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Pattern February Discussion Part II

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DaculaWeather said:
The GFS and Euro are beginning to show the 8, 2, 1 phase sequence, which would at least indicate some colder weather in our future. At least that may be SOME good sign if it continues.






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problem is the mjo has failed so many times this winter it's hard to get excited . Would be nice though. Maybe the models are not reacting to their own MJO forecasts , I don't know. something has to give

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Storm5 said:
So for those wanting winter weather you have the gfs and 4/5 gefs members vs the cmc,euro ,euro ensembles ........

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+ groundhog, +JB, +NAVGEM = Fail
 
Storm5 said:
problem is the mjo has failed so many times this winter it's hard to get excited . Would be nice though. Maybe the models are not reacting to their own MJO forecasts , I don't know. something has to give

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Why do we use these indices if they have such a high failure rate? If I applied the same to the algorithms I use to treat patients, many would not feel better, some might die.


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ATLwxfan said:
Why do we use these indices if they have such a high failure rate? If I applied the same to the algorithms I use to treat patients, many would not feel better, some might die.


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Because the various indices are tools rather than crystal balls. One needs to know how to use these tools. There are tendencies rather than absolutes associated with each and a combo of them is more useful to look at than just one index, alone.

Example: if you tell me that there will be -AO/-NAO/+PNA/-EPO/MJO low amplitude phase 8, it would be quite difficult for it not to be cold in the SE US.
 
I could be crazy, but the UKMET might be implying more separation of the second wave, a bit like GFS.
 
GaWx said:
Because the various indices are tools rather than crystal balls. One needs to know how to use these tools. There are tendencies rather than absolutes associated with each and a combo of them is more useful to look at than just one index, alone.

Example: if you tell me that there will be -AO/-NAO/+PNA/-EPO/MJO low amplitude phase 8, it would be quite difficult for it not to be cold in the SE US.
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Very well said. ;)
 
whatalife said:
Do you have a pic of it?


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Cant tell much from it honestly. But here is what I have:

GZ_D5_PN_144_0000.gif



On the GFS, the Highs are stronger nad pushing a bit harder.. but that 1004 Low there, slides under and South on the GFS on the next frame (after 144hr). We don't have past 144 hr on UKMET to see what's happening. The high being quite a bit weaker is never good though.
 
Here is the GFS at the same time for comparison to the above UKMET:

fff.gif
 
Looking at them side by side, I can see where the GFS solution likely would not happen on the UKMET on future frames. Sadly.
 
Shawn said:
Cant tell much from it honestly. But here is what I have:

GZ_D5_PN_144_0000.gif



On the GFS, the Highs are stronger nad pushing a bit harder.. but that 1004 Low there, slides under and South on the GFS on the next frame (after 144hr). We don't have past 144 hr on UKMET to see what's happening. The high being quite a bit weaker is never good though.
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True...I fully expect the GFS to lose this system on the 18z run...


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pcbjr said:
Very well said. ;)
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Thanks, Phil. You and I were pretty much typing the same thing at the same time.

By the way (I'm not trying to be overly optimistic but am trying to emphasize that we're far from a slam dunk as to what lies ahead for the SE even in the first half of this month), this morning's GEFS base forecasted AO (more negative at all 3 timeframes out 14 days), NAO (less positive all 3 timeframes), and the PNA (more positive all 3 timeframes) were all more favorable for SE cold chances throughout the 14 day forecast period fwiw. Regarding the AO, the 7 day forecasted -1.8 is actually the most -AO 7 day forecast since way back in early Nov!
 
GaWx said:
Thanks, Phil. You and I were pretty much typing the same thing at the same time.

By the way (I'm not trying to be overly optimistic but am trying to emphasize that we're far from a slam dunk as to what lies ahead for the SE even in the first half of this month), this morning's GEFS base forecasted AO (more negative at all 3 timeframes out 14 days), NAO (less positive all 3 timeframes), and the PNA (more positive all 3 timeframes) were all more favorable for SE cold chances throughout the 14 day forecast period fwiw. Regarding the AO, the 7 day forecasted -1.8 is actually the most -AO 7 day forecast since way back in early Nov!
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Exactly - back earlier this AM I posted the charts (I think it's post #36) which gives a good pictorial. Not only were we typing at the same time, we're in complete agreement :D
 
I'm not sure I'd say the MJO has failed this season. It's only been favorable for cold in the east for a few total days in the entire winter. It moved into a semi-favorable state around Jan 15th. Temps went below normal in parts of the region Jan 25th - Jan 31st. They will relax for 2-3 days. then be below normal for the next 3 or so days. It spent around 11 days in 8, 1, 2 and the region was or should be BN for 8 days of the 11 that mirror that path. 8 even favors NW flow/Clippers and we had two clippers in the East 10 days after it spent a couple of days in 8.
 
DaculaWeather said:
The GFS and Euro are beginning to show the 8, 2, 1 phase sequence, which would at least indicate some colder weather in our future. At least that may be SOME good sign if it continues.


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Steve's site has an excellent all model forecast link to the MJO:

http://www.daculaweather.com/4_mjo_phase_forecast.php#

Regarding today's EPS MJO forecast, the MJO is forecasted to be even higher amp in phase 8 during mid-Feb (2/12-16+; yesterday was 2/11-15+)! Looking back at other Feb.'s with high amp phase 8 (1978, 1988, 1999, 2006, 2010, 2012, 2013, 2014, 2016) IF the EPS amplitude should verify, it would be the highest Feb phase 8 amp on record (records back to 1975) other than 1988 and a part of 1999!

My analysis done yesterday (go here if interested: http://southernwx.com/community/threads/february-discussion.99/page-55#post-15600 )

showed an average ATL temp. anomaly for the 45 days of high amp phase 8 in Feb of an impressive 5 colder than normal!

Caveats: 1) the two coldest long periods (-9 in 1978 and -11 in 2010) were during winters that were very cold pretty much regardless of the MJO thanks largely to very strong high latitude blocking. For this supposedly upcoming high amp phase 8 to have much of a chance to be cold, it is vital that the GEFS strongly -AO verify, especially with the NAO still forecasted to be slightly + and the EPO forecasted to be + then.

2) The two highest amp long strings (1988 and 1999) were -1.4 and +0.8, respectively. So, these two were near normal rather than cold while very high amp. However, 1999 was during +AO. Also, 1999 subsequently went to much lower amp (just outside the circle). ATL then got much colder and even got accumulating snow.

3) In addition to 1999, the 2006 and 2012 didn't get the coldest until the phase 8 MJO got much lower in amp (closer to the circle). Based on this along with my January study that showed low amp phase 8 much colder than high amp phase 8 in the SE US and assuming a solid -AO persisting, I think the prospects for a very cold period in the SE would be best if the MJO were to either verify lower amp phase 8 or drop down to low amp phase 8 after an initial high amp 8.
 
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