January 2013 mid-long range disco thread

[Bob Chill]

Didn't we play this game last year?

 

lol- just like the snow cover index this year. But the snowcover thingamajiggy did produce a pretty strong and very useless -AO. 

 

I've been trying to get into ESRL today to pull some NH maps. They've been quite cold on the other side of the globe this winter and also in several winters before that. There seems to be a semi-permanent siberian blocking hp that is playing a role in keeping cold air away from us. 

 

Data set is teeny tiny but some are pointing to a connection with the low arctic ice mins in the fall allow for the hp to become tough to dislodge. It's an interesting concept. We've had plenty of blocking the last 3 years or so but haven't had any real arctic outbreaks to speak of. Sure, canadian air can be seasonably cold but nothing like what parts of europe, russia, and china have been hit with. 

 

Honestly, I hope the concept has zero merit because the low ice mins aren't going anywhere anytime soon. But if it does then real arctic intrusions may be be waning on our side of the globe. When's the last time we had a real arctic outbreak anyway? 

[Bob Chill]

I'm with you but this is basically a kick in the nuts. This wave was timed very nicely in the long range using a lot of factors but the PJ and PV are retreating so quickly. It really is a shame that we couldn't hold on to some semblance of amplification to allow for this wave to do its thing. Then we would be talking Mid Atlantic winter storm.

 

I was kinda hoping for flurries to a dusting. My expectations are solid. 

[mattie g]

Didn't we play this game last year?

You can't win if you don't play.

[WinterWxLuvr]

Hard not to be interested in this feature. It's only hr 108. No surface reflection other than very light precip but still...this resembles something sneaky. 

 

12zgfs500.JPG

Extrapolating the NAM is unwise, so I've been told, but when I looked at its 84 500 map I thought "this has to lead to something, anything"

[clskinsfan]

I'm with you but this is basically a kick in the nuts. This wave was timed very nicely in the long range using a lot of factors but the PJ and PV are retreating so quickly. It really is a shame that we couldn't hold on to some semblance of amplification to allow for this wave to do its thing. Then we would be talking Mid Atlantic winter storm.

 

This to me is the biggest problem. The PV retreating and keeping all of the cold air locked in Canada. Unless we can get that PV displaced or it weakens considerably we are screwed. But like a lot of you have said, who needs the cold with no precip. The model runs the past couple of days have been extremely dry through day ten for the entire CONUS. Maybe we will get the PV to displace in late Jan to go with some storminess. But who knows at this point. Even me the eternal optimist is not feeling real good about the rest of this winter.

[Wonderdog]

Hard not to be interested in this feature. It's only hr 108. No surface reflection other than very light precip but still...this resembles something sneaky.

https://www.amwx.us/public/style_images/American_Weather/attachicon.gif 12zgfs500.JPG

Bob could you explain what is depicted on this map and why Mid Atlantic storm could develop based on this map alone?

[Ji]

the 12z gfs dosnet seem to be showing what the euro weeklies show

[Bob Chill]

Bob could you explain what is depicted on this map and why Mid Atlantic storm could develop based on this map alone?

 

Wes and Co can probably say it much better than me but I'll throw out some basics. I always look at the 500ht and vort panels before I look at surface/850 stuff because the features in the upper levels are extremely important irt to sensible wx at the surface. 500mb is approx 18k' (5400 meters) up in the atmosphere. It's the atmospheric mass middle ground (not middle distance. Middle mass).

 

We talk about 500 heights a lot because they represent lines of equal pressure @ 500mb. Lower heights are associated with lower pressure and colder air and vice versa. Very broad and general statement though. Best to do some basic reading. 

 

Here's a couple of neat images that give the view from a cross section of the atmosphere and not looking down on the atmosphere and pieces panels together in your mind about what is going on at different levels.

