10/29-10/31 Halloween Winter Storm

[Clinton]

3km Nam

[Madtown]

front end south defo north!

[Money]

Looks like some pretty strong winds on 3k NAM also in that run. Encouraging to see models trend stronger with the low as we get closer

[East Dubzz]

How in the world did Chicago manage to pull this one in?! Haha. Hopefully we all get in on a little action!

[Sciascia]

3km Nam

Whoa nelly!

[Madtown]

let's see what that silly gfs has to say now

[snowstorm83]

How in the world did Chicago manage to pull this one in?! Haha. Hopefully we all get in on a little action!

 

Lmao ikr. Not trying to be one of those "Chicago bad" people, but that place is a storm magnet for sure! 

[St Paul Storm]

Wow. Imagine flights cancelled at O’Hare and Midway because of a freak October snowstorm. Wild stuff.

[jaster220]

Last 3 runs of the Euro thru 7 am Friday. Can see how it's been steadily increasing snow across SWMI. Never thought I was in the game tbh-go figure

 

 

 

[Money]

Icon and NAM look nearly identical through hr 30

[jaster220]

3K NAM is just a beauty. Low is stronger/west and beautiful defo band of snow that sits in E IA/WI for hours

 

yeah, SWI really gets the pivot bullseye. 986mb in N. Lk Huron Thursday after dark. Sweet

[Niko]

Last 3 runs of the Euro thru 7 am Friday. Can see how it's been steadily increasing snow across SWMI. Never thought I was in the game tbh-go figure

 

20191028 12z Euro h96.PNG

20191029 0z Euro h84.PNG

20191029 12z Euro h72.PNG

Wow....looking good bud.

[jaster220]

yeah, SWI really gets the pivot bullseye. 986mb in N. Lk Huron Thursday after dark. Sweet

 

Keeps getting lower with every run, lol.

 

NAM = #funtimes

 

[jaster220]

Nebraskan in Chicago. Maybe you're gonna get lucky after all..

 

 

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
909 PM CDT Tue Oct 29 2019

.UPDATE...
909 PM CDT

Tricky forecast overnight into early Wednesday morning as low
amplitude shortwave trough over the southern Plains this evening
races northeast toward the lower Great Lakes by midday Wednesday.
Some backing and strengthening of the low/mid level flow in
advance of this shortwave aided by the thermally indirect
circulation in the right entrance region of the strong upper level
jet will result in a strengthening frontogenetic circulation.

Forecast thermal profiles look to be precariously close to the
rain/snow line, which naturally lends itself to some uncertainties
with respect to p-type and any potential snow accumulations.
However, cross sections through the f-gen circulation show strong
omega co-located with negative saturated EPV, an indication of
weak stability/potential instability. This, combined with the
strong omega, could result in some heavy banded precip. The
heavier precip rates would tend to push thermal profiles more
toward all wet snow due to dynamic cooling. In addition, forecast
soundings look exceptionally favorable for large aggregate
snowflakes, which could result in greatly reduced visibilities
(wouldn`t be surprised to see some 1/2SM to 1/4SM) in the heavier
snow.

Models generally agree that 2m wet bulb temps will remain near or
just above freezing, which given warm pavement temps will result
in melting and snow-to-liquid ratios. However, even with the warm
ground and marginal 2m temps, snow falling at moderate to heavy
clip will accumulate, likely even on roadways. Latest guidance
that has come in this evening would generally tend to support the
going forecast, which has an axis of heaviest accumulating snow
from LaSalle County northeast toward the western and southern
Chicago suburbs. I do have concerns that the fairly light
surface winds could mean less lake warming in Chicago and the
immediate metro area and could allow for more snow falling even
into the city limits. Going to update grids and forecast to hit
snow a bit harder in the city and burbs with a bit more
accumulation, but certainly possible that snow could be a bigger
problem into the metro area than this. Strongly considered
expanding the winter wx advisory northeast into the metro area,
but still not confident in the switch over to snow in the city and
even less confident in impactful accumulations.

Any snow should switch over to light rain and drizzle by late
morning we lose ice nuclei in the clouds and column warms solidly
above freezing.

- Izzi

[Niko]

