The Advertised Pattern Change Looks More Impressive Than One Week Ago

October 15th, 2013 at 9:37 pm by under 4 Warn Weather

Last week’s headline was telling, concerning “Hints of a Pattern Change.”

The signs are now clear we will be heading into a chillier pattern, in stages. What remains unclear is HOW chilly.  And will snowflakes accompany the chilly pattern at any point?

In the broadest sense, the 500mb ensemble means offer good support for below average temperatures most days starting late this week, and amplifying by mid/late week next week. The more erratic deterministic/operational GFS & ECMWF runs at least have decent agreement between themselves on 850 temps dropping to -4 to -5, then -6 by late next week (0 or -1 or-2 generally won’t cut it at this time of the year unless there is unusual upward vertical velocity). In the GFS, the coldest part of the pattern seems to hold off until next Thursday-Friday.

If those temps were to verify, and if we had a cyclonic curvature to the flow, that would favor some snow at high elevations at times, with some possibility of a mix even at lower elevations. While these global models tend to show a predominantly NW flow during that period, they lack the resolution so far out to pick out lesser troughs/short waves which can cause alternate backing and veering of the boundary layer winds. The global models favor some periods of LES or LES/R during this cold period, but amplitudes can lessen between now and then. There may also be a trough in the SW undercutting the amplitude of the western ridge to some extent. So, while there may be some hints of excitement here for snow lovers, the cliche applies; “I wouldn’t get too worked up about it.” Not yet, anyway.

The MJO remains active, but it is weaker and will stay weak to moderate over the next 2 weeks (still considered active) with some possible eastward propagation. That weaker active status is reducing its impact at tropical latitudes to a limited extent. The indices are a mixed bag over the 2 week period. The AO is out of phrase with the NAO, tending to be closer to neutral. The NAO is sharply negative for a while, with a weakening amplitude later in the month, heading upward to neutral or even a little positive by Nov 1. The PNA is positive initially, but there is major spread in its ensemble members in week 2. The ensemble means have a flatter flow close to the end of their runs, which may be reflective of the less favorable NAO & PNA. But I wouldn’t say the mean goes completely zonal…just low amplitude.

Finally, there is continued high confidence for neutral ENSO conditions to continue well into Spring 2014.

219 Responses to “The Advertised Pattern Change Looks More Impressive Than One Week Ago”

  1. Don Paul says:

    Dave…you’re forever in search of contrarian views with a pretty selective viewpoint, which can befall many of us. However, global warming has slowed only in the atmosphere, not the oceans, where it continues unabated. The numbers on the Maunder Minimum involve a far lengthier period of minimal sunspot activity than what we’ve experienced for just a few years, and most solar physicists do not think we’re headed into a comparable period. There is much more evidence in what I posted than the BBC interview article you posted bears. Doesn’t prove he’s wrong…just suggests the evidence is not on his side.

    What you’ve forgotten is that CO2 is incontrovertibly a greenhouse gas, and that its volume continues to increase in the atmosphere. The current 400 ppm of CO2 was simply not a factor during the Maunder Minimum. It is now, and the evidence is overwhelming that no such minimum can “reverse” global warming. It may have a slowing effect to a limited extent, but global warming, with spikes up and down will continue to go on, as modeled (which–as I’ve mentioned ad nauseum was never predicted to be linear).

  2. Dave from Roc says:

    I have not forgotten that CO2 is incontrovertibly a greenhouse gas, Don. I go out of my way to make it clear that I understand global warming is happening, and humans play a role. I don’t think my point of view is unreasonable. And for the record, I am very familiar with the reasoning behind even the more alarmist perspective on global warming. I’ve written more than one research paper in college arguing that global warming is caused by human activity, and that it is a great threat to our way of life – with a focus on the behavior and patterns of Arctic sea ice. That, of course, required me to read many scholarly articles, along with systematically refuting the many ‘skeptical’ arguments. I continue to keep up with the research. And, believe it or not, I even own Al Gore’s book, “An Inconvenient Truth”, and I’ve read his other book “Earth in the Balance.” My point is, I don’t just study / learn the contrarian view. Far from it. My ideas have evolved as I’ve studied both sides.

  3. Jeff from Louth Twp. says:

    I don’t know if everyone already saw this but I found it fascinating…
    Some scientist from the U of CO is carbon dating moss exposed by melting glaciers on Baffin Island.

  4. Don Paul says:

    “Humans play a role” is something of an understatement, Dave. Without human activity, there is virtually no other explanation for the warming which has occurred, according to climate modelers who have maxed out every known forcing mechanism in model runs with CO2 concentrations set back/initialized to early 20th century levels.

  5. Don Paul says:

    Found this post I made on October 26th last year, when the Sandy track forecast still had moderate uncertainty as to the point of landfall:

    “According to CBS, Mayor Bloomberg will probably decide tomorrow whether or not to evacuate up to 375,000 people from parts of lower Brooklyn, Queens, and lower Manhattan. He’ll be getting storm surge information from the NWS to help with his decision. Although it’s never happened in the modern era, should a hurricane make landfall just W or WSW of NYC, the storm surge into Brooklyn, Queens, and possible lower Manhattan has been shown in models to produce enormous flooding which would require such evacuations. It’s an unlikely event, considering all the landfall possibilities, but it’s within the range of track forecasts.” –

    On reflection, while I didn’t have time to go back through the whole thread, one small item I picked up on: I’m sure glad “Weathernut” isn’t on the blog anymore. :)

  6. Jon says:

    Any signs of widespread synoptic snow soon?

  7. Don Paul says:

    No, not at all, Jon. Nor is that to be expected at this time of the autumn in our region, climatologically.

  8. Don Paul says:


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