January Pattern and Storm Discussion II

[burgertime]

The reason the Euro continues to produce a system and the GFS does not is that is closes off more energy at the base of that trough.... just look at the difference by 12z Wed....

 

Thanks Matt, just curious, is it producing snow on the surface just because there is enough energy with the ULL that it is producing the cold air? 

[beanskip]

850 0c line never even makes it into N.C. through Day 7 .....

 

 

Bigger view...maybe something to watch but I will hold off on getting excited until Wednesday. 

[burgertime]

850 0c line never even makes it into N.C. through Day 7 .....

 

Actually on reviewing the SV maps you can def. see it kind of spins another ULL in NC. There is a solid 850 circle and FZ one as well for one frame in the heart of the storm that is just west of CLT and extend into the mountains. It actually starts at 162 and goes through 168. 

[WilkesboroDude]

850 0c line never even makes it into N.C. through Day 7 .....

That is not what I am seeing. I will post a pic in a min.

[WilkesboroDude]

[WilkesboroDude]

Actually on reviewing the SV maps you can def. see it kind of spins another ULL in NC. There is a solid 850 circle and FZ one as well for one frame in the heart of the storm that is just west of CLT and extend into the mountains. It actually starts at 162 and goes through 168. 

 

 

 

[msuwx]

Thanks Matt, just curious, is it producing snow on the surface just because there is enough energy with the ULL that it is producing the cold air? 

Yes, it is dynamic cooling that pulls dome some colder air from aloft. The stronger that 500mb feature remains, the more cold air it can pull down. 

 

850 0c line never even makes it into N.C. through Day 7 .....

Here is a snapshot from the Euro at 850.... you can see that dynamic cooling process at work, bringing the 850s down to near and just below 0C in some spots. 

[Stormsfury]

The reason the Euro continues to produce a system and the GFS does not is that is closes off more energy at the base of that trough.... just look at the difference by 12z Wed....

 

Euro:

Euro.png

 

6z GFS:

GFS.png

 

Potentially the battle of the model biases at work here.   The EURO could possibly be holding it back just enough to close it off, GFS potentially could be overwhelming it with 1) progressive tendencies and 2) northern stream over-dominance.   Either way, there's energy there, just figuring out how much makes it this way is still the real question.    

[msuwx]

Potentially the battle of the model biases at work here.   The EURO could possibly be holding it back just enough to close it off, GFS potentially could be overwhelming it with 1) progressive tendencies and 2) northern stream over-dominance.   Either way, there's energy there, just figuring out how much makes it this way is still the real question.    

Yep, the old 'Euro tends to hold too much energy in the SW' keeps knocking around in my head, but it has been persistent with that scenario, so we'll see. 

[DaculaWeather]

Doing some more research on SSW's. It seems that in January with SSW's, the storm track is an east Gulf track. Good sign for us. 

 

BUT... fewer storms during that period.

[Cold Rain]

Yep, the old 'Euro tends to hold too much energy in the SW' keeps knocking around in my head, but it has been persistent with that scenario, so we'll see.

I remember thinking the same thing with the last cut-off. I believe that system was depicted to cut off deep in the SW and did pretty much that. The Euro kept showing it and think the GFS went that way eventually....if I'm remembering that correctly.

[DaculaWeather]

Another good sign

 

[burgertime]

I remember thinking the same thing with the last cut-off. I believe that system was depicted to cut off deep in the SW and did pretty much that. The Euro kept showing it and think the GFS went that way eventually....if I'm remembering that correctly.

 

It did, it showed it spinning and spinning which is pretty much what it ended up doing before ejecting and really getting torn to shreds.

[Cold Rain]

It did, it showed it spinning and spinning which is pretty much what it ended up doing before ejecting and really getting torn to shreds.

Thanks B. That may be a good sign for this one then.

[burgertime]

Thanks B. That may be a good sign for this one then.

 

You can really see on the paid maps how tight the Euro keeps the energy and makes it a nice ULL heading east. I'm always weary of ULL's though as they seem to have the tendency to ride to our west. If the Euro keeps it this will def. be a thread the needle event. I wanna see that ULL heading through central GA not northern GA....but I'm just being selfish.

[DaculaWeather]

OK... more good news. The new strat charts are updated. 

 

At the 1-5hPa level, we are approaching some of the warmest temperatures we've seen in a SSW event. Winds at 1 hpa down to almost 10 hPa have completely reversed and are now moving west at 60-70 mph, a very substantial increase in speed from a day or two ago. One thing I also noticed was the lower level temperatures. They are compressed so you might miss it, but notice how they are now trending down all all the lower levels.

 

This appears to be a long duration SSW which will help to keep the PV shredded and displaced. Substantial top down blocking will most likely begin occurring very soon. 

 

http://www.daculaweather.com/4_strat_temp_time_series.php

http://www.daculaweather.com/4_strat_details.php - Look at the JFM images on this.

