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Pattern December Dud đź‘€

If we can keep that big west based -NAO and roaring 50/50 that’s showing up, those of us east of the mountains will eventually score. Biggest plus right now is just how good the pacific looks. We get decent pacific for about a week every winter the last 5 years so hopefully this is a trend for the future
 
Myfrotho704_ said:
Euro AI trending to a significantly more suppressed height field for that system of interest. View attachment 154523
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It is. And at 180 this H5 pattern is loaded for bear. Euro and GFS are not that dissimilar either. Going to be interesting to see how this trends the next 72 hours.
ecmwf-aifs-all-namer-vort500_z500-2860000.png
Two massive opportunities. It would be hard for some if not most to score if something like this came to fruition with the TPV rotating under the Greenland block and a steady stream of PVA being injected across the southern U.S. with multiple rounds of northern stream energy rotating north to south.
ecmwf-aifs-all-namer-vort500_z500-1732212000-1732860000-1733313600-40-1.gif
 
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Gotta love this trend. Expanding the ridge axis further east into B.C and drawing out a more impressive piece/extension of the TPV south into Canada. This also plays into the system of interest around D8. Also ensures a more direct delivery further east of the main longwave trough ACF86B55-E744-447E-BC5A-A33BFF7C615C.gif46B9F770-F8C9-4EAF-9DD4-AAD88470A9D2.gif
 
Verbatim from the screenshots @Myfrotho704_ posted, the Euro AI shows a mood flakes to event for the favored areas of the NW Piedmont, and of course a mountain snow event hopefully this trends to include more of NC.

What does the Euro AI show for the pattern following the system? Does it still have it drop the TPV hammer?
 
In trying to figure out what’s driving this year’s TNH/EPO pattern, I went down a deep literature rabbit hole & discovered the existence of the ABNA (Asia - Bering Sea - North America) teleconnection pattern. You can basically think of it as the combination of the EPO/WPO/TNH patterns with the negative phase featuring a blocking ridge over Alaska and a deep cold trough over the E US

This is what the ABNA pattern looks like spatially (both horizontally and vertically) with stippled areas being significant.

IMG_3758.jpeg


What I found more interesting perhaps was the fact that one of these papers suggested that in addition to internal variability, maritime continent SST anomalies in November were apparently important in triggering the onset of a -ABNA pattern (-EPO/+TNH), which sounds a lot like what I’ve noted for the past week or two.

See attached figure here. Also note the east pacific based La Niña

IMG_3759.jpeg


Other relevant pieces of literature:



journals.ametsoc.org

Origin of the Warm Arctic–Cold North American Pattern on the Intraseasonal Time Scale

Abstract The warm Arctic–cold continent pattern (WACC) of near-surface air temperature variability has often been associated with the connection between Arctic sea ice reduction and cold weather over the midlatitude continents. Whether the existence of this pattern is due to variability of sea...
journals.ametsoc.org journals.ametsoc.org
 
We definitely got the right SST look here for getting a negative ABNA (-EPO/+TNH) type pattern in the means this winter with a warmer than average maritime continent and weak, east-based La Niña.

Regression of the Dec-Feb mean ABNA index onto Nov SSTa. Stippled areas are significant.

IMG_3765.jpeg

This Nov so far

IMG_3766.jpeg


The negative ABNA pattern at 500mb


IMG_3764.jpeg
 
FallsLake said:
Got down to 31 here at the house. So I had a freeze!! But the airport (I think) did not get to freezing. So looking at the GFS, it looks like RDU will have to wait another 10 days of so for another chance. Crazy to have the first (official) freeze in December.
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I would take the reading at your house as official over the inaccurate readings at RDU.
 
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