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Winter Storm? Jan 18-19th, 2019


cyclone77
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7 minutes ago, mimillman said:

Interesting evolution on the 3km NAM as well with the very clear move back west

Frankly it would be shocking if it doesn't come back west, given the overall synoptic pattern and land breeze asserting itself tomorrow evening/overnight.

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Calling it a 6.5" total here subject to verification. Generally a happy camper :snowman:

 

Storm positives:

  • Decent hit from a SLP south of the OHR
  • Last-minute ramp-up saving us from total lameness
  • Snow start to finish - no mixing bs
  • Sub-freezing wx leading up to storm meant zero melting underneath
  • Lightweight snow was an easy shovel for old dudes out of shape, lol
  • Gives us a base on which to build upping my interest level several magnitudes for whatever else this pattern wants to deliver
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LOT discussion hits on the things we've been discussing

Lake effect snow showers have shown some strengthening signs
upstream in Wisconsin, a sign colder low-level air is creeping
southward behind the departing cyclone. As it continues to do so,
more widespread light to moderate snow showers should be seen
developing into northeast Illinois early to mid evening. Guidance
continues to indicate a well-defined convergence area and
resultant moderate to heavy lake effect snow band across the
western part of the lake into Wisconsin early this evening and
shifting southward into northeast Illinois mid-late evening.
Forecast lake effect parameters remain generally similar to what
has been seen over the past 24 hours, though for far northwest
Indiana on Sunday morning the magnitude and residence time does
look better.

For this lake effect band, it is not a question of whether the
snow will be heavy, it is more so how long the residence time of
the band in any one place will be. That tends to be a very
challenging characteristic to determine greater than 12 hours in
advance. The lake effect parameters that are solid are the low-
level lapse rates and the convective cloud depths collocated with
the dendritic growth zone of -12C to -18C. This likely will make
up for the overall shallower cloud depths of 4-5 kft. The
inversion heights / equilibrium levels are lower and not what we
typically see for concerns of a six plus inch event. So that
battle of parameters continues. But given consistent high-
resolution model trends and applying lake effect banded snow
conceptual model points toward heavy snow (1+ inch per hour)
likely underneath that band. So a quick several inches along with
very low visibility, both from falling snow and some blowing
snow, is enough to warrant an Advisory. Have different start and
end times around the lake to account for the expected migration of
the band. In Indiana the time window has lower confidence hence
why it is longer, but some of the higher impacts are likely in the
morning into early afternoon.

For total snowfall with lake effect the residence time is the key
factor, so messaging 2 to 6 inches with the higher end a bit more
favored in northwest Indiana. Given the strong advection of the
lake effect parameters, lake effect snow is likely all the way
inland to the southern CWA border of Ford and Iroquois Counties!
The snow should not be that heavy that far inland, but some
accumulation including possibly over an inch is possible in parts
of eastern DuPage, Will, Kankakee, Newton, and Jasper Counties.
Some lake effect snow showers are likely to shift back westward
and possibly back into Illinois Sunday evening/overnight, but
parameters should be weakening as the wind field diminishes.
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8 minutes ago, snowcaine said:

1.5" in Toronto so far. Snow has stopped for now.

We really do have a talent for getting utterly screwed with every system. Our last >8" storm was 4 years ago. Our last >12" storm was 6 years ago.

I think the northern edge scrapes most of the GTA with better snow than the pixie dust earlier. I think this evening will bring an additional 2-4" which might bring some areas especially close to the lake to almost 6"

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5 hours ago, Aleksey said:

@cyclone77 What have you ended up with?

4.8".  Not for sure but guessing ratios were around 10:1.  The snow is light in nature, but it packed in pretty well with all that wind.  The granulated nature of the snow, and only around 100mb of DGZ depth likely kept ratios fairly conservative.  MLI/DVN ended up with 4.2/5.2" respectively.  Amounts around the area were generally in the 4-5" range.  The fact that the snow sort of compacted as it fell makes it a good quality snow, as it shouldn't compact and lower the overall snow depth.  Was a fun, yet kind of frustrating event to track lol.  :snowing:

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3 minutes ago, mississaugasnow said:

I think the northern edge scrapes most of the GTA with better snow than the pixie dust earlier. I think this evening will bring an additional 2-4" which might bring some areas especially close to the lake to almost 6"

Pretty much what I was going to say. I think heavier snow is expected between 10 PM and 2 AM. Is it ever looking cold tomorrow night. Lows down to about 10 below Fahrenheit without the windchill factored in.

