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Armando S

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Armando S last won the day on June 25

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  1. Some activity stirring up in the Eastern Pacific after a relatively slow start. Great "in-situ" example of a passing CCKW just ahead of the MJO wave, which enhances cyclogenesis 1-3 days after the initial passage. Attached is a side-by-side comparison of a VP200 hovmoller (filtered) edited by the great Phillipe Pappin (Atmospheric scientist for U.S. Naval research Lab) and to the right is the same exact premise, except unfiltered and shows an actual visualization of the CCKW (blues/purples = areas of convection/upper level divergence). 60% of formation over the next few days into a tropical depression. Conducive ambient conditions for more organization so we'll see where this goes.
  2. Thought I'd share some of the observations and "in-situ" data i've both collected and monitored. The late April into early/mid-May featured a violent, robust, and severe weather outbreak the U.S. hasn't seen in years! The synoptic and larger-scale forcing that had transpired leading up to this aforementioned period, in a way, dictated the inevitable collapse of the pacific jet-stream giving way to a meridional orientation. If we also look at the 90-day averaged OLR anomaly, we can see what has kind of been both the "elicitor" and overall background base state "signal". Poleward of that standing convective "hotspot" (which to add, still think this weak-Nino doesn't erode and give way to Nina so quickly like some are already presuming), we've gotten some anomalous jet extensions poleward of these ridges. In essence, what i'm trying to show from again - my limited knowledge thus far in this area (albeit a significant boost in comprehension and understanding thanks to some of you guys in here!), and as stated - "in-situ" learning via trial and error, of how we could predict the catalyst for breakdown and retrogression of the RWT. I've taken consecutive zonal/integral AAM tendency plots and just annotated on them via a GIF. Basically, what is shown initially is an episode we had back in April/May as spoken above. It's known that these episodes, or periods, happen over ~ 30-50-day time scales, with even specified periods happening potentially between 10-20 days. On that note, what dynamic variations can speed up such episodes? Anyhow, we can see the poleward U-wind accelerations propagating poleward from the tropics into the mid-latitudes over time before not long, -U shows up south of this poleward propagating westerlies, therefore, an expected breakdown and soon-to-be retrogressed process that'll take place over the next week exactly like what had transpired back in May. Notice the jet-extension thus far beginning June 1st. The last image has been annotated from IBM Chief Met. David Gold, which he discussed the overall "framework" of this synoptic forcing event, but going back to my original content - this entire series of tropics-extratropics interaction via utilizing the GSDM, can we possibly only get better at monitoring these real-time components and forecasting at certain lead times, like lets say, over 2 weeks? We can garner clues and deduce some ideas, but what also makes this tough as i've come to learn, just as the experts here already know, there is so much more to this than just oversimplification that i've presented. This base-state has had a role, and if this -VP200 weren't the way it's now; therefore, the sub-seasonal atmospheric variability would be different. This implies different propagating circulations, and reflecting AAM torques likely. Basically, the premise of this post was to, again, share my observations and have it open for fantastic discourse because it's interesting, and rather "mind-blowing", that many forecasters, meteorologists, experts, etc., have come this far in an imperfect science and still have so much to learn. However, if we can just gain an "advantage" little by little, it can only bring us closer to constructing a more "polished" forecast for long range lead-times.
  3. Excellent analysis, discussion, and conversation Isotherm and others (from the teleconnection thread as well - for some reason, I can't comment on there); Tom - excellent summer forecast as there is no such surprise with how superb you are in conveying and output!
  4. Absolutely ripping +SN and as @brooklynwx99 mentioned regarding cooling within the vertical; the rates increasing as a function of that mixing line maximizing ascent and therefore, cooling the column and keeping that line at "bay". We'll see how far north it makes it up, but then again, it also serves to really incite strong lift just poleward. Thank goodness for that Nova Scotia Sea Ice... or else we'd be absolutely screwed!
  5. Developing 850mb frontogenetical circulation and maturing rather quickly. This process via ageostrophic processes will establish your rapid cooling within the vertical column from surface up towards base of DGZ. Check out that robust LLJ gradient yielding speed convergence only helping to magnify this process as we head into this evening. Right on the “nose” of it. We’ll see some immense rates right within that “battle zone” and see sudden flips to snow.
  6. Check out the Nam’s 850/700 vorticity; certainly a shift in the depiction of 850mb vort as it essentially closes off further south thus allowing an advantage for stronger baroclinicity to occur and more dynamical cooling aloft via omega and upper level divergence via upper level jet streak. H7 verbatim has even shifted further south and west with a more cyclonic curvature indication. Insane low level f-gen circulation as well.
