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Chicago Storm

Nov. 10-11th snow event thing

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So the big question for the area around Chicago proper and into my area is what are temps going to be like for the bulk of the snow?  Is it 32-33 or more like 34-35, because that makes a difference.  In any case, going to be looking at locally lower ratios near the shore.  Water temps near the shore are low-mid 40s while still in the upper 40s farther out in the lake.  

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I'm hoping the cold air makes a stronger appearance. Even though its early in the season, It always breaks my heart to see Central OH go all rain every time.

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DTX is pretty hype this afternoon.

Quote
The main weather concern for this forecast period will be the
potential for widespread accumulating snow on Sunday night into
Monday. Global models have reached better consensus depicting low
pressure developing over the upper Ohio Valley on Monday in response
to a shortwave diving into the region from Manitoba. Latest
deterministic runs are fairly consistent in developing the low along
the baroclinic zone after it clears our area, which gives reasonable
confidence that our area may fall within the northwestern flank
deformation forcing. With post-frontal temps in the upper 20s,
expect snow that falls to stick. Current forecast calls for an area-
wide coverage of several inches of snow with the best chance south
of I-69. Expect forecast refinements this weekend as additional data
is ingested and the track and strength of the low is better
discerned.

 

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It is not easy to get lake enhanced snow into Chicago in early to mid November.  Here's why.

mswt-03.gif.08df82b5eb56de4d4543d2f9550f22b6.gif

Progged low level flow is basically full fetch down the lake over all that mid 40s to nearly 50 degree water.  A lot of November setups will fail because the airmass just isn't cold enough.  One example is 11/24/2004, which had a distinct snow minimum surrounding the lake.  Another case which Alek will remember is 11/21/2015, which kept it raining in downtown Chicago for the majority of the time (while hammering inland toward ORD) until finally switching over toward the end.

In the 2004 case, 850 mb temps were around -5C.  In 2015, they were more in the -6C to -8C range.  This time they are progged to fall to -10C while the low level flow is still directed into the IL shore.  Typically by the time 850 mb temps are that cold at this time of year, the flow has already shifted to favor IN or MI.  

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This seems like one of the rare occasions this early in the season where the lake shore can outperform the burbs. I think the timing of the front is key for the metro area as the more precipitation we can maximize outside of peak daylight hours, the more significant accumulations can be.

Temps are certainly not as marginal as the last event.

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Should clarify that I meant getting higher totals near the lake in northeast IL is not easy to do this early.  This setup is better than many at this time of year, but I have a hard time believing that the shore will outsnow places farther inland like ORD/MDW.  Who knows though with how this winter has started lol

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It is not easy to get lake enhanced snow into Chicago in early to mid November.  Here's why. mswt-03.gif.08df82b5eb56de4d4543d2f9550f22b6.gif Progged low level flow is basically full fetch down the lake over all that mid 40s to nearly 50 degree water.  A lot of November setups will fail because the airmass just isn't cold enough.  One example is 11/24/2004, which had a distinct snow minimum surrounding the lake.  Another case which Alek will remember is 11/21/2015, which kept it raining in downtown Chicago for the majority of the time (while hammering inland toward ORD) until finally switching over toward the end.

In the 2004 case, 850 mb temps were around -5C.  In 2015, they were more in the -6C to -8C range.  This time they are progged to fall to -10C while the low level flow is still directed into the IL shore.  Typically by the time 850 mb temps are that cold at this time of year, the flow has already shifted to favor IN or MI.  

 

 

I know 11/25-26/18 is not as good a comparison because the air mass was also too warm aloft initially but it was another case of full fetch down the lake making it tough to get much accums downtown. All of the snow lakeside fell on the morning of the 26th when low level flow turned northwesterly and cold advection intensified.

 

For Monday I'm not sold yet it's going to be a big deal lakeside for IL. In addition to the low level flow being a full fetch down the still mild lake (could see northerly Island being locked at 33 to even 34 while flow is onshore), the Euro and the NAM are a bit slower with the CAA so 850 mb temps 12z Monday are only about -8 to -9, yielding delta T with Chicago shore water temp of about 15-16 C. Equilibrium levels less than 6kft prior to 12z only get up to just shy of 7kft by 15z, which is pretty marginal. Gonna need the low level convergence to hold back longer over the southwest part of the lake like the 12z Canadian to allow the cold air to deepen and improve parameters as well as cool the boundary layer sufficiently.

 

The 18z GFS is quicker with the CAA but it also is much quicker with flow turning to NNW and favoring Indiana. Even for inland of the lake in IL, the NAM and ECMWF being marginal with thermodynamics during most favored timing of convergent boundary layer flow casts some doubt on how much lake enhancement there will be.

 

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42 minutes ago, RCNYILWX said:

I know 11/25-26/18 is not as good a comparison because the air mass was also too warm aloft initially but it was another case of full fetch down the lake making it tough to get much accums downtown. All of the snow lakeside fell on the morning of the 26th when low level flow turned northwesterly and cold advection intensified.

