Where we're at, where we're going

[usedtobe]

2 major snowstorms showing up on the 12z GFS for Mid Atlantic

Both beyond 240 hours, I wouldn't put too much stock into them. I suspect that they may be gone by the 18Z run but could always show up again on a later run.

[HM]

Wes, I agree that the time of year and La Niña "touch" to the pattern will certainly find a way to screw the Mid Atlantic; but at the same time, you have to respect the solutions some of the data are spitting out. I don't care what anyone says; if that 50-50/-NAO retrograding block is doing what the GFS says, you better believe there is a heightened risk for a significant event. I would like to see the ECMWF show this pattern and quit burping the "ultimate future" too soon.

[Ji]

Both beyond 240 hours, I wouldn't put too much stock into them. I suspect that they may be gone by the 18Z run but could always show up again on a later run.

http://www.americanw...40-the-pattern/

agreee...but gfs is showing what could happen if this pattern indeed plays out

[CoastalWx]

Wes, I agree that the time of year and La Niña "touch" to the pattern will certainly find a way to screw the Mid Atlantic; but at the same time, you have to respect the solutions some of the data are spitting out. I don't care what anyone says; if that 50-50/-NAO retrograding block is doing what the GFS says, you better believe there is a heightened risk for a significant event. I would like to see the ECMWF show this pattern and quit burping the "ultimate future" too soon.

The 00z EC ensembles weren't quite as bullish with the storm chances like the 12z gfs ensembles were, but I'd say some of the key players are there as well. Both place the nao block almost identically at 300 hrs out. Not bad. I think the signal for something possibly near 12/2...give or take.....has been there for a while.

[HM]

The 00z EC ensembles weren't quite as bullish with the storm chances like the 12z gfs ensembles were, but I'd say some of the key players are there as well. Both place the nao block almost identically at 300 hrs out. Not bad. I think the signal for something possibly near 12/2...give or take.....has been there for a while.

The 12z ECMWF is coming in now, so we'll see if it can get back to the older solutons/GFS. It wouldn't be wise to get "wise" in a winter like this one but I have to respect those classic features that are showing up in the long range. Obviously, all this means nothing if they aren't real. I agree that the first week of December is looking ripe and Dec 2-4 seems to be a period the GFS ensembles are agreeing on a strong -h5 anomaly over the East.

[Ji]

Euro is interesting on Thanksgiving morning.

At IAD its showing temps about 38-39 degrees with 850 temps at around 0 with .43 of qpf. Rain but a cold rain

[tombo82685]

The 12z ECMWF is coming in now, so we'll see if it can get back to the older solutons/GFS. It wouldn't be wise to get "wise" in a winter like this one but I have to respect those classic features that are showing up in the long range. Obviously, all this means nothing if they aren't real. I agree that the first week of December is looking ripe and Dec 2-4 seems to be a period the GFS ensembles are agreeing on a strong -h5 anomaly over the East.

Euro looks like a trainwreck still. Transient shot of cold air. Day 10 though has a nice looks to be west based -nao and a decent pos pna looks like. Only issue is it looks like the ao is severely positive because there is really no cold air in canada at all, well in reguards to what it could be.

[okie333]

Euro looks like a trainwreck still. Transient shot of cold air. Day 10 though has a nice looks to be west based -nao and a decent pos pna looks like. Only issue is it looks like the ao is severely positive because there is really no cold air in canada at all, well in reguards to what it could be.

"No cold air in Canada" would be a severely negative AO, not severely positive.

[tombo82685]

"No cold air in Canada" would be a severely negative AO, not severely positive.

ahh ok sorry bout that, i thought it was the other way around.

[Dr No]

I'm glad I will be in western PA Thurs/Fri. I can see the front getting stretched out around 95 with a wave moving along it. I might luck out this year.

[HM]

The ECMWF simply dislodges the 50-50 low / weakens the PV, while the GFS doesn't. The GFS has a classic, strong PV in a perfect position for an East Coast snow storm. I'm waiting for the euro ensembles...

[usedtobe]

The ECMWF simply dislodges the 50-50 low / weakens the PV, while the GFS doesn't. The GFS has a classic, strong PV in a perfect position for an East Coast snow storm. I'm waiting for the euro ensembles...

Last night's euro esnembles still were on the cold side.

[tombo82685]

The ECMWF simply dislodges the 50-50 low / weakens the PV, while the GFS doesn't. The GFS has a classic, strong PV in a perfect position for an East Coast snow storm. I'm waiting for the euro ensembles...

It looks like it still has the -nao correct?

[usedtobe]

It looks like it still has the -nao correct?

Yes and actually looks interesting at 240 hrs.

[HM]

It looks like it still has the -nao correct?

Indeed but this is a vague term. Let's look at the players:

1. Classic, strong Greenland block.

2. Thanksgiving storm that ultimately forms into a new PV

3. Disturbed Pacific pattern/high frequency wave pattern.

4. Retrograding GOA low toward the Aleutians, but I don't think it becomes a classic Aleutian low. It may revolve around back into Alaska and then come back at a later time. But it is still important for the time period we are interested in which is Nov 25-Dec10.

Now the GFS likes to make points 1 and 2 into your classic retrograding west-based block / 50-50 low set up while the ECMWF says, "not so fast." Both models agree on 3 and 4 and it is why they are having so much trouble. If the PV fails to develop and position correctly and/or the block fails to take full control by retrograding, then the NAO might as well be positive.

A very interesting pattern is about to unfold and certainly not a common one in the last 20 years.

[HM]

Last night's euro esnembles still were on the cold side.

Perhaps that all-too-familiar opEC bias is coming into play here with overdeveloping waves and being too slow exiting the West?