  7. Yes, @CCB! basically hit the nail right on the head. You have with what appears, to be a drastic and notable shift in not only thermodynamic structure, but kinematic "playing field". Below is the NAM wet bulb temps with a noticeable cyclonic circulation off the delmarva, and along this thermal boundary (dividing line), you have 1. DPVA and some mid-level deepening aiding in noticeable curvature offshore in a diffluent pattern 2. increasing theta-e gradient 3. ostensible vertical velocity (700mb) between ~ 6z - 9z Friday night/Sat... Going to catch people off-guard most certainly beginning with tomorrow morning's event...
  8. I believe this fully, and am not surprised by this trend if you look at the last several runs of the NAM 3km/12km with respect to the f-gen circulation intensity/magnitude. You can even see the responsive sinking via 700mb T. adv. Really no shortage of CVA either currently occurring in conjunction with robust QG-forcing (moisture/warm advection) streaming from South/Gulf area. So far, i'm liking what i'm seeing for the areas that have been shafted since Nov. I mean, look at this upper level jet with tons of ageostrophic flow and general embodiment of the south. It's this UPJ that will enhance your surface/ageostrophic flow, and looking at real-time obs, it's hard to not like what is unfolding.
  9. @Isotherm Thank you! To answer your question, no - here is the link. Indeed they're very useful! Enjoy http://ds.data.jma.go.jp/tcc/tcc/products/clisys/mjo/composite.html
  10. @Isotherm wonderful post as always! Going over just some data today being that guidance, especially 12z in the long range displayed with what'd be verbatim - an actually conducive h5 pattern - atypical of what we've seen thus far for a stretch. I began to check some of the "governing" facets that may or may not make those depictions true. Sure enough, it appears as you've already stated, that across the 30N belt, we're beginning to see a diminished depiction of net easterlies (sub-tropical highs - not what we want for NE cold/snow prospects) in conjunction with net westerlies (added momentum) seen at the 40-55N belt (impedes mid-latitude anticyclones from fully propagating poleward into subpolar/arctic domains, therefore, limiting any amplification and continuing the same theme). With apparent cross-equator rossby wave dispersion and interaction (MJO), favorably placed -VP, OLR, u850/200 current with lagging, it just makes sense to see something like what 12z NWP printed out today, post 25th. Even checking out the SOI index, we can see the net negative values accumulating in intervals and via this graph below shows its significance of a southward drop, relative to the timeframe seen as well (back to mid Jan). For one, i've seen some of the organic methods to a > -20 point drop, and there is some merit for sure, towards positioning the mean trough towards the East with an equator-ward adjusted STJ, therefore and hopefully, imparting net easterlies above 40N. Interestingly enough, if you take an EOF composite here that blends the going forecast (CFS) and real-time obs., of the zonal winds at 850/200mb and outgoing long wave radiation (also seen occurring presently), you get a 500mb composite of this below. I'd say early March offers quite something that we've failed to see come to fruition!
  11. This setup relative to the last two probably has the "best" favorable working kinematics going for it in terms of frozen precipitation (snow) vs. rain. Last 8 runs of the GFS shows a developing and more noticeable confluent flow and even the angular momentum (notice towards latter half of gif you see that kink in the isobars) is decompressing the flow downstream, which helps to keep the flow over Mid-Atlantic from buckling too much via WAA compelling the low levels. Even the ageostrophic component to this (i.e. - 250mb upper level jet) not only shows a pretty favorably placed right rear entrance region, but, note where the right LEFT exit region is superimposed.
  12. This is truly the first time this winter i've seen a highly desired and favorable harmonious conglomeration of hemispheric/synoptic forcings that many of us have been waiting to see work in motion together. I took a few different snippets of what i'm referring too and there is also the aspect of equator-ward rossby wave breaking into the Atlantic (saw this back in mid Nov) that is not shown in this, but adds to the excitement of finally(?) seeing everything that has been anticipated at a much earlier date, now manifesting. Biggest +AAM contributions in the tropics, +EAMT rebound incoming that helps incite a pacific jet extension and shift that GOA ridge eastward thus allowing the mean trough to nudge and shift east, and lastly a monstrous WWB/coherent wavenumber-1 type, MJO wave right over the dateline and is being enhanced via a rossby wave. We may even see this occur into phase 8 as well regarding amplifying the signal, but remains to be seen. Anyhow, it really aligns very nicely with the post 20th period and man i'm excited! While not necessarily a true +PNA pattern being shown in the medium and longer range, a +TNH pattern (below for visual purposes, except it's a composite for Jan, but remains similar and to get point across) appears to develop with a pumping STJ to add. -NAO signal still remains legit given this standpoint. Likely expect more corrections on NWP via synoptic pattern across N.A.
