Typhoon Tip

It's times like these I wish CPC still had the 'Model Diagnostic Discussion' product. I found that very useful back in the day. Every so often, a guidance would go astray. Invariably, you go read the discussion, which disseminated pretty soon after the model release actually ..., and it would read like this: "WV IMAGERY SUGGESTS THE NAM INITIALIZED BETWEEN 10 AND 15 KTS TOO LOW WITH THE WIND MAX VELOCITIES ASSOCIATED WITH THE WAVE SPACE SET TO IMPACT THE UPPER MA AND NE REGIONS ... RECOMMEND NOT USING IT IN LIEU OF ..." ...x y z that do not appear to contain this error...etc. something like that. This smacks as missing something in the grid but who knows -

trend is even more coherently demonstrated comparing the 78 from 00z to this 12z's 66 That really won't take 6 cycles to be right with the pack... That much correction taking place again... twice tops would do the trick

Left is 72 hours from 00z last night. Right is 60 hours from 12z this morning. Same interval demoing a clear trend... The NAM prooobably does this incrementally catching up routine for the next 6 or 8 cycles.

I suggest your analysis late last night was pretty spot on. When the 500 mb isotachs have less "kink" inflection, the low is pancaked. This NAM run is both a tick more inflected, and also just has a stronger core wind max and PV field in the core. These two factors are the "finally seeing" identifiers. So this incrementally moved toward the consensus, albeit only a small move. This will probably do this on every cycle through tomorrow night ...at which time it then suddenly has a run that has 24" falling in 3 hours -LOL It makes sense when we're running a wave space through a compression that's so extreme it's sort of on the edge of total suppression. But this is a strong wave space, so if the compression gives it any window and the cyclone response becomes a rather abrupt correction/emergence

I could see you flipping to snow when rates are high, and then light cold rain... back and forth for a couple hours, then the low gets abeam of your latitude and the cyclogenic feedback related dynamic height falls... more backing llv flow, etc etc, while still having mechanics aloft and suddenly, you burst heavy snow with wind for 3 hours then it's over. just to the reader ... we need to keep in mind that that this f'er is going to be hauling ass. I could almost visualize the radar looks less like a rotating region of returns, and more like the whole thing is rolling backward - the cyclostrophic response and the forward speed of the low pressure are nearly the same speeds.

I was just taking a closer look at the 06z RDPS ... At 69 hrs, it has the 0C 850 mb isotherm S of even Scott... with a 992 mb low passing through climo needle slot lat/lon for Pike snow. Yet it has the mix line NW of Boston at that time. I get it that it's 925 mb is probably doing the trick there, but that validity comes into question for me. There's a +PP N of this system, in general, and once the pressure well gets going SW of the region, and lowers further as the low makes it's closest approach ... despite the higher resolution of the RGEM that total synoptic circumstance will tend to back the flow more. Combining with vertical fixing in the cold sector, that's isothermal in the sfc to 850 ..probably -1C .. I could see that busting that mix line too far NW ... 30 or so mile say... if a 06z RGEM were the final solution. Which it's not. Still, there's plenty in that handling/model run to pick apart.

Zero limitation on snow accumulation unless it is straight up 36 F and it's mixed cat paws. Soaked cotton ball snow type would stick. I've seen 8" at 34.5 with snow that's borderline silvery. This concern is part of the mania cycling that can be identified in the addicted model cinema user's stages of stoned. It's like they can't take an optimistic look, because they need the downer to make the next model run a more potent high. LOL

You're not alone in noticing this ... Using the telecon to assist, there's arguments against it tho, with the PNA .. it's perturbation timing is off on the 22nd. The operational run, the one doing the more obvious ticking ..., is having a domestic battle with its ensemble family, because the index derivative comes from the ens mean, and the higher resolution operational version - tough call. This system we're monitoring for 80 hours from now has the benefit of a small + perturbation in the index. The next one is the 24/25 thing... The 22nd is a local time scale nadir between the 20th and 24th +d(PNA). Uuusually ( no always) these numerical telecons spurn forecaster valor at least some way, some how.

We've seen some pretty fantastic accumulation rates in smaller periods of time over the years. I'm not worried about the 6-9 hr window of this event, necessarily - but ... there should be a limit to this system's intensity based upon the fact that a lot of the mechanics are so tightly couched in a highly compressed field. This is a bit of a neg offset to vitals, like diffluence ... DPVA ...etc mechanics, which in general would foster better UVM and ultimately the wholesale event strength. I almost wonder if the Euro cluster is seeing that limitation. By doing so, it would limit the sfc cyclonic genesis field and there you go... a slightly weaker/flatter appeal. I just wanna caution that the EPS was a better performer of the event last week, which the American models spent a couple day's worth of cycles with deep scary bombs along the New England coast. EPS never really wavered... it proved ultimately wrong, because it did snow, and 2-5" was a better performance than it had ... but weighting error, it was much closer to reality than those gaudy GFS monster solutions. As an aside ...there is a mantra that 'past performance doesn't dictate future results' yeeeah. I personally feel that is a shield folks use to fend off solutions, in hand, that are less than d-drippy. In reality, if/when we are in the same essential pattern circumstance, which we are, there certainly is some value in how well a given guidance has been performing relative to that period time span. It'll be interesting to see where we are this evening, in guidance with this thing ...as we will be < 72 hours - a time when models tend to stop trying to wonder off consensus more (typically).

