Hoosier

Boy I'd be nervous on that southern end... CMI, IND, etc. Even if it ends up mostly snow, daytime temps are probably going to cost some of it.

It looks to me like the southern stream closed low has slipped south of the border, but I largely agree... any bigger surprise would come from the handling of the northern stream.

Duration does look better east of the DVN cwa. In fact, it looks like it could be snowing here for ~24 hours with little/no breaks. It is one of the reasons why I am fairly bullish on getting over 4"... in a short duration storm, there is less time to make up ground if you get off to a bad start.

fwiw, the warm season "equivalent" if you will of below zero low temps in Chicago is a high of 93+. Relatively similar number of days with a low below zero and a high of 93+ since records began in the 1870s (there have been over a thousand days of each) and also when looking from just 1980 onward when O'Hare became the official site.

Personally I'd need a lot more than this to "wipe out" all the misery. Not like we are talking about an 18-24" big dog.

There is some variance in the 2m temp progs on Wednesday, with the NAM generally being coldest and the Euro on the warmer end. If the warmer solution pans out, then it could cause some of the initial snow to get wasted in some areas... this would be less of an issue with northward extent where later onset of late afternoon/early evening is better timed with the start of the nocturnal cooling cycle.

Still going after that, can't post map because I am driving

-1 and colder

Probably the most optimistic I have been all season at this distance about getting 4+, which admittedly is not saying much.

This would probably be a wide zone of 4-6" when factoring in ratios.

Agree with that. There is some room for this system to come north but without a negatively tilted trough, not sure how much.

The ICON would be ok.

Yeah, sun angle is more noticeable.

I looked by decade as well since 1980 (when the official site moved to O'Hare, though it has moved around on the O'Hare premises through the years) and the 1980s produced a ridiculously large number of below zero days... not surprisingly given the notorious arctic outbreaks back then. Then there was a substantial dip in below zero days in the 1990s and 2000s, while the 2010s actually rebounded a bit. A decrease in the number of below zero days would be expected in a warmer climate, with a corresponding increasing rate of winters without any below zero days. So far the overwhelming majority of winters still produce below zero temps, but perhaps this one will make the list of ones that don't. We have a cold snap coming after the next storm which has a good shot to produce subzero readings in parts of northern IL but perhaps not into Chicago. Climo obviously starts becoming more hostile pretty soon.

ORD still hasn't had a below zero temperature this winter. For some historical context, less than 10% of Chicago winters (this includes November to March for purposes of this post, not just limited to DJF) have failed to have a below zero temperature. It has only happened twice since the official observation location moved to O'Hare -- 1982-83 and 2011-12.

I am confused here. If Alek has DAB+ and you have DAB-, would that put the regular DAB around Algonquin to Highland Park?

Last hurrah coming through now. Degree or two colder would've helped as accumulation efficiency was hampered a bit.

Alek is uncharacteristically late with the first call.

We have a big se ridge again but the phase looks a bit sloppy.

Curious when you will change over because I won't be far behind.

Will be nice to get the current storm out of the way but this 24 hr period pretty much fits it in

Rates definitely picked up quickly. Sideways snow. Band of 30+ dbz looks well positioned to train here for a while.

Snow underway here too.

This would be fairly lengthy for an afternoon or overnight afd let alone an "update." Nice job LOT. Area Forecast Discussion...UPDATED National Weather Service Chicago/Romeoville, IL 1110 AM CST Sun Feb 9 2020 .UPDATE... 1110 AM CST The general theme of this afternoon`s forecast continues with moderate snow expanding across the area and peaking through 2 pm. True heavy snow rates, while much more transient than continuous in a lot of the CWA, will bring very low visibility and quick snow- covered roads. As expected low-level warming has inched surface temperatures upward to 32-34 in advance of the snow in northeast Illinois and northwest Indiana, so areas where the rate is not heavy or very short-lived heavy, impacts on treated roads may be pretty limited. No changes to the ongoing Advisory. We should be able to end some western and southern areas before expiration. The regional mosaic looks more of March than the first half of February, with a semi-convective presentation across central and southern Illinois and Indiana, and more stratified precipitation across far northern Illinois into Wisconsin. The southern area is associated with a sheared mid-level short wave and associated 65 kt 500 mb speed maximum entering far western Illinois, and equally attributed to the robust low-level jet/moisture transport in place. This low-level jet presently is observed at 70 kt at 850 mb on the St Louis 88D and TDWR. Not surprising that this rapid warm advection source has steepened lapse rates and resulted in convective behavior in central Illinois, and this area will move across the southeast third of the CWA or so (south of a Streator IL to Gary IN line). There likely will be some pockets of mixed precipitation with this, including ice pellets/very small hail based on upstream mPing reports. Any snow within this area should be very transient given the warm nose aloft and warming low-level temperatures, but any snow could come down quite heavy for short spurts given the rich wintertime moisture, instability, and precipitation rate- driven wet-bulb cooling all indicated on the 12Z ILX sounding. Further north, the snow is being driven more directly by the short wave`s forcing as well as the stronger wave`s forcing and warm advection zone of lift. For far northern Illinois (north of I-88) this is still expected to be where the longest duration snow is and better thermal profiles to support average ratios as opposed to the wetter much lower ones south. Observations have shown 1/2 to 1 mile visibility in that far northern area or immediately upstream, and Rockford area webcams have shown quick deterioration between 1030 and 11 am. This remains the most favored area for isolated totals of three inches or a little higher. For in-between...basically I-80 to I-88...there likely has been some moisture robbing from the activity to the south and narrowing the window of time for the appreciable snow. Visibility in this area has not been particularly low in snow thus far, and webcams have indicated snow struggling to stick on at least main roads. The RAP and HRRR this morning have indicated this area receiving less QPF, with sort of a bimodal QPF presentation in the CWA and observational trends are showing reflection of this. Difficult to say if this will extend into the Chicago area which also has some of the milder surface air temperatures (33-35), but either way there will be a period of moderate snow with gusty winds so at least some temporary low visibility and some hazardous travel expected through 2 pm. Again snowfall amounts are really difficult to say in this semi-convective situation, especially south of I-88, with just a slight amount in some places to a quick couple inches in others. The message continues to focus on the short period of very low visibility and hazardous travel. The snow ending/transition to drizzle time from 1-2 pm west to 2-4 pm east looks good, with the entire far north (near WI state line) likely to hang onto impacting snow through mid afternoon. Intensity on this should be diminishing though after 2-3 pm. MTF

Some model indications of a split in totals in the LOT cwa, with somewhat heavier amounts in the northern and southern cwa. We'll see if it plays out that way.