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Winter Weather Potential - January 20-27


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11 hours ago, RickyD said:

May i inject a question i am not understanding.  How can arctic (polar air) be so quickly whipped like a little cur puppy and run --- by what we labeled a Modoki el nino?  We are not getting zonal flow, so i don't understand how it is being scoured SO FAST... Not just here, but above the Mason Dixon Line...  And i need more than a - or plus Nao etc type answer...   Frustrated in Calhoun...  🙂 

We've had a split flow in the Pacific thanks to a Rex block, but both are still Pacific origin. We have a progressive flow. It really does come down to the fact that we have no Atlantic blocking, regardless of what you may like to hear different. 😉

In order to prevent the progression of troughs, you have to have a blocking high. Watch this animation. Notice once we get the blocking (the banana highs) across the top, how the cold builds and stays in place. Once the -NAO weakens, the cold trough lifts out. That blocking prevents the progression of the pattern and locks the cold in place and actually helps to make it stronger as it continues to get reinforced.  You can also see that the cold stays in place longer, so storms have to go under and not through.  Right now is seems like a zonal flow since there is nothing to slow down the progression of systems. Blocking, blocking, blocking... we live in the south. Things have to be just right for us, not nearly so much for those folks in the north. 

847428553_GEFSEnsemblesNorthernHemisphere500hPaZAnom(no)-24.gif.37a8de8deb4e4bdf5210f9848cbff4c6.gif

 

But here is part of the problem in the models. 

This image is today, and shows the building -EPO ridge out west and an east-based weak -NAO. Even though the NAO is weak and too far east, it still helps to buckle the jet stream and drop colder air over the east US. 

Snap346062331-24.thumb.jpg.0c9986165a746d0b3d0d64058182d2ee.jpg

 

This is a GFS forecast for the 28th. Notice the -EPO ridge continues to build, forcing storms to go up and over, but look at the Atlantic. We now have a positive NAO (low over high) and that opens up the east coast trough and allows things to shoot off to the NE. Notice how flat the flow is over the US with no real buckling of the jet. 

Snap346062330-24.thumb.jpg.7f9b0f373d56ef5a2a979ee24006bba2.jpg

 

The confusing part, is the GEFS shows a MAJOR -NAO.... so big discrepancies between the deterministic and ensembles. 

gefs_nao_00-24.png.6740a1d35806e9da565c8f632e2e9d11.png

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Ok... going out on a limb by creating this post, but I believe there is enough model justification to warrant it.  No guarantees! 😜 The models are all beginning to show threats for this time peri

Ok, I've been playing today. So for your viewing pleasure, we're going old school. Here's your "Local on the 8's" the way the Weather Channel USE to do it in the early 90's, and this is real live data

Ok folks... here are my thoughts about what is going on right now.  With such an active pattern, the models are totally worthless and of no help at all past 5 days, not even the ensembles. We're

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2 minutes ago, Wendy4 said:

How confident are we about Tuesday  Into Wednesday of next week for snow. We are within a week of this forecast. 🤞🤞🤞

🙂 I wish I could tell you that we have a lot of confidence, but I wouldn't be telling you the truth. I do think we can say with confidence that we will be getting pretty cold, but right now it's impossible to time any storms that may bring winter weather. I think we can also say pretty confidently that the Tue-Wed time frame IS a favorable period for a chance for snow, but nothing to hang your hat on right now.

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NWS Atlanta this morning

Quote

In general, the GFS and Euro are in good agreement regarding the
overall pattern, through the long term, with the GFS-FV3 lagging
behind while elongating the cold front. The result is a chance for
precip from ranging from early Tuesday morning through Thursday
morning. Both the GFS and Euro agree on the highest chances of
precip coming during the day on Tuesday, with precip falling behind
the cold front. The Euro hints at some snow flurries behind the line
of storms where the GFS is much more bullish with light snow
coverage with chances all the way down to central Georgia. Both then
clear out with high pressure settling in with a weak shortwave
moving through Wednesday night. the Euro keeps this wave dry while
the GFS hints at light snow flurries possible for far North Georgia.
The GFS-FV3 on the other hand, elongates the cold front, pushing it
through slowly on Wednesday. It's much drier than the Euro and GFS,
but still has a strong signal that we could see so mixed/frozen
precip through the area on Wednesday instead, even into central

