December 24-25 Snow Potential

[snowstormcanuck]

1 hour ago, harrisale said:

Visiting the parents for the holidays, about 30 mins west of Toronto. May actually pull off 6-8" thanks to lake enhanced easterly flow as the low slides just to my south. Ended up right in the jackpot zone. 

Also worth noting the largest recorded Christmas Eve snowfall for Toronto is 1.4". Should smash that record tonight!

What a great Xmas gift!

 

Hard to believe how historically we see such little snow on Christmas Eve.

I think 4-6" as general rule looks good. 6-9" in that LES band. HRRR seems to like Oakville-Hamilton more than Toronto-Mississauga for that.

[purduewx80]

3 minutes ago, Chicago Storm said:

Lake enhancement making it as far inland as just past ORD now...

 

was just noticing on COD radar there is also an apparent smokestack plume emanating from near dekalb/shabbona. soundings show the southerly flow just above the surface. anyone know what is out there that could do that?

[Snowless in Carrollton]

Had just a little bit of snow here in Richmond, IN near the OH border but its already melted. Sun is out and its several degrees warmer than forecast. Not expecting any accumulation the rest of the day.

[Chicago Storm]

7 minutes ago, purduewx80 said:

was just noticing on COD radar there is also an apparent smokestack plume emanating from near sycamore. soundings show the southerly flow just above the surface. anyone know what is out there that could do that?

The only thing I can think of where it's originating from is the wind farm. Don't think there are really any big factories south of I-88, most are north of it.

[TugHillMatt]

3 minutes ago, Snowless in Carrollton said:

Had just a little bit of snow here in Richmond, IN near the OH border but its already melted. Sun is out and its several degrees warmer than forecast. Not expecting any accumulation the rest of the day.

I don't think it's as negative as you may think. There is a nice batch of snow in the southern half of Illinois moving your direction. Unless you were referring literally to just the "day"time....

[purduewx80]

2 minutes ago, Chicago Storm said:

The only thing I can think of where its originating from is the wind farm. Don't think there are really any big factories south of I-88, most are north of it.

wow, that's a first then. 

[BuffaloWeather]

This is the best lake enhanced setup for Toronto that I've seen in quite sometime. HRRR has 6-10" across Metro. 

[Hoosier]

RC update

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1115 AM CST Sun Dec 24 2017

.UPDATE...
1115 AM CST

Have made no changes to going winter weather headlines. Steady
light to occasionally moderate snow for most of the area and
temperatures in the upper teens to mid 20s is resulting in
hazardous road conditions for the busy Christmas Eve travel day.

The main focus this morning has been on the development of lake
enhanced/lake effect snow band into Cook County due to strong
lower level convergence along the southwest portion of Lake
Michigan and good thermodynamics despite fairly low inversion
heights. This band, per reflectivity and Chicago webcams, is
likely producing the heaviest snowfall rates of any area
currently. The transient nature of this band lifting northward
along the Cook County shore will keep accumulations in check, but
still expect highest IL metro totals in this area, of 3-5".

This afternoon, the northward movement of the band will cease and
it will likely shift southward, clipping the Cook county shore
again and then shifting into Northwest Indiana. Residence time
over Lake and Porter counties will determine top end snowfall
amounts in these counties, which is still a bit uncertain. Latest
high-res guidance suggests a fairly progressive band, which could
keep accums in check somewhat. Did not make changes to the
forecast message for Lake IN and Porter of 4-7/4-8 storm total
amounts.

For the rest of the area, except in the southern CWA counties, it
appears that snowfall rates are being kept more so in the light to
occasionally moderate range due to small flake size, which can be
seen visually outside the office window and has been relayed to us
by spotters. This appears to be the result of a bit of dry air in
the DGZ (not supersaturated with respect to ice in the DGZ) noted
on forecast soundings. To maximize snow ratios and rates in the
presence of a deep DGZ (which we do have), supersaturation of the
DGZ is needed, which doesn`t appear will fully occur. In addition,
while the strong mid-level wave over the region is providing more
than adequate lift, this lift is not consistently ideally locally
within the DGZ.

With all the above being said, there is still a few to several
hours to go of light to occasionally moderate snowfall rates, so
snowfall totals should end up fairly close to the advertised
ranges. Furthermore, the presence of small flakes is quite
effective in reducing visibility, with multiple sites down to 3/4
to 1/2 mile and even a few occasionally down to 1/4 mile. Given
this and the cold temps allowing for snow on road surfaces, travel
likely remains hazardous for much of the area. The snow will quickly
end from west to east (outside of lake effect snow) from mid
afternoon into the early evening

[BuffaloWeather]

Some nice Meso lows setting up north of Chicago. Those can have snowfall rates over 4" per hour. 