Impressive positive tilted upper level PV anomaly is forecasted to
dig into the Four Corners tonight before phasing favorably with
seasonally strong southern stream jet axis. Increased momentum
ejecting through the subgeostrophic trough base will then help
favorable jet dyanmics aloft in causing rapid negative tilt to PV
anomaly and spin-up cyclogenesis from the Ohio River Valley into the
central Great Lakes. The big development with this Halloween storm
system is that the ECMWF is back with a 991 mb surface cyclone over
Georgian Bay 00Z Friday. Very strong direct PV advection will
increase in warm advection will lead to categorical rain during the
daylight Thursday. Looking at short duration window of relatively
drier conditions centered around the 21-00Z timeframe as a midlevel
dry slot could lift directly into the state. Conditions will remain
wet and damp, but a reprieve in falling precipitation may happen.
Inherent uncertainties exist with the details because of latent heat
anomalies and their impact on forcing timing/magnitude and
thermodynamic profiles. Given amount of warm advection and the track
of the cyclone, support an all rain solution during the daylight
hours with a total changeover to snow all areas after sun down. A
couple of items that need to be ironed out...1. Presence and
longevity of cold conveyor deformation axis Thursday night. Current
trajectory of latest ECMWF/NAM suggests a flatter system overall and
less likelihood for dry slot to clear out all of the area. A more
developed deformation could bring multiple inches of snow to
forecast area north of I 69, particularly the Thumb. 2. The other
item that needs to be watched closely is what sort of high wind
potential exists for the cwa. Current trajectory of the storm and
wind direction forecasts suggests a high impact wind event could
occur for those areas downwind of Saginaw Bay in Tuscola and Huron
counties.

[jaster220]

Even OHweather is chiming in for the Chi-town situation (he's a Met, working in NJ currently)

 

I'm at work and have had a fun few hours pulling my hair out over this...I like 2-4" all the way into the W and S suburbs including LOT and JOT (maybe MDW or just west) and even ORD if the precip gets far enough north.  I have no idea what the immediate Chicago area will do, gut says white rain but Izzi's point about the weak onshore flow initially is good and banded snow can trump the UHI if you aren't blowing wind off of a 50 degree lake so that could be fun.  The flow does turn more onshore quickly so they may start as a sleety mix, go to mostly snow for a time, then go back to mostly rain before it gets too out of hand in Chicago.  There's definitely enough slantwise instability for banded moderate to heavy snow probably enough fgen to focus it (omega on the NAM is decent but have definitely seen better).  Ratios will suck but 2-4" should be attainable into the W and S Chicago suburbs (I have no clue where the N cutoff is but someone near or just N of DPA/ORD will be disappointed.  This should impact the commute where it's mostly or all snow (also if there's any sleet mixing in that would help with road stickage) as a moderate to heavy wet snow will put a thick layer of slush on roads. 

 

[Niko]

Clinton- did ya get any snow outta this system?

[Clinton]

Clinton- did ya get any snow outta this system?

Not yet, currently have a mix of rain, sleet, and snow.  Expect accumulations to start tomorrow afternoon.

[jaster220]

  lovin this stuff amigo!

 

Impressive positive tilted upper level PV anomaly is forecasted to
dig into the Four Corners tonight before phasing favorably with
seasonally strong southern stream jet axis. Increased momentum
ejecting through the subgeostrophic trough base will then help
favorable jet dyanmics aloft in causing rapid negative tilt to PV
anomaly and spin-up cyclogenesis from the Ohio River Valley into the
central Great Lakes. The big development with this Halloween storm
system is that the ECMWF is back with a 991 mb surface cyclone over
Georgian Bay 00Z Friday. Very strong direct PV advection will
increase in warm advection will lead to categorical rain during the
daylight Thursday. Looking at short duration window of relatively
drier conditions centered around the 21-00Z timeframe as a midlevel
dry slot could lift directly into the state. Conditions will remain
wet and damp, but a reprieve in falling precipitation may happen.
Inherent uncertainties exist with the details because of latent heat
anomalies and their impact on forcing timing/magnitude and
thermodynamic profiles. Given amount of warm advection and the track
of the cyclone, support an all rain solution during the daylight
hours with a total changeover to snow all areas after sun down. A
couple of items that need to be ironed out...1. Presence and
longevity of cold conveyor deformation axis Thursday night. Current
trajectory of latest ECMWF/NAM suggests a flatter system overall and
less likelihood for dry slot to clear out all of the area. A more
developed deformation could bring multiple inches of snow to
forecast area north of I 69, particularly the Thumb. 2. The other
item that needs to be watched closely is what sort of high wind
potential exists for the cwa. Current trajectory of the storm and
wind direction forecasts suggests a high impact wind event could
occur for those areas downwind of Saginaw Bay in Tuscola and Huron
counties.

 

[Niko]

Not yet, currently have a mix of rain, sleet, and snow.  Expect accumulations to start tomorrow afternoon.

Good luck to ya amigo....

[Niko]

  lovin this stuff amigo!

Looks interesting, I'll tell ya that bud!

[Clinton]

Good luck to ya amigo....

Thanks, I'll be on the southern edge hoping to get 2 or 3 inches

[Niko]

Thanks, I'll be on the southern edge hoping to get 2 or 3 inches

I can see your area receiving a couple of inches of snow. (1-3" in the game) Kinda gets you in the holiday spirit

[Clinton]

I can your area receiving a couple of inches of snow. (1-3" in the game) Kinda gets you in the holiday spirit

Looks like the GFS wants to get things going tonight, I guess we shall see.

