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January Pattern and Storm Discussion II


Cold Rain

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Yep. It's hard to put a finger on any storm threats though. Maybe there's something there after 1/20....we'll have to see how the pattern evolves.

I'm not too excited about the system this week yet. That bowling ball coming through could pick up a spare for some folks, but it could just as easily be a gutter ball too. Not quite enough evidence to get totally onboard yet, but also not enough to poo poo it either. It'll be fun to see how the next couple of cycles trend.

 

Yeah, I always figured it would be suppressed. The op models seem to be back and forth from run to run on the storm. I still think we are headed for a below normal period for at least a few weeks. The ensembles have been consistent in showing this. I am not too concerned with the +nao as the lower heights from the vortex are playing with the nao index. We are in prime climo time now so slightly below average is great for the upper south. The op models seem to take things to extremes a lot, hard to trust them beyond 100 hours. The last thing I want is a major arctic outbreak and storms too far south. Time will tell as it always does.

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Cold or Not Cold:

Point: Euro Ensembles maintain a ridge-west/trough-east look from D5-D10. Doesn't look warm at all. Latest CFS looks C O L D too. MJO looks to go into Phase 7-8. Also, the lag for effects felt by the recent Strat warming would tilt the scale toward cold. Lastly, the latest Euro Weeklies support a colder than normal pattern (we'll see what they have to say this evening).

Counter Point: Operationals show an amplified followed by zonal look. There is no real west-based -NAO showing up in the modeling. The PDO is still negative. Plus, factoring in how winter has gone so far, might give some pause for believing a sustained cool-down.

I'd lean in the direction of a sustained cool period coming. But I'm a big weenie and maybe only seeing what I want to see. But even though there are no guarantees, I think the evidence points more strongly in that direction as of this morning.

Good morning.

 

The 6-10 on the ensembles looks really good for cold weather.  Ridging west and troughing east.  Nice looking PNA signature on the ensembles for this time period.  It will be interesting to see if the ensembles are correct for the 11-15 period in breaking down the PNA rather quickly.

It will also be fascinating to see how the SSW affects the modeling going forward.  I am wondering if what we are seeing in the 6-10 is b/c of this warming or if it's just the appetizer before the main course. 

 

One thing is for certain..................A LOT to be ironed out over the coming 4-6 weeks.

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New video from DT:

 

You know, granted the guy is a bit of an a-hole, but I find his videos very informative and pretty funny.  Thanks for posting that.  I think we should all chip in and buy him a new microphone though.  My ears are bleeding from all that crackling.

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Interesing run of the 12z NAM -- the main players now getting in its range in the 48-60 hour time period where it is more reliable.

 

Main change from 0z to 12z run is that all the main features are slightly (but not insignificantly) further south. The SE ridge is slightly farther south, the southern 500 closed low and the push of cold air.

 

(At least through 63 hours). Southern system might be a touch weaker as well. The 0z NAM at 75 hours had a tiny closed off 850 low, a feature not apparent on the 12z run.

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As of this morning, all levels above 30hPa are cooling again. However, the heat is propagating downward, all levels below 30 hPA are warming. All the graphs haven't updated yet. http://www.daculaweather.com/4_strat_temp_time_series.php

 

01mb9065.gif

 

70mb9065.gif

 

This is what makes me wonder about the relationship between SSW's and actual weather.  I understood it to be that these SSW's didn't really have an affect at our latitude until the downwelling process to the lower levels occurred.  I am guessing the arctic air shown with the vortex moving toward Hudson's Bay IS a part of this process, but what has come throught the plains into arkansas, tennessee, and other parts of the south is not..............  fascinating stuff and much of it we have just begun to scratch the surface about what it all means and how it affects the sensible weather.

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Interesing run of the 12z NAM -- the main players now getting in its range in the 48-60 hour time period where it is more reliable.

Main change from 0z to 12z run is that all the main features are slightly (but not insignificantly) further south. The SE ridge is slightly farther south, the southern 500 closed low and the push of cold air.

(At least through 63 hours). Southern system might be a touch weaker as well. The 0z NAM at 75 hours had a tiny closed off 850 low, a feature not apparent on the 12z run.

If you extrapolate the NAM, which is always dangerous to do, it looks no bueno for areas east of the mountains.

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This is what makes me wonder about the relationship between SSW's and actual weather.  I understood it to be that these SSW's didn't really have an affect at our latitude until the downwelling process to the lower levels occurred.  I am guessing the arctic air shown with the vortex moving toward Hudson's Bay IS a part of this process, but what has come throught the plains into arkansas, tennessee, and other parts of the south is not..............  fascinating stuff and much of it we have just begun to scratch the surface about what it all means and how it affects the sensible weather.

Yes, several weeks (generally 2-3) have to pass after the main warming to see changes a the surface and  we are seeing the downward propagation of the temperatures. The wind reversal was the big piece we needed in order to "break" and displace the vortex, and that has happened. There have been rather large pressure changes in the upper atmosphere that will make themselves known over the next couple of weeks. 

 

time_pres_HGT_ANOM_JFM_NH_2013.gif

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Yes, but not compared to 0z run in the earlier hours of the run.

Much more interested in trends now than what the NAM actually ends up showing at hour 84. Through 72, the 500 low was south of the 0z position at every frame.

I'd like to see it hang back a little bit...we'd be walking a fine line then with a more suppressed solution, but we need the cold to press a bit more before the ULL comes in...otherwise, it might very well end up more north and warmer.

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Then late in the run, the NAM takes a strong closed low NE -- more of a Missouri Valley/Ohio Valley/Northern Tenn. Valley hit.

 

Becoming more apparent that SOMEBODY is going to get a big hit from this system -- but who?

Thanks for the play by play.  I peeked b/c I have many friends in northern middle Tennessee.  Looking at 500, there would be no chance at a northern tn valleysnow hit.

 

That baby is more of a northern arkansas, southern missouri, western Kentucky snow.  All that said, it is the NAM from 72 on so......................not really worth dissecting all that much would be my guess.

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Thanks for the play by play.  I peeked b/c I have many friends in northern middle Tennessee.  Looking at 500, there would be no chance at a northern tn valleysnow hit.

 

That baby is more of a northern arkansas, southern missouri, western Kentucky snow.  All that said, it is the NAM from 72 on so......................not really worth dissecting all that much would be my guess.

May just be my geographic ignorance, but I thought the Tennessee River flowed up into southwestern KY?

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May just be my geographic ignorance, but I thought the Tennessee River flowed up into southwestern KY?

Part of the Tennessee river is a divider between west and middle Tennessee, but it does run north into southwest Kentucky.  When the term northern TN valley is used most people in middle Tennessee take that to mean the area just north, northeast, and northwest of Nashville.

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