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Pattern Nippy November

KyloG said:
Euro comes in with rain starting late tonight through Sat night.

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And down right chilly the whole time it's raining too... looking like a couple of raw days ahead

edit: oh and breezy, Saturday just looks kind of miserable
 
Rain Cold said:
The -NAO domain is pretty small, compared to the whole NH. There are a lot of misconceptions floating around about the NAO. People hear -NAO and just sort of assume that it means cold and snow and stuff. Not saying you do that, but you can just read all the posts during any given winter, fawning all over the NAO, and you can tell how important it is in the minds of the general weatherboard poster. I do it too.

The deal is, the -NAO can matter or not matter all that much. It really depends on quite a few things. It matters how negative it is. It matters as to what shape it is/how it's configured. Whether or not it's east-based or west-based matters. Is it a temporary ridge or is it a more stable ridge...or even a block? Where is the block located? All of this matters.

An ideal -NAO suppresses and slows the flow. It helps storms both amplify and stay farther south. Suppressing the flow south, keeps colder air farther south. So, in a sense, an ideal -NAO is really good. However, something else is important: What kind of air is being suppressed south? Very cold arctic air? Or seasonal air? Or mild Pacific air? Those things are driven from outside of the NAO domain.

In the end, the NAO only influences what is available for it to influence. If the PV is way over in Siberia, where it can stay for a long time, then even an ideal -NAO may serve only to eliminate torching as opposed to create a stable, cold pattern. This is why I like to look at the H5 height maps. That gives me a good idea of where key features are, how they're configured, and what the over all flow pattern looks like.

What we are going to want to see is the PV find it's way over to our side of the hemisphere. Things like a -EPO can facilitate cross-polar flow and help that process take place. We will want to see more than just a -NAO transpire in order to establish a cold and potentially snowy pattern for the eastern and southeastern US.

The key take-away for me is that if the atmosphere has a recurring tendency for supporting a true -NAO this year, then that is different from many previous years. And it says to me that when a cold regime sets up on our side of the globe, the chances of that cold being directed south, and in a more sustained fashion, go up significantly. Then it just becomes a matter of timing with respect to storm chances. In that event, a -NAO would effectively open the window wider and keep it open longer, which we need all the help we can get here in the SE.

I know that's a TLDR post, but it's lunch time, and it's too cold to go for a walk. Hopefully, like Larry said, the EPS will confirm. And hopefully, the PV doesn't spend all of December in Russia. I don't think it will.
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Let it hang out in Russia for a bit to generate some wicked cold air then dump it into Canada and the US as it moves back to our side. AKA Siberian express.


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metwannabe said:
And down right chilly the whole time it's raining too... looking like a couple of raw days ahead

edit: oh and breezy, Saturday just looks kind of miserable
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Well, guess I'll have a good excuse to not get up the leaves this weekend.
 
CADEffect said:
I know this is what we all want for the PV to move more on our side. However, I can’t recall we had a timeframe of more then 30 days before it begin switching back to the other side (our side). To my knowledge a -NAO doesn’t really help our chances with a cold outbreak correct?


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Cold outbreaks typically come calling during the latter stages of a -NAO when said ridge starts retrograding over and west of Greenland. They’re not quite as intense overall as those that are associated with a -EPO (because those air masses typically originate in Siberia and not the Canadian Archipelago), of course w/ said -EPO we always run the risk of getting shafted by a downstream SE US ridge. Hard to win em all.
 
Stuck on 37F for a while now. If this holds all afternoon we will finish the day with a -28 degree departure from normal
 
Hope this coastal shifts another 100 miles to the east, do not want 2-3" of rain this weekend, though it looks pretty unavoidable at this point....
 
If this thing shifted closer or has more precip on the west side than is currently modeled ... we could be dealing with a bigger sleet and freezing rain threat because dryer and cooler air filters in at a certain point
 
GaWx said:
After looking at the beautiful 12Z GEFS, never mind the 0Z EPS as I think it was too warm (warm as in near normal not a torch by any means). Other than about a 36 hour period of near normal 11/21-2, the rest of the 12Z GEFS is colder than normal, which takes us through the rest of the month thanks largely to a strong and longlasting -NAO! Based on the GEFS doing well recently with the NAO despite its cold bias, there may soon be talk about the chance for November of 2019 to be one of the coldest Novembers on record. In the meantime, I expect the 12Z EPS to correct colder from a likely too warm 0Z run. And yes as was asked, it has had a warm bias recently just like the GEFS has been too cold overall.
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The 12Z EPS 11-15 verdict is in: the SE is a little cooler than the 0Z but still near normal overall and not nearly as cold as the solidly colder than normal of yesterday's 12Z EPS or today's 12Z GEFS. Most folks will probably not care for this run, especially since it is so much warmer than the GEFS. But remember that the EPS has been warm biased recently although the GEFS has a cold bias. What's the best solution right now? I'd go about halfway in between, which would favor the period averaging slightly colder than normal.

Anyone staying up for tonight's 0Z EPS? Remember that it is a whole hour earlier thanks to reverting back to standard time. Or set your Euro alarms. The newer Euro alarms now can be set for the EPS!
 
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