Georgia. The current forecast blends these 3 scenarios with each
having some consistency to their claims from the previous night.
Guidance has been putting a signal for some winter precip around
this time for the last several days with no clear indication on
which way Mother Nature will go. Seemed appropriate to include at
least a slight chance of each possibility. Although if you hold my
feet to the fire, I'd lean towards the Euro (front Tuesday, little
chance of frozen precip with higher temps and dry the next several
days afterwards).

 

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I keep imagining Mother Nature and God, having coffee -- and planning to mess with us.  

"I know!  Let's give them every possible indication that it's going to be a snowy winter -- and then make it NOT snow!"

(Then they laugh and laugh...)

🤣

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Just now, Bagsmom said:

I keep imagining Mother Nature and God, having coffee -- and planning to mess with us.  

"I know!  Let's give them every possible indication that it's going to be a snowy winter -- and then make it NOT snow!"

(Then they laugh and laugh...)

🤣

Or...

"Let's keep them waiting and thinking that nothing is going to happen, then we'll hit them so hard, they won't know what hit them. 🙂 " 

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Here's the GFS NAO verification and forecast. Notice a few things.

  • The NAO was only negative around the first of the year. All of January to this point has been positive.
  • The 7 day NAO forecast only has a .85 correlation with reality
  • The 10 day NAO forecast only has a .67 correlation with reality
  • The 14 day NAO forecast only has a .35 correlation with reality. Monkeys randomly picking would give better results. 

nao_verify-24.thumb.gif.cc73ab7c58490054da1af56d9f0d6e3d.gif

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37 minutes ago, NorthGeorgiaWX said:

Or...

"Let's keep them waiting and thinking that nothing is going to happen, then we'll hit them so hard, they won't know what hit them. 🙂 " 

That's a glass half empty vs a glass half full, for sure! ^

 

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10 minutes ago, NorthGeorgiaWX said:

Here's the GFS NAO verification and forecast. Notice a few things.

  • The NAO was only negative around the first of the year. All of January to this point has been positive.
  • The 7 day NAO forecast only has a .85 correlation with reality
  • The 10 day NAO forecast only has a .67 correlation with reality
  • The 14 day NAO forecast only has a .35 correlation with reality. Monkeys randomly picking would give better results. 

nao_verify-24.thumb.gif.cc73ab7c58490054da1af56d9f0d6e3d.gif

I’m assuming this means our confidence with the accuracy of the NAO forecast is pretty much nil.

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1 minute ago, firefighter556 said:

Teaching moment? Lol (what does this mean?)

The NAO (or North Atlantic Oscillation) is a pattern that is very important in the winter, especially for us. Look at this image.

This pattern is a positive NAO. You see an area of low pressure over Greenland, with a corresponding area of high pressure to the south. Now imagine both of those spinning, the low counter-clockwise and the high clockwise. What does that do? They act like big pumps that funnel the jet stream between the two, and creates a very fast flow of warmer Pacific air over the US.

nao_pos.png

 

Now look at this picture. This is what we want to be seeing, but haven't so far. Here you have high pressure that forces the jet stream and cold to drop far south because it can't go anywhere else. If that high pressure remains in place (as well as the west coast block or -EPO and a -AO over the pole) then we end up with an extended length of time at the base of that east coast trough, and that's where we want to be for winter weather.  

nao_neg.png

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1 hour ago, NorthGeorgiaWX said:

Or...

"Let's keep them waiting and thinking that nothing is going to happen, then we'll hit them so hard, they won't know what hit them. 🙂 " 

Also let's make it snow in the middle of the work day again and see how prepared for snow we truly are! Glad I live ten minutes from home now!

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It's snowing lightly in Blue Ridge right now. Is it greedy of me to want more, heavier, and faster?! lol

 

EDIT* It was just a very small passing patch. Just like that, it's gone lol

Edited by SlicNic13
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