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Historic Lake Effect Event?! 11/17-11/21


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A strong ridge of high pressure extending to Alaska and NW Canada
will dislodge a plume of arctic air southward, flowing down across
the Great Lakes within a deep trough of low pressure over Hudson Bay
and to the Great Lakes. Temperatures at 850 hPa will lower to -10/-
12C over the warm Great Lakes, with delta T`s between the lake
surface and 850 hPa of at least 20C. This will result in ample over-
water instability to help in formation of very strong lake bands.
This cold airmass will linger over the Lakes through this period,
producing not only lake snows, but also much below normal surface

Starting off Thu night the primary low will be near the Soo, with
weak surface ridging pulling off to the east. A shortwave will be
nearing the east end of Lake Erie, and together these features will
back the surface winds to SW. A secondary shortwave crossing
southern Lake Michigan early Friday morning will allow for general
southwest flow to continue for 24-36 hours, bringing significant
lake snow accumulations where bands persist the longest.

Off Lake Erie...

Backing surface winds will put the focus as early as Thursday
evening across Buffalo metro area. Strong surface convergence and
upward omega forcing, combined with increased moisture with the
passing shortwave should allow a singular band of precipitation to
quickly become established. The cooling aloft will allow for
primarily snow, though a mix of rain/snow will occur early
Thursday evening near the immediate lakeshore.

Once this band sets up, it will remain fairly stationary late
Thursday night and through the day Friday though there could be some
varying persistence to the band, so this will still need to be
considered. There continue to be hints of a weak shortwave trough
moving through, veering steering winds to 250 direction. NAM and
Canadian indicate this, but didn`t drift axis of heavier snow
too far south. Local knowledge is once the band becomes
developed, it is very hard to push it too far south. The strong
convergence enhanced by the attempt at the band drifting south
will just lead to impressive omega values, along with deep
moisture in the snow DGZ and lake induced equilibrium levels
rising to over 20K feet. This as the band of snow will be
oriented along the long axis of the lake will produce very
intense snowfall rates of over 3 inches per hour. Seeing how
this narrow, intense band of snow will then not oscillate much
into Friday night, this is where this band will have the best
chance to produce feet of snow. The highest totals may very well
end up across the Buffalo Metro area (downtown and towards the
airport with 240 wind) or just to the south to the south if wind
direction veers to 250.

Climatologically, the northern flank of this snowband will have a
very tight gradient, while the southern flank will have accumulations
fan out with lesser gradient. This tight gradient usually occurs
when the lake is still warm as it is here with values in the lower
50s at the top of end of what is typical for mid November and with a
cold airmass overhead as well as equilibrium levels up towards H5 or
15-20kft AGL. This northern flank is also where we expect the
stronger inbound winds as well as the highest snowfall rates to
occur. Warnings remain in place. Did upgrade Wyoming county due to
combination of snow through Thu morning and that county being on the
far southeast edge of the strong band of snow Thursday night and
beyond. Snow band still looks to push into Niagara and Orleans
counties later Friday night and Saturday so watch remains up there
for now due to later impacts of the snow bands.

The higher lake equilibrium levels as well as well as increased lake
instability may bring a few rumbles of thunder within the lake snow
band. This may occur later Thursday night and through Friday
night...with lightning possible over Lake Erie and to about 20-25
miles inland.

Off Lake Ontario...

Winds will back about 3 hours later off Lake Ontario such that to
start this period lake snows will be oriented over Oswego and
southern Lewis. A quick backing of the winds will steer the lake
bands northward quickly, towards Watertown just past midnight. No
change in this expected evolution.

Once this lake effect snow band sets up through the overnight
Thursday night, it will remain fairly stationary through the day
Friday with the synoptic pattern forcing a general southwest flow.
The strong convergence leading to decent omega values, along with
deep moisture in the snow DGZ and lake induced equilibrium levels
rising to over 20K feet will allow this band of snow to oriented
towards Jefferson County with the snowfall rates of 3 inches per
hour. The axis of greatest snowfall this period will likely be
directed at Watertown and towards Philadelphia. Late Friday into
Friday night seems when highest rates will occur.

