Winter 2021-22 Short/Medium Range Discussion

[A-L-E-K]

hyde park looking like a good guess, guidance almost saying loop but gonna hedge east with climo

[A-L-E-K]

ready 2 b buried

[Louieloy102]

18Z HRRR projecting a foot and a half over the lake lol

[mimillman]

59 minutes ago, A-L-E-K said:

hyde park looking like a good guess, guidance almost saying loop but gonna hedge east with climo

I’d say even further East than that, having lived in Hyde park for 4 years and being consistently disappointed from these events 

[A-L-E-K]

climo is what it is on this side of the lake, but this is a sneaky area on the north shore around glenview/evanston that seems to do well with these setups,

still liking my 1-2 call here 

[featherwx]

35 minutes ago, mimillman said:

I’d say even further East than that, having lived in Hyde park for 4 years and being consistently disappointed from these events 

hope not, especially given that I'm on the western fringe of HP. either way, should be an interesting drive to the Illinois Medical District for work tomorrow morning. 

[Hoosier]

10 minutes ago, A-L-E-K said:

climo is what it is on this side of the lake, but this is a sneaky area on the north shore around glenview/evanston that seems to do well with these setups,

still liking my 1-2 call here 

iow, the jackpot will either be north or south of downtown 

[A-L-E-K]

[Chicago Storm]

obviously cut in half whatever the HRRR is showing


.

[A-L-E-K]

1 minute ago, Chicago Storm said:

obviously double whatever the HRRR is showing


.

agree

[Hoosier]

7 minutes ago, Chicago Storm said:

obviously cut in half whatever the HRRR is showing


.

What do we do about the 3km NAM?

[Chicago Storm]

What do we do about the 3km NAM?

polish it.


.

[Chicago Storm]

surprised ya'll haven't mentioned the RAP. it's even further west, with inches into SE Lake Co IL.

[A-L-E-K]

Gfs looks good

[Hoosier]

Ricky in on the afternoon afd

 

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

.SHORT TERM...
Issued at 327 PM CST Thu Jan 27 2022

Through Friday...

Bottom Line Up Front:

1. No changes planned to the ongoing Winter Storm Watch headlines
(12am-12pm Friday) with the decision to upgrade to warning and
potential expanded areal coverage of the advisory expected this
evening.

2. Conditional threat for higher-end totals (6"+) exists near the
lakeshore from Chicago south toward Gary, IN, but will be dependent
on residence time of the heaviest snowfall rates under the lake
effect band.

3. A quick dusting/coating of snow will be possible area-wide
this evening and early overnight as scattered snow showers move
across the area behind the cold front (before the lake effect band
gets going).

A cold front is currently in the process of moving across the area
this afternoon. High temperatures today in the lower 30s were a
welcome change from the cold the past few days. Some areas were even
able to get some sun thanks to clearing behind the front. Clouds
will quickly fill in this evening with increasing chances for
scattered snow showers and flurries into this evening. These look to
be fairly low impact, but there may be some minor visibility
reductions and a dusting on surfaces that could make untreated
roadways slick. Temperatures overnight fall into the single digits
and teens which will allow any snow that falls to accumulate more
readily.

With the westward trend holding steady in the afternoon model
guidance with respect to the lake effect snow band overnight into
Friday morning, we have opted to not make any changes to the ongoing
Winter Storm Watch. Will let the evening shift get another look at
things as to whether confidence in a dominant band setting up in the
watch area will warrant a Winter Storm Warning or Winter Weather
Advisory for a more transient band.

Conditions remain favorable for a heavy lake effect snow assuming a
dominant single band evolves. Favorable fetch with north to
northeast winds across the lake, strong lift in the cloud layer, and
sufficient lake induced instability would support snowfall rates of
1 to 2 inches per hour and visibilities under 1/2 mile. The concern
is that conditions look similar to what occurred this past Sunday
morning over the south half of Chicago and Illinois/Indiana state
line and especially Lake County.

Uncertainty with the residence time of this band over any specific
area remains low, however, with a progressive band or one that goes
stationary for a few hours both plausible outcomes. 2 to 4 inches of
snow does appear likely for any areas that see the lake effect snow
band. If it can stay over one area for long enough period,
accumulations nearing 6 inches to possibly exceeding this are still
firmly within the realm of possibility. With a fairly sharp cutoff
in snowfall amounts expected, far inland areas of Cook and Lake
IN counties may only see a dusting, if that.

Those out traveling near the lakeshore, including downtown Chicago
south along the lakeshore into northern Lake County, IN will need to
be prepared for rapidly changing conditions where the lake effect
snow band sets up overnight tonight into the Friday morning commute,
including the I-90/94 corridor.