[homedis]

1 minute ago, Hoosier said:

RC update

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1115 AM CST Sun Dec 24 2017

.UPDATE...
1115 AM CST

Have made no changes to going winter weather headlines. Steady
light to occasionally moderate snow for most of the area and
temperatures in the upper teens to mid 20s is resulting in
hazardous road conditions for the busy Christmas Eve travel day.

The main focus this morning has been on the development of lake
enhanced/lake effect snow band into Cook County due to strong
lower level convergence along the southwest portion of Lake
Michigan and good thermodynamics despite fairly low inversion
heights. This band, per reflectivity and Chicago webcams, is
likely producing the heaviest snowfall rates of any area
currently. The transient nature of this band lifting northward
along the Cook County shore will keep accumulations in check, but
still expect highest IL metro totals in this area, of 3-5".

This afternoon, the northward movement of the band will cease and
it will likely shift southward, clipping the Cook county shore
again and then shifting into Northwest Indiana. Residence time
over Lake and Porter counties will determine top end snowfall
amounts in these counties, which is still a bit uncertain. Latest
high-res guidance suggests a fairly progressive band, which could
keep accums in check somewhat. Did not make changes to the
forecast message for Lake IN and Porter of 4-7/4-8 storm total
amounts.

For the rest of the area, except in the southern CWA counties, it
appears that snowfall rates are being kept more so in the light to
occasionally moderate range due to small flake size, which can be
seen visually outside the office window and has been relayed to us
by spotters. This appears to be the result of a bit of dry air in
the DGZ (not supersaturated with respect to ice in the DGZ) noted
on forecast soundings. To maximize snow ratios and rates in the
presence of a deep DGZ (which we do have), supersaturation of the
DGZ is needed, which doesn`t appear will fully occur. In addition,
while the strong mid-level wave over the region is providing more
than adequate lift, this lift is not consistently ideally locally
within the DGZ.

With all the above being said, there is still a few to several
hours to go of light to occasionally moderate snowfall rates, so
snowfall totals should end up fairly close to the advertised
ranges. Furthermore, the presence of small flakes is quite
effective in reducing visibility, with multiple sites down to 3/4
to 1/2 mile and even a few occasionally down to 1/4 mile. Given
this and the cold temps allowing for snow on road surfaces, travel
likely remains hazardous for much of the area. The snow will quickly
end from west to east (outside of lake effect snow) from mid
afternoon into the early evening

Nice write up! Lake effect has definitely been increasing our snowfall rates for a while, a nice little Christmas surprise

[Jackstraw]

For the rest of the area, except in the southern CWA counties, it
appears that snowfall rates are being kept more so in the light to
occasionally moderate range due to small flake size, which can be
seen visually outside the office window.....

Now thats some good old fashioned forecasting! lol.  Good discussion though. About 1/2 in. here, getting a little dry slotted.  Hoping the returns out west will intensify as they approach or gonna bust low.  As usual right on the line of blanket or dust.

[Stebo]

36 minutes ago, Tarheel17 said:

Going to squeeze in a run right before snowfall starts here NE of Detroit.

First snowfall of more than 1.5 inches for me in the past 3 years, and no chance of rain/ice/or sleet mixing in this time.

I'm out on Harsens Island, already snowing here, like sugar snow.

[cyclone77]

12 minutes ago, Hoosier said:

RC update

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1115 AM CST Sun Dec 24 2017

.UPDATE...
1115 AM CST

Have made no changes to going winter weather headlines. Steady
light to occasionally moderate snow for most of the area and
temperatures in the upper teens to mid 20s is resulting in
hazardous road conditions for the busy Christmas Eve travel day.

The main focus this morning has been on the development of lake
enhanced/lake effect snow band into Cook County due to strong
lower level convergence along the southwest portion of Lake
Michigan and good thermodynamics despite fairly low inversion
heights. This band, per reflectivity and Chicago webcams, is
likely producing the heaviest snowfall rates of any area
currently. The transient nature of this band lifting northward
along the Cook County shore will keep accumulations in check, but
still expect highest IL metro totals in this area, of 3-5".

This afternoon, the northward movement of the band will cease and
it will likely shift southward, clipping the Cook county shore
again and then shifting into Northwest Indiana. Residence time
over Lake and Porter counties will determine top end snowfall
amounts in these counties, which is still a bit uncertain. Latest
high-res guidance suggests a fairly progressive band, which could
keep accums in check somewhat. Did not make changes to the
forecast message for Lake IN and Porter of 4-7/4-8 storm total
amounts.

For the rest of the area, except in the southern CWA counties, it
appears that snowfall rates are being kept more so in the light to
occasionally moderate range due to small flake size, which can be
seen visually outside the office window and has been relayed to us
by spotters. This appears to be the result of a bit of dry air in
the DGZ (not supersaturated with respect to ice in the DGZ) noted
on forecast soundings. To maximize snow ratios and rates in the
presence of a deep DGZ (which we do have), supersaturation of the
DGZ is needed, which doesn`t appear will fully occur. In addition,
while the strong mid-level wave over the region is providing more
than adequate lift, this lift is not consistently ideally locally
within the DGZ.

