January 24 - 31 Cold Blast

[sbnwx85]

The all-time coldest max temp ever recorded in South Bend is -8 in 1899. I think that record will be shattered.

[Hoosier]

46 minutes ago, beavis1729 said:

Crazy. Will be fun to see the HRRR temps over the next couple of days. 

Oh yes.  It can be aggressive over snowpack.

[HillsdaleMIWeather]

Brace yourselves, Mass Wind Chill Watches are coming

[HillsdaleMIWeather]

I actually wonder if the NWS offices are gonna possibly put the "THIS IS A PARTICULARLY DANGEROUS SITUATION" tag on some of the WCW's that get issued

[Chicago WX]

Bullseye, pretty much, on the 12z Euro. 

 

[sbnwx85]

14 minutes ago, HillsdaleMIWeather said:

I actually wonder if the NWS offices are gonna possibly put the "THIS IS A PARTICULARLY DANGEROUS SITUATION" tag on some of the WCW's that get issued

Usually I like my PDS watches to be of the tornado variety but I'd be okay with a PDS Wind Chill Watch/Warning.

[cyclone77]

Looks like the bitter wind chills have arrived early in Iowa.  Knoxville currently has a wind chill of -54 courtesy of a biting 750kt north breeze.

[SchaumburgStormer]

1 minute ago, cyclone77 said:

Looks like the bitter wind chills have arrived early in Iowa.  Knoxville currently has a wind chill of -54 courtesy of a biting 750kt north breeze.

Hahaha, what is that ~860mph? 

[cyclone77]

5 minutes ago, SchaumburgStormer said:

Hahaha, what is that ~860mph? 

Yeah like 863mph lol.

On a serious note the Euro continues to indicate max (or I guess min lol) potential may be Thu morning.  Ridge axis moves in and calms winds over a very deep snow pack.  WAA will already be taking place off the surface, but we've often seen a lag in the reflection down near the surface in a powerful arctic air mass in prior events.  It actually got colder than the 00z, and now shows -35 to -39 from the QC northwestward through north-central IA.  Simply amazing.

If the timing of the ridge axis is correct it will just come down to if there's any clouds streaming in from the west with that incoming WAA.

[Hoosier]

So here's my first call for Wednesday's low at ORD. 

I have spent the last couple days looking at the models and looking back at historic cases, and based on those things, I believe any guidance showing a low warmer than -25 is probably too warm.  So then the question is how low?

Progged 850 mb temps and the amount of expected snowcover at ORD and upstream generally match or exceed the coldest historic cases.  In this case, the coldest temps aloft also come in during the night/early morning, so pretty good timing.  It was tough coming up with a number given the variance in the guidance for 2m temps, and that is where the historic cases were helpful.  

I'm going with a low of -29 to break the all-time record low of -27 from 1/20/1985.  I'd be lying if I said I had a lot of confidence in that particular number, and I certainly didn't want to stray too far above an established all-time mark (here's looking at you FV3).  I would give about a 60-70% chance of the record being tied/broken, so more likely than not but still a very reasonable chance that it comes up a little short.

[Hoosier]

12 minutes ago, (((Will))) said:

Should have a contest for Chicago's low and high that day and maybe other areas. Not often we get cold like this to toy around with.

Good idea

[hlcater]

6 minutes ago, Hoosier said:

Good idea

Maybe do multiple locations as well? 

[Chicago Storm]

2 hours ago, beavis1729 said:

Crazy. Will be fun to see the HRRR temps over the next couple of days. 

Probably will show some -40's somewhere at a nearby colder location.

[Hoosier]

LOT lowered ORD to -23.  Even that value with no downward adjustments would be the coldest temp since 1/20/1985.

[sokolow]

For Weds 1/30 I will take lo -30 for a nice round number and to one-up Hoosier and a hi of -20 for crank-to-eleven levels of raw suffering freezepocalpyse

[Hoosier]

5 minutes ago, sokolow said:

For Weds 1/30 I will take lo -30 for a nice round number and to one-up Hoosier and a hi of -20 for crank-to-eleven levels of raw suffering freezepocalpyse

You want to qualify the -20 as daytime high in case of a midnight high? 

[beavis1729]

Minot ND is 40 degrees now, and should be -30 Wednesday morning. 

