Typhoon Tip

In the eventuality that is storm comes to actually verify ... more so than less, I really don't think this ICON model is going to even see it until the model runs beginning ~ 30 hours from now. Prior to that, it seems to have very little assessment as to how the SPV over the NE Pacific will be forced by the PNA mode change - I suspect that has to do with the ICON technically being a meso model ( on 'roids as it were ) and not seeing the domain over the Pacific that is ultimately driving/responsible for said PNA evolution - it's a question I'm wondering.... In other words, outside of its spatial domain. I wish I could see the hemispheric scope of the ICON ...but, being that it is the ICON and I have not seen it perform very well, anyway, over the longer term for just about anything I've seen that is mid range <-- to short range relay, I'm not really inclined to bother. I have read a little about it... According the German org that hosts it, it is a Icosahedral Nonhydrostatic model - basically, ... take the Earth, and cut it up into a icosahedron ..well... one can find all here: https://www.dwd.de/EN/research/weatherforecasting/num_modelling/01_num_weather_prediction_modells/icon_description.html Anyway, I'm just wonder how seamless these jigsaws are, considering that the PNA covers a bigger area than 1/20th of the spherical surface area of the planet. Just speculation here , but if the PNA mode change is not integrating properly across the conjoining polyhedron regions, then it may not be driving the SPV split event right --> shitty returns over eastern N/A mid latitudes.... Or, it's on to something... I don't know if the simpler explanation is really bearing truth in this particular instance, however.

There's some era relativity there ... You know, ... given the state of the art of modeling infrastructure/ .. 'AI' and a circulation less saturated with gradient and velocity, D4 would incrementally more confidence than any D5 ..That was always the critical performance 'trust' threshold of the Euro. I do want to get on the other side of 30 hours. As I wrote - probably too long for many read... lol - last hour, there are is contention as to what and how much of it gets ejected out of the NE Pac SPV breakdown. The GFS is either going to win probably the greatest coup attempt in the history of modeling ... or, lose in that debate.

Thanks for posting this ...as I'm late catching up this morning - I noticed the rather impressive leap of the GEFs mean ... back toward more impact implications/ EPS look, compared to the previous two cycles. The EPS has been more consistent - as others assuredly either know, or should be keeping track. The GEFs being less so, but recently leaning toward acquiescence is probably a red flag against the operational for this particular system. NO, I don't think this is a crisis for the model the rest of the winter, either -