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2 hours ago, geddyweather said:

Hindsight of course is 20/20, but a few of the 12z/18z runs (12z GFS, 12z CMC, 18z 12kNAM are the ones that appear in my head from memory) from Thursday had the setup nailed down the fairly well in IN/OH/parts of SEMI. Of course then things went down the drain at 00z that night setting up 24 hours or so of flat out mayhem. It will be interesting when this is all said and done to look back more deeply and determine what the system itself did, how it affected models in the close ranges, and if there is anything models could do to get a better grip on occurrences like this. 

My question is why did people believe it in the first place. These stronger storms almost always come north the day of because the WAA pushes back against the high pressure more than predicted

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5 minutes ago, cyclone77 said:

4.8".  Not for sure but guessing ratios were around 10:1.  The snow is light in nature, but it packed in pretty well with all that wind.  The granulated nature of the snow, and only around 100mb of DGZ depth likely kept ratios fairly conservative.  MLI/DVN ended up with 4.2/5.2" respectively.  Amounts around the area were generally in the 4-5" range.  The fact that the snow sort of compacted as it fell makes it a good quality snow, as it shouldn't compact and lower the overall snow depth.  Was a fun, yet kind of frustrating event to track lol.  :snowing:

ORD had 0.28" precip and 5.0" snow.  Granted that precip total is likely underdone given we are talking about ASOS in windy conditions.

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15 minutes ago, Ottawa Blizzard said:

Pretty much what I was going to say. I think heavier snow is expected between 10 PM and 2 AM. Is it ever looking cold tomorrow night. Lows down to about 10 below Fahrenheit without the windchill factored in.

Yep, as much as it sucks missing out on the 12-20" totals across the border at least almost everyone in the GTA will have 2-6" (6-15" for the winter storm warning areas) to go with the cold. Bare ground and cold would have been awful. 

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Got maybe an 1 1.5 inches  There's still hope! lol

Mesoscale Discussion 0031
   NWS Storm Prediction Center Norman OK
   0321 PM CST Sat Jan 19 2019

   Areas affected...Southern Illinois...far western Kentucky...and west
   central into central Indiana.

   Concerning...Heavy snow 

   Valid 192121Z - 200015Z

   SUMMARY...Rain, freezing rain, and sleet will continue to transition
   to snow from northwest to southeast with moderate to heavy snowfall
   expected across this area through the remainder of the afternoon and
   into the evening.

   DISCUSSION...In the last hour, winds have shifted to northerly up to
   2 km on the KIND and KVWX VWP as the 850mb low has started to shift
   east of that longitude. This has started to switch rain to snow
   across portions of this area with a continued transition expected
   over the next several hours. The developing deformation band will
   likely have snowfall rates in excess of an inch per hour. Therefore,
   significant snowfall accumulations are likely through the evening
   before the system shifts east and drier air moves into the area. In
   addition to the impacts from the rapidly accumulating snowfall,
   winds of 20 to 30 mph with gusts as high as 40 mph will cause
   significant blowing and drifting and visibility restrictions. This
   will become particularly impactful during the evening hours as a
   colder airmass advects into the area and leads to a drier snow which
   will be more prone to blowing and drifting.

   ..Bentley.. 01/19/2019
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5.5" in Columbus Grove as of now, measured from a sheltered potting bench. Possibly low balling as there are some 6" reports not far to my north, but measurement elsewhere is simply not possible. Several 18-24" drifts here which will grow even more as the defo band and winds continue into the night. Took a quick spin around the country block a couple hours ago, roads were atrocious and visibility was <300ft at times. 

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