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Winter 2021-22 Short/Medium Range Discussion


Chicago Storm
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Question for you Ricky— in events like these, do you ever consult with your colleagues in heavy lake effect zones (Marquette, Buffalo, GR), or are the way these events unfold very specific to the region?
It's not super practical from a going into an event time-frame to do that sort of consulting with other offices. More common would be to have webinar presentations where tips and suggestions for LES could be shared by forecasters in some of the more LES prone offices. Some of our forecasters also spent part of their careers at MQT, GRR, IWX, to name a few.

So they bring that experience with them. Additionally, while big LES events are less common overall in our area, we do tend to get at least a few lower end to moderate events, so our forecasters with several to many years of experience have that in their mental database. We also have had some good west and south side of the lake events within the past 10 years to build from, of course including last February.

Gino just shared a lake effect pointers presentation with the staff as a refresher for our experienced forecasters and to assist our newer forecasters. Just the near term changes with tonight's event show the challenges we face in forecasting and trying to message these events.

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Here's the evening afd from Gino.  Gotta feel for the folks at LOT... so much bust potential being at the mercy of something of this nature in a highly populated area.

 

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
931 PM CST Thu Jan 27 2022

.UPDATE...
Issued at 931 PM CST Thu Jan 27 2022

Have issued a winter storm warning for Lake IL, central, and
northern Cook Counties and a winter wx advisory for DuPage,
southern Cook, and Lake County IN.

Regarding the synoptic and thermodynamic environment for lake
effect snow (LES), no changes from thinking of the previous
shift. Very favorable environment for a dominant, intense single
lake effect snow band to develop and move ashore into northeast IL
overnight into Friday morning. Forecast soundings show convective
layer encompassing the entire dendritic growth zone (DGZ) and
given the strong instability and expected land breeze convergence
band, should see strong ascent through the DGZ. Set-up appears
favorable for 2"+ per hour snowfall rates during the most intense
portion of the LES band (09z-16z).

There has been a near unanimous shift westward shift in hires
guidance in the placement of the LES band, which places the risk
of heavy snow farther north into the metro area. Unfortunately,
there are inherent uncertainties that come into play when trying
to forecast meso-gamma scale phenomena like this. It is also not
uncommon for bands to "wiggle" around and there is still spread
in the various hires guidance on placement of the band. While
additional shifts in the forecast placement of the band are
possible, we are within the time window that a decision needed to
be made, so have trended the higher snow accumulations farther
north and west, though not as far north and west as most of the
00z hires guidance.

The westward shift in the guidance actually increases confidence
that there could be a longer residence time for some areas.
Confidence is increasing that max snowfall totals will end up at
least in the 6-8" range and not out of the realm of possibility
that there could be isolated double digit totals. Given the timing
of this event (during the height of Friday morning rush hour) and
the inherent uncertainties in exact placement of the band, opted
to err a bit on the side of caution with headlines. Certainly
plausible that band ends up just east of Lake IL and/or Dupage
county, or stays mainly west of Lake IN, but felt the course of
least regret was to go a little big and risk some headline areas
falling short of expectations.

The WSW and forecast grids are out and updated text forecast
products will be issued momentarily.

- Izzi

 

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This is why we should still have the lake effect snow advisory.
And eastern region offices still do them. I think what we settled on (using winter storm watch and warning for higher end LES) is probably more confusing to some users. My preference would've been either to stick with status quo like eastern region went back to, or to simplify the name to a Winter Weather Watch, Warning, and Advisory, and specify the phenomena in the What bullet in the text. Storm implies a larger scale system, vs a mesoscale convective phenomena like LES. Sometimes it can be both, such as last Feb for Chicago and NW IN, so LES warning or advisory wouldn't have been ideal either.

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Hmmmmm, this is disappointing. On GR Level 3 there doesn't seem to be a base reflectivity product available for the Chicago-area terminal Dopplers (ORD, MDW). Is this normal? Was hoping to get a closer look at this band than can be done from KLOT.

It’s available on GrLevel 3 and RadarScope.


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