Seasonally ... ? - perhaps. ( Sorry ... wasn't a part of this conversation's immediate history but just an ob on model performance) The GFS has been reasonably consistent. The GGEM has been reasonably consistent. The Euro has been reasonably consistent. The problem is... the GFS does not agree with the GGEM, nor the Euro. The verdict is still out regarding this particular storm, which I feel - full disclosure - like the Euro and GGEM are likelier to succeed, given to some abstractions/ personal observations regarding GFS biases since these recent new version releases. That's by know means a declarative - ... This is a unique situation. As I outlined yesterday there are two points of handling contention: The first being ... there is a majority/ multi-model cluster consensus for the SPV, situated initially over the NE Pac/GOA region, to getsdisrupted - beginning at ~ hour 24 from the 06z initialization. After which, that's when things get complicated. En masse, the SPV gets 'split' .. All models/blends there in, essentially portray some percentage of its vestigial mechanical power as retrograding W under/along the EPO domain ( I annotated this in the charts a few pages back/yesterday if interested... ), while the rest of it gets bumped down stream over N/A mid latitudes - consequentially giving rise to whatever does ultimately manifest along the E/NE coasts. Correctly handling the ballast of that vorticity shearing/ conservation is like trying to predict which way an egg will roll off a ruler's edge, when starting from a position that's more or less precisely balanced. The second aspect ... regardless of 'how much' gets ejected downstream post the split, as it is nearing 100W ( about 2 days from 06z's initialization), the rapidly rising PNA offers some known model error prone as to the fuller( lesser...) extent of the aft region of ridge response. That is part of the total wave length of the storm - for those less privy. If immediately on the tail of the S/W ( say ...nearing Iowa), the ridge bulges more, the S/W will dig more. Now ... I am not entirely sure about the following notion... but from what I have been observing it "looks" as though the GFS is taking more of the SPV, post split, westward with the retrograde motion... Contrasting, the Euro and GGEM take crucially more so southeast. By the way, if one bothers to look at the 12z yesterday morning GGEM and Euro evolution, and compare them to the 00z, you can see how handling of that ridge in aft region of the S/W ejection is excruciatingly sensitive. Ever so subtle in the Euro, perhaps a little more coherent in the GGEM, those heights are higher, and they've slowed the progress of the total cyclone space, while adding intensity - just from slightly higher ridge heights across those cycles. I can't stress enough...this is a very powerful wave in these higher resolution models. Really even the GFS .. But is' flatter wester ridge appeal, ...it's sort of maybe "manufacturing" it's on destructive interference, whilst the other models are trying to reduce that offset factor. The Euro is < D5 ... mm. All the models are at 48 to 60 hours lead, for whether there will be a real S/W over the CONUS at all, so that pretty much wipes out any remaining doubt in my mind as to "weather" we'll see a storm evolving here. Switching the title of the thread to 'tracking' as opposed to 'potential'. It's also helping that the -PNA --> +PNA, emerges a negative teleconnector centered on the OV, both numerically in the GEFs derivatives, but also spatially in the pretty art of the EPS/GEPS/GEFS graphics, that really also nods to the logic that the GFS is again fighting the consensus as an outlier - perhaps even the very physics of the mode change. There is an interesting irony about this ... The Euro and GGEM have generationally been more guilty of leaving behind mechanics... while the GFS has a kind of genetic lineage to be more progressively biased. These models types have improved over subsequent versions ... but from time to time one can still get a vague sense that their tendencies still lurk. This is a situation where respective camps appear to modus operandi.

Yeah that’s essentially projecting a severe winter storm … this run is a slightly slower/deeper version of the 12z. watch the ridge in the west this run and compare. It’s slight taller and immediately the system slows down trading E for S component in system translation speed. It’s subtle but that’s 12+” vs 6-9” keeping in mind it’s the GGEM

Re Jan 7: Mentioned this in the banter... Sensitivity - to me - resides two fold: one is in the correct handling of the western N/A ridge aspect as the PNA enters mode change during this week. That can be a problem as to the true arc extent of the ridge envelopment; particularly if/when ejecting a very potent mid/u/a/ S/W through the field - if handled improperly and is bigger ... the burgeoning does so immediately aft of the S/W which is an accelerating constructive feed-back. Moreover feel the antecedent table is setting with height reduction/resistance over the Gulf/FL/ and adjacent Atlantic. These S-SE regions down toward lower 580s dam, with less than 50 kts balance geo-str wind, signals less destructive interference. Watch out for rapid rising PNA with nested mechanics! We await the the ridge amplitude and the following... 2ndly, the bifurcation in the 30 to 40 hour range wrt to the SPV over the NE Pac. The PNA changing mode disrupts that...and recent GFS operational takes the ballast on a retrograde motion, whilst the Euro cluster takes more SE as our S/W in question. Depending on which is crucial. I suspect the Euro at this range, however, given to it's superior resolution and correction/tech in play. Basically... watch this for more than merely SNE and points NE for impact. Plenty of time...

