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Armando S

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Armando S last won the day on October 11 2019

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  1. Nicely put @CCB!. Further regarding your point of climo. and base state, I've taken all 10 positive IOD events since 1960 (BOM's data records) and plotted the velocity potential for DJF and then alone for Feb. Here were those years plotted below with respect to 500mb (all +IOD years). Now granted, this is simply just plotting years with obviously different variables (i.e. base states different, hemispheric forcing, PV strength, etc.), but nonetheless; it's obvious as to the IOD's low-frequency forcing influence across the globe in terms of convection tied to the extratropical circulations, especially this winter alone. Now, with this being said, the Indian Ocean's LF actually becomes more favorable with time in a mean DJF composite, vs. earlier in the winter as it renders favorable wavelengths across the Pacific and obviously towards N.A. We can see via -OLR, the tenacity of the Indian Ocean's footprint (oval) since early Jan (actually extends well before, but just focusing on this year), but notice in the time-longitude plot axis of how that -OLR and low freq. has shifted towards the Dateline and continues to do so. In essence, it's increasingly likely that we can at least salvage February (maybe not as a whole) in certain timeframes. The other issue, however, is this persistent strong SPV and the profound coupling it has had with the troposphere, and @CCB! alluded to it (also said the same exact thing) - it has likely prevented favorable +AAM injection into the mid-latitudes (you want momentum to propagate into the mid-latitudes so that it favors poleward rossby-wavebreaking and ignites a series of events to garner an "unstable" (meridional) troposphere waveguide), but the bulk of +AAM has been largely confined to the tropics and up towards the subtropics) Using relative AAM to show a "framework" of your net westerly and easterlies (measuring net wind injection or deduction relative to Earth's rotation), and you can see through this how that orange (+AAM) has not been able to shift poleward into the mid-latitudes and -AAM anomalies (blue = ridging so if you think about it, in the NH the flow is clockwise around HP, thus going against the mean westerlies) have been dominating since early Jan., while the compensation of that slowing down of momentum is now "forced" into the polar latitudes (net integrated momentum aka +NAO/+AO. think about it in terms of a cyclone and the flow being counterclockwise, which add the aspect of a stronger then normal PV and that coupling). It's really just off the chart, literally. That large +AAM anomaly you see is from a robust WWB (MJO) passing along and into the W. Hemisphere @amugs what David was stating in that tweet is that if you read from the above, given the large surplus of momentum in the tropics (frictional torque, so your net westerly or easterly wind bursts), you'll typically see a then Mountain torque spike across East Asia. In this case, the large mountain chains and including the Southern Hem. (thanks to this strong +AAM event along Eq. Pac) are all contributing to a HUGE spike in total AAM globally speaking. So what this'll end up doing is allow for extended jet streams in both hemispheres and you can visualize this below (18z gfs 250mb). Also below is a helpful way to visualize what net momentum anomalies do (+AAM is associated with El Nino and vice-versa for -AAM typically) globally, but compared to that of the present GWO diagram on the right (lagged by a few days), you can see how it's also literally off the chart. We're likely going to see this orbit into the subsequent phases (which is what he was also talking about, not the MJO RMM phases) before crashing into 8-1 (may not verbatim, but just to understand the point), and this will then return to an overall net -AAM (balanced all throughout the globe in terms of U-wind). I suppose the best way to visualize his statement in that tweet regarding a big event is that if you're standing along the edge of a fast moving stream; you then take a boulder/object and allocate it towards the middle, you'll see your downstream flow now meander slowing it down to extent. Applying this net negative momentum to a now JetStream after its been in *net positive momentum *, what happens if you have a meridional (north to south) pacific jet? Transporting tropical air poleward while you advect polar/colder air southward - you're bound to see cyclonic activity manifest hence a strong event. Now, i'm still reading some literature and have "amateur" knowledge in terms of GLAAM, GWO, etc., so understanding the gist of it at least is certainly helpful. Anyhow, i know we have experts on this topic, but any further feedback or information don't hesitate to state!
