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Pattern Fail or Fab February 2023 Pattern Thread

rburrel2 said:
Let's punt the first s/w and role with the 192hr GFS.View attachment 131613
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If I was a betting man, I'd place my bets entirely on the 2nd system & ignore the first one.

There's almost no realistic chance the cold/dry air gets way out in front of the moisture on arrival with the first system, which is usually a death sentence for CAD/overrunning events.
ecmwf-ensemble-avg-east-mslp_anom-5533600.png

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Webberweather53 said:
If I was a betting man, I'd place my bets entirely on the 2nd system & ignore the first one.

There's almost no realistic chance the cold/dry air gets way out in front of the moisture on arrival with the first system, which is usually a death sentence for CAD/overrunning events.
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wow, yea I didn't check the 00z EPS for the day 9 threat but dang it has a nice wedge signal for sure.
 
Webberweather53 said:
If I was a betting man, I'd place my bets entirely on the 2nd system & ignore the first one.

There's almost no realistic chance the cold/dry air gets way out in front of the moisture on arrival with the first system, which is usually a death sentence for CAD/overrunning events.
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View attachment 131619
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Yeh definitely agree. It’s honestly pretty simple & really doesn’t need any deep explanation in any way. (Not a knock).. you simply get the cold air in place & let the overrunning take place, and there just isn’t any indication that is going to happen. Hopefully that second system starts showing up everywhere. Maybe VA can get a thump from the first. But I think it’s a fight with them also between extremely wet snow or either a cold 35° rain.
 
Mitch West said:
Yeh definitely agree. It’s honestly pretty simple & really doesn’t need any deep explanation in any way. (Not a knock).. you simply get the cold air in place & let the overrunning take place, and there just isn’t any indication that is going to happen. Hopefully that second system starts showing up everywhere. Maybe VA can get a thump from the first. But I think it’s a fight with them also between extremely wet snow or either a cold 35° rain.
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We're having an entirely different conversation if this is a cut-off upper low &/or coastal cyclone. Having the cold air already is nice in those cases, but it's not the end of the world because the precipitation formation processes are totally different.

In overrunning/CAD, it is absolutely necessary to have the cold show up before the moisture does, because the entire time the column is warming from warm advection aloft that's generating large areas of light-moderate stratiform precipitation.
 
Webberweather53 said:
The 12z GEFS looks pretty decent to me for a potential CAD next weekend following this coming week's overrunning event.

Just need to see the SE Canada vortex slow up/dig a bit more here & we'd have something worth talking about.


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Hopefully the Euro throws a bone with this. Guess we are about to find out.
 
All I see on these model maps are warm solutions for the Eastern Half of the nation with little mirages that occur in the long-range due to the transient positive PNA appearances that sometimes pop-out within the progressive, sometimes split-flowed, pattern. The entire Northern Hemisphere from Siberia to Bermuda looks terrible for major winter storm chances all the way into the I95 section of Mass. When I lived in NJ and PA, the only events I could look forward-to in this type of pattern would be some thread-the-needle/over-running event, but most of the snow would fall in the Ohio Valley and Appalachians. That's where snow may fall Northern Alabama/Mississippi to Western Apps, which is something I called in my forecast. The source of most of the cold air is coming from Eastern Russia/Alaska Arctic regions, and that usually favors cyclones in the Western/Central US and Newfoundland to Central Atlantic.

Yick. This warm vortex looks ready to phase over the Atlantic to create some fish storm.
3719b50b-79dd-4a7a-bb2a-092ebbed3f8d.gif
 
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This is about the only thing that needs to change on the ECMWF Ensemble in 7-8 days to yield a strong CAD/ice storm next weekend.

Screen Shot 2023-01-28 at 12.53.18 PM.png



Very workable setup here, with cold air already well established by the time any moisture could overrun it from the W-SW. The only issue of course is the vortex over Atlantic Canada gets out of the way just a tick too soon, favoring CAD erosion &/or more of an in-situ vs classic CAD. That kind of thing isn't difficult to change this far out though.

I certainly can see some potential here, particularly for the western piedmont & foothills


ecmwf-ensemble-avg-east-mslp_norm_anom-5555200.png
 
Webberweather53 said:
This is about the only thing that needs to change on the ECMWF Ensemble in 7-8 days to yield a strong CAD/ice storm next weekend.

View attachment 131640



Very workable setup here, with cold air already well established by the time any moisture could overrun it from the W-SW. The only issue of course is the vortex over Atlantic Canada gets out of the way just a tick too soon, favoring CAD erosion &/or more of an in-situ vs classic CAD. That kind of thing isn't difficult to change this far out though.


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Step for step just like it’s OP. Well established CAD for 48-72 hours but moisture doesn’t start overrunning it until 12-24 hours too late.
 
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