 

 

 

 

 

 

Shortwave troughs (small troughs embedded in the long wave flow) typically have an area of vorticity (spin) at the base. Deeper the trough the bigger the spin. The chart I clipped from the GFS is showing a shortwave trough with an area of spinning air at the base. Way to complicated to explain all the hows and whys surface lows do or don't pop near these areas but for folks like us the whole process of learning starts with simply understanding what the 500, 850, and surface panels are showing at the same time. Then you can start drawing some conclusions. Once you get comfy with those 3 panels you can start digging in deeper with 700mb rh and uvv's , jet structure and stuff like that if you want to. 

 

You'll see me and others post often about crappy and good vort passes. Whenever the 500 vort passes to our n and w it is best to lower expectations. The X on the panels represents the area of highest vorticity or the center of the vort. X passing N&W = bad and X passing to the S&E = Good.

 

A pass to the N&W puts us on the warm air advection side. Never a good thing for us. We want it to pass somewhere below us at all times. We typically only score on the cold side of vorts and upper level lows (closed upper level lows are closed lows @ 500mb). You will see them often referenced as bowling balls. If you see a trough on a 500 panel with a closed contour (circle) at the base of the trough then that is a closed upper level low. 

 

I highly recommend using this guys web page. Great presentation and simple explanations of everything for people who have never taken a met class. 

 

http://www.theweatherprediction.com/

[Bob Chill]

Bluewave made a really good post in the climate change forum. I haven't read through the referenced papers yet but I will over the next couple of days. 

 

The atlantic side of the arctic ice area has been without question much lower than in proportion to the other areas. There's a lot of speculation why including the AMO and stuff like that but I'm not too worried about knowing why it's happening as much as I'm interested in the effects the open ocean is causing on arctic and NH circulation patterns. 

 

Good maps and read here. 

 

http://www.americanwx.com/bb/index.php/topic/38490-less-arctic-sea-ice-and-increased-eurasian-extreme-winter-cold/#entry1961034

[clskinsfan]

Bob. Thanks for the link. That is a great site.

[usedtobe]

Wes and Co can probably say it much better than me but I'll throw out some basics. I always look at the 500ht and vort panels before I look at surface/850 stuff because the features in the upper levels are extremely important irt to sensible wx at the surface. 500mb is approx 18k' (5400 meters) up in the atmosphere. It's the atmospheric mass middle ground (not middle distance. Middle mass).

 

We talk about 500 heights a lot because they represent lines of equal pressure @ 500mb. Lower heights are associated with lower pressure and colder air and vice versa. Very broad and general statement though. Best to do some basic reading. 

 

Here's a couple of neat images that give the view from a cross section of the atmosphere and not looking down on the atmosphere and pieces panels together in your mind about what is going on at different levels.

 

500mb.JPG

 

 

500mb2.JPG

 

 

 

Shortwave troughs (small troughs embedded in the long wave flow) typically have an area of vorticity (spin) at the base. Deeper the trough the bigger the spin. The chart I clipped from the GFS is showing a shortwave trough with an area of spinning air at the base. Way to complicated to explain all the hows and whys surface lows do or don't pop near these areas but for folks like us the whole process of learning starts with simply understanding what the 500, 850, and surface panels are showing at the same time. Then you can start drawing some conclusions. Once you get comfy with those 3 panels you can start digging in deeper with 700mb rh and uvv's , jet structure and stuff like that if you want to. 

 

You'll see me and others post often about crappy and good vort passes. Whenever the 500 vort passes to our n and w it is best to lower expectations. The X on the panels represents the area of highest vorticity or the center of the vort. X passing N&W = bad and X passing to the S&E = Good.

 

A pass to the N&W puts us on the warm air advection side. Never a good thing for us. We want it to pass somewhere below us at all times. We typically only score on the cold side of vorts and upper level lows (closed upper level lows are closed lows @ 500mb). You will see them often referenced as bowling balls. If you see a trough on a 500 panel with a closed contour (circle) at the base of the trough then that is a closed upper level low. 

 

I highly recommend using this guys web page. Great presentation and simple explanations of everything for people who have never taken a met class. 