 

For Monday I'm not sold yet it's going to be a big deal lakeside for IL. In addition to the low level flow being a full fetch down the still mild lake (could see northerly Island being locked at 33 to even 34 while flow is onshore), the Euro and the NAM are a bit slower with the CAA so 850 mb temps 12z Monday are only about -8 to -9, yielding delta T with Chicago shore water temp of about 15-16 C. Equilibrium levels less than 6kft prior to 12z only get up to just shy of 7kft by 15z, which is pretty marginal. Gonna need the low level convergence to hold back longer over the southwest part of the lake like the 12z Canadian to allow the cold air to deepen and improve parameters as well as cool the boundary layer sufficiently.

 

The 18z GFS is quicker with the CAA but it also is much quicker with flow turning to NNW and favoring Indiana. Even for inland of the lake in IL, the NAM and ECMWF being marginal with thermodynamics during most favored timing of convergent boundary layer flow casts some doubt on how much lake enhancement there will be.

 

Sent from my SM-G965U using Tapatalk

 

 

 

 

 

 

 

Thanks for the thoughts as always.  Looking quickly at Chicago snow records in the first half of November, there's not a whole lot of significant snow events to try to use to compare 850 temps, and even fewer since the better upper air data started back in the late 1940s into the 1950s.  Might be worth taking a look at what kind of setup was in place in the mid November 1996 or 1997 event that dumped on Lake county IL, though I think a mesolow may have been responsible for that.  

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am I missing that this looks like a 1"-2" event? Which isn't crazy for early November. That said, if we get a snow cover the cold thereafter will be something to talk about.

 

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1 minute ago, Gino27 said:

Not really sure what the NAM just put out... looks like nothing for pretty much most of the Midwest except for lake effect areas.

The NAM just being the NAM...

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Just now, Jim Martin said:

The NAM just being the NAM...

I figured. My hope is that this thing can get its act together and lay some nice snow down for Central OH.

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29 minutes ago, Chicago Storm said:

11/14-15/1997 is another western shore LES event.

That is the one I mentioned, but couldn't remember if it was 1996 or 1997.  Somebody did a case study on it that I read many years ago... I thought maybe it was LOT that wrote it but I can't find it now.  Anyway, that event looks like it had 850 mb temps around -6C to -8C which cooled to -9C or -10C.

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8 hours ago, Gino27 said:

Not really sure what the NAM just put out... looks like nothing for pretty much most of the Midwest except for lake effect areas.

Not quite in the Nam's wheel house yet.

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Sheesh, GRR's AFD reads like it's middle of winter..

 

.DISCUSSION...(Today through next Friday)
Issued at 305 AM EST Sat Nov 9 2019

We have three significant weather events to watch in the next
week. First is the jet lift event Sunday night into midday Monday.
All the models have some version of this event but given how
often we get a significant precipitation event when we are in the
entrance region of a 140 to 150 knot jet core as a surface wave
develops on the front to our south, I would say we may well see
enough snow Sunday into into midday morning to cause significant
travel issues near and south of I-96. The latest run of the ECMWF
has between .25 and .40 inches of water falling as snow south of a
line from Lansing to Kalamazoo. We need to watch this to see how
this plays out since the jet causing this is part of the reason we
get all that cold air Tuesday into Wednesday.

The polar jet that causes that surface wave Monday finally gets
east of here Monday evening. It is at that time we get into the
really deep cold air and inversion heights rise above 10,000 ft.
Since we have an east coast storm at that point, winds through 700
mb will mostly be from the north or north northwest Monday night
into early Wednesday. So, this will create a narrow but intense
dominant lake snow band that for the most part will stay near and
west of US-131 Monday night into early Wednesday. AT locations
like South Haven there is strong lift centered in the DGZ, which
is in the 2000 ft to 5000 ft layer (where the clouds will be).
This could be a warning class event (over a very narrow area)
during this time. Winds will be 15 to 25 mph with gusts over 30
mph with heavy snow falling for many hours in locations like
South Haven and Covert.

Meanwhile inland of that due to the north winds and the dominant
snow band not much will happen, it will just be cold! Maybe a few
flurries or light snow showers but not much accumulation. Record
low highs are in the mid to upper 20s (27 at Grand Rapids and
Muskegon, 29 Lansing and Baldwin, 26 Jackson) so record low highs
are more than possible. Even if the sun comes out at inland sites.

There is of course another upstream Pacific system that moves into
the Pacific Northwest Tuesday night. That boots this cold air
system east and brings warmer (relative to Tuesday and Wednesday)
air back to the area. The warm advection snow event is more than
possible Thursday. If that happens most of the area would see 2 to
4 inches of snow before afternoon temperatures warm into the 40s
Friday into the following weekend.

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