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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


HxHGCUO.gif


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.
 
griteater said:
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


HxHGCUO.gif


yZoxMl5.png
Click to expand...
It’s interesting. Last dec-jan the lower stratosphere (30-50mb) became unfavorable for blocking into late dec/January as we ended up getting the WPAC forcing regime to setup that gave us the -EPO/+PNA combo. Hudson Bay vortex setup but absolutely no blocking, fast flow and sheared waves, very timing reliant. Looks like this time that strat becomes less favorable but not as unfavorable as -NAM continues to show up especially the lower down you go, but I see lots of wave breaking on the smoothed Ensemble means. Really wanna try this pattern out with a block, considering fast flow was the problem last jan.
 
griteater said:
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


HxHGCUO.gif


yZoxMl5.png
Click to expand...

I'm nervous that we get the pacific ridge oriented incorrectly or off by like 2 degrees and we take an L here. That said all signs do point to go. I think even if we were to fail early it would be similar to last year where we would eventually get there
 
SD said:
I'm nervous that we get the pacific ridge oriented incorrectly or off by like 2 degrees and we take an L here. That said all signs do point to go. I think even if we were to fail early it would be similar to last year where we would eventually get there
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Trough just east of HI backs up or the Aleutian low lifts, we get a ---- tilt/Nina esque NPAC ridge. That’s the scary part
 
Myfrotho704_ said:
Trough just east of HI backs up or the Aleutian low lifts, we get a ---- tilt/Nina esque NPAC ridge. That’s the scary part
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Yep it's the same fight we fight when this pac ridge goes up. We win big or we take a fat L there's not much middle ground. Like i said I think we are good this time but if you aren't sweating a little bit can you give me that confidence
 
SD said:
We complaining about below normal now?
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I wouldn’t call it complaining. I just think it’s worth pointing out that all major ensembles have a warming trend around the 21st through Christmas Eve. . It’s still around average but it’s been backing off each run. I just feel like that’s worth mentioning


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Loganelliott99 said:
I wouldn’t call it complaining. I just think it’s worth pointing out that all major ensembles have a warming trend around the 21st through Christmas Eve. . It’s still around average but it’s been backing off each run. I just feel like that’s worth mentioning


Sent from my iPhone using Tapatalk
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Do you understand why that's happening? Have you looked at the plumes to see what's changing or are you just throwing out a post salad? I'm asking this honestly not trying to be a ----
 
SD said:
Yep it's the same fight we fight when this pac ridge goes up. We win big or we take a fat L there's not much middle ground. Like i said I think we are good this time but if you aren't sweating a little bit can you give me that confidence
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The D10 Euro shows how to do it the right way, but it's hard to put a lot of stock in one 10 day deterministic model run, particularly when the other two major suites show something different. Whatever the orientation of features at H5, we absolutely need the PV in eastern Canada, pressing the height field south. With the propensity for blocking this year, I'd give that pretty good odds of verifying at some point soon. Will there be any stability to it? That's a different question and harder to foresee.

At the very least, we should have a period of alignment between high latitude blocking with very cold air on our side of the globe coming up soon. We could do worse.
 
SD said:
Do you understand why that's happening? Have you looked at the plumes to see what's changing or are you just throwing out a post salad? I'm asking this honestly not trying to be a ----
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Yeah I do after going back and reading everything


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