 

 

 

[Cold Rain]

You can really see on the paid maps how tight the Euro keeps the energy and makes it a nice ULL heading east. I'm always weary of ULL's though as they seem to have the tendency to ride to our west. If the Euro keeps it this will def. be a thread the needle event. I wanna see that ULL heading through central GA not northern GA....but I'm just being selfish.

I hear you. I'd like to see it take the track you describe and maintain its strength longer. Looks like it holds together just long enough to give western areas a burst before it dies. If the cold presses a little bit more that the model is showing, it could force the track a little south, I suppose. But the offsetting factor is that it might kill it more quickly. I dunno, at this point, it looks like we're on the edge of a knife with this one....

[DaculaWeather]

We're seeing wind anomalies of -80m/sec or almost 180 mph!

 

 

 

[DaculaWeather]

Pressure anomalies are tremendous

 

 

 

[ncwinterwxman]

WOW ^^^  An incredible event for sure...As of the last update on the 10th, it appeared that the MJO wave was holding its own as well...I still think it will go around to phase 8 and then maybe 1. 

[DaculaWeather]

The MJO is taking the short path across phase 7 and headed toward 8

http://www.daculaweather.com/4_mjo_phase_forecast.php

[Cold Rain]

Pressure anomalies are tremendous

 

time_pres_HGT_ANOM_JFM_NH_2013.gif

Dac, I don't know enough about this stuff to frame this in very much context or offer much worthwhile commentary on it, but man, I appreciate you adding it to the discussion.  Really, what I know is that SSW>no SSW in terms of chances for blocking and cold.  But this event seems to be a really favorable one.  So again, thanks for the updates and the data!

[DaculaWeather]

SSW's, especially strong ones, develop huge blocks. This almost guarantees very cold temperatures for the southeast and much of the eastern US. It's also why you'll see the AO tank negative

[ncwinterwxman]

WOW ^^^  An incredible event for sure...As of the last update on the 10th, it appeared that the MJO wave was holding its own as well...I still think it will go around to phase 8 and then maybe 1. 

 

Also, you can clearly see that a spike in the PNA is on the way

 

[DaculaWeather]

Over the next week or two, I believe you'll see some radical changes in the teleconnection indcies as well as the model depiction of what's going to happen. These are extremely strong changes happening in the upper atmosphere and this could very well be a historic SSW that is occurring. The best I can tell, the strongest SSW recorded was in 1977 and we are approaching that strength with this one. Here's a summary of that event:

 

 

 

 

[Carvers Gap]

Looking at CPC's PNA ensemble this morning shows it going positive about the time the models show it going cold.  Also, the AO is going in the tank.  The NAO looks relatively neutral.  Looks like a cold set-up for the upper south.  From what I can tell, if that pattern were to take hold(keeping in mind their have been many false positives this winter), looks like the northern stream energy would dominate most of the time.  However, the tendency for the past many months is to transport moisture into the TN Valley - Robert has mentioned this continually.  Could(stress could) be a very good set-up for the southern Apps if the cold can establish itself.  Normally, I am a -NAO person in terms of looking for winter storms in this area.  Right now, I believe the +PNA will have to do the heavy lifting if we are to get snow.  If this happens, I think Robert's ideas for winter would be validated.  The only thing that bothers me is that somewhere during the middle of last winter, i remember thinking it was going to get very cold.  Could very well be a winter where temps are well above normal(we just logged a +20 @ KTRI) and snow goes normal.  Looks like a potentially wild pattern if the models verify.

[Cold Rain]

Over the next week or two, I believe you'll see some radical changes in the teleconnection indcies as well as the model depiction of what's going to happen. These are extremely strong changes happening in the upper atmosphere and this could very well be a historic SSW that is occurring. The best I can tell, the strongest SSW recorded was in 1977 and we are approaching that strength with this one. Here's a summary of that event:

1977_strat_warming.png

Sounds like fun times ahead. Will be interesting to watch for sure!

[BullCityWx]

Actually on reviewing the SV maps you can def. see it kind of spins another ULL in NC. There is a solid 850 circle and FZ one as well for one frame in the heart of the storm that is just west of CLT and extend into the mountains. It actually starts at 162 and goes through 168.

I think it's a product of evaporational and dynamic cooling more than anything. The air s pretty dry and actually fairly chilly before it hits. We'll see if it holds.

[oconeexman]

If this does set up like its forecast to does that open the door for Alberta Clippers? Serious question...haven't seen a strong clipper in a while!

[WilkesboroDude]

HPC

IF THIS ARCTIC AIR CAN ESTABLISH ITSELF QUICKER THAN THE GUIDANCE SUGGESTS ON MON INTO TUES... THIS HAS THE POTENTIAL TO BE A MUCH MORE SIGNIFICANT ICING EVENT FOR THE TN VLY AND POSSIBLY INTO THE MID-ATL REGION.