  2. Some robust SLP readings currently, but this initial band pushing in is helping to increase our mixing ratios (saturating); therefore, helping to allow the "main" event to fall easier and take advantage of the baroclincity and frontogenetical circulation that'll push into the region within the next few hours. Here's our leading 850mb LLJ "nose" ushering in strong WAA (strong low level jet as well) and speed convergence (forcing for ascent) out ahead of the main shortwave/trough. This f-gen circulation is sloping back with height over across SW PA and Ohio. This is expected to propagate NE into the metro's, but the issue is since the DGZ is higher and wind advecting through it > 50 knots, you're not really making great dendrites (thus ratio's decrease), but again it's also contingent upon how much ascent makes it into the DGZ, plus it's possible the snow growth region can down-well as it doesn't always remain stationary during an event (i.e. just checked the DGZ for NYC metro a hour ago where it was 2200m aloft, now down to 1200m). Should be interesting nowcasting.
  3. Honestly, I concur that it even begins after this event next weekend. With NWP especially in the medium and longer term, the reshuffling of mass distribution and planetary synoptic alteration will likely render error at such a large lead-time (split flow especially causes chaos).
  4. Well, we can begin to see an emerging (some kelvin wave activity as well) MJO convectively active wave from the MC and along the Eq. Pacific, as this will begin an onset of rossby wave dispersion going forward - which means in essence, the welcomed synoptic pattern flip, relative to what has been endured. CPC 8-14 day analogs certainly would be accepted and welcomed with "open arms", and further partitioning of some positive momentum into the STJ can be seen via 12z GFS rather nicely (consistent with MJO propagation across the Pacific) with a split-flow verbatim. Certainly last week of January offers intriguing potential. Lastly, check out the anticipated jet extension and Rossby wave-breaking that occurs over the course of the next week and a half (monster NPAC anticyclone verbatim on the 330K PVU 12z GEFS).
  5. I've been monitoring the state of the tropics, but more specifically using some hovmollers such as the CFS below and to be honest, this is the first time thus far (in a while in fact), a low-frequency standing signal (purple contours) appears right up to 180* longitude. You typically find this in a +ENSO walker circulation. If to be true (which I think continues to have merit the more i just observe) and we do see a coherent MJO convectively active wave emerge into the W. Hem., we'll be seeing more corrections in NWP and ensemble suites as the days progress towards the end of the month and into early Feb. The shifts today as some posted already aren't surprising, as a that Aleutian ridge will shift eastward into Alaska, with downstream lower heights and cP air masses following suit, pressing the baroclinic zone gradually. Last 4 chi200 maps (courtesy of Carl Schreck) shows the evolution on the right hand side of gauging the -VP. You'll see the same constructive interference you see above in the hovmoller below, with the LF wave centered right along/on the international dateline as we move into the 3rd week of January with bonafide subsidence across the eastern IO and MC. This also would be consistent with establishing a +AAM propensity (at least for the time-being temporally-speaking) in the tropics, and into the subtropics and eventually mid-latitudes. Theoretically, this would then allow for +EAMT --> jet extension --> Bering Sea/Aleutian low --> pushing an AC into Alaska. Even see this on today's 18z GEFS in the extended (consistent with MJO propagation and extra-tropics interconnection of torques) as ~ +1030mb +SLP extends into Southern Asia (18z GEFS). Notice how the -VP pushes passed the 180 meridian? Here's the most recent VPM index, which IMO are a better way to diagnose and analyze MJO and -VP because it utilizes U850, VP200, and U200 vs. RMM indexes (which by now has been mentioned copious amount of times the caveats with them, but not to say it shouldn't be used.) Verbatim the GFS, we can see the higher amplitude orbit into the central Pacific. I'll admit there is some uncertainty with the MJO itself and coherency, but I also believe it's probably the best signal we're about to see since late November. Lastly, I figured to show the state of the stratosphere - more specifically, its medium term and to compare nicely with the above regarding a propagating MJO signal. Once we begin to see a higher amplitude +GWO/AAM orbit (consistent with tropical convection and global circulation via MJO), we'll likely see some tropospheric perturbations rendered, allowing for at least some weakening, and helping to elongate its strong structure thus far. You can see this on the GEOS scaled PV below (400K which equates to a bit lower then ~ 120mb so lower end of the stratospheric vertical column) this process manifest, but with some stretching of PV towards Canada. Given this, what i'm uncertain of is the extent of Pacific and Atlantic wave-breaking and how poleward these ridges can extend into the polar latitudes given the still modeled, resilient SPV; albeit weakened relative to its current state. Nonetheless, lastly here is Paul Roundy's LP height regression maps and notice the ridging out across the West with that Aleutian low as we open up February. It'll be important to monitor the state of the tropics because just by looking at models and NWP, one must understand that it's these processes above that really end up dictating our synoptic and planetary rossby wave configurations. I like what I see going forward for at least the very end of Jan and early Feb. This process will be a gradual one and not something that happens overnight. We shall see!