You folks of this forum's interest region are on the fence nearing Jan 7, for a short duration snow/ potential ending as wind combo - Sensitivity - to me - resides two fold: one the correct handling of the western N/A ridge aspect as the PNA enters mode change during the week - that's usually a problem as to arc extent with that envelopment, but is problematic here... because we eject a very potent mid/u/a/ wind max through the field and said amplitude - if handled improperly and is bigger ... - does so immediately aft of the S/W. That creates more depth in the TV, and with height resistance over the Gulf/FL/ and adjacent Atlantic coming toward the lower 580s with less than 50 kt balance geo-str wind, that signals less destructive interference, such that has been the case the vast majority of times this early winter. 2ndly, the bifurcation in the 30 to 40 hour range wrt to the SPV over the NE Pac. The PNA changing mode disrupts that...and recent GFS operational takes the ballast on a retrograde motion, whilst the Euro cluster takes more SE as our S/W in question. Depending on which is crucial. I suspect the Euro at this range, however, given to it's superior resolution and correction/tech in play. Basically... watch this for more than merely SNE and points NE for impact.

Ha hahaha... no schnikies - I mean it'd take two shifts to analyze the whole set - you think you'll population the dbs and make ur AFDs in time.

heh ... my interpretation of that is different I guess. That looks like an actual temperature/thickness distribution that is marginal, as those correlate to scalars of the isohypses; meanwhile, the flow configuration is still in the positive mode of the PNAP. It's 'warmer than normal' heights in general but 552 heights can host 536 thickness, and we have the flow nadir anchored near 80W. Having said that, ...yeah, it is annoying. Lol. I mean there was less contention in the previous version(s).

Heh... I always thought that description best fit the EPS... which it may - just sayn' I've often found that if the operational run "looks" more(less) favorable, the EPS mean does too, in the relative scope.

Holy Schitchel ! He/she used to be one of my favorite mid rangers down in NCEP .... "..Arctic air will dig across the central then eastern U.S. behind the windy and precipitation focusing low to include a threat of plowable snow from the Great Lakes/Ohio Valley to the Northeast. Another quickly developing heavy snow/ice threat with some aforementioned uncertainty is on tap underneath Thu into Fri from the TN/OH Valleys through the Appalachians/Mid-Atlantic to the Northeast by frontal low/coastal storm genesis..."

Greatest anomaly ... relative to climo as it were. Not cold - but I think that's what you meant. Anyway, La Nina this or that aside ..that's about the best your ever gong to see 300 hour ens mean. In fact, typically by that long lead we end up with spaghetti that averages more annular looks. That's sick structure for this range ... but one with an aspect ratio, proportional to the endearing winter enthusiast, being the best part lol.

That's a complex answer. Lol... ( hey, consider who you're asking ) Short answer, I don't believe so. Long answer: Personally... that phenomenon you mention, I've often had 'chicken vs egg' problems with that. I think that perception has that the wrong direction. Basically, change was already taking place, if perhaps "intangibly," before it manifests on charts. Then, a storm event materializes because of and sometimes on top of the emergence threshold of the pattern modality. Here's the thing, because it wasn't coherently seen, that gives the illusion that the storm- event was the cause... It's really the other way around. So if you can figure out how to parse that paragraph of conceptual jargon out, and formulate an impression of what I'm trying to say, I'd be very proud of you... In this case, The governing mechanics of the Jan 7 system is entering the hemisphere during a pretty significant whole-scale reshuffling of the pattern. Really...from well west of the Date Line and the plastic island of the bounding Pac, ...all the way around to Greenland, today vs the 300 hour range end up bearing much less comparative likeness. That really begins to occur from Wed ...Thursday on, within which this Jan 7 deal plays its cards and quite likely gets a physical enhancement, too. "What ever happens in Vegas, stays in Vegas" ... On the other side of that Wed/Thu pattern boundary/reshuffle, think 'removing the memory' of the previous regime.

Right on schedule arrives the mid season break down of the leading ENSO signal ...

Ha! ... uh, I dunno 'bout that. It's more like the population of the initialization grid. There used to exist this "model diagnostic discussion," back when it was carried under the NCEP banner. But then it became WPC ... etc, and I don't think it's covered there? But they would flag this in discussion and surmise how it may/or not have effected the model processing. Now would be a good time for that -

Lol... dude we get it.

