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Pre-Christmas (Dec 21-23rd) Winter Storm

Chicago Storm

By Chicago Storm,
in Lakes/Ohio Valley

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RCNYILWX
RCNYILWX

As much as the high end Kuchera ratios are overdone (24:1+ in western IL/eastern IA on last night's insane 00z GFS), banking on 10:1 ratios is also underdone. With the exception of 1967, Chicago's #2

RCNYILWX
RCNYILWX

. Sent from my SM-G998U using Tapatalk

OHweather
OHweather

Just looking at the last several Canadian and GFS runs, seems like the general waveguide over the US isn't changing much, but changes upstream/downstream of our trough over Canada are influencing how

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Roger Smith

Roger Smith

Posted
Posted
8 minutes ago, schoeppeya said:

Anybody know the average SLP error for this time range?

At this stage it's probably more like the average positional error, I think the pattern emerging will sustain a 960-970 low somewhere within 200 miles of Detroit in any direction. There is probably about a 10% chance of this continuing to push further north on later model runs to the extent that MSP and DLH get the sweet spot, and there's maybe a 10% chance of it returning to a coastal, a 20% chance it's more like an Apps runner, and various other percentages closer in to the consensus track today. With the heights crashing on all guidance and -40 C air mass emerging out of northwest Canada already today, can't see how this fails to deepen explosively once it rounds the base of the trough. I think there could be minor shifts back towards the Ohio valley to Cleveland sort of a track as the cold air pushes in ahead of the final wave and forces it to take a sharper curve around TX-AR. As intense as this looks now, there are ways it can actually become more intense. It really doesn't pull in a lot of Gulf moisture for example but a sharper trough might do that. 

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andyhb

andyhb

Posted
Posted

Could actually see severe blizzard conditions verify over a pretty large area if this thing is as intense as it could be.

This one checks off all the boxes as of now.

“A severe blizzard has winds over 72 km/h (45 mph), near zero visibility, and temperatures of −12 °C (10 °F) or lower.“

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mimillman

mimillman

Posted
Posted 
Issued at 221 PM CST Sun Dec 18 2022

Tuesday through Sunday...
All eyes in the long term period are on the late week cyclone and
intrusion of bitterly cold air along with dangerous wind chills
late this week into the weekend.

Confidence continues to steadily increase that a potentially
crippling blizzard could impact portions of the region later this
week, the timing of which couldn`t be worse for holiday travel.
If, and how severely, our forecast area (CWA) will be impacted
depend on the exact track of the cyclone and to some extent the
magnitude and timing of the forecast rapid deepening.

Medium range guidance has been advertising a powerful cyclone
spinning up over the Great Lakes or northeast U.S. for days now,
with a pretty sizable spread in where the storm will
develop/track. There was a cluster of guidance favoring a Great
Lakes target region, which would increase chances for major
impacts in our CWA, with a second cluster favoring the New England
resulting in disruptive, but far less extreme winter weather
locally. Trend in ensemble guidance over the past 48 hours has
been decidedly away from a New England cyclone and toward
cyclogenesis farther west over the Great Lakes with recent runs of
the GFS/GEFS making the significant shift west.

While track guidance has shown (pretty typical) variability, the
theme of rapid, and potentially explosive, deepening of the
cyclone has been a fairly consistent theme in guidance for days
now. The expected intensity of the cyclone combined with the very
strong arctic high (>1040mb) over the northern and central Plains
leads to high confidence in a noteworthy high wind event with this
system.

The eventual track of the cyclone and timing of rapid/explosive
deepening will determine where the very high impact winter
weather/potential blizzard will set up. Given recent model and
ensemble trends, our CWA lies very solidly within the potential
threat region. The incipient wave that is forecast to spawn this
system is still located north of Alaska across the Beaufort Sea,
so it still has a lot of distance to cover with plenty of time for
shifts in guidance. It isn`t uncommon for models to make leftward
adjustments to the track of powerful cyclones like this, so it is
important not to get locked in on a forecast track yet.

At this distance, it is also advisable not to focus on individual
operational runs of models, as operational runs will likely
exhibit variability in the strength and especially track over the
next couple or days. This run to run variability in operational
runs is often not an actual "trend" but rather "noise" in the
range of possibilities at this distance. Rather than focusing on
noise level changes in operational runs, focusing on trends in
ensemble data the next couple of days should prove more meaningful
as we look to hone in on location and magnitude of the threat.

In addition to producing blizzard conditions, the high winds will
likely cause lakeshore flooding (which shore depends on track of
cyclone) and dangerous wind chills well below zero. Currently,
most guidance strongly supports advisory level wind chills (-20
to -30F) Friday into at least the first half of the Christmas
weekend, with some potential for even a period of warning level
(colder than -30F) wind chills as actual air temperatures plummet
below zero. All indications are that our high temp Christmas Day
will be the coldest since the mid 90s and possibly one of the top
five coldest on record. Any power outages resulting from the
strong winds greatly increase potential danger of the cold spell.

We strongly urge everyone to pay close attention to later
forecasts, particularly if you have holiday travel planned.

- Izzi

 

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Chicago Storm

Chicago Storm

Posted
  • Author
Posted
4 minutes ago, michsnowfreak said:

When is the all important sampling?

 

There are several pieces the the puzzle that are being sampled today and tomorrow.

However, the main wave is being sampled today/tomorrow over Alaska, and then will be sampled over SW Canada and the Pac NW on tomorrow/Tuesday once again.

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ChiTownSnow

ChiTownSnow

Posted
Posted
4 hours ago, Chicago Storm said:

Still a few days away from that.

Should current guidance pan out... Lead snow chances possibly as early as Wednesday night, but main system snow generally Thur/Fri.

So look for the late Tuesday or Wednesday time frame.  Given holiday maybe more late Tuesday?  Assuming current guidance continues 

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RCNYILWX

RCNYILWX

Posted
Posted
How would this Chicago storm compare to 1967, 1979, 1999? More wind and power outages I assume. Can’t wait for Tom Skilling and WGN forecast maps.
As currently modeled by the ECMWF and GFS, this storm would be worse than GHD I. The extreme cold in addition to the snow and similar magnitude winds is a game changer.

Sent from my SM-G998U using Tapatalk

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Sciascia

Sciascia

Posted
Posted
11 minutes ago, RCNYILWX said:

As currently modeled by the ECMWF and GFS, this storm would be worse than GHD I. The extreme cold in addition to the snow and similar magnitude winds is a game changer.
 

I didn’t think it was possible to experience something worse than GHD I. I remember those winds vividly, so violent.

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