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Wintry Machine Learning Mauler 1/30-2/1

My sis in ATL was quite surprised when I just told her she could get another winter storm this weekend (snow this time). But I did downplay it a bit due to very high uncertainty since many models have had little or none there. The west trend may end up their big friend and so I wanted to mention the snow chance. Based on her surprised reaction, a snow threat there this weekend is not the talk of the town at least yet.

When was the last time ATL had 2 winter storms within a week of each other? I’ll probably check. Exciting times to be a SE wx tracker!
 
GaWx said:
My sis in ATL was quite surprised when I just told her she could get another winter storm this weekend (snow this time). But I did downplay it a bit due to very high uncertainty since many models have had little or none there. The west trend may end up their big friend and so I wanted to mention the snow chance. Based on her surprised reaction, a snow threat there this weekend is not the talk of the town at least yet.

When was the last time ATL had 2 winter storms within a week of each other? I’ll probably check.
Click to expand...
Last year lol
 
GaWx said:
My sis in ATL was quite surprised when I just told her she could get another winter storm this weekend (snow this time). But I did downplay it a bit due to very high uncertainty since many models have had little or none there. The west trend may end up their big friend and so I wanted to mention the snow chance. Based on her surprised reaction, a snow threat there this weekend is not the talk of the town at least yet.

When was the last time ATL had 2 winter storms within a week of each other? I’ll probably check.
Click to expand...
Last time I recall back to back was 2011. Hothlanta. Not looking it up. Curious if my memory is reliable (prolly not).
 
Really good AFD from KCAE regarding the potential and something they've observed this winter season with modeling. Worth a read.



Key Message #2: Guidance continues to show the potential for an
impactful snow event this weekend across the forecast area.

The overall message has not changed regrading this, albeit
confidence is slowly increasing in the setup as we get closer to the
event itself. Over the next 24h, a robust PV anomaly is forecast to
rotate around the center of a 500 hPa low between the Hudson Bay and
the Great Lakes states. This vorticity anomaly is forecast by
guidance to then push southward into the upper Midwest and Great
Lakes states by Friday as it is driven southward by increasing upper
level ridging emerging out of western Canada. By this point, a broad
area of vorticity is forecast to be at the base of the trough in
Texas associated with the southern stream of the jet stream, with
guidance in good agreement that the parent vort max will begin
phasing with this vorticity plume and dig into the southeastern
CONUS by this point. Broad, robust lift is then forecast to yield
rapid cyclogenesis along the Carolina coastline, with a broad
precipitation shield developing between the upper low and the
surface low. Cold air across the region, in association with a gelid
airmass pushing southward out of Canada, will favor all snow/rain as
opposed to the rain/snow/sleet/freezing rain that we typically see.

Model guidance is clustered tighter than it was about 24 hours ago
when we were first getting a handle on this and seeing some level of
model consistency. Guidance trends (if you can find them) have
generally favored a similar pattern that we have anecdotally
observed over the last few weeks, which is to slightly amplify
the overall pattern as the event approaches. In this case, that
means a slightly stronger shortwave, slightly further west, with
the upper low taking on a negative tilt somewhere over the TN
Valley and Georgia. AIFS/GFSAI/Canadian guidance was the first
to really point to this yesterday & has continued to do so, with
the physics-based GFS/ECMWF moving in that direction over the
last 24 hours as well. As such, the former grouping of models is
favored currently because of consistency & the way they`ve
verified recently. Additionally, guidance has had a slow but
noticeable uptick in forecast QPF associated with this system.

While all of this is the case, the forecast still contains a good
bit of uncertainty. These events are difficult to pin down & as
described above, there are a lot of moving pieces to this forecast.
As I always tell my friends & family when they ask about snow around
here, "it takes a lot of luck and good fortune for us to get decent
snow in the deep south because so much needs to align just right".
Well, the winds of fortune may be blowing in our favor, at least for
snow-lovers, this weekend. Confidence is growing that an impactful,
if not significant, snow event could be on tap across the Carolinas
on Saturday and Saturday night. It should also be mentioned: the
airmass Saturday and Sunday looks downright frigid.
Temperatures are unlikely to get out of the low 30s for highs
either day, with lows in the teens. A Cold Weather Advisory is
likely in this period as well. So please stay tuned to the
latest forecast as things are likely to continue changing and
adjusting over the next couple of days!
 
bouncycorn said:
AIFS-ENS trend. AIFS/AIFS-ENS have something weird going on between the 0z/12z and 6z/18z runs...

View attachment 190451View attachment 190452
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They're not getting the best data. The best example shown is just doing the F+000 trend on the vorticity, and there's something to note in Canada and the Pacific in the CONUS view.

We'll legitimately just have to see when it comes into CAM-land.
 
Kennedy said:
How much happy fluffy snow brings power lines down? Asking for a friend
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It's not likely to bring down any. Power lines themselves are not going to collect snow to bring them down. If there are overhanging trees it's possible that if they have enough foliage still on the limbs at this time of year to collect snow, that could weigh them down and bring them down on top of the lines.
Overall it's a few orders of magnitude less likely that a clean snow will bring down power lines unlike the threat of freezing rain that we were facing last weekend that is a whole other story. That's when power lines get pulled down by their own weight of collecting ice on the surface and even clean tree limbs collect ice and are brought down on lines to cut out the power.
 
screenshot-1769586302315.png

This is the NWS Blend of Models. The UK and ICON seem to have lost our storm so this is weighed heavily by the GFS and Euro. This would put a lot of people in the zone to receive snow and seems like a reasonable solution for now.
 
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weather bubba said:
View attachment 190457

This is the NWS Blend of Models. The UK and ICON seem to have lost our storm so this is weighed heavily by the GFS and Euro. This would put a lot of people in the zone to receive snow and seems like a reasonable solution for now.
Click to expand...
The UK somewhat brought the storm back this last run.
 
c4b4c468d6b62b665604ba01b3a5e953.jpg

Increase for many


Sent from my iPhone using Tapatalk
 
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