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December Mid/Long Range Discussion


WxUSAF
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18 minutes ago, WinterWxLuvr said:

Latest gfs shows a tendency for the troughs dipping into US that currently are too far east imo slowly becoming more aligned with the Mississippi River as time progresses which I think gives us better opportunities. 

Agree 120%!  I have felt for quite a while that our precipitation deficits can at least partially be blamed on trough axis too far east.  IMO our precipitation chances including snow would increase with a trough axis persistently closer to Nashville/Cincinnati instead of D.C.

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44 minutes ago, WinterWxLuvr said:

Latest gfs shows a tendency for the troughs dipping into US that currently are too far east imo slowly becoming more aligned with the Mississippi River as time progresses which I think gives us better opportunities. 

Yeah, the only thing is to temper expectations, but it's kinda fun to see the H5 map change with every run.

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8 minutes ago, psuhoffman said:

 

2 minutes ago, psuhoffman said:

There’s definitely some good juju percolating for second half of December and beyond. Hopefully some of our more sensitive subforum posters can make it!

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11 minutes ago, WxUSAF said:

 

There’s definitely some good juju percolating for second half of December and beyond. Hopefully some of our more sensitive subforum posters can make it!

Interesting that 09/10 is being bantered about. Late December Snowpocalypse was followed by a kind of boring January with a couple of small events and then boom. I know some are concerned with the position of the Aleutian low. But look at its position heading into the December blizzard. Looks pretty similar to the predominate position we are seeing on guidance to me. We just arent seeing a southern stream storm next week. Now the one after that?

dwm500_test_20091218.gif

 

 

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19 hours ago, AtlanticWx said:

it's nice knowing there's a shot. just a few runs ago, GFS had a storm near that same time which was about to slam us but it didn't go far out enough

Paging @AtlanticWx, I need your snow forecast for RIC in the below thread.  You did not supply that number, and you cannot receive private messages. 

 

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16 minutes ago, clskinsfan said:

Interesting that 09/10 is being bantered about. Late December Snowpocalypse was followed by a kind of boring January with a couple of small events and then boom. I know some are concerned with the position of the Aleutian low. But look at its position heading into the December blizzard. Looks pretty similar to the predominate position we are seeing on guidance to me. We just arent seeing a southern stream storm next week. Now the one after that?

dwm500_test_20091218.gif

 

 

That was such a beautiful set-up. Perfect AL low position, ridge pumped over Idaho, and the trough going neutral/negative over the Mississippi, then confluence/blocking to our north.

Similar look out west here on the ensemble ~ 12/5. It's more progressive than 2009 so we don't get the southern stream amplification, but it's worth watching at a minimum, and encouraging to see as we head into better climo. 

gfs-ens_z500a_namer_26.png

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29 minutes ago, clskinsfan said:

Interesting that 09/10 is being bantered about. Late December Snowpocalypse was followed by a kind of boring January with a couple of small events and then boom. I know some are concerned with the position of the Aleutian low. But look at its position heading into the December blizzard. Looks pretty similar to the predominate position we are seeing on guidance to me. We just arent seeing a southern stream storm next week. Now the one after that?

dwm500_test_20091218.gif

 

 

This is a composite of every 8" snowstorm at BWI in a Nino year since 1957-58.  There were 20 such storms.  As you pointed out... the trough in the north Pac is there on the mean, and there on almost every one of those storms in the set.  Most of those storms are January to March but a few were in December.  

829735210_8inchNinoSnowsatBWI.gif.e4ada60ac71c2a0f22bd840295ba2c6c.gif

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1 hour ago, psuhoffman said:

This is a composite of every 8" snowstorm at BWI in a Nino year since 1957-58.  There were 20 such storms.  As you pointed out... the trough in the north Pac is there on the mean, and there on almost every one of those storms in the set.  Most of those storms are January to March but a few were in December.  

Do you have a composite of December snowstorms at BWI? or even Nov-Dec? 

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4 minutes ago, psuhoffman said:

This is a composite of every 8" snowstorm at BWI in a Nino year since 1957-58.  There were 20 such storms.  As you pointed out... the trough in the north Pac is there on the mean, and there on almost every one of those storms in the set.  Most of those storms are January to March but a few were in December.  

829735210_8inchNinoSnowsatBWI.gif.e4ada60ac71c2a0f22bd840295ba2c6c.gif

“usually” what happens is that all those features (NPac trough and western ridge) are west of those positions leading into the storm and then they roll east with the big storm. 

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1 hour ago, WxUSAF said:

“usually” what happens is that all those features (NPac trough and western ridge) are west of those positions leading into the storm and then they roll east with the big storm. 

Seems like we have a -NAO with the 50/50 low being the stronger signal.. two >+120dm regions not related to the storm, so that's a strong signal. Also to note is that in -NAO we are drier than average at a 0.40-0.50 correlation, so it usually hits big or much less (STJ phasing). 

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15 minutes ago, Stormchaserchuck1 said:

Do you have a composite of December snowstorms? or even Nov-Dec?

I lowered the criteria to 3" at BWI in order to get a larger sample size.  These are all Nov/Dec 3" snows in Nino years since 1957. 

284837196_NovDecNinoSnow.gif.e6e55bb0f3b5a70c4ceb9804b6086894.gif

Not much difference, BUT I would note that while the trough in the Pacific does still encroach into the west coast the deeper trough is definitely centered west towards the Aleutians and there is a more significant PNA ridge present in the composite mean.  I do think this supports the notion that we need a more perfect pacific pattern to snow in a nino early v later in winter.  

 

My main point earlier was just...its fine for this pattern to not be working in November and early December... but if its still too warm in January/February I don't want to hear any of this "the pacific isnt good" crap.  We've snowed plenty with this exact pacific pattern in past el nino's.  That was all I was trying to show.  

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20 minutes ago, WxUSAF said:

“usually” what happens is that all those features (NPac trough and western ridge) are west of those positions leading into the storm and then they roll east with the big storm. 

You mean like this...

Stage1.thumb.png.f5d6f007651746501db54db7ab28a604.png

Which rolls forward to this

stage2.thumb.png.f7c7b7680b6b405f355e69ada016d2bc.png

There are imperfections and I am not saying even in January that this would be a HECS, but IMO the bigger problem why this probably won't be even a smaller snowstorm is its early December and the temperature profile absent a direct arctic airmass just isn't quite ready to support this type of progression yet.  

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1 hour ago, clskinsfan said:

Interesting that 09/10 is being bantered about. Late December Snowpocalypse was followed by a kind of boring January with a couple of small events and then boom. I know some are concerned with the position of the Aleutian low. But look at its position heading into the December blizzard. Looks pretty similar to the predominate position we are seeing on guidance to me. We just arent seeing a southern stream storm next week. Now the one after that?

dwm500_test_20091218.gif

Look at the sharp west coast ridge though. It counteracts the Alaska low temporarily and the ridge crests over Idaho as the trough goes negative over Missouri.

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