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Pattern February 2024
- Thread starter SD
- Start date
this is exactly what you want to see with this upcoming pattern dump some northern stream/energy from the TPV into that trof and boom you have a pretty legit cold feed 
GFS looks like it’s about to revert back to Garbo because it doesn’t effectively dig the S/W from the TPV, but the CMC just joined the train 
If you are into the stratosphere stuff, Judah Cohen had a good post yesterday. Excerpt below.
Source: https://www.aer.com/science-research/climate-weather/arctic-oscillation/ (See "Impacts" section)
"...As I discussed back in November, Canadian warmings overwhelmingly transition to just two other PV phases - one is a larger sudden stratospheric warming but most commonly to a stretched PV. A Canadian warming can transition to other PV states (in the strong PV category) but it is significantly less likely. I don’t see another SSW anytime soon but the threshold for a stretched PV is much lower. I think in the time frame of the second week of February and even possibly mid-February a stretched PV is becoming more likely. This should help end the very mild pattern in place across North America. The intensity and duration of cold weather associated with the stretched PV is yet to be determined.
I want to end with one wild card. As usual I show the latest polar cap geopotential height anomalies (PCHs) plot in Figure 11, but occasionally I have also included the North Atlantic regional version of the plot, with the most recent in Figure iv. In Figure 11 one cannot observe the typical “drip” of warm/positive PCHs from the stratosphere to the troposphere often on a timescale of two weeks. Instead, the warm/positive PCHs in the stratosphere associated with last week’s major warming come to an abrupt end and independently warm/positive PCHs appear or emerge in the troposphere in early February. But looking at the North Atlantic regional PCHs (below) a different understanding is suggested. Warm/positive PCHs in the mid to upper stratosphere associated with last week’s major warming first “drip” or descend into the mid to lower stratosphere this week. This first leg down can be seen in Figure 13b with the polar stratospheric warming centered over Greenland. Then “drip” further into the troposphere in early February. Since this is only the North Atlantic regional plot, it is strongly suggestive of the return of Greenland blocking, though for now I don’t see much evidence of this in the weather model forecasts."
Source: https://www.aer.com/science-research/climate-weather/arctic-oscillation/ (See "Impacts" section)
"...As I discussed back in November, Canadian warmings overwhelmingly transition to just two other PV phases - one is a larger sudden stratospheric warming but most commonly to a stretched PV. A Canadian warming can transition to other PV states (in the strong PV category) but it is significantly less likely. I don’t see another SSW anytime soon but the threshold for a stretched PV is much lower. I think in the time frame of the second week of February and even possibly mid-February a stretched PV is becoming more likely. This should help end the very mild pattern in place across North America. The intensity and duration of cold weather associated with the stretched PV is yet to be determined.
I want to end with one wild card. As usual I show the latest polar cap geopotential height anomalies (PCHs) plot in Figure 11, but occasionally I have also included the North Atlantic regional version of the plot, with the most recent in Figure iv. In Figure 11 one cannot observe the typical “drip” of warm/positive PCHs from the stratosphere to the troposphere often on a timescale of two weeks. Instead, the warm/positive PCHs in the stratosphere associated with last week’s major warming come to an abrupt end and independently warm/positive PCHs appear or emerge in the troposphere in early February. But looking at the North Atlantic regional PCHs (below) a different understanding is suggested. Warm/positive PCHs in the mid to upper stratosphere associated with last week’s major warming first “drip” or descend into the mid to lower stratosphere this week. This first leg down can be seen in Figure 13b with the polar stratospheric warming centered over Greenland. Then “drip” further into the troposphere in early February. Since this is only the North Atlantic regional plot, it is strongly suggestive of the return of Greenland blocking, though for now I don’t see much evidence of this in the weather model forecasts."
Still the CMC is rather mid because it brings energy right back to the GLs afterwards 
Here’s the 4 run trend from the GFS… there is no trend, we either settle with a pacific origin wave that cuts off ots and we get WAA back in quicker and a ridge more rooted to the subtropics, or we inject a TPV ext into it, bring the can ridge more poleward and undercut quicker
Here’s the 4 run trend from the GFS… there is no trend, we either settle with a pacific origin wave that cuts off ots and we get WAA back in quicker and a ridge more rooted to the subtropics, or we inject a TPV ext into it, bring the can ridge more poleward and undercut quicker
rburrel2
Member
Yea, the verdict is still out on this timeframe. Seems like every piece is on a knife's edge from going one way or the other.
The 12z Icon looked great and hopefully the Euro has a similar look.
It's looking increasing likely we will get the mega wedge with a high pressure possibly rooted all the way in Northern Canada and knifing it's way through our area. I've seen those type CAD events overperform before on a few occasions. Problem is it won't matter if there no cold available. A piece of the TPV has to drop down and provide some cold dry air to tap in to for us to get wintery.