Though the snow band will not be oriented along the long axis of
Lake Ontario, an upstream connection to Lake Erie snowband is
becoming more and more evident and will enhance the snows over
Jefferson County. Here snowfall totals will also be measured in
feet, and have kept the warning going. The snow band initially
clipping southern Lewis with warning amounts will then clip the
northern portion of the county Friday and Friday night. There was
enough confidence in seeing warning amounts in both of these areas
for Lewis to upgrade it to a warning.

There is also a potential for thunder to occur within the more
intense portion of the Lake snowband over Lake Ontario and into the
western half of Jefferson County. Likewise to Lake Erie, the taller
lake equilibrium heights and high delta T`s will create an
environment that will allow for charge separation and lightning to

Off both Lakes...

Winds will begin to increase during the day Friday. Gusts towards 35
mph near the shoreline will create blowing snow...that with the
heavy snowfall will lower visibilities at times to just a few
hundred feet. Travel late Thursday night and through Friday night
will be very difficult.

Outside of the lake effect snowbands the weather will be fairly
quiet. Skies will begin to clear some during the day Friday, though
still cold. The clear skies Friday night outside of the lake plumes
will bring a cold night, with overnight lows 10 to 15F across the
inland Southern Tier as well as the southern Tug Hill. Apparent
temperatures in these regions will drop into the low single digits
Friday night.

Strong trough still on track to drop across the region quickly on
Sunday. Variable intensity snow showers and squalls possible as that
occurs, with best chance early in the morning. By afternoon moderate
intensity northwest flow lake effect will be ongoing especially
Southern Tier and south of Lake Ontario. Chilly and blustery with
highs in the mid to upper 20s.
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11 minutes ago, LansingWeather said:

Im actually flying up for this storm, going to be my first of these storms, Ive chased a lot of events in SWMI. Im going to be staying at the regency so if anyone else is going to be around feel free to DM me. Hopefully the band comes right in over my hotel and not just south lol.

What are you driving once there?

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13 minutes ago, BeauDodson said:

What are you driving once there?

Unfortunately, my jeep with good tires and lockers and a winch is stored in Orlando. I was going to drive it up, but thats a long drive while "hurrying" so Im driving some run of the mill sedan.


Which means I wont really be able to drive around in the storm. But if the cutoff is like it was in 2014 I can at least get close and walk around. (I need to buy warm clothes, all my winter gear is in FL as well lol)


Im still hoping that downtown buffalo is in the band. Fingers crossed.

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1 hour ago, BeauDodson said:

Hoping I can come in from the south tomorrow afternoon. 

Sounds like they will close it.  

Unsure another way in.


I think I might be 'out' on this one because of that decision... which I support.

I'm only 4 hours away so it'll hurt a little bit.

Some thoughts related to the discussion that I've seen in this thread:

1) I wouldn't trust the HRDPS on this one or for anything in the US - it's just a bit too close to the boundaries for my liking. That can cause some weird output along the outer edges of the modeling system.

2) I wouldn't trust the NAM12km on this either (or anything >3km). I mentioned this before, but you really need higher resolution models to capture moisture flux for LES. It's basically a topographically induced, semi-stationary thunderstorm. Would you trust QPF from courser models for any convective event? I hope not. Regardless, QPF is still a challenge for NWP for a number of reasons.

3) Use high-res ensembles for this one. I'd recommend using the High Resolution Ensemble Forecast system (HREF) for QPF.

4) Once the band forms, I'd lean towards the HRRR (only for init. +~6 hours) since I trust its data assimilation.

5) I expect crazy totals from this.

I hope you guys live stream this!

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41 minutes ago, SyracuseStorm said:

Evening all- I am out in Buffalo for work until Friday- gonna be a tough trek back to Cuse Friday but know how to navigate these bands.

Funny, was in elevator at my hotel and met a guy from TWC out here covering the storm.  Not sure what was more impressive, the jacket or the case of Labatt Blue.  Super nice guy!

Jim Cantore is here in Buffalo, was likely him. One of my all time favs.

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