Oh... I know ( or 'think' I do - ) what happened. The American model products don't correct ( don't think nearly to the scale or degree that the foreign clusters do ) for input garbage. This smacks pretty loudly as the GEFs 'AI' gulping in back-wash initialization - it's sacked the whole ensemble mean too deeply and pervasively for me to believe this was organic. I bet the Euro negated faulty inputs. That said, I do think there is going to be some uncertainty wrt to the SPV spit over the NE Pac, and how much gets inserted downs stream. And if/should the ridge bulge in the back side, that ups the ante -

I'm really curious what is causing the flip flops in the GFS ...when comparatively, the Euro has been considerably more stable. Aren't we giving them the N/A input/grid. Lol. The GFS was competitive this season ( at least ..) but if this thing goes on to be a moderate or even low end major storm success, this is going to be a pretty significant indictment of the GFS' middle range forecast performance...

Update: Short version, the super synoptic evolution supports S/W's NOT (as much) being mechanically neutered ( negatively interfered ...) as they come eastward across the country. There is contention among the model types, and within there own continuity/handling therein, as to what and how much will actually be there. Critical time intervals to know that answer appears about 36 hours from now ( estimating - ) More details ... The S/W mechanics responsible for what was D7, now ... D5.25, originates from a rather usual source. This is not the typical trace-back to the date line, or delivery through the EPO domain ...etc, where it can be observed in WV channels and assessed over longer, real-time analysis, then balance against model performance/ initialization issues ... Being able to do that will service confidence or doubt. Can't do this with this guy... It's coming from that SPV split, as it appears to bifurcate as seen above. The GFS has been flip flopping as to how much then retrogrades west under Alaska, vs how much injects over N/A. More goes west, less goes east... vice versa, = storm or no storm. The PNA rise is still in tact in the various guidance ens means. In fact, it was well discerned yesterday... and that has continued if anything even more so on the 00z. Numerical interpretation of the GEFs mean would suggest both this system, and a one out mid month ( ...fuzzy 12th+) are on the table, due to that correction, and then modulation out in time...etc. That said, the interesting aspect is that now model in either the Euro/EPS or GEF members ..et al, really look Archembaultian about this/ .. as in a bona fide correction event. Believe me...that would make this more confident as the total scaffolding would be face smackingly clear. "As is," this appears to be a maintenance trough translation - basically normal periodicity. But, the PNA --> PNAP super synoptic considerations appear to to be more in constructive interference for just about anything for a change. Including this, and that's why we're having discussions. That said, I'm not sure the western ridge won't respond more and show some 72 hour lead adjustments that increase the y-coordinate of the arc of the ridge. It may not ... but, this is a PNA pattern change is numerically impressive...going from -2 to + .5, or even +1 SD is huge amount of implicit alteration in the mass-field distribution, and it is doing so quickly in both the EPS/GEFs. The western ridge could certainly expand more so, as the numerology of this would allow room for that. I'm not sure why we have to have this flat ridge aspect to it. It may.... "maybe" be related to the fact that there is a very modest positive bias to the outlook curve, wrt to the verification curve. pure speculation though... That's probably nit -picking and irrelevant given to the nature of that rise - it would be unlikely to error that much.

It's more than then just the GFS operational, tho - as was just sneaky mentioned in a brief sentence now scrolled ... the entire ensemble mean of the GEFs has lost this - all but small vestiges. Essentially ... gone. hmm ... Hopefully either it, or the Euro's EPS et al, will be 100% correct. That way we get to chide and humiliate one or the other for being uniquely abysmal -

Ha. Well there’s some seasonal relativity there … yeah it’s the GGEM and outside of day 5 at that but 132 looked like it’d be better performing but the 138 hyper contracted the system into the dimensions of a thunderstorm. Jesus

This is probably where the Euro’s control mechanisms come in handy

Bottom line it’s gonna do this probably for the next two days

Yeah no kidding. meanwhile the GGEM destroys

GFS is carrying the system still. That ICON was just weird. this thing is slipping initialization