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Isotherm

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Isotherm last won the day on December 9

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About Isotherm

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  1. Isotherm

    Stratospheric Discussion and Forecasting

    The closest recent example as far as similar timing (mid/late December), QBO state (easterly 50mb), and SSW type (displacement) is December 2000. However, this again underscores how the evolution of the SSW is very important, and can be deleterious. The December 16th 2000 displacement event pushed the SPV vortex directly toward the Gulf of Alaska (opposite of this year's evolution with the vortex going into Eurasia). The effect was that January 2001, while it was colder than normal in our area, was a more benign month than December 2000 b/c the vortex situated itself in the Gulf of Alaska - perfect spot for blowtorching Canada. So the sensible weather pattern actually worsened a bit due to the SSW. This won't happen in the present year, as the vortices will be shoved toward Eurasia, so higher heights are going to flood the EPO, PNA, and NAO/AO domains. Late December 2000 displacement event. Note this was a great progression for Europe cold-wise.
  2. The GEFS is now detecting the NATL jet bend, too, redolent of the likely weakly negative NAO which we discussed yesterday. The airmass on this run becomes conducive by the 21st-22nd. The EPS actually largely accords with that notion now -- 21st/22nd trough into the Great Lakes -- before it slips back into delusional land by the 24th/25th with the meteorologically unsubstantiated retrogression into the West.
  3. In the words of the great Albert Einstein, the definition of insanity is doing the same thing over and over again, but expecting different results. It's quite mind-boggling how some continue to analyze the D15 EPS w/ such fervor as if God himself had carved the answer in stone. I do not bother engaging with those ostensibly closed to the notion that they're practicing erroneous meteorological analysis. My patience is wearing quite thin, and it's a waste of time and energy. This is one of those periods wherein one simply steps back and waits for progression to occur as expected, then invariably, once the pattern begins, that same crew, referred to by Einstein as insane, will claim that this is "what was expected" all along, uprooting and shifting goalposts faster than the Niagara Falls flows downward.
  4. Without seeing the z150, z70, z50, etc., vortex orientation, one can't make that conclusion based upon this snapshot. Keep in mind that the stratospheric vortex tilts sometimes significantly, vertically, during a stratospheric warming event. Initially, there won't be a strongly negative NAO, but it will be weakly negative beginning in late December in my opinion, sufficient to modulate the jet not insignificantly.
  5. Isotherm

    Teleconnections: A More Technical Discussion

    Much depends on the eventual outcome of the displacement/stratospheric vortex progression. W Europe will transition into cyclonic flow initially, as the SPV gets squashed equatorward, but if a full SSW realized, and the warming can push the SPV sufficiently equatorward into Europe, the flow will then turn northeasterly. This wouldn't likely occur until early January, so the pattern change timing for W Europe would probably be about 10-14 days after North America. If the stratospheric warming ends up weaker than progged, the W Europe pattern may not be as severe, but I still do think January could be colder than normal in W Europe as I favor a -NAO.
  6. The latest data for the GWO/AAM and attendant torques has updated, and it continues to suggest all systems go for my anticipated transitional period, 20th-22nd, with airmasses cold enough to support snow from that point onward.
  7. Isotherm

    Teleconnections: A More Technical Discussion

    @Bring Back 1962-63 Great post, David, and thanks for posting all of the images. Nice to see GWO progressing rapidly from 8 --> 5 exactly as @Tamara and I were discussing last week -- the negative/momentum removal phase was quite diminutive indeed, with the background +AAM state resuming. Large +MT spike over the past week which is aiding adjunctively in massive wave 1 vertically propagating energy into the stratosphere. This expeditious progression into octant 5 GWO further bolsters the argument that we're already seeing the termination of this putative relaxation period before it even begins. I maintain my transitioning date around the 20th-22nd, with the airmass cold enough to support snow in the Northeast (if there is a short wave) prior to Christmas, and the cold pattern really amplifying beyond Christmas as all major indicators collide. Very interesting times ahead.
  8. This is a great post by meteorologist, Jay, "tornadojay" on another board -- the images speak for themselves, and once again underscores a point many of us have been emphasizing -- The last 2 runs of the EPS excites me in the fact of the potential amplification of the pattern out in the Pacific. When I wrote my college paper on the amplification and spatial variations of the 500 mb patterns for 1995-1996 vs 1996-1997, one thing from the observations was quite clear.... the bullseye zone for major troughing was near the longitude near Hawaii which really sent things into motion for major stuff for us. Though it’s way out in time, the last 2 runs have a pretty strong signal of this which really gets the amplification moving across the U.S. ...also showing an old school print-out from feb 96 from my paper
  9. Concur again here. If the NAO domain does not respond as expected in the 21st-26th period, we'll have cutter issues through that period [if it's -EPO / +NAO]. The two keys to the proper evolution are Pac. forcing induced W US ridge handling and the height response downstream over the NATL.
  10. One could have seen the trough retraction vs. prior runs coming on the GEFS. It's akin to a student averaging their math test scores: say you have ten tests in the 90s, and one or two tests in 40s. That will decrease the mean significantly. The operational run w/ the ludicrous trough amplification in the West contaminates the mean height signal. Other point lost in all of this, and something I've broached in many prior posts, is the NAO domain. Notice the geopotential height correction, significantly more positive in the NAO domain around the 21st versus prior runs. This will continue as the models typically don't detect the stratospheric modulation until < 10 days. A stronger -NAO will invariably aid in countervailing a Central US trough with some height suppression in the Northeast. Also, examining the MJO plots, the ECMWF now looks more accurate than the GFS in terms of its MJO depiction collapsing / coherency diminution in p4, versus the GFS robust p5 signal. So, again, utilizing meteorology and not modelology here, I think the GEFS is now mishandling that transitioning period as well a bit. Note the disparities in the NAO domain, with material increase in heights on the latest 12z run. This was a major positive shift even though the trough axis aligning in the CONUS worsened, for erroneous reasons in my view. I won't allow mercurial model iterations to domineer me into a particular stance, and the reasons delineated here seem sound to me. This appears to be the most intense "inter-web battle" over a one week period I've seen in awhile (and I won't prevaricate - my competitive edge makes me quite curious to see the outcome).
  11. The compliments are very much appreciated, @amugs, @ZACH. Agree, it's a real shame that this one snuck up on us.
  12. Exactly, and this is verbalized perfectly. The EPS snapshots from circa a week ago implied a stable, blowtorch pattern (which was extrapolated out on the weeklies run that caused the uproar). I read discussion of possible 3+ week relaxation period at that time. Clearly, the implication was apocryphal.
  13. Well, not even 24 hours from when we had our debate/discussion yesterday, and the 12z EPS run has already largely caved to the GFS based guidance, with significant alterations in the 19th-23rd period as anticipated, harmonious w/ the forcing. Maybe someone else can juxtapose the EPS changes, as I can't right now.
  14. Isotherm

    Stratospheric Discussion and Forecasting

    I don't think there's any reason to be enamored with a split. Splits tend to be a bit more high-risk for us, while displacements are often more reliable for North America as far as winter impacts. Regardless, an official SSW isn't required for the winter to continue evolving as anticipated.
  15. Isotherm

    Stratospheric Discussion and Forecasting

    Precisely, and great post here @earthlight. It will provide a colder than normal pattern, a active one, though not severely cold. I provided an example I believe here and elsewhere of a displacement event in which the SPV was shunted to Eurasia -- late January 1987. February 1987 was much colder than normal over the Northeast US (about -3 to -4).
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