Strong trough next 16 days, some model uncertainty in the long range

A constant barrage of fronts and troughs will threaten areas from west of the appalachians to the rockies.

Trough 1 at 108 hrs:

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GFS 7 day running mean departure with the first trough. Pretty much in agreement with the euro weeklies which has the centre of the cool over the western ohio valley/midwest. It has departures surpassing 4 blow normal for the 7 day mean.

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Second trough at hour 268 along with a front ahead of it on the 21st. Starts west and then progresses eastwards.

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Hour 240:
GFS:

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For week two we can see that the lower temperature anomalies have shifted east quite a bit and are now centred over the great lakes region.

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Indicies back this up with a -NAO,-AO +PNA and -EPO:

Canadian keeps the trough positioning stronger and further west. It doesn't really move much or weaken over the 2 week period. The canadian migrates the trough eastwards slowly but doesn't lift it out as fast as the GFS. The canadian keeps it around until the end of its range 375 hours.

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The GFS is uncertain about the pattern past hour 288 with more of a zonal flow across NA. The euro on the other hand lifts the trough out by around the 26th like the GFS but then pops a strong ridge into the east centered in the midwest and great lakes. So we can see the uncertainty moving into the longer range as we get into october.


Heres the 16 day period as a whole on the GFS. Much Colder then normal departures seems very certain between all the modelling:

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Some Winter Ideas, MEI theory...

I believe that this warm summer will be leading the way to a cold winter season this year. 

Look at this summers negative NAO pattern that dominated.

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Look at the -NAO that dominated in the 1950's. These are the summers with a PDO that has flipped from + to - and a warm AMO. 

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Here are the temperature departures in the summers of the 1950's. 

And the departures from the summers of 1952-56 have the core of heat centered in the central u.s, much like the past few summers.

Drought occurred in those summers as well and voila, the same thing is happening now.

Notice how similar our current pattern is to the 1950's because of the same -PDO and +AMO regime.Taking a look at the second el nino of the 1950's(much like this year is the second el nino since the PDO flip) we can see the -NAO in the summer of 1957 as well as warmth in the nations mid section.



Lets see what dec-feb looks like that year.
December is a blow torch!

Better:

WOW!

Not bad as well.

There was a negative NAO that summer and then a positive spike for 3 months, highest in december and then into the tank for the rest of winter. I'm not saying that the same exact result will occur this winter but the overall pattern will stay the same. This is a good analog. 

All of this raises the question, why is the NAO negative so much of the time? Lets think about this logically. When you flip the PDO to negative and you cool the tropics the air will dry out before cooling .This will cause hot and dry summers across north america. More daytime heating is caused by a "snowball effect" because of the dryness. Since the AMO is warm pressures will stay low over the atlantic while the pacific is cold causing higher pressures over this area. This causes the NAO to stay negative most of the time because of the ridge that builds over the atlantic. The NAO is negative but it is still warm across NA. We also have to take into account the fact that the NAO has less of an effect in summer. Pressures from the 1950's are low across NA because of the dryness caused by the response from the PDO flip.

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Last 3 summers have similar pattern.

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So how does this translate in winter time. Well in an el nino pressures lower across the pacific as well as the atlantic because of the warm mode and el nino. The colder nights and natural cooling created by the PDO flip causes a natural compensation causing higher pressures across NA. This is why I believe that this winter will be a cold one. We will also see a negative NAO overall because of the warm AMO. Many upcoming winters will average colder then normal( as long as the SST's are right for it as well as other factors). The next few summers will average warmer and hotter then normal as well because of the physical realities of the pattern we are in(proven by the 1950's). So it is the -NAO during summer, the -PDO along with the pre existing decadol driver that sets up a reaction across NA. Its not the pattern that we want to change but the natural evolution and different seasonal reactions.
Blizzardof96