Major Late Season Heat Possible Again 10/2 ---?

[Jonger]

14 minutes ago, rainsucks said:

Lol @ Jonger's wishcasting

That's what is being shown for the period.

[rainsucks]

2 minutes ago, Jonger said:

That's what is being shown for the period.

The 12z Euro would support multiple days near 90 if it were to verify, lol. 

Also, everyone knows the GFS has a severe cold bias in regards to surface temps, come on...

[Hoosier]

I was looking at the GFS 2m temps, and to me it looks like they are underestimating the warmth by quite a bit, especially with north/east extent.  Like the recent episode, one would think this regime should favor mixing to at/above 850 mb.  It would seem like a better indicator of the potential would be to add about 14-15C to the 850 mb temps in less developed areas... and 15-16C in cities, areas that have been really dry, and downslope areas (when clouds aren't an issue of course).

[wisconsinwx]

2 hours ago, Jonger said:

Looks like a 4 to 5 day heat wave, but about 5-10F lower.

Today was so nice. Why anyone would want to lose out on this kind of weather is a mystery to me.

This past heat wave was 7 solid days of hell.

Luckily that would make it tolerable (even for us) with the exception of your family trip.  MKX is not biting just yet, at least through Wednesday, on anything past mid 70s.

[Jonger]

1 hour ago, wisconsinwx said:

Luckily that would make it tolerable (even for us) with the exception of your family trip.  MKX is not biting just yet, at least through Wednesday, on anything past mid 70s.

Oh, it's gonna be hot.... just not 7 straight days of hell.

mid 80s are fine... if anything it should keep the lakes warm for LES season.

[Hoosier]

The GFS has been flopping around on the details so I don't trust this run, but I just have to post this prog because of how utterly ridiculous it is.  Yes, that's nearly 80 degree temps in the IA/IL/MO area... at 7 am in October.  Out in advance of a strong low pressure

[Hoosier]

80 degree streak should commence at ORD on Monday.  I'm not ready to make a call about how long it lasts, but there's a possibility (or even likelihood) that it could get into some unusual company.  

There have been 15 streaks of 4 or more consecutive 80+ temps in Chicago entirely within the month of October.  That list narrows down to just 4 streaks when increasing the length to 5 or more days.

 

[Hoosier]

Also, taking a look at the 6 October 90+ degree days on record in Chicago, all occurred on days with 850 mb temps around 17-19C and 925 mb temps around 24-25C, which is pretty much what you'd expect.  So if models are progging temps at those levels on any afternoons, in combination with mostly sunny skies, then it would be a decent possibility (again only reinforced by the recent dryness).

[Hoosier]

You'd have to call it severe divergence between today's 12z GFS/Euro operational runs by the middle of next week.  Euro really puts an end to the unseasonable warmth while the GFS keeps it going longer.  

[Stebo]

1 hour ago, Hoosier said:

You'd have to call it severe divergence between today's 12z GFS/Euro operational runs by the middle of next week.  Euro really puts an end to the unseasonable warmth while the GFS keeps it going longer.  

Considering the upcoming teleconnections of +AO/+NAO/-PNA, the Euro is going to be wrong about the early shut off. It is overdoing the push behind the system late next week.

[Hoosier]

24 minutes ago, Stebo said:

Considering the upcoming teleconnections of +AO/+NAO/-PNA, the Euro is going to be wrong about the early shut off. It is overdoing the push behind the system late next week.

I was also thinking with that kind of ridging/amplification, a slower lean would make more sense.  I guess we'll find out.

[rainsucks]

p sure the euro has a tendency to speed things up too much as well. Its performance has been atrocious lately, so I wouldn't put much stock in what it's showing.

[Hoosier]

Well, regardless of how long it lasts, I have decent confidence in ORD surpassing the warmest max temp from October 2007 (which was 87).  The current output verbatim would get it close to that, and with such an anomalous setup with the core of the upper level ridge just south along with 850 mb thermal ridge in the area, I feel it's more likely that any correction would be toward somewhat warmer thermal profiles aloft on some of these days.  

Doing the math on Chicago's 90 degree days in October, they have only occurred in 3-4% of Octobers.  In my own personal opinion, I would already give it about 10x that of occurring next week (so about a 30-40% chance), which may need to be adjusted as things become more clear. 

[Hoosier]

12z UKMET really slowed down the frontal progression from what it had previously. Sometimes it seemingly acts like a preview of what the Euro does so we shall see.

[Hoosier]

1 hour ago, Hoosier said:

12z UKMET really slowed down the frontal progression from what it had previously. Sometimes it seemingly acts like a preview of what the Euro does so we shall see.

Not this time.  Still a very quick progression on the 12z Euro.

[IWXwx]

Beat me to it. The Euro has the front entering the subforum Wednesday morning and well to the east by Thursday morning. I like the Canadian's depiction of keeping the heat around until Saturday. Then there's the GFS...let's just say that there's no consensus.

[Hoosier]

26 minutes ago, IWXwx said:

Beat me to it. The Euro has the front entering the subforum Wednesday morning and well to the east by Thursday morning. I like the Canadian's depiction of keeping the heat around until Saturday. Then there's the GFS...let's just say that there's no consensus.

Something is causing fits, and it looks like it lies on how that trough ejecting from the west mid-late week behaves and how quickly it is able to flatten the ridge.  

As mentioned, you'd think it would take longer to break down a ridge like this than what the Euro is suggesting.  How much is the question.  

[Chicago Storm]

The GFS has started trending towards the ECMWF. We'll see if it continues...