  6. The window for a winter storm between ~ 6th-10th has some "legs". What was once poised as a depiction of the entire TPV allocating into Alaska and remaining there for a few days opening up January (currently north of Alaska so not entirely wrong by NWP), has now shifted towards the main TPV allocating towards Greenland. However, a piece will break off from the main lobe. Concurrently, the combination of a short-term, incoherent to-a-degree weak MJO, will be and is now shifting into the WHEM. Look at the verified WWB via GFS hovmoller of the 850mb +U event earlier this week. This helps to encourage an ephemeral amplified pacific waveguide with support of a NPAC anticyclone manifesting. Combined with renewed Sea of Okhotsk trough, the flow downstream (with that broken off TPV piece shifting east into W. Canada) will render transient cold high's and the entire synoptic 500mb flow will be quasi-zonal given the strong +NAM state. Also, the strong (record breaking cold actually via 50-90*N min temp forecasted) state of the SPV does also stifle pacific ACWB to an extent. The 12z GEFS shows this process as discussed above, and i'm including the z200mb MJO lagged composites that support this sentiment above. You can see the evolution within the P7 pentad anomalies with the exception of the expected and modeled NAO domain being positive while the lagged composite shows it negative. It's more-so establishing the state of the pacific i'm trying to convey, which in summary supports the notion of a little window for a shot at a winter storm east of the Apps (thread-the-needle). Carl Schreck's -VP maps shows the various modes of tropical convection and forcing, and note the progression of the weak MJO wave entering into the WHEM. Is this enough to help facilitate snow into the metro areas? Well, it's probably the best shot we have since late November/early Dec. However, given that we'll likely won't see a jet extension (jet retraction rather) early mid-month, and with what may be constructive interference with that low frequency standing wave of the +IOD (despite weakening, the "footprint" still lingers over the E. Indian Ocean) and lack of a sustainable momentum source to render continued SPV perturbations *short/medium-term*, the support for transient ridging in the East makes sense bearing any "curveballs".
  7. Hello all! I wanted to wish every member here a very wonderful and joyful Merry Christmas to you and your families! God Bless!
  8. Superb analysis @brooklynwx99 and posts today as one who is aware of the content he posts expects no less! Not much to further add, but finally having the time to take a look hemispherically (from a synoptic perspective), I find the upcoming subjective period (12-18 -- 12-23) being discussed a really interesting one; as exciting as it may appear given the tracking perspective, I find it just as interesting these "mini" periods amidst a "sea" of not as a "jackpot" , slam dunk, base-state regarding GLAAM (keep in mind Tom's and Tamara's posts), *BUT*, it doesn't mean you can't have certain periods of meridional patterns. Anyhow, its been discussed, but it's these transient waves emanating from the tropics/E.A. (function of dual-modes of competing tropical variability with large amounst of LHR), where these aforementioned waves can be "missed" in NWP. It's going to certainly be active, and you throw in these synoptic waves that result in rossby-wavebreaking (Anticyclonic wave break over the pacific in the ECM DT loop -- paper i've referenced earlier a while back shown were a consistency of a poleward displaced PJ with ACWB and is seen several days later having a CWB sequence --> -NAO), which can render these ephemeral anticyclones poleward into the higher latitudes. I've decided to show this very case with the ECM 500mb heights via a neat illustration (may not be as robust verbatim, but nonetheless, "just for fun" to show and has some merit); black circle = TPV, White pentagon shape = an interesting s/w that breaks off and actually breaks cyclonically downstream --> poleward ridge into Greenland, and the yellow square to illustrate the induced, poleward AC that actually cuts-off from the mean flow and propagates westward. You can even see how gorgeous of an illustration it's via DT loop (so sexy lol), but *IF* we can manage a setup as such verbatim (still lead-time for this to alter), the fact that this process of PAC ACWB --TPV descends into NA --> N. All CWB.... ooof.