 

http://www.theweatherprediction.com/

 

Bob, that's a pretty good and simple answer.   How the atmosphere responds to a trough also depends on the systems tilt and neutral and especially negative tilt troughs generally produce stronger upper level divergence than positive tilting shearing troughs.  Also,  it depends on the density of the airmass and where the front is located.  The positive tilt and location of the front so far south are why the models are not doing much with your trough.  If the front was closer to us, it probably would have a nice wave develop for us. The way it stands now, that seems unlikely. 

[Wonderdog]

Wes and Co can probably say it much better than me but I'll throw out some basics. I always look at the 500ht and vort panels before I look at surface/850 stuff because the features in the upper levels are extremely important irt to sensible wx at the surface. 500mb is approx 18k' (5400 meters) up in the atmosphere. It's the atmospheric mass middle ground (not middle distance. Middle mass).

We talk about 500 heights a lot because they represent lines of equal pressure @ 500mb. Lower heights are associated with lower pressure and colder air and vice versa. Very broad and general statement though. Best to do some basic reading.

Here's a couple of neat images that give the view from a cross section of the atmosphere and not looking down on the atmosphere and pieces panels together in your mind about what is going on at different levels.

https://www.amwx.us/public/style_images/American_Weather/attachicon.gif 500mb.JPG

https://www.amwx.us/public/style_images/American_Weather/attachicon.gif 500mb2.JPG

Shortwave troughs (small troughs embedded in the long wave flow) typically have an area of vorticity (spin) at the base. Deeper the trough the bigger the spin. The chart I clipped from the GFS is showing a shortwave trough with an area of spinning air at the base. Way to complicated to explain all the hows and whys surface lows do or don't pop near these areas but for folks like us the whole process of learning starts with simply understanding what the 500, 850, and surface panels are showing at the same time. Then you can start drawing some conclusions. Once you get comfy with those 3 panels you can start digging in deeper with 700mb rh and uvv's , jet structure and stuff like that if you want to.

You'll see me and others post often about crappy and good vort passes. Whenever the 500 vort passes to our n and w it is best to lower expectations. The X on the panels represents the area of highest vorticity or the center of the vort. X passing N&W = bad and X passing to the S&E = Good.

A pass to the N&W puts us on the warm air advection side. Never a good thing for us. We want it to pass somewhere below us at all times. We typically only score on the cold side of vorts and upper level lows (closed upper level lows are closed lows @ 500mb). You will see them often referenced as bowling balls. If you see a trough on a 500 panel with a closed contour (circle) at the base of the trough then that is a closed upper level low.

I highly recommend using this guys web page. Great presentation and simple explanations of everything for people who have never taken a met class.

Bob, thanks for the lesson. I really appreciate it.

http://www.theweatherprediction.com/

[WinterWxLuvr]

Don't laugh, but I don't think we can just dismiss the 78 + hour time frame.  There are hints of possibility.

[stormtracker]

Don't laugh, but I don't think we can just dismiss the 78 + hour time frame.  There are hints of possibility.

 

 

I agree...until Wes comes in and tells us we're fools.    Heavy disclaimer...yes, we all know it's the NAM.   At 84 hours...but the GFS had something similar....it may be flurries, but we are very, very desperate at this time. 

[Deck Pic]

I have no idea why we have a bad PAC....

 

[Ian]

Mentioning the 84 hr nam is almost too bad for the weenie thread.

[FrederickWX]

Smells like desperation in here.  But hey, maybe February will be rocking?

[Ian]

Smells like desperation in here.  But hey, maybe February will be rocking?

 

you got snow.. you arent allowed to complain

[Subtropics]

I agree...until Wes comes in and tells us we're fools.    Heavy disclaimer...yes, we all know it's the NAM.   At 84 hours...but the GFS had something similar....it may be flurries, but we are very, very desperate at this time. 

You know things are bad when the possibility of flurries gets tracked. We are such a southern state.