My point was lowered to -24 on both Wednesday morning and Thursday morning. High of -14 on Wednesday. 

[whoosh]

2 hours ago, Hoosier said:

I have spent the last couple days looking at the models and looking back at historic cases

Thanks for doing and sharing the research and analysis. I have a question about snowcover ....
How does the quantity of snowcover matter, given the cases of >=3" ?
I've only come up with two most important impacts of any snowcover. One is for providing a cold surface of less friction for cold air masses to move over on their way south; depth of cover wouldn't matter at all. The other is as an insulator/reflector of radiant heat; of this I'm more uncertain on the impact of snowcover depth, but I'm not groking any significant difference between 3" and 9".

 

[Hoosier]

10 minutes ago, whoosh said:

Thanks for doing and sharing the research and analysis. I have a question about snowcover ....
How does the quantity of snowcover matter, given the cases of >=3" ?
I've only come up with two most important impacts of any snowcover. One is for providing a cold surface of less friction for cold air masses to move over on their way south; depth of cover wouldn't matter at all. The other is as an insulator/reflector of radiant heat; of this I'm more uncertain on the impact of snowcover depth, but I'm not groking any significant difference between 3" and 9".

 

Good question.  There are diminishing returns to the impact of snow depth as the numbers get bigger.  Having 0" or 6", having 2" or 8", having 18" or 24", all are a difference of 6" but that difference matters a lot in the first case, less in the second case and I would say virtually no impact between having 18" or 24".  

[Geoboy645]

I never thought that these readings would ever be seen in my area in my lifetime.Well I was wrong. I wonder how cold the temps/windchills are going to be at our normal cold spots like lone rock,black river falls,or camp douglas.

[cyclone77]

Still a ways away, but I'm gonna go with an all-time record low at MLI on Thursday of -33.  Only concern for me is upstream clouds that can sometimes come in a little faster than expected.  At this point all other ingredients are pretty nicely lined up for an extraordinary low temp event for the area.  

I have a feeling many of us will be looking back at this thread in the years to come.  

[Hoosier]

1 minute ago, cyclone77 said:

Still a ways away, but I'm gonna go with an all-time record low at MLI on Thursday of -33.  Only concern for me is upstream clouds that can sometimes come in a little faster than expected.  At this point all other ingredients are pretty nicely lined up for an extraordinary low temp event for the area.  

I have a feeling many of us will be looking back at this thread in the years to come.  

Yeah, the normal cold spots could get out of control if conditions are prime/nearly prime, as they look to be.  Will be fun to watch.

I'm even thinking minus mid 20s are possible at ORD.  Normally would not entertain anything much under -20 there on a night so dependent on radiational cooling, but I feel like some non traditional thinking is warranted in this case with how low the starting point will be on Wednesday evening.  If any "radiational cooling setup" could pull off temps well under -20 at ORD, it's this one.

[AppsRunner]

At least locally, the NAM/3k are much more "mild" compared to the GFS. Lows on Weds Night only drop to around -15 to -20, compared to the GFS and -27. Further east towards WI/IL it seems to be much more certain of a lock for all-time record cold. 

[cyclone77]

36 minutes ago, Hoosier said:

Yeah, the normal cold spots could get out of control if conditions are prime/nearly prime, as they look to be.  Will be fun to watch.

I'm even thinking minus mid 20s are possible at ORD.  Normally would not entertain anything much under -20 there on a night so dependent on radiational cooling, but I feel like some non traditional thinking is warranted in this case with how low the starting point will be on Wednesday evening.  If any "radiational cooling setup" could pull off temps well under -20 at ORD, it's this one.

The daytime temps on Wed are looking like they really could be something special.  Euro and GFS both show temps still around -20 at midday for much of northern IL.  Wish there was some sort of stat that tracked peak daytime temps for situations like this.  Daily max won't tell the true story since the max temp over northern IL will likely be at midnight.  I predicted a daytime high of -14 at ORD in the contest thread, but there's a shot it stays under -15.  More importantly, there's a good shot the temp doesn't bump back above -20 until after the noon hour.

[Hoosier]

13 minutes ago, cyclone77 said:

The daytime temps on Wed are looking like they really could be something special.  Euro and GFS both show temps still around -20 at midday for much of northern IL.  Wish there was some sort of stat that tracked peak daytime temps for situations like this.  Daily max won't tell the true story since the max temp over northern IL will likely be at midnight.  I predicted a daytime high of -14 at ORD in the contest thread, but there's a shot it stays under -15.  More importantly, there's a good shot the temp doesn't bump back above -20 until after the noon hour.

