights, Buchanan, Paw Paw Lake,
Dowagiac, Cassopolis, Edwardsburg, and Marcellus
316 PM EST Fri Dec 31 2021 /216 PM CST Fri Dec 31 2021/

...WINTER WEATHER ADVISORY IN EFFECT FROM 1 PM EST /NOON CST/
SATURDAY TO 7 AM EST /6 AM CST/ SUNDAY...

* WHAT...Snow expected. Total snow accumulations of 4 to 7
  inches. Locally higher amounts possible, especially near Lake
  Michigan.

* WHERE...In Indiana, La Porte and St. Joseph Counties. In
  Michigan, Berrien and Cass Counties.

* WHEN...From 1 PM EST /noon CST/ Saturday to 7 AM EST /6 AM
  CST/ Sunday.

* IMPACTS...Travel could be very difficult.

* ADDITIONAL DETAILS...Snow, possibly mixed with rain at the
  start, will develop Saturday afternoon and may become heavy at
  times late Saturday afternoon into Saturday evening.

[mimillman]

26 minutes ago, Hoosier said:

I do remember the HRRR being overzealous with lake contribution in some previous setups.  But even cutting it down would result in isolated 12"+ amounts near the lake. 

Warning just issued for you

[Sciascia]

3 minutes ago, mimillman said:

Warning just issued for you

Congrats @Hoosier! Much to my surprise, Boone County got one too. Doesn’t mean I’ll get more snow, but pink on the weather map always looks better than purple.

[Hoosier]

14 minutes ago, CANNOTDIVIDEBY0 said:

I remember HRRR being pretty good for that one. Had 19 IMBY and ended at 18.6 

I think it may be too aggressive this time though.  I'd like to see better delta T and inversion heights.  So i'm not willing to go with 18" amounts near the lake.  12"+, ok. 

[sbnwx85]

Not advocating for a WSW in my county...but a little surprised IWX didn't go with one for LaPorte and Berrien. I think they'll do a little better with snow totals thanks to the lake.

[Natester]

In other news, freezing drizzle is causing alot of travel problems in central and western Iowa.  Reports of many crashes.  Roads in eastern Iowa are so far wet according to the Iowa 511 road conditions map.  The NAM and the HRRR picked up the freezing drizzle potential a couple days ago.

[CANNOTDIVIDEBY0]

From Tom skillings Facebook post 5 minutes ago.

 

As a certified professional weenie, I'm taking this to the bank.

[Hoosier]

If ORD gets a little over 8" with this storm, they would be sitting at the average snow to date as of Jan 2.

[TheNiño]

9 minutes ago, CANNOTDIVIDEBY0 said:

From Tom skillings Facebook post 5 minutes ago.

 

As a certified professional weenie, I'm taking this to the bank.

Didn’t expect him to be so bullish. Here’s his full write up from his post…

WINTER STORM TO HIT THIS WEEKEND WITH ALL THE METEOROLOGICAL ACCOUTREMENTS--HIGH WINDS (GUSTS TOPPING 35 MPH) PRODUCING BLOWING AND DRIFTING, HEAVY SNOWFALLS WIDESPREAD 5 TO 9" TOTALS, LOCAL ONE FOOT TOTALS POSSIBLE LAKESIDE COUNTIES (COOK AND LAKE COUNTIES IN BOTH ILLINOIS & INDIANA)--ARCTIC BLAST AND SUB-ZERO WIND CHILLS TO FOLLOW

It's now clear--a major winter storm firing on all atmospheric cylinders--is headed this way for the New Year's weekend. What a way to begin 2022! 

The patchy drizzle and areas of fog currently underway in the deceptively mild 40+-deg pre-storm Friday air will give way to far more wintry conditions rapidly in the mid and late morning hours of Saturday. What is to follow will be wind-driven snows, likely to be "lake- enhanced"--in other words intensified in counties adjoining Lake Michigan, which may well lay down the Chicago area's heaviest snowfall since 7.7" fell at O'Hare and 8.8" fell at Midway this past Feb 8-9.

HERE ARE KEY POINTS REGARDING THE WEEKEND SNOWSTORM FORECAST----

-Winter storm watches may well be upgraded to winter storm warnings for the period later Saturday morning through Saturday night

--Snow is likely to begin in the city during the 10am to 12 noon time frame Saturday and snow may continue falling into early Sunday in lakeside counties into Sunday morning--shifting as lake snow squalls into northwest Indiana Sunday,

--Heaviest snowfall is likely to occur in the city from around 2pm Sat through 10pm Sat night--though lakeside snow squalls could produce snowbusts into early Sunday lakeside counties

--Current thinking on accumulations: 5 to 9" generally--but with lake enhancement likely to play an outsized role in snowfall near Lake Michigan, it's not out of the question lakeside counties like Lake and Cook counties in Illinois and Lake County, IN could see totals topping 10" and evening reach a foot in some harder hit locations.

--Winds will become a big factor--strengthening in gusts to 35mph and, along Lake Michigan and in open areas, locally to 40 mph.

--Colder air drawn into the storm will fluff snow up making it more susceptible to blowing and drifting

--The coldest temps and wind chills of the season to date are to sweep into the area with air temps falling to single digits from Chicago and west by daybreak Sunday amid howling north winds. This will generate wind chills dropping to into the 5-above to 8-below range from Chicago west--moderated to 5 to 15-above in northwest Indiana because of winds off the lake--but falling there during Sunday.

--Skies are likely to clear from Chicago west Sunday

The storm is currently centered in Colorado and is due to track eastward to far southeast Missouri by Saturday evening and into southern Indiana Saturday night. And it may not be the last snow system we see in the coming week. There are indications of the potential for another toward Thursday next week.

 Chicago will sit between two wind maxima at jet stream level Saturday and Saturday--each contributing to "atmospheric left"--the tendency of air to be lifted and cooled as it rises through the atmosphere. This both cools the air to condensation and produces precip. It also drops air pressure as air is drawn away from the surface and this leads to the powerful winds we'll see develop with this storm. Wind speeds will be increasing overnight and gusting to 35 mph and higher by later Saturday and Saturday night.

Meteorologists look at the temp drop which occurs in the lowest mile of the atmosphere as an indicator of potential lake enhancement--and this storm's backside will meet the criteria in spades. Temps from the lake surface to a mile aloft will drop by 23 to 32-deg between evening Saturday and Sunday morning.  A drop of 16 to 20-deg is all that's required--so it's not unreasonable to expect the 41-deg lake waters to yield moisture supoporting the storm's snow shield.  As surface winds become more NNW rather than NE Saturday night, the low level temps will plummet very likely overcoming any melting that the warmer lake waters might otherwise promote. So it appears a good bet we'll be seeing higher accumulations in some lakeside counties of northeast Illinois and northwest Indiana. 

I'm posting a variety of graphics to help you follow developments with this system--one likely to be the biggest winter storm generator of the past 10 months at least--and certainly of the young winter 2021-22 season.

In the storm's warm sector, there will be active severe weather and possible tornado production--and, ominously, this may occur in some of the same areas hit by the horrendous tornado outbreaks of the past several weeks.

[Sciascia]

They may not always hit on their assessments, but LOT does a great job when it comes to informing everyone about how they think a storm will unfold.

[ChiTownSnow]

He's getting more and more bullish in his old age. 

[Natester]

18z RGEM and 18z GFS a tick south of 12z.