  13. Below is a signal i've truly yet to see all winter long; a stable constructive interference, intra-seasonal signal with what also looks like a dual-low frequency mode along and east of 180 degrees. This is the stability that many have been anticipating and expecting, but has yet to develop until about now. There is indeed an impressive Eq. Rossby wave that has allowed for some slowing and even causing chaos in those RMM phase diagrams (which be careful to use as they don't always tell the whole story). It's these depiction however, that kicks off with what looks to be our best conducive stretch of wintry prospects early-mid Feb into about late month. Sometimes, you just have to step back, and look at it from a wide view. Notice where the robust center of convection is and a coherent signal as well with some convection hanging back towards the MC. It's no coincidence that the EPS and GEFS are at odds with each other starting valid next week. It's here below, at this time stamp, that begins the divergence and this is attributed to the parameterization of there tropical forcing forecasts and initialization. I'm inclined to believe, based on what i've attached and been watching daily, that the EPS is correct in this poleward ridge into Alaska with a positive tilt, therefore, inducing lower heights downstream faster than its counterpart - the GEFS. Some similarities, but the difference is poleward amplification and it's stymied by its MJO progression. I'd expect a correction towards the EPS in time, but nonetheless, I do like the upcoming gradient pattern. Thereafter, it's interesting given +AAM in the tropics and a soon-to-be big +EAMT rebound and pacific waveguide shuffling that'll allow - bearing more curveballs, a +PNA depiction post ~ 20th with a potent window of actual Greenland blocking. i'm definitely intrigued by the cyclonic wave breaking that'll be occurring all the while this period happens and if we can get that retrograding signal to commence (0z/6z GEFS showed it as Geoff displayed). Despite the emotional rollercoaster, you have to just prevail against the "noise". Split flow, retrogression, and added westerly inertia.... not an easy thing for guidance. We'll see where it goes, but its hard not to like the period starting next week.
  14. In a general sense - the N.H. synoptic pattern and forcing mechanisms are finally changing and is evident through the waveguide around the mid-polar latitudes as a result from successful downwelling from the stratosphere. It's as @Isotherm put it; in a way, it has been a paradox because it was this event alone that has caused such disruption for the Mid-Atlantic and Northeast's sensible weather regarding snow and improper timing that has stemmed from such a decoupled state between the troposhere and stratosphere. Now we are truly beginning to see the long anticipated auspicious effects, properly couple with the troposphere -- therefore, rendering a highly receptive troposphere where it now will favor HLB and successful retrogression of polar positive geo. heights (likely to now dominate into Feb). That outline in yellow is basically looking at coupling and why we're now seeing more positive heights manifest into Greenland and Arctic. g this synoptic pattern below is a precursor for heights retrograding into Greenland and disseminating into the polar latitudes. This is the change that we've been waiting for and is bonafide. This is the feature (Europe High) that is favored from anticyclonic wave breaking across the Atlantic that changes in tilt, direction, and magnitude. Yes, this is a very good thing.
  15. "Main premise of this - available arctic air, confluence, not too shabby of an Atlantic domain, plenty of shortwaves rotating around a broadening and retrograding TPV with split flow, and now throw in a favorable coinciding MJO to boot with a -EPO (also some evidence of +PNA - ridge axis still questionable, but there). Also keep in mind that this is all happening amidst a retraction out in the pacific. We've seen time and time again poor timing of the TPV and its placement in conjunction with shortwaves. To see it first impart this weekend a sharp "nudging" and unfavorable orientation towards the Northeast to subsequently broaden and allocate back towards the west with diving shortwaves on the backside should have this group more stoked. Several opportunities heading into end of month and early February! Beware the volatility. " (my post Monday) There was discussion also today from reading pertaining to the TPV and shortwaves in the mix. Without a doubt, guidance is struggling with next week's synoptic mid level flow - and just to illustrate this concept, i've decided to show it through the illustrious GFS.... valid midweek next week, notice the profound difficulty in trying to decipher the positioning of the TPV, shortwave energy, and synoptic features such as the ridge out west. However, keep in mind as I show subsequent gifs of a similar thing in common - A long wave trough (via TPV injection) and its tilt. Also, that shortwave seen jumping around NewFoundland and Labrador and its implications(?) GEPS valid same time: Look at the allocation and tilt of the TPV (a clear retrogression) and that s/w south of Greenland and expanding heights across SE Canada as a result. Its surface translates to a better depiction for visual purposes; Look at the confluence zone back up into SE Canada (here is 1030mb high). This *could* have wintry implications and this may not be done trending since it's relevant on all NWP including EPS. GEFS - same thing and similar with the shortwave also in the aforementioned location and general vicinity. Also an inclination towards a negative tilt. There is a shortwave also that is rounding the bend of this entire long wave trough (won't take much to see this eject itself a bit more out ahead to make this interesting) GEFS surface - look at the common theme here and that confluence zone backing up also... Monitoring closely... then watch as this TPV shifts out and diving shortwave for next weekend... that is intriguing! We're headed in the right direction... this type of pattern is a "keep yourself on your toes".
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