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Isotherm last won the day on October 14

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About Isotherm

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    Veritas Vos Liberabit

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  1. Isotherm

    ***Winter Countdown Thread 2018-2019***

    Thanks. I think it's important that we all attempt to refrain from the temptation of confirmation bias, which is quite prevalent in atmospheric science due in large part to greater uncertainties/more room to selectively interpret information as favorable to preexisting viewpoints. We are all victim to this occasionally. Often times, once a position is "chosen" we subsequently try our best to find data that supports that chosen stance whilst concurrently ignoring or assigning less weight to negative information. Constantly impugning one's own views and desires takes discipline because our temptation is certainly to fall into the trap of seeking that which we desire to occur, weather wise.
  2. Isotherm

    ***Winter Countdown Thread 2018-2019***

    2002 is quite a bit better in both the Pacific and Atlantic, in my opinion.
  3. Isotherm

    ***Winter Countdown Thread 2018-2019***

    @dmillz25, I typically like to wait until the second week of November; targeting November 7th-10th right now.
  4. Isotherm

    ***Winter Countdown Thread 2018-2019***

    I have a few general thoughts of commentary: 1. The low-sea ice mediated amplification of subsequent Arctic blocking appears to be a weak argument from my standpoint; the vast majority of fall/warm seasons have featured subnormal sea-ice, so how can one differentiate the trend from an actual, robust, statistically significant signal? Otherwise, every year portends blocking because Arctic sea ice has generally been lower than normal for quite a protracted time. 2. The atmospheric-oceanic disconnect - which Zac actually alluded to in his essay - is salient to note. We have seen a not insignificant FT/MT spike over the past week; the ineluctable consequences of which are rising tendencies of angular momentum; but, GWO has [to date] remained displaced from canonical Nino-esque phases, and the step-wise pattern seems to continue to indicate occasional Nina-esque predilection to the atmospheric regime. Low-frequency forcing and the attendant Nino-induced walker cell alteration has been very much delayed. A cursory examination of walker cell orientation/CHI forcing suggests a rather Nina-esque regime over the preceding 30-day period. Now, that should change, in theory, over the coming weeks. But it's something I'm monitoring closely, as an oceanic Nino w/ atmospheric Nina-esque propensities will have disparate effects from an oceanic-atmospherically coupled Nino. 3. The positive NAO this October is an auspicious signal for winter blocking. 4. The assertion of some guidance to intensify the ENSO event into mod-strong Nino is likely apocryphal. If the JAMSTEC were to verify, a 2015-16-esque pattern would develop. I continue to think the peak ONI will be weak Nino. 5. Strong, persistent high-latitude blocking is still not a given this winter, contrary to what many long-term models indicate. The interminable +NAO era wherein we experienced virtually no -NAO days throughout the entire winter is likely over, however. This isn't exactly an aggressive call; it's actually a safe call, really. But the persistent, unabated +AO/NAO couplet is unlikely this year. 6. I'm not yet convinced that this is as good a winter as some sources purport in the East due to indeterminate aspects of the atmosphere forcing tendencies, as well as blocking duration and persistence uncertainties, especially in the Arctic/Atlantic. This upcoming period up through early November carries the most weight as far as incorporation into my NAO forecast, and the blocking forecast in general. Bottom line: much to consider again this year! And with weak ENSO, I don't think anyone should feel as if this winter is a slam-dunk forecast one way or another.
  5. Isotherm

    ***Winter Countdown Thread 2018-2019***

    @Snowy Hibbo, Zac -- great disquisition and presentation of your ideas. Enjoyed the read; thanks for sharing. I think we can all concur that we hope you verify!
  6. Isotherm

    October 2018 Discussion & Observations

    Similar here -- 38.8F low. Beautiful, chilly morning. I think we'll have our first 32F in rural/suburban NJ either Thursday night or next weekend (21st), which would be fairly close to the long term average of October 18th for Freehold.
  7. Isotherm

    October 2018 Discussion & Observations

    I was thinking this morning that maybe we'll see a near normal timing of peak foliage for the first time in what seems like decades. It's been awhile since we've had a colder than normal second half of October. Historically, we should peak around Halloween, but the last 5-10 years have averaged closer to November 6-10th, some yearly anomalously late. Nights in the 40s strongly mediates the induction of anthocyanins in trees, so, given the prospective pattern, I'd anticipate an explosion of color after about a week of nights in the 40s, probably beyond October 21st.
  8. Isotherm

