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showmethesnow

Aug Mid/Long Range

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Spent to much time doing a post in the Hurricane thread so I don't have time to do up a post at this time. But since I have started this thread the last couple of months I figured I might as well now. Will try to get something up tomorrow morning before we leave on a weekend trip.

Until then here is something to keep you entertained. (Figured those that live in our local deserts would enjoy this :whistle:)

 

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Looking over things I think heading into the end of the month month may get a little interesting. It will all be dependent on the -NAO breaking down in the coming week or two. See that and I think we could be looking at an extended heat wave (compared to seasonal norms) as well needing to keep an eye on tropical (post in the Hurricane thread detailing my thoughts).

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1 hour ago, mattie g said:

I thought that a +NAO in summer correlated more to cool weather. If that's the case, then why would the breaking down of a -NAO result in heat?

 

Really don't know whether a +NAO normally correlates to cooler weather or not during the summer. Will take your word for it. But I am not even sure we do see a +NAO, looks neutralish maybe very weak positive at the end of the extended looking at the maps. Brings up the question, what is typical for a neutral state? But besides that I generally focus on long wave patterns and indice values are of secondary concern. Pulled these out of my other post in the tropical thread. As you can see below we are dealing with a strong -NAO through hour 120 which is backing the flow inducing a deep trough in the eastern US and cooler temps that come along with it.

 

120hr500mb.gif.dc4c8bc92719a594385eb392951939e1.gif

 

Now this is the last 5 days of the extended. We now have a neutral to maybe a weak positive NAO from just eyeballing it. There is no longer backing of the flow so we are seeing the flow flatten and withdraw to the north which is allowing higher heights and ridging to build in from the south along with the heat that should come with it. Right now the heat anomalies at the end of the extended are minor but the look at the end of the GEFS is suggestive of building heat. I go into a little more detail in the tropical thread if you care to read it.

384hr500mb.gif.8fc0359f76a03b96409e978977c834df.gif

 

 

 

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You could simply consider this September may turn out a little different than last September 

 

 

 

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9 hours ago, EastCoast NPZ said:

Why on earth is an august heatwave interesting?  1.  It's awful, and 2. It happens every single year.

Yeah, exactly. Building heat? Doesn't it need to cool down in order to build heat? The heat built in June and hasn't changed since. It's not "building heat" it's continuing heat.

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Thought I would revisit my post from the 7th to see how well the GEFS is handling the extended so far.

Below is the 5 day mean for the end of the extended from the 7th.

384hr500mb.gif.c32c4d6037df5b465a9b006419fd35de.gif

 

Now here is the latest run for that same period of time 8 days later. Not to shabby. Still shows the breakdown of the strong -NAO, withdrawing and flattening of the flow through the CONUS, and the height builds from the Atlantic through the south and into the SW. The PAC isn't too bad either though it does have the Pacific NW troughing and the Alaskan ridging/higher heights both shifted somewhat west. If you notice the weakness (circled in gulf) that split the higher heights through the south that we do not see on the previous map. That may be indicative that the GEFS sees the possibility of tropical through that region and in fact we do see systems popping up here and there on the op runs.

GEFS500mb5day.gif.021d59c7bea5110630b2ef77c90262bc.gif

 

Now with this shift of pattern (IMO all the result of the breaking down of the strong -NAO) we are seeing temps begin building once again through the region after a short cool down to normal to below normal temps before hand.

1054248781_5daytempanoms.gif.4a0573e076ec0f35075453971cd17233.gif

 

But unlike my thoughts previously of this possibly being a long duration event with the heat ever increasing the GEFS has other plans. And if you guessed it might do with the NAO you would probably be right. We once again are seeing height builds and ridging moving into Greenland (-NAO). Thus we are seeing temps cooling down as the SE Atlantic riidging/higher heights are being knocked down once again as the mid-latitude flow shifts south in response to the blocking.

extended5day500mb.gif.197a50f267afda504389fbd575ce8906.gif

 

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As @Ian has been showing on twitter, GEFS has been in a habit of dumping a trough/cool temps in the eastern CONUS late in the run very often this summer.  Still waiting.

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6 hours ago, WxUSAF said:

As @Ian has been showing on twitter, GEFS has been in a habit of dumping a trough/cool temps in the eastern CONUS late in the run very often this summer.  Still waiting.

Not really sure I buy the long range cool down either. Felt a week ago that that period of time would feature some fairly impressive heat relative to norms and I still am leaning that way. Guess we will see. 

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2 hours ago, showmethesnow said:

Not really sure I buy the long range cool down either. Felt a week ago that that period of time would feature some fairly impressive heat relative to norms and I still am leaning that way. Guess we will see. 

I too am interested as to how well it does in the cold season coming up.

 

 

 

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