[WxMatt21]

Nice long term AFD discussion by IWX this afternoon. We have talked a lot about the 2007 analog lately, and the CPC seems to be weighting that year pretty heavily, too: 

Very warm weather is ahead next week with high temperatures in the 
80s as an upper level ridge builds into the area. Highs of 90 or 
higher in October are extremely rare (has only happened once in 100+ 
years at Ft Wayne). Highs in the 80s are much more common. The 
pattern we are in now closely resembles the early fall "analog" of 
2007. During this year, late September was warm and dry, with highs 
in the 80s several times. This pattern 10 years ago extended into 
early October. There is a reasonable correlation of very warm temps 
separated by short, cooler breaks between this year and 2007.

As far as the blend, attempted to go above highs and below rain 
chances. Believe the EC continues to be an outlier and was 
contributing to higher rain chances and lower temps in the blend Wed-
Fri. It looks like any break with the warm temperatures will be 
short with highs returning to near 20 degrees above normal shortly 
after the end of the forecast period.

[Hoosier]

Although not explicitly forecasting it, the LOT afd mentions temps near 90 possible on Tuesday.

I'd go like 88 for now as current thermal profiles aloft look a little too cool for 90, but the current thermal part is the key there.  It wouldn't take much more warming aloft to bring 90 into play. 

[Powerball]

1 hour ago, Chicago Storm said:

The GFS has started trending towards the ECMWF. We'll see if it continues...

So has the GGEM.

I need it to at least stay warm through Friday, when I'll be flying down south.

[rainsucks]

5 minutes ago, Powerball said:

So has the GGEM.

I need it to at least stay warm through Friday, when I'll be flying down south.

In a way the GGEM extended the warmth into the weekend. It's not a reliable model at all, so I don't trust it.

[Chinook]

1 hour ago, WxMatt21 said:

Nice long term AFD discussion by IWX this afternoon. We have talked a lot about the 2007 analog lately, and the CPC seems to be weighting that year pretty heavily, too: 

I may be late to the game on this, but you know what happened next, in winter 2007-08, 71.7" of snow at DTW, and 58.1" of snow at Toledo.

[Hoosier]

18z GFS made a large shift toward the ECMWF with the frontal timing.  Still not quite as fast...

Then the warmth surges back in toward the weekend.

[BuffaloWeather]

GFS and Euro ENS are warm up until about Oct 10th, beyond that is anyone's guess. 

[Chinook]

This is kind of interesting. The 12z GFS temp trace for Chicago is up to about 81 for the warmest day next week. The new GFS must simply have a built-in warmth that is not present in the GEFS members. look at how often the GFS is above the ensemble plumes

[RCNYILWX]

Models are still handling mid to late work week differently but whether via frontal passage and/or clouds/precip issues, better agreement now on Monday and Tuesday being the only very warm days in the central and western sub, with Wednesday likely quite warm farther east if a GFS like scenario verified. The quicker frontal passage of the Euro op and GEM does have support from 00z EPS ensemble mean.

Lots of uncertainty next weekend on op models and ensembles, with possible attempt in bringing back warmth at least aloft but again potential clouds/precip issues.

All in all, Tuesday would appear to be best day as things stand now to challenge October 2007 peak temps in western sub including Chicago. A tool we have locally for 925 mb climo using top 1/3 percentile and warmest values of the day suggests mid to upper 80s (85-88) in northern IL.

Monday is warmer on Euro and GEM and they may support mid to upper 80s using warmest 1/3 percentile and warmest of day, while GFS is slightly cooler aloft and more supportive of low 80s. Unless models come in with mid 20s at 925 mb, currently leaning against 90 occurring on Tuesday at ORD.

[Hoosier]

2 hours ago, RCNYILWX said:

Models are still handling mid to late work week differently but whether via frontal passage and/or clouds/precip issues, better agreement now on Monday and Tuesday being the only very warm days in the central and western sub, with Wednesday likely quite warm farther east if a GFS like scenario verified. The quicker frontal passage of the Euro op and GEM does have support from 00z EPS ensemble mean.

Lots of uncertainty next weekend on op models and ensembles, with possible attempt in bringing back warmth at least aloft but again potential clouds/precip issues.

All in all, Tuesday would appear to be best day as things stand now to challenge October 2007 peak temps in western sub including Chicago. A tool we have locally for 925 mb climo using top 1/3 percentile and warmest values of the day suggests mid to upper 80s (85-88) in northern IL.

Monday is warmer on Euro and GEM and they may support mid to upper 80s using warmest 1/3 percentile and warmest of day, while GFS is slightly cooler aloft and more supportive of low 80s. Unless models come in with mid 20s at 925 mb, currently leaning against 90 occurring on Tuesday at ORD.

Yeah, not as impressive/uninterrupted as it once looked.

Wednesday could have sneaky warm potential in northern IL if the front slows down a bit... even by 6 hours.  It should be a pretty warm start on Wednesday morning with winds staying up a bit overnight Tuesday.   Although it's a second rate model, the 12z GGEM has a significantly slower frontal passage and suggests a very warm Wednesday around Chicago.

[Hoosier]

HRRR and RAP did fairly well in general in catching onto warmer outcomes with the late September warm spell, so I will be interested to watch those models coming up.

[Chicago Storm]

HRRR and RAP did fairly well in general in catching onto warmer outcomes with the late September warm spell, so I will be interested to watch those models coming up.

Indeed. I'd go with whatever they show due to the mentioned great performance.