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Pattern Dazzling December

The Euro at 240 has by far the best pattern for SE US cold and storm chances. Ridging up over the pole, directing legit arctic air southward into the US, a sort of east-based -NAO, maybe migrating westward, a PV in SE Canada, squashing the SE ridge, a high pressure zone moving eastward through the Midwest to tap the arctic air, an Aleutian low setting up, which would presumably continue to promote ridging in the EPO space, and energy in the STJ. The trough over HI is not ideal, as that promotes a trough in the SW US. You really want to see that trough east of HI. Anyway, it's a pretty sweet map.

ecmwf_z500_mslp_nhem_65.png

ecmwf_T850a_us_65.png

The CMC at 240 is rather ho hum. Nice HI trough/western trough couplet, mild central US ridge, no blocking, PV way up in Canada. Looking at the animation leading up to that image, it looks like it's maybe improving through time. Meh

gem_z500_mslp_nhem_41.png

gem_T850a_us_41.png

The GFS looks like buttmunch and doesn't really get better. Nice persistent west coast troughing.

gfs_z500_mslp_nhem_40.png
gfs_T850a_us_40.png

As has been said, the GFS appears to be not very good in the LR. That said, the atmosphere really wants to have a western trough so bad it can't stand it. We have to be wary of that. And, the D10 GFS H5 map looks similar to the CMC. But, the Euro shows the best way to defeat the SW US trough tendency. Hopefully it's right. If it is, the SE should have a shot or two of getting some wintry weather heading into Christmas week. At least it should hopefully feel like Christmas, which is supported by the ensembles.
 
Neat look here on the EPS Mean of Cali wave kicking east into Texas in suppressed flow days 7-10

vqVmXnn.gif
 
Starting to get more bullish on a solid cold period east of the Rockies to the Deep South from just before Christmas into the 1st week of January. I think we'll see modeling improve with that as we go thru next week. Excellent sequence shown on the EPS for +EAsiaMtnTorq with strong high moving into SE Asia (1st loop). This should combine with the tropical convective signal emerging into the WPac next week (2nd loop) to move us into a --EPO / +PNA look. In addition, this sequence during La Nina favors a continuation of the current generally negative AO / NAO regime (3rd image).

See: https://blogs.reading.ac.uk/weather...-predict-north-atlantic-and-european-weather/

"...During La Niña years we also find the teleconnection from the MJO phases 6–8 makes the NAO– regime occur up to 2.5 times as often as the full climatology – this signal travels via the stratosphere, warming it and slowing the stratospheric polar vortex (Figure 4), with the total pathway taking around 20 days. There is a strong subseasonal link between the stratospheric polar vortex and the weather regimes throughout all winters [7], however, it is during La Niña years when there is the strongest subseasonal link between the MJO and the stratosphere [6]."

gKZafBQ.gif


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yZoxMl5.png
 
Well just had a chance to look at latest model runs and i see that makes me change my mind. Both the EPS and Canadian Ensembles have been steady as she goes and things are progressing pretty much on the timeframe they’ve been showing. I agree with Fro on the potential in 15th-25th period for winter weather potential with a focus on the 18th-23rd as that’s when the teleconnections appear to line up the best.
 
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