The 12z Icon looked great and hopefully the Euro has a similar look.
It's looking increasing likely we will get the mega wedge with a high pressure possibly rooted all the way in Northern Canada and knifing it's way through our area. I've seen those type CAD events overperform before on a few occasions. Problem is it won't matter if there no cold available. A piece of the TPV has to drop down and provide some cold dry air to tap in to for us to get wintery.
tonysc
Member
Me too Mitch, I'm over here in Greenwood and I would love to see something like that.
R2R trend on the GEFS. Would love to see that trough around Atlantic Canada dig more, but taking the right steps here 
You can see at 500mb the ridge going up through AK and the Aleutian Low establishing itself. The SW trough is in the process of pinching off and will allow the core of the cold to drop in farther east:
The 850s showing up in western Canada are cold. This is probably underdone, given the height of the ridge going up.
You can see at 250 mb the howling jet across the south and the split flow out in the Pacific....kind of an Omega block look:
It shows up really well on the 2 PVU pressure map too:
Add in the strat warm and it's impact on the NAO that the models aren't even picking up on yet, and by Valentine's day, we're going to be rocking. I'm thinking a major winter storm for the SE around 2/18. Let's go!!
The 850s showing up in western Canada are cold. This is probably underdone, given the height of the ridge going up.
You can see at 250 mb the howling jet across the south and the split flow out in the Pacific....kind of an Omega block look:
It shows up really well on the 2 PVU pressure map too:
Add in the strat warm and it's impact on the NAO that the models aren't even picking up on yet, and by Valentine's day, we're going to be rocking. I'm thinking a major winter storm for the SE around 2/18. Let's go!!
D
Deleted member 609
Guest
If he’s in I’m in. Let’s do this.
This is the most impressive analysis of 384 hr output I've ever seen. I can't think of even a single thing that could derail this
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The 850 0 degree moved from *checks notes* New York City to just between 40 and the border in NC on the GEFS around day ten.
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It's over man just ask a few here that make sure we know they think it is
Euro unloads a TPV into the NE US at day 7 ? just need a southern stream wave to eject from out west 
Here comes a wave entering the western US 
You got a little something down there over Mex. Seems like it would probably get squashed, but who knows.
Has wedgie written all over it.
backdoor front?
Euro ends off beautifully 
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I hate to make this comparison, but it's almost the exact same wave orientation. Just pull the low into SE Canada and let the wave develop.
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Ok I’m glad someone said before me, but I couldn’t help but notice this.
Greenland / Davis Strait ridges are nice, but nothing can block up and slow down the flow across the CONUS like a slow-moving low over the Northeast / off the NE Coast.
Absolutely beautiful progression right there. Interested to see if the EPS continues or picks up more in the signal. Had some hits last night for this period
The one big difference I see is the big block over Greenland in 2004, with the weaker one in Central Canada. It allows for a slower lift-out of the 50/50 off the NE coast and the trajectories out of Canada are more favorable. I would guess that the air to the north would be chillier too, but without the maps, it would just be a guess. Anyway, it's remarkably similar, other than that. Here's a map of that event, from the NWS in Raleigh:
Looking at Grit's animation above, there appears to be just enough ridging north of the low to hold it in place longer. Big, big positive factor, if true.
EPS looks better so far, better trough around Atlantic Canada and a stronger ridge in Canada 
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Control run pulls the ol' weathermachine(deep deep cut) move and crush, kills and destroys the storm to the south.
SnowwxAtl
Member
Prolly suppose to be whamby, but this take me down everytime! ?????
Still a weak signal on the EPS like last run, but making strides at H5, digging the Atlantic Canada trough more, raising heights over the Great Lakes and Canada and loosing the subtropical ridge influence, and the shortwave looking much improved. Plenty of time here to turn this into something or trend worse. Normally in my experience CAD winter storms like to show up between day 7-10, this is barely entering day 10 
RIP early Feb torch 
Blue_Ridge_Escarpment
Member
Earlier Feb looks the most promising to me with a mega CAD event most likely
That's a southern slider set-up isn't it?
It would be if we can keep the 50/50 in place.
Hopefully we have multiple chances between early Feb to mid-Mar, but who knows. 1 chance would be a start for us east of the Apps. But yeah, the weeklies try to move things into a better pattern by kicking that SW trough east while building an AK ridge. We actually need some renewed momentum in the Pac Jet to do that because the initial big jet extension coming in a few days dies out.
Just looking at the surface anomaly charts here on the weeklies from Feb 3 to 23, it is showing low pressure in EAsia being replaced with high pressure (+EAMT), and shortly thereafter, the Pac Jet extends and the Aleutian Low swells and moves east...then the southern stream across the CONUS becomes active again. Long way out of course, but that Feb 17-23 timeframe has the best look at the moment IMO.
