The Power of the EPO ridge, something we can all learn from!

[Gibbsfreeenergy]

VAwxman:

Posted 06 December 2007 - 09:44 AM:

Most folks in the eastern half of the nation focus on the NAO as far as geting things cold, and that is obviously a very important piece of the puzzle, but what often gets overlooked is the ability of ridging in the EPO position to just overwhelm the influence of the SE ridge. Take a look at these 500 mb anomalies forecast for Saturday evening.

<img class="bbc_img linked-image" alt="Attached Image: monthly_12_2007/post-717-1196951229.gif">

At first glance, you would likely say, wow, what a warm pattern from the Plains eastward, but think again. Let's look lower at the 850 mb anomalies.

<img class="bbc_img linked-image" alt="Attached Image: monthly_12_2007/post-717-1196951374.gif">

Some impressive cold shown in the Dakotas, but nothing major elsewhere. Take note especially of the anomalies from Kansas City to Chicago... above normal both places. Now lets go to the surface map.

<img class="bbc_img linked-image" alt="Attached Image: monthly_12_2007/post-717-1196951639.gif">

Whoa! Both Kansas City and Chicago are both in the 20s... well below normal... not to mention the 15-20 below normals farther northwest in places like Des Moines and Minneapolis! Even into the Lakes and Northeast, the cold is way more impressive that one would think from the 500 mb anomalies. This is a classic example of how the Pacific pattern can trump the SE ridge in many areas, outside of the immediate Southeast. A strong ridge in the EPO position with a vortex in eastern Canada and a general positive tilt trough back into the Southwest is ideal for this, as it builds very high pressures over Canada, and these highs push low level cold underneath the ridging aloft (northerly flow in the low levels, but southwesterly aloft). So you have to obviously look at much more than the 500 mb pattern, and as always, watch your source regions!

As a side note, this type of pattern screams overrunning with enhance potential of significant ice storms. See Jan-Feb 1994. No this is not going to be that extreme, but the general setup is not far off, though the ice threat is shifted farther north and west with the current pattern since the SE ridge is stronger this time.

Another side note... The cold air often presses farther south than what models initially show, especially in the mid continent, so something to keep in mind also. Fun forecasting ahead!

Now if we can just find the images!

[Ginx snewx]

Please make sure Ryan reads this Shabbs, he thinks I make this s h I t up.

[Gibbsfreeenergy]

Please make sure Ryan reads this Shabbs, he thinks I make this s h I t up.

What did he think you made up?

[Ginx snewx]

How low level cold can slide in despite the SE ridge, despite what 5 H says, great post by Brian, stuck with me.

' This is a classic example of how the Pacific pattern can trump the SE ridge in many areas, outside of the immediate Southeast. A strong ridge in the EPO position with a vortex in eastern Canada and a general positive tilt trough back into the Southwest is ideal for this, as it builds very high pressures over Canada, and these highs push low level cold underneath the ridging aloft (northerly flow in the low levels, but southwesterly aloft). So you have to obviously look at much more than the 500 mb pattern, and as always, watch your source regions!'

[wxmx]

12z GFS is extreme indices. EPO goes to the tank, then soon after the NAO goes to the tank, and finally the PNA rises to new heights. This fantasy run would make this Nov the coldest since probably 1989 for most of the CONUS.

[Gibbsfreeenergy]

Hammer time

[Gibbsfreeenergy]

did anyone save the Vawxman rap?

[VAwxman]

did anyone save the Vawxman rap?

LOL... if you insist.

My, my , my, my...

This trough hits, so hard

Makes me say, Oh my Lord!

Thank you, for blessing me

With a big cold high and dual blocking.

It feels good, when it all comes down,

A strong polar flow from Santa's hometown.

And you know, as such

That this is a trough, uhh, you can't touch!

[CT Rain]

Please make sure Ryan reads this Shabbs, he thinks I make this s h I t up.

lol... you just claim every cold push will have "heavy, heavy low level cold".

[VAwxman]

lol... you just claim every cold push will have "heavy, heavy low level cold".

Now I know who CT Rain is lol.

[buckeye]

12z GFS is extreme indices. EPO goes to the tank, then soon after the NAO goes to the tank, and finally the PNA rises to new heights. This fantasy run would make this Nov the coldest since probably 1989 for most of the CONUS.

probably too little too late for that. We have a seasonal cool down later this week, then a blowtorch into the first half of next week. After that who knows...but i wouldn't bet the farm on the trough setting up shop over the east.

[Gibbsfreeenergy]

LOL... if you insist.

My, my , my, my...

This trough hits, so hard

Makes me say, Oh my Lord!

Thank you, for blessing me

With a big cold high and dual blocking.

It feels good, when it all comes down,

A strong polar flow from Santa's hometown.

And you know, as such

That this is a trough, uhh, you can't touch!

epic win

[wxmx]

probably too little too late for that. We have a seasonal cool down later this week, then a blowtorch into the first half of next week. After that who knows...but i wouldn't bet the farm on the trough setting up shop over the east.

Yep, probably too late for that run... but remember CONUS!=East. Anyway, that was yesterday, and though it's still cold, the latest run is not as cold.

[Ginx snewx]

lol... you just claim every cold push will have "heavy, heavy low level cold".

BS Ryan, thats a blatant spin doctor response.

[Guru Of Reason]

epic win

Yeah. Love it. I would love for there to be a video for this song. The rapper would be wearing a parka.

[Guru Of Reason]

Hammer time