Man is that haulin’ ass in this ICON run moves some 350 mi between 72 and 78 hrs. basically 60 mph cyclone translation speed - gee wonder why the models have been having issues with structure and placement

0Z RGEM’s close to bombogen deepening rates unfortunately it’s an overall warmer solution though

GFS ens just beginning to see the 24th Spattering of members over eastern NE with a couple deep members. It’s primitive as signals go and more members likely yet to join … provided the compression continues to ease The op version is for the moment a vast west outlier

It's interesting how the low in a lot of the flat versions during the prior consternation ...were detonating out along the right exit region (outer S side of the purple streak), but as this came thru the last 36 hours ...gradually the modeled low has migrated under that streak. It could continue across and end up on the polar side of that sucker. There's some feedbacks tho - where the lower level thickness gradient is packed, that's usually where the low tracks.

They should all be detecting at this point forward...

Not exactly shocked we are at this state that we are with this thing. I mentioned to Jerry when he started this thread the other night that in this situation ... it was a good thread. I know, because truth be told ..i was about to launch myself lol. Anyway, the higher resolution operational guidance versions were probably going to pick up on this idea prior to the coarser resolved ensemble members, definitely their normalized mean there after. It was unlikely, given that this system emerges or disappears inside of decimal variances ( due to all the compression ), that the ensemble mean would altogether be very useful in the medium range. I thought at the time that < 72 hours ...but 96 ..same idea in principle. Should we get Charlie Browned at this point it's may be fair to consider it a failure at a systemic level with the tech. Upper light to lower moderate event. May cap a little higher than that. In fact, details like CF over eastern shore points and even some straight up OES banding undercutting the mid level goodies ...there's ways to cheat us up a tad.

3 and 4 days ago the GGEM solutions looked remarkably similar to the total mean as it stands right now, when the other guidance were pancaked. This is a mid range coup at this point ...unless we get Charlie Browned ... It could be a tick NW of the reality as of the day's runs, but in principle ...this is kinda its storm

The GFS versIon of the flow medium across the country has a definitive difference to the Euro leading the 24th. Not sure which will turn out ultimately real. GFS has a western ridge node moving bodily eastward thru southwestern Canada/Pac NW leading up thru the 23rd and that allows less shearing with the trough back east in its solution --> system up the EC. Euro holds this ridge node farther west; in fact, it's not even clear if it ever comes east, rather just sort of dissolves. Anyway, that opens the flow up in the east. Wave space arguments become a negative interference for amplitude --> no system up the EC

Just in my opinion the trend in the Euro is more telling here. Also, it looks like the EPS is ahead of the game comparing to the operational. The 06z EPS ( from what I can tell...) was about where the operational is now, but the EPS of now is closer than the operational. In other words, the op version is playing catch-up This is red flag that the correction vector in the operational is NW of prior runs.

I suggest at this point you go all in on a society halting ... no j/k. Confidence is up for an event - I'm not sold on magnitude. Like I've been saying/reasons why ... this really should cap at mid scale

Right, re the LE quadrant and initiating and so forth. I'm bummed we don't see more u/a diffluent geometry with acceleration region over central NE... while that 500 mb jet is punching underneath That's when you get the meso bands with lightning

Last I saw him was at an nws presentation down in canton, ma a year and a half ago. He was well... bald, but doing well. - his words. He was like, 'yeah, back in the day when i had as much hair as you' I remember him on air in like ...1986.

I'm on the fence with that aspect ( bold ) ... There's a lower ceiling to this because the total diffluence aloft is being offset by the fact that the s/w space is entering a region that is already moving so fast. ↓ diffluence limits q-g (quai geostrophic) forcing and that ↓ UVM potential ...that outta ache up some heads... lol ... anyway, I don't think we can get carried away with this one

how about the near triple stream phase 28th + ha

Yeah, agreed ... the 23-25th is probably the next viable risk period - nod to any model that speeds that up by a day between now and then, because of the underlying mode of circulation being what it is - fast. Just something that's been air apparent to me about that period, is that said mode of circulation is slowing. I spoke at length about this, yesterday, ...and then immediately the Euro's 12z run "re-compressed" the flow. The GFS however has maintained its idea of slowing things enough that the next series of wave mechanics have better ability to conserve it's total vitality as it runs up the flow at that time. That's why it's been more robust with that development. The CMC is not as relaxed... it's speeding up the same wave complex, but also has it suppressed because - time to iron this out. But ...as the present event that's looking above median confidence at this point, was all but gone yesterday ... these compression patterns can be overcome, too

agreed ... I was commenting on the RGEM earlier - prior to this 12z cycle but still is so... There's not much hope ( to me ) of this being a ptype issue NW of very SE zones given a 'super' blend of what's available in guidance. Also, I thought at glance that this may be very meso banded ... it may be to some degree, but the 300 mb critical 'fan' jet doesn't actually exist in this situation in either the GFS or CMC. The wind maxima are collocated S of the region. I'm not sure that will supply the slant wise polarward tug aloft that is needed for better frontogenic forcing - interesting