  9. Thus far, my area has come away with probably just around 2-2.5" (no bonafide measurement, just local reports and eyeballing). Overall, not much has to be added given the catching up across this thread, but for those who ended up reaping the benefit of mesoscale banding, congrats. Others.... well, always next storm .... the one thing - and it's something i never take for granted, is the fact that with my present state of being a student in the field, I have the privilege to learn from storms such as these! Not just that, but being able to dissect, observe, and analyze the "what went wrong" aspect and/or other generic things like geography for example, has truly bolstered my knowledge and awareness so that it betters myself, and those on here as well! This forum goes without saying, but it's just one big happy digital family (with some exceptions of some posters... lol). Radar trends appear to finally fill in via mid-level H5 low finally allocating towards and within the vicinity of Delmarva. Few more hours of snow with lateral banding now easing in intensity, therefore, more snowfall can now reach the ground spatially.
  10. Over the next few hours, once the lower and mid-level lows allocate towards south of Mason-Dixon into Delmarva, that radar will quickly “light up”.
  11. Cross section using H7 VV. We'll see some sloping of frontogenesis with height as well. NAM 3KM showing plenty of lift below and into the DGZ. We'll see the DGZ grow especially under best dynamics. evolution from tomorrow morning into evening (added 0z tues frame so 7pm)
  12. Currently sleet mix with some rain here (NENJ). Check out the H9-H5 mesoscale banding from today’s 12z NAM. You’ll start to see it all of a suddenly manifest after ~16z tomorrow. There is even a bit of hinting at a doubled-structure F-gen circulation attempt if you look around 20-22z especially. Some CSI may even be released given forcing for ascent, saturation, and synoptic evolution of the mid-level low (look to the N and NW of the SLP). Mesoscale banding will surprise many where some overperform and we, vice-versa (aka “woah the sun is out over here”).
  13. Non wx nor storm related, but a sincere Happy Thanksgiving to you all! Pat and Geoff, i’m so grateful to you guys and appreciate what you’ve done for me and just so happy to be apart of this SENSATIONAL forum with WONDERFUL members!! Wx-related: NWP when looking at the dewpoints Sat. night, they’ve remained fairly consistent *prior* to WAA and isentropic uplift. Despite eroding of low level cold and downstream confluence, watch that frontogenesis-circulation suprise some (especially interior).
  14. So i've been watching the medium-long range, and i've taken into account the MJO biases and corrections. The GEFS (NCEP RMM) had it erroneously traverse back into phase 8-1, while the EMON/EMOM (EPS medium ensemble suite) has had the RMM phase diagrams propagate the forcing through the Indian Ocean, albeit low amplitude given the constructive interference with the antecedent low-frequency +IOD signal. Take a look at the last several runs of the GEFS. Since we know that NWP takes into account many physical components and fluid dynamics - including tropical convection diagnosis, it's no coincidence that we've seen a correction to a lower amplified, evinced suppressed NE Pac. anticyclone/EPO. In fact, the GEPS has even shifted towards a lower amplitude NE PAC rex block (which also can be coined as such). The EPS? It has remained rather consistent and I also included that last 3 runs just to make a point. Now, it's *not* to say this won't impart a downstream response of polar high's given the anticyclonic flow regardless upstream, it's just the discrepancy we see of how much of +GPH's manifests into the EPO domain. This does, however, make a difference in terms of timing with what appears to be a stormy/unsettled beginning to December, it's just the overall trend and mid-level flow isn't as propitious as what may it have looked last week (i.e. broader downstream trough) in conjunction with a transitioning NAO. Check out the split-flow on the GFS, which is focused on end of month into the first week of December. Few things to note; if timed (which the premise of this post is that the entire flow will be more of a synoptic progressive/semi-progressive pattern) right, this could render an interesting window (~5th-9th?), stronger Atlantic jet (indicative of -NAO diminution), and towards the end we see the Pacific flow influence; this is to likely render the moderation period and consistent with IO forcing/lag composites into ~week 3 (post early Dec). I think we have a legit shot for something early December, but it turns likely unfavorably for a bit thereafter, which appears to be collectively agreed upon.
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