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John1122

Fall 2017 Great Tennessee Valley Outlook

156 posts in this topic

Apps runners can work well, especially for the western half of the valley, so even if it didn't do that much here, I'd like it for the western folks to get some nice winter storms. Plus, some of the most absolutely beastly winter storms in the history of the area were apps runners. Someday another of those will happen. We used to receive huge 12-20 inch snows across a large part of the entire valley at least every 10-15 years.  Not sure when the last really widespread one was. Knoxville probably hasn't recorded a 10+ inch snowfall since 1993. 

 

Best case scenario tracks for winter storms in the Valley are these two. With the clipper systems that dig being a 3rd.

1)

Coasal+Runner.jpg

 

2) 

Apps+Runner.jpg

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I am much more encouraged too, by the QBO now that I've been looking more at what Carvers spoke of regarding it's effects on blocking. In it's easterly phase the -NAO is much more common that when it's in it's westerly phase, though it's no lock that it will bring the -NAO/AO.

It was supposed to flip back towards easterly last December but was delayed for the first time in decades of observation. Now it has flipped back easterly and will be in the easterly phase for the next year or so as it cycles.

There were excellent maps posted yesterday in the SE form regarding -NAO and it's effects in La Nina years. As I've often observed, the drivers of NAO/AO/PNA/PDO far outstrip the ENSO factor in our weather. The maps posted yesterday confirm that. -NAO/AO La Nina winters were frigid in the East. +NAO/AO winters were very warm.  

The QBO being neutral or negative didn't always mean a great winter. But many of our notable winters were negative or neutral QBO years. The same with the +QBO, not all were bad winters but most of our warm winters featured the QBO in it's deep westerly + phase. 

Sometimes you have winters where nothing seems to apply. Winter 2010-2011 was fairly cold and very snowy for me. The QBO was positive. LaNina was strong. The February NAO was was mildly positive. The PNA was negative and I still manged multiple February snow events in a strong La Nina year. The temps weren't subzero frigid in 2010-11 but they were cold enough to make for a good winter despite most indications that it shouldn't have been one, with snow events in December, including a large White Christmas, and several in January too.

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Thanks to all of the posters who are making this a great thread.  Some really good stuff.

Recent model runs of the Euro and GFS and ensembles are pretty cold beginning next weekend.  Hoping to fire-up the wood stove.  We will see where the Euro goes this afternoon.  The 0z EPS was chilly.  Seems a recent trend is a above normal heights over Alaska days 10-15.

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On 10/20/2017 at 1:48 PM, John1122 said:

Apps runners can work well, especially for the western half of the valley, so even if it didn't do that much here, I'd like it for the western folks to get some nice winter storms. Plus, some of the most absolutely beastly winter storms in the history of the area were apps runners. Someday another of those will happen. We used to receive huge 12-20 inch snows across a large part of the entire valley at least every 10-15 years.  Not sure when the last really widespread one was. Knoxville probably hasn't recorded a 10+ inch snowfall since 1993. 

 

Best case scenario tracks for winter storms in the Valley are these two. With the clipper systems that dig being a 3rd.

1)

Coasal+Runner.jpg

 

2) 

Apps+Runner.jpg

The western parts probably cringe over these maps.The Valley has so much diversity pertaining weather it's not even funny.Storm track is so crucial,someone unless it's a super storm is going to basically miss out.

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