[FrederickWX]

you got snow.. you arent allowed to complain

 

You had snow... it was just in liquid form. 

 

In all seriousness, no complaints about MBY.  However, I am disappointed for you guys closer to DC that got shut out during this brief window of cold.  The pattern is looking pretty unfavorable the next few weeks, which is why I mentioned February, half joking, half serious.  Maybe we get a window of winter starting the last week of January, and carrying on into February, so you guys can get some snow too.  Hoping.

[WinterWxLuvr]

FWIW, a few of the GFS members get some measurable precip in here at various points during the weekend with 850's cold enough. Also a couple with semi interesting solutions about a week out.

And a week out has been anything but written in stone this year.

[Wonderdog]

Precip in Texas is more impressive at 42 hrs on 0z NAM compared to hour 48 on 18z run.

[mitchnick]

a decent synopsis of the Euro weeklies that came out Monday in case you were on a desert island, and I don't mean East Potomac Park

http://www.accuweather.com/en/weather-blogs/anderson/long-range-forecast-model-update-trends-warmer/3507298

 

 

[usedtobe]

a decent synopsis of the Euro weeklies that came out Monday in case you were on a desert island, and I don't mean East Potomac Park

http://www.accuweather.com/en/weather-blogs/anderson/long-range-forecast-model-update-trends-warmer/3507298

 

Thanks,  I hadn't seen any interpretation of them or them for that matter. 

[EastCoast NPZ]

Not that I think it's in the cards, but on that Accuwx site Frank Strait alluded to the strat warming event now occurring and said the GFS model hinted at the cold outbreak (finally) being on the NA side of the globe, likening the potential outbreak to '85.

[usedtobe]

Not that I think it's in the cards, but on that Accuwx site Frank Strait alluded to the strat warming event now occurring and said the GFS model hinted at the cold outbreak (finally) being on the NA side of the globe, likening the potential outbreak to '85.

 

 

The Berlin site does show a stratospheric warming event but that doesn't mean we automatically end up getting cold even if we get one.  The weakened polar vortex will make it easier to get a negative AO but tat doesn't mean the cold will be aimed at us.  The pattern on the extended shows cross polar flow suggesting that someone in north america will get really cold down the road but right now it looks to be pointed more west and central than east.  

[Ji]

The Berlin site does show a stratospheric warming event but that doesn't mean we automatically end up getting cold even if we get one. The weakened polar vortex will make it easier to get a negative AO but tat doesn't mean the cold will be aimed at us. The pattern on the extended shows cross polar flow suggesting that someone in north america will get really cold down the road but right now it looks to be pointed more west and central than east.

It dosent mean we stay warm either. Models shows central and west getting first then shifting east by jan 20

[nw baltimore wx]

The Berlin site does show a stratospheric warming event but that doesn't mean we automatically end up getting cold even if we get one.  The weakened polar vortex will make it easier to get a negative AO but tat doesn't mean the cold will be aimed at us.  The pattern on the extended shows cross polar flow suggesting that someone in north america will get really cold down the road but right now it looks to be pointed more west and central than east.  

 

As far as snowfall is concerned, wouldn't we rather the be on the eastern or southern edge of any major cold outbreak?  My guess is that wherever the coldest temperatures set up, it would likely be dry.

[Ji]

As far as snowfall is concerned, wouldn't we rather the be on the eastern or southern edge of any major cold outbreak? My guess is that wherever the coldest temperatures set up, it would likely be dry.

Ya we don't need it to be 10. We need it to be 30 with precip

[Bob Chill]

Ya we don't need it to be 10. We need it to be 30 with precip

 

I was just going to post something similar. From mid-Jan to mid-Feb a slightly below normal airmass gets the job done. The real fun with arctic air happens when it invades us behind a big miller A. Snow melting away a couple days after a storm sucks. I think 02-03 was the last time we had a real lasting snowpack. Even 09-10 melted kinda quick considering we got like 10 feet of snow.