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Nov. 10-11th snow event thing


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Solid afd

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
149 PM CST Sun Nov 10 2019

.SHORT TERM...
149 PM CST

Through Monday night...

Primary near term concern is the accumulating snowfall expected
tonight into Monday.

Water vapor imagery early this afternoon shows upper trough over
western Canada digging southeast into the northern tier of states.
Guidance is in excellent agreement in showing an amplification of
this trough as it digs southeast into the northern Plains Monday
and Great Lakes Monday night into Tuesday. This trough will
dislodge a lobe of record breaking early season Arctic air and
drive into the Midwest and our area Monday night into Tuesday.

As this trough digs southeastward, tightening geopotential height
gradient ahead of the trough will result in a strengthening jet
streak downwind of the trough with guidance developing a 140-150kt
250mb jet from the Cornbelt east-northeast into southeast Canada.
This will place northern IL and adjacent areas in the favorable
right entrance region of the jet, where thermally direct
ageostrophic circulation will result in strengthening low-mid
level frontogenetical circulation tonight into Monday.

The result will be an expansion and some intensification of the
swath of precipitation currently over South Dakota into southwest
Minnesota. Precipitation should spread into northern IL this
evening with thermal profiles initially supporting some rain
before a quick change over to snow most areas. The exception will
likely be immediately downwind of Lake Michigan where marine
influences will hold temps up a bit and delay the change over to
snow until after midnight most likely.

Forecast vertical cross sections across the tightening thermal
gradient show 2 to 3 different f-gen circulations with this band
tonight into Monday morning. Generally speaking, omega is not
forecast to be overly strong during the event and overall not
seeing any strong indications of instability (slant-wise or
upright) that would point toward any convective enhancement to the
snowfall. None the less, all indications are that there will be an
extended period of light to moderate snow, likely resulting in
widespread 2-6" accumulations, heaviest along/north of I-88/290
corridors and near the lake in northwest Indiana.

Hi-res models continue to suggest there will be a lake enhancement
to the snowfall into northeast IL late tonight into early Monday
morning, and into northwest IN Monday morning into the afternoon.
Initially, the depth of the cold air tonight isn`t terribly great
resulting in marginal lake induced equilibrium levels which would
certainly support some lake enhancement but suggests the lake
enhanced snow won`t get too out of hand. Depth and magnitude of
the cold air will be on the increase Monday, resulting in stronger
lake induced instability and deeper convection/more vigorous lake
enhanced snow. As the lake effect parameters improve the band is
expected to become increasing progressive and shifting east into
and across northwest Indiana.

There are a lot of moving parts that introduce potential errors
in our forecast snowfall over the immediate Chicago area and far
northwest Indiana. Above freezing temps should result in a
portion of the initial QPF advertised in the models not contributing
to snow accumulations and either falling as rain or melting snow.
Conversely, lake effect is notorious for being fickle and
difficult to forecast. Similar set-ups ave been known to over-
perform with heavier snowfall rates and totals and this is
certainly possible, especially Monday as the instability
increases. For now, just mentioned the potential for isolated
higher totals (>6") near the lake, but it is possible that areas
near the lake could end reaching warning criteria. At this
juncture, given the uncertainties, felt an advisory was the
reasonable route to go and not get too hung up on the threat for
some isolated totals reaching warning criteria (>=6" in 12 hours).

Northerly winds of 15 to 25 mph with some gusts to 30 mph are
expected Monday which could result in some minor blowing and
drifting problems in open areas, but winds are expected to be
pretty marginal for blowing/drifting. The exception will likely be
near the lake, particularly in northwest Indiana where gusts of
35 to 40 mph are likely Monday and should result in a more
substantial blowing and drifting problem.

- Izzi

 

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7 hours ago, Powerball said:

I've been lurking and waiting to see how long it would take you to get hyped up. It's absurdly early for a snow event this significant (then again, so was the Halloween snow event for Chicago).

When's the last time DTW saw 4"+ of snow this early in the season?

The top 10 biggest snowstorms in Detroit history (1880) on or before November 12th are:

6.2" Nov 8/9, 1921

6.0" Nov 2/3, 1966

5.7" Nov 6/7, 1951

4.6" Nov 10/11, 1898

4.1" Nov 11, 1984

3.9" Nov 10/11, 1933

3.6" Nov 9/10, 1913

3.4" Nov 11, 1892

3.1" Nov 11/12, 1959

3.0" Nov 9/19, 1894

 

So as you can see most of these are way back in the day. There have only been 5 snowfalls of 4" or greater this early, and chronologically they go 1984, 1966, 1951, 1921, 1898.

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Have to laugh at the 3 county wide area in north central Ohio (of which I am in the dead center of) that breaks up the solid string of winter headlines that runs from Montana to Maine.  Can't say I blame CLE for holding off - just shows how tough it is to get it to snow around here.

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3 minutes ago, Chinook said:

18z NAM Kuchera snow ratio snow totals (to hour 33.) There are these super weird holes in the snow accumulation that shouldn't be there. It makes snow disappear off the map. Seriously.  Could somebody program these post-processing schemes better?

GRIwO6E.jpg

How do you get the counties and totals???  I've looked and looked, but can't find them!

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3 hours ago, michsnowfreak said:

The top 10 biggest snowstorms in Detroit history (1880) on or before November 12th are:

6.2" Nov 8/9, 1921

6.0" Nov 2/3, 1966

5.7" Nov 6/7, 1951

4.6" Nov 10/11, 1898

4.1" Nov 11, 1984

3.9" Nov 10/11, 1933

3.6" Nov 9/10, 1913

3.4" Nov 11, 1892

3.1" Nov 11/12, 1959

3.0" Nov 9/19, 1894

 

So as you can see most of these are way back in the day. There have only been 5 snowfalls of 4" or greater this early, and chronologically they go 1984, 1966, 1951, 1921, 1898.

Guess I missed the 1984 score, and totally forgot 1966 hit Detroit, not only further west. All others were indeed prior to DTW's existence as I figured. Thx for posting. 

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1 minute ago, RogueWaves said:

Guess I missed the 1984 score, and totally forgot 1966 hit Detroit, not only further west. All others were indeed prior to DTW's existence as I figured. Thx for posting. 

 

1 minute ago, RogueWaves said:

Guess I missed the 1984 score, and totally forgot 1966 hit Detroit, not only further west. All others were indeed prior to DTW's existence as I figured. Thx for posting. 

Youre welcome. Another thing, this will be the only storm that is followed by such bitter cold. The other ones seemed to be more typical November type wetter snows.

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