beavis1729

Ha. Now that there is extensive snow cover, I'd rather put all of our chips in on the cold. But if the choices are "cold with snow" or "extreme cold with not as much snow"...can't go wrong wither way. Nice 1060 high in MT at Day 8-9 on the 12z GFS; the Euro showed something similar yesterday. I'm sure there are maps showing this data...but I don't think the lower 48 has ever had a pressure this high in February in recorded history. Fun times ahead...

Sure, why not

I edited the title to change the dates to Feb 7-12, as there is growing consensus of a prolonged cold snap. IMO, how extreme on any given day is still TBD. 6z GFS still shows significant cold temps here...and that's even before the true cold drops down around Days 7-9. Seems like more of a radiator set-up overall, where nights are extremely cold but it warms up (relatively speaking) during the day because the airmass itself is not brutal...though still colder than normal. It's like the freezer keep regenerating, with all of the snow cover and consistent high pressure in a colder-than-normal airmass. It shows 8 consecutive days of subzero low temps here, with some days not getting much above 0...not easy to do this time of year. Really an amazing GFS run for prolonged arctic cold, verbatim...noting the usual op run caveats further out in time.

Yeah, 12z Euro is a "delayed but not denied" situation. Usual caveats on a Day 10 op map...but you don't see this every day. 1058 mb high in MT, with temps 60F below normal. Not bad.

Other models besides the GFS are getting on board...although of course it's still a ways out. 12z GEM and UKMET are showing widespread -20s and even a few -30s in IA...with -20s poking into IL. Uncle Ukie needs a new scale...

The overall trend on the models (not necessarily each individual model) over the past 12-24 hours seems to be: (1) Delay the core of the arctic outbreak a bit (2) Initial shot of extreme cold focused a bit further north and west, even as the airmass/source region itself is still brutally cold (3) Prolong the residence time of the cold air around here, even if not as extreme on a given day. With that said, the various models are still not in agreement and are flipping a bit from run to run...possibly due to a potentially more organized storm system prior to the cold air dump. 12z GFS at hour 99 shows temps as low as -53 in NW Manitoba. Here's 12z Sunday morning:

Yep. The source region for this airmass is modeled to be brutally cold on the GFS - see this wind chill map for hour 114. At the very top of this image in far NW Manitoba (around 59N), the color is off the scale...but the point WCs are as low as -89F. It just keeps getting colder up there on each subsequent GFS run. Yesterday, the modeled WCs in that area were -75F to -80F. I haven't seen this type of cold in Canada in a very long time...

18z GFS doubles down. Not expecting it to verify this cold, but crazy to see this on a day 6-7 map.

Time for a separate thread...I'll start with madwx's comments from the long range thread, and a Day 7 Euro prog. The cold arrives sooner on the GFS, and is more intense. ---------- Euro in agreement with cold starting Friday after the EOW system with the core of the coldest temps on Sunday thru Tuesday with some slight moderation after that. Some relevant record mins and low maxes for the period at MSN 5 -21 1936 -8 1895 6 -19 1977 -5 1875 7 -21 1875 -2 1893 8 -22 1899 -7 1875 9 -28 1899 -15 1899 10 -25 1899 -5 1899 11 -22 1885 -6 1899 Notable that all those 1899 dates are during the great Arctic outbreak where ice floes came out of the mouth of the Mississippi and New Orleans got down to their all time record of 6.

18z GFS with even colder wind chills into far NW IL. This is probably among the top 5 coldest modeled wind chills that I've ever seen in the state. Not putting too much stock in these extremes yet, due to the well-known GFS cold bias at range...and of course it's still 7 days out. And some -70s on the map northern Manitoba...just a bit chilly. 12z GEM and 18z GFS v16 are actually starting to show wind chills worthy of advisory/warning criteria...but it's mainly -35 to -45 in the coldest areas instead of -50s. Either way, I think the probability of a significant arctic outbreak is increasing. We'll see if it ends up being near record breaking (say 30+ degrees below normal), or just a run of the mill cold snap (say 20-30 degrees below normal). Today is the anniversary of the 2019 cold snap, where Rockford's -31 broke its all time record low by 4 degrees...with a period of record 100+ years.

