Jump to content

Welcome to our forums!

Sign In or Register to gain full access to our forums. By registering with us, you'll be able to discuss, share and private message with other members of our community.

Welcome!

Thanks for stopping by the Weather Forums! Please take the time to register and join our community. Feel free to post or start new topics on anything related to the weather or the climate.


Photo

MJO Discussion


  • Please log in to reply

#1
Bryant

Posted 22 January 2014 - 06:34 AM

Bryant

    Daily Contributor

  • Members
  • PipPipPipPipPip
  • 1811 posts
  • LocationBellingham, Wa

It was encouraging to have a few people message me and ask me to start this thread back up, and it's something I planned on doing anyways. While I continue to learn about the MJO and use it to help make forecasts, this thread not only helps me strive to learn, but allows me to go back and see my errors for further learning.

 

Back on Dec 22nd, I made a call that a new MJO wave would emerge over the Indian Ocean sometime around mid January, and I was completely wrong. I anticipated things to move quicker than they have been, but that's exactly why I'm watching everything much closer this time around. This is my first time closely watching the MJO, so I'm definitely prone to multiple errors =P. The MJO is currently over the Western Hemisphere (8-1), where the signal is very weak. Typically during neutral ENSO, once the MJO passes by the dateline, the convection associated with the MJO dies off. The upper level winds associated with the MJO are still evident however.

 

If you've looked at an MJO forecast recently, you've noticed a strengthening signal in the Western Pacific.

 

30kslz7.gif

 

I've mentioned before that other "noise" in the tropics can easily alter the above plots, and this is one of those times. The strengthening signal you see is actually a Kelvin wave in the West Pac which is typical while he MJO is in the Western Hemisphere. As shown in the forecast, it's likely we'll quickly see this signal die off and head back towards the inner circle. As this Kelvin Wave travels east however, the convection over the tropical Pacific diminishes which also removes the support for an extended Pacific jet. This in turn will allow the +PNA ridge to break down and be replaced by cooler conditions, as well as bringing relief to California hopefully.

 

259aijc.gif

 

 

Taking a look at forecasts and previous history, I'd say it's possible we see an MJO wave emerge over the Indian Ocean in the next 2-3 weeks. Until that happens, we may return to an overall +PNA pattern after the potentially brief breakdown beginning of the month. Taking an educated guess (once again based off history), I'd say the MJO reaches the eastern Indian Ocean/ Maritime Continent, which are favorable for cold in the west, in about 3-4 weeks. This is still a huge learning process for me, and I could easily end up being completely off or wrong all together... but time will tell.

 

21b4y13.gif



#2
snow_wizard

Posted 22 January 2014 - 07:47 PM

snow_wizard

    The Snow Wizard

  • Mods
  • 10631 posts
  • LocationCovington, WA
I'm glad you restarted this thread. I hope people find it here.
Death To Warm Anomalies!
 
winter.jpg

Winter 2016-17 Stats

Total snow = 9.8"
Days Min 32 or below = 61
Days Max 32 or below = 1
Days Max Below 40 = 29
Coldest Min = 16

#3
Bryant

Posted 23 January 2014 - 12:10 AM

Bryant

    Daily Contributor

  • Members
  • PipPipPipPipPip
  • 1811 posts
  • LocationBellingham, Wa

I'm glad you restarted this thread. I hope people find it here.


Thanks Jim, I'm sure they will. Its amazing how so many factors correlate with one another. The MJO correlates with the SOI spike nicely, which also correlates with the AAM and ENSO conditions. While the MJO is a repeating oscillation, it seems to go in tandem with the LRC which I still use here and there. Good fun!

#4
primetime

Posted 24 January 2014 - 09:05 PM

primetime

    New Member

  • Members
  • PipPip
  • 55 posts
  • LocationCarolina

Thought this was an excellent write-up on the MJO and it's impact over the next month or so...

