Jump to content
  • Member Statistics

    17,589
    Total Members
    7,904
    Most Online
    LopezElliana
    Newest Member
    LopezElliana
    Joined

Medium/Long Range thread


HM

Recommended Posts

  • Replies 1k
  • Created
  • Last Reply

Here are some December 250mb anomalies. The 2004/1972 minus 1996/1961 image is meant to show what may happen this December when NAO is positive. The 1996/1961 image alone shows a more typical La Nina circulation while the first outlines maybe that El Nino-touch.

 

Full-on +PDO/El nino/-NAO look from 2000, 1989 and 1985 are also shown for fun.

 

 

post-176-0-97283800-1384546084_thumb.jpg

 

post-176-0-77682600-1384546093_thumb.jpg

Link to comment
Share on other sites

HM,

 

Out of  your original Nov nern Pacific analogs the only one I would toss would be Nov 1972 because that enso was too strong, otherwise, all of the other at least related to enso are within reach. Its funny how 85-86 made this list too. I admit I am a qbo novice and taking a very simplistic approach, but that winter matched the qbo tendency as well as oct temps and at least was not a sparse Oct Eurasian snow cover (it was close to average) month.

Link to comment
Share on other sites

The 12z EURO has a nice looking pattern as we head into the end of November;

 

It kind of resembles what most people were talking about this winter, a northern stream dominant winter with many Miller Bs. 

 

attachicon.gif11.gif

+ PNA, west-based -NAO what's to complain about? Maybe a Manitoba Mauler at the end of November/beginning of December?

Link to comment
Share on other sites

HM,

 

Out of  your original Nov nern Pacific analogs the only one I would toss would be Nov 1972 because that enso was too strong, otherwise, all of the other at least related to enso are within reach. Its funny how 85-86 made this list too. I admit I am a qbo novice and taking a very simplistic approach, but that winter matched the qbo tendency as well as oct temps and at least was not a sparse Oct Eurasian snow cover (it was close to average) month.

 

As you know, I defined the set strictly by the NE PAC setup. It is interesting to know that 1972 was one of those "conflicted years" where it wasn't quite like a normal El Nino. I thought it was fitting that it showed up, lol. But yeah, as an overall analog, 1972 is definitely terrible. But on a subseasonal-scale, you can occasionally get signals from odd years, regardless of ENSO.

 

1985-86 had a quiet sun thing / +PDO going on but yeah the similarities have been strong. What a frigid December! Sometimes it is the way the MJO forcing times that makes things play out like they do, temperature-wise. In 2000, we also had IO forcing in early-mid Nov that propagated out, bringing on a classic El nino-look.

 

Models do not have a clue right now how to handle that forcing.

Link to comment
Share on other sites

Why does it look like we might get a classic El Nino look as HM described above? Check out the SST anomaly chart. However at this point there are some cool pools until you get near the SA coast.

 

anomp.11.14.2013.gif

Last winter the -pdo probably worked against any developing nino (as the models had outlooked to occur, they had a warm enso bias).  As of the October update the dynamical models average 3.4 departure was a Mr. Blutarsky 0.0C.  With that warm pool in the eastern Pacific, one could see less resistance this winter. I'm curious with the next update if the dynamical and statistical models edge upward.  Regardless, the rest of the Pacific is not as hostile as last winter.

Link to comment
Share on other sites

As indicated by the teleconnections last weekend, most of the global models now have an east coast storm next Wed/Thurs.  The 06Z GFS too warm for the I-95 corridor, but there is still time to change.

GFS ensembles are looking warm as well. Still the odds of a storm for the middle of the next week are looking good. 

Link to comment
Share on other sites

 

Nothing has really changed. Generally, above normal temperature regime estimated from 11/15-25 would then become more El Nino-like 11/25-12/10. And when I say that, the reader should know that El Nino-like entails PNA, split flow. I see variability for December because of the oncoming El Nino-like forcing messing with the La Nina-like background state. We could definitely see some snow before this month is over and December could actually see a few events. I do not see any signs of anything major but I do see waves of interest. The conflicted Pacific and generally more +AO this Dec should promote higher variability than we've seen for the last 5 winters or so.

 

If the MJO didn't exist or died out, December 2013 would most likely end up with a 1990, 1978, 1967, 1961 type of look. Should the forcing not progress into the phase 7-8-1-2 realm in December, then expect a more typical regime like the years mentioned. However, between the tropical forcing and what I am seeing with global winds / RWB, I think the NAO / split team combo should form 11/25-12/10. Low confidence for sure...

No changes... models may finally be picking up on the correct forcing and it propagating east. Notice the newer runs continue to extend the Pacific Jet and push the subtropical high more east, across the western Pacific. This sets up the +PNA (forcing this time of year with coherent MJO 5-6-7-8-1 is cold across eastern CONUS).

The +AAM is building up at the Subtropics and -AAM regime is near 50N heading to 60N 11/25-12/10. The NAO will oscillate more than usual into early December as anticyclones try to break up there but fail. The reason they fail is because of the strong stratospheric vortex. The pattern in the troposphere will continue to alter mid-month and begin retrograding as forcing passes through western hemisphere. If there is enough cold air around, we could see a winter storm just before the holidays; but, I suspect it will be messy.

Depending on if the NAO can flip and how quickly the forcing gets back into the IO, the tendency for warmth will start to go up in the last third of December. As is the case with the first half, low confidence again applies here since everything relies on perfect timing.

Link to comment
Share on other sites

 

Phases too late....puts too much emphasis on northern progressive jet...a typical gfs bias at play here

 

The NAO signal is fake. Anticyclones are trying to break up there but it is not quite the classic -NAO. So, there really is nothing to slow down the PJ. The PJ has a very compact height gradient with strong anticyclonic shear on the south-side. This is really inhospitable for phasing. Therefore, the GFS solution is just as likely as a cold rainstorm (where southern wave is stronger and amplifies on its own before PJ crushes it).

There isn't a bias and it certainly isn't present here.

Link to comment
Share on other sites

Weather World is calling for a split flow accross the US the next month with frequent cold shots and a 'wild' beggining to winter

that'll do....

HM has me nervous about the pseudo -NAO (and of course his logic makes sense...always does).  We can do alright in a split flow, but too often find ourselves on the wrong side of the fence.

 

Nut

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Guest
This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...