My brother lives in Mequon, probably right by there. He reported similar (10”), with a 19” depth.

Bring it...what can go wrong with an op and non-v16 GFS prog 11 days away??

Good snowfall with this storm...then preserve some/all snowpack until an arctic outbreak like some GFS progs have been showing...

3 here, coldest of the season. Some others...although it could have dropped lower intra-hour 6-7 AM. I think all are the coldest of the season, except ORD was also 8 on Christmas morning. ARR -3 RFD 0 DPA 2 DKB 2 JOT 6 ORD 8

I infiltrated Chicago Storm's mind when he moved to Naperville. Sneak attack.

With the usual caveats on a 16-day GFS map...it's interesting that Chicago's daily low temp records during the entire period from Feb. 7-25 (with one exception*) are all from 1936 or earlier...and most were from the 1800s or very early 1900s. Probably due to the recent UHI and the colder overall climate back then, which allowed snow cover/depth to generally persist further into February both here and in the source region. *Record low of -8 on 2/19/2015

Yep, with a slight edit. We barely hung on imby, until the current snowfall...and it was mainly in neighborhoods and sheltered areas. The more urbanized areas and busier streets had a lot of bare spots. I'm about 25 miles south of the WI border, as the crow flies.

That's a great paper. I was only 4 years old and lived in KC at the time...would have been amazing to experience. Yeah...I believe Antioch, IL had 105.6" of snow, with a peak depth of 38" and around 115 consecutive days of 1"+ depth.

Yeah, sucks. At one point it looked like a 2-3” snowfall. Maybe a silver lining is that this precursor wave helped moisten the column for the upcoming storm. Devil’s advocate says that the models should already be accounting for this, yet they are still trending weaker.

All good. I do think it can come across as a bit selfish when areas near I-80 and IKK may unfortunately miss out on the storm entirely...and at the same time you and I are concerned about not getting 6"+. I think that's what some other posters are alluding to. Mimilliman and baum are good posters, as are most here. It's not personal.

Yep, agree overall. With that said, I think it's natural to be on edge and worry before the storm...thinking more about what could go wrong vs. what is likely to occur. For northern LOT specifically...a couple days ago it looked like the initial/separate WAA snow tonight would be 2-3", now it may only be a dusting. So, that doesn't help. And, although I know op runs should be taken with a grain of salt at range, there were a couple of op Euro runs showing close to 2 feet in northern LOT...which now is nowhere to be found. It's all relative. Plus, if the storm really does weaken/shear out due to the effects of the block, it's likely to take a bit more southern route...which could favor the heart of the city instead of the northern areas. And, even if lake enhancement does occur, it may tend to favor the lakeside counties instead of McHenry and further west. Again - all else being equal, I think there are still concerns in northern LOT, especially away from the lake...just like there are (different) concerns elsewhere in LOT and northern IN and into MI. That's why we need a true spread-the-wealth storm...so that everyone shares in the fun. I initially thought this storm might be it...but it appears to be transitioning to a narrow swath of heavier snowfall for a lucky few. And by heaviest, I mean 10"+. Not meant to complain...just human nature to be on edge a bit, given the snow drought that many of us have experienced over the last 2-3 years.

ding ding ding...regardless of where the exact swath of heavy snow sets up, there are fewer clunker members than before. Not completely eliminated, but progress. And the map is 10:1 ratios. If the 18z and 0z Euro ensembles follow suit, I think we're in business.

Good to see the mean increasing...but it's still under 4". Need to move in the right direction quickly, and eliminate the non-event plumes. Not trying to be a debbie, but hard to shake the fact that a complete non-event is still a possibility.