Brendan Heberton

It's hard to be surprised, really, that probabilities for higher-end snowfall
totals to end this week and this weekend have dropped. As we covered in this
week's SOTA
[https://www.weather5280.com/2021/01/31/the-state-of-the-atmosphere-sunday-january-31st-2021]
, deterministic models have struggled in recent weeks and the prospects of a
bigger snow event (especially Wednesday and Thursday) across Northeast Colorado
was fading. 

Still, the trusty gamblers continue to show some hope for snow lovers, and we
continue to track those changes set to arrive after another day or two of very
mild February weather. 

The latest gamblers show about a 50% chance we make or break an inch of snow
through Wednesday night in Denver, with a 40% chance we hit the 3" mark between
Thursday morning and Sunday. As you can see, surrounding cities are more or less
in the same boat, with slight shifts in the odds depending on where you look. 

As of Monday evening there remains considerable differences in the modeling with
how things will pan out. The European is back on a nice snow event for the
Denver metro area, with the GFS now shows the best chance for snow in Denver
this weekend – a bit of a flip from yesterday! Both models indicate we could see
RAIN at lower elevations Wednesday night, changing to snow – but perhaps too
late for much accumulation depending on which solution to believe. 

Here's the latest European model output for Denver – showing actually some
appreciable moisture Thursday (though it has about 0.2" of the 0.5" not falling
as measurable snow!). IT does show the two additional snow chances on
Saturday/Sunday, and perhaps Monday – but is, for the moment at least, not
putting much stock in either of those solutions. The amount of QPF from this
model feels a bit overdone at this time, even accounting for some potential to
see locally heavier bands of snow develop late Wednesday night as we transition
to snow. 

The GFS shows a blip for Thursday, and only rain in the city. A "better" snow
chance with the cold air intruding this weekend, but it keeps most of it 1)
light and 2) up across the northern metro area and plains vs in Denver. Still,
something. 

For now we'll continue to focus on what to expect Wednesday night and Thursday,
and see how Friday night Saturday looks as we get closer. 

Wednesday night/Thursday feels like a 0 - 2" event at lower elevations, with
perhaps 1 - 3" across across the Palmer. The key will be seeing which way the
trend goes in the next day or so, but seems like the models trying to put
something more meaningful together are struggling here. 

The PNA forecast from a week ago or so actually panned out pretty well. It did
just want it needed to do to give us a fighting chance in capturing a storm, but
still it looks like we will struggle to put together accumulation this
week/weekend. If the Euro pans out, well, then the snow lovers will be happy and
we can say we told you so – but at the moment there's just want too much noise
to feel good about any outlook or another. 

One thing to note, is that while yes, we look for shifts in the PNA whether from
+ to - OR - to + for when we might catch a storm, in running some numbers the
correlation for wet for Northeast Colorado is actually better this time of year
going from + to -, or the opposite of our current situation. As we head deeper
into February toward March and April that flips. 

Source: NOAASource: NOAAThe PNA is set to go negative again after this brief
blip positive, which should keep the west under the influence of some colder
weather as we move into February, and of course will keep us keeping a close eye
on things. 

Not a no-go for snow just yet late in the week, but there continue to be plenty
of obstacles in the way if you're hoping for some meaningful accumulation. Let's
see what tonight's data brings us, and we'll pass along an update again soon.

An update on the late week pattern change as snowfall probabilities drop