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Pattern January 2021 - Joyless January

Avalanche said:
Yes. LOL
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Well... no. You definitely should not be worried about sfc high locations on a 10-15 day ensemble mean.

Why?

Ensemble means this far in advance smooth out individual waves and cold sfc highs that descend into the CONUS during that period, the sfc highs won't be quasi-stationary over the Canadian Rockies as the ensemble mean shows due to mixing by transient waves in the mean flow.
 
We're likely headed towards the day +20 - +40 composite pattern in late Jan/early Feb. Once high-latitude N Pacific goes up, they'll initially be a transient SE ridge w/ a cold dump from the Arctic & Siberia into the Canadian Rockies ~Jan 20th, followed by massive shots of arctic air into the CONUS thereafter w/ said pattern probably lingering into at least the beginning of February.

 
Avalanche said:
LOL, everywhere but where I want it.
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That's actually textbook where we want the high for Miller A events thanks to @Webberweather53's chart.
Snow and cold are entirely possible as long as we aren't getting low pressure to flood into the CONUS.
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prateptype_cat_ecmwf.us_se.png
Euro shows what Icon shows
 
Last time we saw a -PNA/-NAO pattern like what's being modeled in late January was Mar 2018.

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Could you imagine doing this pattern again a month earlier in the calendar year when there's actually legit cold air to work w/? 3 accumulating snows in less than 2 weeks in mid-late March for the I-40/85 corridor is pretty darn impressive, wonder what that would translate to if it was late Jan/early February instead.

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Webberweather53 said:
Last time we saw a -PNA/-NAO pattern like what's being modeled in late January was Mar 2018.

View attachment 65047


Could you imagine doing this pattern again a month earlier in the calendar year when there's actually legit cold air to work w/? 3 accumulating snows in less than 2 weeks in mid-late March for the I-40/85 corridor is pretty darn impressive, wonder what that would translate to if it was late Jan/early February instead.

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I can’t find great maps, but 2/25/15 maybe close as well?
 
The extended GEFS & Euro weeklies keep kicking the can down the road on when the -PNA tries to completely take over the pattern.

A few days ago, the GEFS showed the pattern going to -PNA dominated garbage by Jan 31. It took yesterday's run 4 days longer to get to that look due to a stronger -NAO near initialization and in the medium range dampening the SE ridge. I expect that trend to probably continue.

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Dewpoint Dan said:
Webber, is this map showing 12-18" for Central Louisiana accurate ?View attachment 65058
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No, the totals in this area were on the order of 4-6" at most.

NOHRSC is okay for large-scale analysis of snowfall but it can be pretty bad for individual storms and in localized areas. It's one of the many reasons I currently manually make every one of maps by hand to ensure quality above all else.

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See: https://www.weather.gov/source/crh/snowmap.html?zoom=8&lat=39.19&lon=-83.59&hr=48
 
If we could shift that trough south, then stuff could maybe break containment and we get another flizzard AD48D9C5-9AE2-427B-ABE6-2134DB03BACC.pngF511461D-7845-4FC6-B7B2-6616EB70A0F0.png
 
FallsLake said:
The PNA going negative still scares me. The AO and NAO at least stay negative. And as Webber has pointed out, we can score without a positive PNA (..maybe with better odds). But man oh man:
View attachment 65061
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The only thing we are losing with a -PNA is the threat of Miller A cyclones. If a winter storm shows up with the -PNA in place, we’re much more likely gonna get overrunning or Miller B. Could also see a sneaky clipper or two in this pattern as well
 
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