[jaster220]

Impressive positive tilted upper level PV anomaly is forecasted to

dig into the Four Corners tonight before phasing favorably with

seasonally strong southern stream jet axis. Increased momentum

ejecting through the subgeostrophic trough base will then help

favorable jet dyanmics aloft in causing rapid negative tilt to PV

anomaly and spin-up cyclogenesis from the Ohio River Valley into the

central Great Lakes. The big development with this Halloween storm

system is that the ECMWF is back with a 991 mb surface cyclone over

Georgian Bay 00Z Friday. Very strong direct PV advection will

increase in warm advection will lead to categorical rain during the

daylight Thursday. Looking at short duration window of relatively

drier conditions centered around the 21-00Z timeframe as a midlevel

dry slot could lift directly into the state. Conditions will remain

wet and damp, but a reprieve in falling precipitation may happen.

Inherent uncertainties exist with the details because of latent heat

anomalies and their impact on forcing timing/magnitude and

thermodynamic profiles. Given amount of warm advection and the track

of the cyclone, support an all rain solution during the daylight

hours with a total changeover to snow all areas after sun down. A

couple of items that need to be ironed out...1. Presence and

longevity of cold conveyor deformation axis Thursday night. Current

trajectory of latest ECMWF/NAM suggests a flatter system overall and

less likelihood for dry slot to clear out all of the area. A more

developed deformation could bring multiple inches of snow to

forecast area north of I 69, particularly the Thumb. 2. The other

item that needs to be watched closely is what sort of high wind

potential exists for the cwa. Current trajectory of the storm and

wind direction forecasts suggests a high impact wind event could

occur for those areas downwind of Saginaw Bay in Tuscola and Huron

counties.

 

If these storms keep taking this track and amping up the way they have been, just a matter of time til we see this..

 

[Madtown]

hey there gfs...no cavin yet

[bud2380]

GFS with about 5” IMBY. I’ll take that for sure.

[Niko]

Looks like the GFS wants to get things going tonight, I guess we shall see.

Exactly and at least its on the right track....

[Niko]

If these storms keep taking this track and amping up the way they have been, just a matter of time til we see this..

 

Bliz of 78-Toledo.jpeg

Dang! Reminds me of the EC blizzards

[Stormhunter87]

Dam I know 10:1 is a hard sell in October but my family in central Illinois is in the jack zone based on Nam and gfs.

[Hawkeye]

00z Euro has Cedar Rapids down to only 0.10" precip.  Other models are a bit more.  Regardless of the exact amount, this system could have been so much more for Iowa.  The pieces of energy just aren't going to interact quite as well as necessary.  Oh well.  I suppose I'd rather save the biggies for winter.

[Grizzcoat]

Parts of Chicago area now under WWA. ORD and MDW now reporting snow or a mix. Tom steals the show once again!!! HA!

[Tom]

Parts of Chicago area now under WWA. ORD and MDW now reporting snow or a mix. Tom steals the show once again!!! HA!

TBH, I'll take whatever snow falls as a win-win in any situation for late October.  I also like setting records which by all accounts will happen tomorrow for Halloween which is pretty neat.  I'd much rather prefer seeing big snows as we head deeper into November so it can stick around for longer periods.  

[Grizzcoat]

Just when I thought this system couldn't peter out anymore ; both RAP and HRRR really drying it out-  hopefully not a trend. T/D depressions are not favorable and I think much of the radar echoes in E.Ne and W.IA is virga. By the time saturation occurs much of the forcing will have moved E. Oh well...

[Tom]

Snow is starting to accumulate as I have my first coating of the season.  Nice big flakes falling and some heavier radar returns trying to budge north.  Extremely sharp cutoff right over my county.  Coldest temp of the season (32F)...#letitsnow

 

 

 

[Clinton]

Based on what is happening here right now it looks like the GFS is handling this system the best.  I am currently 34 with a mixed bag of precip which is what it is calling for.  The GFS puts down accum snow here this evening which seems reasonable the Euro says I should have a inch on the ground already in which I don't.

[Tom]

I can't help but think about how this system will look like in future cycles and could end up being a true Arklatex bomb if the pattern sets up just right.  It's nice to see the models show a significant intensification of the SLP as it tracks up the OHV where the LRC's Long Term Long Wave Trough is taking shape.

[Clinton]

I can't help but think about how this system will look like in future cycles and could end up being a true Arklatex bomb if the pattern sets up just right.  It's nice to see the models show a significant intensification of the SLP as it tracks up the OHV where the LRC's Long Term Long Wave Trough is taking shape.

It could happen right around Christmas. 

[Tom]

It could happen right around Christmas. 

It's hard to say right now how long the LRC is going to be this year.  Gary Lezak said some years the cycle has been up to 60 days long and as short as 40 days I believe it was.

[Madtown]

hows it looking up this way?