With all the above being said, there is still a few to several
hours to go of light to occasionally moderate snowfall rates, so
snowfall totals should end up fairly close to the advertised
ranges. Furthermore, the presence of small flakes is quite
effective in reducing visibility, with multiple sites down to 3/4
to 1/2 mile and even a few occasionally down to 1/4 mile. Given
this and the cold temps allowing for snow on road surfaces, travel
likely remains hazardous for much of the area. The snow will quickly
end from west to east (outside of lake effect snow) from mid
afternoon into the early evening

Nice write-up.  Interesting note about the lack of supersaturaion throughout the DGZ.  Gonna have to watch for that in future systems while perusing the forecast soundings.

[MikeGold]

44 minutes ago, blackrock said:

Snowing very nicely here in West Michigan. Flakes are medium-sized. Not big dendrites, but certainly not the smallest that has fallen in these parts. That will come later this week when the air is cold and dry and we get Pixie dust lake effect snow. Definitely snowing moderate to heavily...Not quite to an inch yet, but getting there quickly. Nice to have our existing snowpack looking fresh again.

Dendrites appear to be excellent..."medium-sized" is probably the best way to describe it. Expecting a 14 to 1 ratio.  

[Chinook]

Moderate snow and 1/2 mile visibility at Goshen and Warsaw, Indiana. I am watching this sort of closely, as I am in central Ohio.

[snowstormcanuck]

34 minutes ago, BuffaloWeather said:

This is the best lake enhanced setup for Toronto that I've seen in quite sometime. HRRR has 6-10" across Metro. 

It likes the western burbs more, but immediate lake shore including downtown should do fine.

It's been several years since we've seen a setup as decent as this. Probably not since December 14, 2013.

 

[jlauderdal]

Pixie dust now...dont think oakbrook, il gets past 3 inches and thats generous

Sent from my SM-G950U using Tapatalk

[Snowstorms]

Winds aloft tonight will be key in determining where that LES band sets up off Lake Ontario. 

Most of the snow will fall in a relatively short timeframe leading to 1-2" rates per hour across the GTA. I think west of DVP and south of Highway 7 towards Burlington has a good chance of seeing 5-7", locally up to 9+".

Let it snow! What a nice Christmas gift as mentioned earlier. 

 

[Hoosier]

Lake band looks to be mostly offshore from Chicago now, but a couple reports around 3" from the northern end of the city and just north.

[Powerball]

To my amazement, RAP and HRRR continue to increase snowfall amounts.

Latest run is now showing 7-8" in the city (not including tomorrow's LES).

[IWXwx]

1 hour ago, Hoosier said:

Now here's a 00z NAM forecast sounding for the same location, but valid an hour earlier (15z).

Deeper DGZ on the NAM but more importantly, better omega in the DGZ.  

Megan at IWX mentioned this issue in her past couple of discos...

"Snow ratios will be the key in this event and likely present the biggest bust potential. Ratios may begin and end on the high side with deeper DGZ but bulk of the ascent/best supersaturation is above the DGZ for a majority of the event...favoring more plates and columns. DGZ also becomes much more shallow late in the day with steeper lapse rates and moderate precip rates will favor decent compaction. For now have gone with an average 15 to 19:1...yielding a solid 3-5" of synoptic snow."

[Snowstorms]

19 minutes ago, Powerball said:

To my amazement, RAP and HRRR continue to increase snowfall amounts.

Latest run is now showing 7-8" in the city (not including tomorrow's LES).

Detroit is some snow magnet. Never repels, always attracts!  

Stay safe! Merry Christmas! 

[IWXwx]

loLAF delivering the goods....

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
132 PM EST SUN DEC 24 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0131 PM     SNOW             3 W WEST LAFAYETTE      40.44N 86.97W
12/24/2017  E3.5 INCH        TIPPECANOE         IN   TRAINED SPOTTER  

            ABOUT 3.5 INCHES SO FAR. 

[Chicago Storm]

0.9" at ORD as of noon.

[ConvectiveIA]

We ended up with a solid inch, some "drifting". I'm fairly satisfied

[n1vek]

DTX just popped a Winter Storm Warning. 5-7" through midnight for the city and Eastern burbs.

[beavis1729]

48 minutes ago, Chicago Storm said:

0.9" at ORD as of noon.

[Hoosier]

A bit over 2" here.

The lake enhanced band looks likely to eventually make landfall in northwest Indiana to my east.

[Stebo]

11 minutes ago, n1vek said:

DTX just popped a Winter Storm Warning. 5-7" through midnight for the city and Eastern burbs.

[Geoboy645]

Well I was not expecting it to snow at all today. It's not much,but hey its white out so that's nice.  I think I got about 1" or so so far. At least Christmas will be a white one now.