    ***Winter Countdown Thread 2018-2019***

    Geoff, just wanted to respond to this now -- thank you very much for those kind words -- my silence isn't necessarily an assent or dissent to some of the ideas posted by others in this thread; haven't had time to examine everything more closely in awhile, but I will offer my thoughts here when I do!
  9. Hi everyone, The gradual, step-wise diminution continues as September's global temperature anomaly on UAH is now down to +0.14c. As I've been noting in a couple of my posts hitherto, this drop isn't a surprise, mostly due to the significant cooling that the southern hemisphere has undergone over recent months. Conversely, the NHEM is still running quite warm. Nonetheless, I believe this will begin to countermand some of the erroneous ideas postulated by some during the 2016 super Nino: namely, "this will establish a new base/plateau, from which we will warm further." I formerly partook in climate change discussions elsewhere awhile back, and the general consensus on that forum was that the 2016 Nino would establish a new plateau. I disagreed then, and I still disagree. Current global temperature anomalies have returned to that which we experienced pre-super Nino, throughout much of the 2002-2015 period, around +0.1c to +0.3c. Aside: Just a cursory note regarding the QBO -- taken in a vacuum, it should not be a cause for concern in and of itself. There are case examples of -QBO / strong vortex winters and +QBO / weak vortex winters. For instance, 1963-64, 1969-70, and 1977-78 all featured weakly positive QBOs, but were quite blocky winters. The modality itself is only one factor. As most already know here, it's not only the modality, but also the trend, magnitude, interaction w/ other variables, background forcing, ENSO state, among others.
  10. Yep -- unfortunately -- partially a function of the warm AMO/west Atlantic anomalous warmth. We've been in the warm autumn regime for almost two decades now; I do expect this to change soon. It may not be within the year, but it will be within the next several years (AMO).
  11. The pattern hasn't changed at all. It's just that the nights are lengthening so quickly, the atmosphere can't produce days in the upper 80s/low 90s. Most of next week is 77-80F; yes, nice weather, but well above normal. Low temperatures in the low 50s is anything but impressive at this time of year. Usually I've had at least a few nights in the low-mid 40s by this point in the autumn. Really didn't want to see another autumn with green leaves until November 5th, but it's not looking good so far. We'll need to see the MJO forcing propagate further east to inject Nino-esque momentum into the atmosphere.
  12. Isotherm

    ***Winter Countdown Thread 2018-2019***

    I think we've all been saying this for the past 7 years - seems like Groundhog Day (a slight exaggeration - but admittedly, late winter/ruin spring pattern is rather agonizing). Unfortunately, our collective "hopes" don't tend to have much effect.
  13. @Bring Back 1962-63, David -- really great, enlightening recapitulation above. It's nice to see literature comport with our more hypothetical understanding of some of the mechanisms. And I believe, as you noted prior, that we are all 'correct' regarding the influence of the IOD. I'm not certain if there is a significant amount of papers on the NAMER/downstream effects, but of course, one may hypothesize what certain modalities and sub-variants of the IOD may implicate as far as global circulation patterns. For example, a stronger -IOD, empirically, certainly does tend to enhance the genesis of robust +ENSO events (as I believe was the case prior to 2016); further, the state of the walker cells in the IO/WPAC can presage the type of intra-seasonal tropical forcing, or even LF tropical forcing paradigm we may experience, which of course has downstream impacts by way of rossby wave train modulation / momentum transfer, etc. There are so many pathways to consider -- very fascinating!
  14. I concur, at least initially. We'll have to see the extent to which the MJO propagates eastward, among other variables, but through early October, I think there's a high chance that we see models gradually correct a bit stronger with the WAR. This will implicate a corridor of rainfall through the Northeast via enhanced baroclinicity. Incontrovertibly, the upcoming pattern will be a significant step cooler from the past couple of weeks, but the "genuine" cold air probably remains over the Rockies/Mid-west/Lakes through at least D10-12. We'll see thereafter. I'm not sold on a cool October yet.
  15. Hi, Geoff, I'm fairly certain that @swamplover56 is correct in that a distinct propensity does exist for October to augur DJF departures, in other words, there is a positive correlation b/t October temperature and DJF temperature departures. I'd need to revisit the data to ascertain the current r value, but if I remember correctly, it was approximately 65-67%. So, in about 2/3 of cases, a cooler than normal October should foreshadow a cooler than normal DJF.