Special indeed.  I am really geeking out over this lol.  The greatest arctic outbreaks occurred before I was born or when I was very young, and I've wondered how long it would take to experience something like one of those outbreaks from the 1980s.  The answer:  less than 3 more days.

[OHweather]

I’m curious to see what happens Wednesday night for obvious reasons.  The coldest 925mb temps are during the day Wednesday, with weak return flow developing by Wednesday night.  But with a clear sky, fresh and deep snowpack, and still quite weak gradient there should be a corridor that tanks with cold spots easily dipping to -30, maybe a few -40s in some sheltered areas?  Dew points will be near -30 and it’s not hard to drag them down when it’s that cold.  My hunch since this is radiation driven Wednesday night that the coldest is just west of Chicago, though the lows Wednesday morning will all be advection driven so might do quite well in the city.  It will be interesting to monitor any attempt at WAA and high level clouds as mentioned.  At the moment both look to be too late for parts of eastern IA/northern IL into WI, but possible flies in the ointment for all time record cold.  Have to imagine if the boundary layer flow is less than 8 or 10 knots it’d quickly decouple over the deep snow pack Wednesday evening. 

[cyclone77]

9 minutes ago, OHweather said:

I’m curious to see what happens Wednesday night for obvious reasons.  The coldest 925mb temps are during the day Wednesday, with weak return flow developing by Wednesday night.  But with a clear sky, fresh and deep snowpack, and still quite weak gradient there should be a corridor that tanks with cold spots easily dipping to -30, maybe a few -40s in some sheltered areas?  Dew points will be in the -30s and it’s not hard to drag them down when it’s that cold.  My hunch since this is radiation driven Wednesday night that the coldest is just west of Chicago, though the lows Wednesday morning will all be advection driven so might do quite well in the city.  It will be interesting to monitor any attempt at WAA and high level clouds as mentioned.  At the moment both look to be too late for parts of eastern IA/northern IL into WI, but possible flies in the ointment for all time record cold.  Have to imagine if the boundary layer flow is less than 8 or 10 knots it’d quickly decouple over the deep snow pack Wednesday evening. 

The old all-time record at Congerville IL of -36 certainly seems breakable if we can get everything to align.  Sure would be awesome for IL to put a -40 on the board.  For ASOS/AWOS sites I think the best chance for that would be at either the Sterling or Rochelle site.  If the ridge ends up a little further east than the way it looks now then Dekalb/Aurora would also have a good shot.

[OHweather]

17 minutes ago, cyclone77 said:

The old all-time record at Congerville IL of -36 certainly seems breakable if we can get everything to align.  Sure would be awesome for IL to put a -40 on the board.  For ASOS/AWOS sites I think the best chance for that would be at either the Sterling or Rochelle site.  If the ridge ends up a little further east than the way it looks now then Dekalb/Aurora would also have a good shot.

I definitely think it would have to be a rather rural, sheltered site that's preferably in a relative hole to attain, as it's simply hard to do.  There was a Wunderground station next to a ravine against a cliff in extreme NE OH that tagged -39F in February 2015 (would've tied the state record if an official station) in a slightly less impressive airmass...so I think it's doable, but it certainly needs to line up perfectly to happen.  Ideal radiating conditions will be needed, and seem attainable, so we will see.

[SchaumburgStormer]

1 hour ago, Hoosier said:

Special indeed.  I am really geeking out over this lol.  The greatest arctic outbreaks occurred before I was born or when I was very young, and I've wondered how long it would take to experience something like one of those outbreaks from the 1980s.  The answer:  less than 3 more days.

I am pretty pumped as we are approaching what I would consider to be unfathomaly cold. A double digit negative temp is a noteworthy event in this climo, this is something really incredible that I am not sure is really sinking in with the general public. 

I am hearing a lot of “oh it will be cold, but it won’t be that bad”. We are projected to hit temps where vehicles and homes start doing weird things. I just feel bad for my coworkers at the PD who are working those shifts! 

[MNstorms]

With snow today and cold following some schools in Minnesota will get all week off.