[tombo82685]

Perhaps that all-too-familiar opEC bias is coming into play here with overdeveloping waves and being too slow exiting the West?

coastalwx just said that euro ens are warming leaning more towards the op euro.

[HM]

coastalwx just said that euro ens are warming leaning more towards the op euro.

All that matters is what they do with the 50-50 low. If it is warming because it handles this feature like the ECMWF...okay....if not, then it may appear to be warm from the heights but might not actually be because of the 50-50/CAD. Unfortunately, I haven't looked yet so someone else has to comment on the ensembles.

[wxmx]

It looks like it still has the -nao correct?

Kind of...

[HM]

Yes and actually looks interesting at 240 hrs.

This solution is better than the old solution, I think. I would rather have it warmer/stormier than cold and dry with a terrible placement of a l/wv trough.

[okie333]

Indeed but this is a vague term. Let's look at the players:

1. Classic, strong Greenland block.

2. Thanksgiving storm that ultimately forms into a new PV

3. Disturbed Pacific pattern/high frequency wave pattern.

4. Retrograding GOA low toward the Aleutians, but I don't think it becomes a classic Aleutian low. It may revolve around back into Alaska and then come back at a later time. But it is still important for the time period we are interested in which is Nov 25-Dec10.

Now the GFS likes to make points 1 and 2 into your classic retrograding west-based block / 50-50 low set up while the ECMWF says, "not so fast." Both models agree on 3 and 4 and it is why they are having so much trouble. If the PV fails to develop and position correctly and/or the block fails to take full control by retrograding, then the NAO might as well be positive.

A very interesting pattern is about to unfold and certainly not a common one in the last 20 years.

Wasn't this the same thing that happened last year around the beginning of December?

[HM]

Wasn't this the same thing that happened last year around the beginning of December?

This pattern has come up more since 2007 but over the last 20 years hasn't be common. As far as last year at this time, it was more of a -EPO/NAO combination with the high over exactly where the models are putting a low. Here check it out-->

[okie333]

This pattern has come up more since 2007 but over the last 20 years hasn't be common. As far as last year at this time, it was more of a -EPO/NAO combination with the high over exactly where the models are putting a low. Here check it out-->

Try 10-20 days later in 2009.

[HM]

Try 10-20 days later in 2009.

You're right, it was Dec 10-15 that the PV moved into S-C Canada with a N PAC high and -NAO. The -NAO trumped the Alaskan low.

Hopefully we get the same results as last December!

[HM]

It also makes sense that this has shown up more since 2007 when the -PDO really bottomed out and the +AMO was near peak, then throw in the solar card which has been weak. Thankfully, all this adds up to the rPNA/-NAO happening more frequently than the 1980s, 1990s and 2000-2007. The last time we got a taste of -PDO, the Atlantic/solar factor were far from cooperative, comparably-speaking.

[nzucker]

You're right, it was Dec 10-15 that the PV moved into S-C Canada with a N PAC high and -NAO. The -NAO trumped the Alaskan low.

Hopefully we get the same results as last December!

This looks like a Niño pattern that we're not going to see this winter...the ECM and GFS both agree in placing a huge vortex over AK, whereas this composite from 2009 shows above normal heights in the Beaufort Sea and North Slope area. The Alaskan low last December was a lot weaker than the feature currently showing up on modeling for the post-Thanksgiving pattern.

[CoastalWx]

All that matters is what they do with the 50-50 low. If it is warming because it handles this feature like the ECMWF...okay....if not, then it may appear to be warm from the heights but might not actually be because of the 50-50/CAD. Unfortunately, I haven't looked yet so someone else has to comment on the ensembles.

The ensembles came in a little warmer for the east..it looks like they trended lower with heights out in the GOA and west coast. It does turn this into a late blooming miller-b after looking like an inside runner...probably because the upper level low is so dam strong, and digging. This is for D10-12.

After that, it still looks pretty good and in fact, trended even strong with the west based -nao. It's pretty clear GOA region and eastern Pacific will be the cause for some to start drinking heavily. Sometimes we have to take that extra step that everyone hates to do, when it comes to pattern changes.

[HM]

This looks like a Niño pattern that we're not going to see this winter...the ECM and GFS both agree in placing a huge vortex over AK, whereas this composite from 2009 shows above normal heights in the Beaufort Sea and North Slope area. The Alaskan low last December was a lot weaker than the feature currently showing up on modeling for the post-Thanksgiving pattern.

He can correct me if I'm wrong but I think he was just trying to show that last December also saw this unique pattern. I don't think anyone is thinking the results will be the same.

[HM]

The ensembles came in a little warmer for the east..it looks like they trended lower with heights out in the GOA and west coast. It does turn this into a late blooming miller-b after looking like an inside runner...probably because the upper level low is so dam strong, and digging. This is for D10-12.

After that, it still looks pretty good and in fact, trended even strong with the west based -nao. It's pretty clear GOA region and eastern Pacific will be the cause for some to start drinking heavily. Sometimes we have to take that extra step that everyone hates to do, when it comes to pattern changes.

I am seeing the mean on ecmwf.int but we don't have 192h+ from Allan yet (I like those maps better). But from what I can tell, you're right. The ensemble mean is definitely warmer than last run but also more threatening late in the period. The first week to 10 days of December sure look active, if anything else.

[nzucker]

Do you think the Atlantic blocking is finally going to overcome the poor Pacific to produce a coastal or redeveloping SWFE, HM?

Also, do you feel the NAO is retrograding too far west which is allowing that 50/50 low to move towards the Plains and phase more energy into a potential lakes cutter?