There are signs in the model guidance that the southern end of the
lake effect band trends toward more of a meso-low situation as it
recedes back over the lake and pushes eastward. Expect majority of
the accumulating snow to end by mid to late morning with lingering
lake effect flurries possible into the afternoon.

Petr/Castro

[A-L-E-K]

Point is bullish 

[mimillman]

though admittedly looking like I bust this time 

[purduewx80]

Good bit of ice on the lake near the shore. 

[mimillman]

This was from Jan 20, 2019 from when I used to live downtown. This was @Hoosier lake band if I remember correctly.

[Chicago Storm]

surprised ya'll haven't mentioned the RAP. it's even further west, with inches into SE Lake Co IL.

bump, even more so now.


.

[homedis]

NWS Chi being bullish, latest graphic showing localized 6"+ in immediate chicago area. Hoping that verifies, but feeling a healthy 3"-4" here in W. Loop.

[Baum]

48 minutes ago, Chicago Storm said:

bump, even more so now.


.

I'll be posting my totals by noon tomorrow 

[mimillman]

Hoosier starting to get worried

[Hoosier]

6 minutes ago, mimillman said:

Hoosier starting to get worried

Meh.  I try to not get too heavily invested in these things ahead of time as there's too much that can go wrong and put the band somewhere else.  At least there is a system to track after this passes.

[Chicago916]

West trend in the lake band didn't correct back yet. Likely headlines for Cook soon? Bet lots of people will be caught off guard for tomorrow morning's commute.

[Baum]

1 hour ago, Hoosier said:

Meh.  I try to not get too heavily invested in these things ahead of time as there's too much that can go wrong and put the band somewhere else.  At least there is a system to track after this passes.

exactly.

[RCNYILWX]

Fun/busy shift today. Had we not inherited a watch for Lake County Indiana, might have done things differently. Fresh in my mind, had the Sunday morning event that I worked during, that had warning type impacts into Lake County and probably an hour or two away from that south of downtown Chicago.

Scenario of a more progressive band and/or earlier mesolow causing heaviest snow to slip back out over lake or band going nearly stationary for a few hours were all plausible scenarios. So with the watch already for Lake County, opted to expand into Central and South Cook zones and treat it more like a warm season convective watch. Lake effect is convection, so always higher uncertainty than synoptic at shorter lead times due to mesoscale uncertainties that can't be ironed out until some of the observational trends show the cards of how it may play out.

Not too concerned about the HRRR/RAP trends yet until seeing the rest of the 00z CAMs. We did hint at higher impacts getting into northern Cook zone (north shore burbs) though decided to just keep watch for the zones we went with at noon and let the evening shift resolve the headlines. We have two of our better LES forecasters there (Gino, and Kluber, who made warning upgrade for Lake IN on Sunday), so we're in good hands this evening.

Edit: In case anyone comes across this later, didn't want to mix messages with the updates done by the evening shift tonight. Great example of the nature of the beast that is LES forecasting. We trended toward the more western convergence placement on the day shift, but that still wasn't enough as it appears from latest guidance and upstream obs. We know these sorts of shifts are within the realm of possibility, but also still can only go by the guidance we have at hand to put out the forecast at the time.

[Chicago Storm]

Early 0z guidance is shifting LE westward, targeting more from Kenosha down into Lake and N-C Cook Co’s.


.

[Chicago Storm]

This is suddenly becoming a more interesting overnight shift at ORD. Obviously dependent on trends being correct, and the LE not doing anything wonky.


.

[mimillman]

32 minutes ago, RCNYILWX said:

Fun/busy shift today. Had we not inherited a watch for Lake County Indiana, might have done things differently. Fresh in my mind, had the Sunday morning event that I worked during, that had warning type impacts into Lake County and probably an hour or two away from that south of downtown Chicago.

Scenario of a more progressive band and/or earlier mesolow causing heaviest snow to slip back out over lake or band going nearly stationary for a few hours were all plausible scenarios. So with the watch already for Lake County, opted to expand into Central and South Cook zones and treat it more like a warm season convective watch. Lake effect is convection, so always higher uncertainty than synoptic at shorter lead times due to mesoscale uncertainties that can't be ironed out until some of the observational trends show the cards of how it may play out.

Not too concerned about the HRRR/RAP trends yet until seeing the rest of the 00z CAMs. We did hint at higher impacts getting into northern Cook zone (north shore burbs) though decided to just keep watch for the zones we went with at noon and let the evening shift resolve the headlines. We have two of our better LES forecasters there (Gino, and Kluber, who made warning upgrade for Lake IN on Sunday), so we're in good hands this evening.

Sent from my SM-G998U using Tapatalk
 

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?