 

http://www.wsi.com/b...nd-of-february/


  • Phil likes this

#5
Phil

Posted 04 February 2014 - 12:59 PM

Phil

    Forum Fantastic

  • Members
  • PipPipPipPipPipPipPipPip
  • 12691 posts
  • LocationCabin John, MD.

Thought this was an excellent write-up on the MJO and it's impact over the next month or so...

http://www.wsi.com/b...nd-of-february/


Couldn't agree more. Only thing I'd add is discussion of the dampened SAO amplitude, which might help folks understand why the stratosphere-mesosphere domain does what it does.
Personal Weather Station, Live Stream on Wunderground:
https://www.wundergr...BETHE62#history

Warm season 2017
Thunderstorm days: 7
Severe days: 4
Rain total: 10.80"
High at/above 90*F: 4
Warmest high: 96.4*F
Warmest low: 73.7*F

#6
richard mann

Posted 10 March 2015 - 02:51 PM

richard mann

    Advanced Member

  • Members
  • PipPipPipPipPipPip
  • 3405 posts
  • LocationParadise, CA

That is an impressive MJO .. and in a favorable phase for an AR event (Atmospheric River event) somewhere along the west coast in 10-14 days.

 
http://theweatherforums.com/index.php/topic/831-march-2015-pnw-discussion/?p=73949

Why. ? ... Would that be, if I may ask, more specifically. (?)


---twitter_logo-t12.png

#7
IbrChris

Posted 10 March 2015 - 05:50 PM

IbrChris

    Moderating Meteorologist

  • Meteorologist
  • PipPipPipPipPip
  • 1901 posts
  • LocationTigard, OR and Portland, OR (work)

 
http://theweatherforums.com/index.php/topic/831-march-2015-pnw-discussion/?p=73949

Why. ? ... Would that be, if I may ask, more specifically. (?)

"Atmospheric river" (AR) is a corridor of moisture extending from the subtropics into the mid-latitudes, generally parallel to the 500 mb flow. It is influenced by the MJO as the MJO-driven tropical convection over the Pacific is the source region for the atmospheric river. The MJO may enter the preferred phase for an AR event and not be conducive to an atmospheric river event if the longwave pattern over the mid-latitude Pacific is not conducive.

Here is a graphic that illustrates the teleconnection between MJO and AR events along the west coast:
http://en.wikipedia....merica_rain.png

As you can see the westerly jet across the Pacific must either be far enough suppressed (through a split or through an amplified trough) to draw the moisture northward. AR events often occur well offshore in the central Pacific and occasionally they can orient themselves nearly meridional (ie moisture moves N toward Alaska).

Here is a short primer on atmospheric river events along the west coast of the US, with some sample literature:
http://journal.front...2014.00002/full



 


  • Webberweather53 likes this

The Pacific Northwest: Where storms go to die.


#8
richard mann

Posted 10 March 2015 - 05:59 PM

richard mann

    Advanced Member

  • Members
  • PipPipPipPipPipPip
  • 3405 posts
  • LocationParadise, CA

-
.. Certainly enough information provided here above from which to gather and put together a useful perceptive. Appreciate the response. 
 
I still don't know what to make of or how to "read" the [stupid], yellow and grey, segmented lines through different main sectors "MJO Index" charts. But this steering will likely work as impetus to increase my interest in working to do so.
 
 ... With this, I'm thinking that with working through what's been pointed to here above within this threadmore specifically dedicated to the phenomenon, .. this with and if also perhaps "Cliff Mass" speaks about it at some point, within one of his Blog postas with what you've done here - in response to cousin "Phil's" having dropped up what he has more MJO focused .. over in the main PNW section  http://theweatherfor...ussion/?p=73952and the professor's, having worked to connect the oscillation up to something more specific, more PNW related, .. I might even (ultimately.) find myself as knowledgable where considering it as perhaps say, ENSO.


---twitter_logo-t12.png