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Wintry 1/26-1/28 Winter Storm Potential

Just to illustrate how much models can change with key details even 120 hours out, let's look at the FV3 for the system that is moving through the Midwest currently. Here is the 6z run of the FV3 on Friday for the 5H look.
1548169375639.png

Now notice the 6z run from this morning. Notice the heights aren't pressing down NEARLY as much and our energy is a good bit more amped as well. This is why we often see the classic NW trend. Such a scenario and adjustment NW/stronger is well within the realm of possibility for the system Sunday/Monday we are tracking.
1548169417983.png
 
One last map. Notice the 5h trend with our PV and heights lifting north over the past 4 runs of the ICON? This is what almost always brings the N trend as the heights relax some as we near verification. I wouldn't write this one off yet. Plenty of time for things to shift back north.
icon_z500_mslp_us_fh78_trend.gif
 
snowlover91 said:
One last map. Notice the 5h trend with our PV and heights lifting north over the past 4 runs of the ICON? This is what almost always brings the N trend as the heights relax some as we near verification. I wouldn't write this one off yet. Plenty of time for things to shift back north.
Click to expand...

This is what is taking our cold air away too, right? Is the hope that the north shift will allow some interaction to help pull down some cold air? Or dynamics will help make up the difference?

I guess this is an example of how we're always threading the needle to get a good system down here.
 
snowlover91 said:
Just to illustrate how much models can change with key details even 120 hours out, let's look at the FV3 for the system that is moving through the Midwest currently. Here is the 6z run of the FV3 on Friday for the 5H look.
View attachment 12547

Now notice the 6z run from this morning. Notice the heights aren't pressing down NEARLY as much and our energy is a good bit more amped as well. This is why we often see the classic NW trend. Such a scenario and adjustment NW/stronger is well within the realm of possibility for the system Sunday/Monday we are tracking.
View attachment 12548
Click to expand...
snowlover91 said:
One last map. Notice the 5h trend with our PV and heights lifting north over the past 4 runs of the ICON? This is what almost always brings the N trend as the heights relax some as we near verification. I wouldn't write this one off yet. Plenty of time for things to shift back north.
View attachment 12550
Click to expand...

And just an example of how fast things can change on the models, the FV3 was showing this yesterday evening.

1548112814908.png
 
That’s a massive PV press
c6813dc9e1311321b928e7a2d2bda3ab.jpg



Sent from my iPhone using Tapatalk
 
Benholio said:
This is what is taking our cold air away too, right? Is the hope that the north shift will allow some interaction to help pull down some cold air? Or dynamics will help make up the difference?

I guess this is an example of how we're always threading the needle to get a good system down here.
Click to expand...

I believe so yeah on the north shift allowing for some interaction to pull down cold air. If this system trends north and is timed correctly with the northern stream, they should interact and pull down cold air. If this wave is left behind by the northern branch then based off what I'm seeing it's going to simply drift SE in the gulf...and some of the runs have been wanting to make it look tropical storm-ish later on.
 
Benholio said:
This is what is taking our cold air away too, right? Is the hope that the north shift will allow some interaction to help pull down some cold air? Or dynamics will help make up the difference?

I guess this is an example of how we're always threading the needle to get a good system down here.
Click to expand...

It's a pretty complex setup but by the time this storm moves through our airmass is slowly modifying (warming). The track of this wave, how much it amplifies and how much if any northern stream phasing there is are important to the eventual track. If the PV is pressing south it will suppress our wave and it won't amplify in time. That is what models currently show. Personally I am expecting them to back off the PV pressing south in the next few days and if that happens this could jump north but it's also possible models are correct with pressing the PV this far south, it's hard to know this far out.
 
This run of the GFS looks like it may be quite suppressed as the PV is pressing south more through 84.
 
GFS so far appears to be a step in the right direction. Initially the PV presses down more but then the PV appears to let up a bit more. Still likely a suppressed run but might be a positive first step.
 
Yeah going back to that FV3 run, I can actually see how this would work if this wave would interact and phase with that northern stream branch that rotates down. It was a miss though.
 
Very far south track normally looks good to people like Phil and myself, but it does no good without an Arctic surface high to the north to tap into.
 
GeorgiaGirl said:
Yeah going back to that FV3 run, I can actually see how this would work if this wave would interact and phase with that northern stream branch that rotates down. It was a miss though.
Click to expand...

Yeah it just missed this 12z GFS run but it was a shift north for the GFS still and IF it had phased with that northern energy it would have looked more like the 00z UK and some of the FV3 runs. This storm isn't dead yet.
 
Robert West said:
I just don't see us getting the cold air we need even if we get this thing to scrape us. This is a very interesting time coming up regardless, especially with the anafront approaching. Lot of energy out there.
Click to expand...

If we actually do get a phase with a part of the northern branch, it could work out. Otherwise this thing seems like its pretty wound up.
 
It might actually show 850s to warm but all you need is dynamic cooling, pretty dry air at the sfc and aloft and if you were to get heavy precip to fall the column would crash to a isothermal sounding, but this applies for more climo areas
 
Hard to tell on these rough maps but it appears the FV3 JUST missed a big phase.
1548174231924.png

For comparison here was the 6z run, notice how far apart the two waves are and a bit stronger PV press.
1548174270460.png
 
Robert West said:
I just don't see us getting the cold air we need even if we get this thing to scrape us. This is a very interesting time coming up regardless, especially with the anafront approaching. Lot of energy out there.
Click to expand...

It would need to phase with the northern stream and that would deliver enough cold air for isothermal soundings and snow as long as the track is offshore.
 
snowlover91 said:
It would need to phase with the northern stream and that would deliver enough cold air for isothermal soundings and snow as long as the track is offshore.
Click to expand...
When you say phase with the Northern stream, what exactly do you mean? I'm not going to pretend like I understand what yall mean anymore with that. I have a idea, but I want to be sure. Are you referring to the energy behind it?
 
snowlover91 said:
Hard to tell on these rough maps but it appears the FV3 JUST missed a big phase.
View attachment 12562

For comparison here was the 6z run, notice how far apart the two waves are and a bit stronger PV press.
View attachment 12563
Click to expand...

Looking at the 12z GFS, the southern wave wasn't much faster, but the northern wave and PV was slower. That trend would work too.
 
Robert West said:
When you say phase with the Northern stream, what exactly do you mean? I'm not going to pretend like I understand what yall mean anymore with that. I have a idea, but I want to be sure. Are you referring to the energy behind it?
Click to expand...

The northern stream waves are the ones diving out of Canada. In the picture I posted it would be the one extending from GA up through the Great Lakes region. Our southern stream wave is the one that is south of LA. To get a phase you want these two waves to meet together but if one is in front of the other they will miss or have a delayed interaction keeping this suppressed and out to sea. The 12z FV3 was very close to a nice storm, only a few hundred miles/hours in timing faster with the southern or slower with the northern and we would have a nice storm.
 
Myfrotho704_ said:
It might actually show 850s to warm but all you need is dynamic cooling, pretty dry air at the sfc and aloft and if you were to get heavy precip to fall the column would crash to a isothermal sounding, but this applies for more climo areas
Click to expand...

I think if we get a phase then we really wont have to worry about cold air as much.

I will say I think we’re starting the day off better than where we ended last night. Small small baby steps.
 
Our 5H energy is not even its own piece yet. It’s still wrapped around the large pacific gyre. In 24 hrs it will begin to become more pronounced as it’s own wave.

So I could see large shifts occurring for the next 24hrs. By then the wave will be starting to take shape and we will be approaching or at 5 days out.

There is still time.
 
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