Where we're at, where we're going

[usedtobe]

There are two problems with the pattern right now. One is in the Pacific. The evolving position of the vortex over the Gulf of Alaska with low heights pushing into the Pacific Northwest on the longer ranges makes it hard to get a southern stream system going so most of surface lows are coming across the country far enough north that it is hard to hold the cold air over our region. Also, we don't really have a nice vortex in the Atlantic in the proper position. Note in the the 500h forecasts for the Dec and Feb storms last year. Note the difference in the re areas over the Atlantic, the blocking is farther east and the vortex near nova scotia is weaker this year

http://voices.washingtonpost.com/capitalweathergang/2010/11/why_was_last_year_so_snowy_par_1.html

and compare them with the same type of chart this year.

http://www.meteo.psu.edu/~gadomski/ENSHGTAVGNH_6z/f120.html

Blocking often tries to build back west and that is what the models are trying to do on the longer ranges. However, they have been too aggressive bringing the blocking high westward this winter and during westerly QBO years, the tendency is for a more eastward based negative NAO. Combine that with the LA Nina tendency towards a negative PNA pattern and getting a big snowstorm becomes tougher, not impossible, but tougher than a year like last year.

Or look at the D+10 500h pattern from last night.

[tacoman25]

Where is your winter forecast?

Chuck said he's been too busy to write one up this year. He did include a brief summary of his thoughts for certain periods this winter in the -NAO thread from a couple days ago.

[Damage In Tolland]

Chuck said he's been too busy to write one up this year. He did include a brief summary of his thoughts for certain periods this winter in the -NAO thread from a couple days ago.

In this thread or another one? Do you have the link?

[tacoman25]

In this thread or another one? Do you have the link?

This one.

http://www.americanwx.com/bb/index.php?/topic/2069-big-nao-numbers-in-for-november-2010/

[das]

If the 18z GFS ensembles verify, this could make a run at the most -NAO period on record!

10 Days away, and the ensemble mean is forecasting a >50dm anomaly! I've never seen this before.

From a statistical standpoint, that is a fantastic, unbelievable picture.

[Cheeznado]

The 12Z Euro op has a 582DM contour over most of central Greenland and a small 588 east of there next Wednesday.

Too much of a good thing? Really too bad the Pacific may not cooperate, it is nice to see the cold air but I much prefer snow to go along with it.

Keep an eye on the period beyond the 17th, sometimes a snow for someone along the eastern seaboard develops when the strong -NAO is waning rather then in the heart of the cold air. Until then, the LES and upslope areas will be the winners.

[CoastalWx]

The 12Z Euro op has a 582DM contour over most of central Greenland and a small 588 east of there next Wednesday.

Too much of a good thing? Really too bad the Pacific may not cooperate, it is nice to see the cold air but I much prefer snow to go along with it.

Keep an eye on the period beyond the 17th, sometimes a snow for someone along the eastern seaboard develops when the strong _NAO is waning rather then in the heart of the cold air. Until then, the LES and upslope areas will be the winners.

It's insane, but like you said...sometimes is too much of a good thing. Hopefully it doesn't flip in January, but at this point..having it weaken a little would probably allow more cold into the north tier of the US.

[NJwinter23]

The 12Z Euro op has a 582DM contour over most of central Greenland and a small 588 east of there next Wednesday.

Too much of a good thing? Really too bad the Pacific may not cooperate, it is nice to see the cold air but I much prefer snow to go along with it.

Keep an eye on the period beyond the 17th, sometimes a snow for someone along the eastern seaboard develops when the strong -NAO is waning rather then in the heart of the cold air. Until then, the LES and upslope areas will be the winners.

I was hoping this 12th to 13th event would time very nicely with a spike in the NAO towards neutral...Unfortunately the whole regime is turning too east-based on top of recovering briefly towards neutral

[Amped]

There are two problems with the pattern right now. One is in the Pacific. The evolving position of the vortex over the Gulf of Alaska with low heights pushing into the Pacific Northwest on the longer ranges makes it hard to get a southern stream system going so most of surface lows are coming across the country far enough north that it is hard to hold the cold air over our region. Also, we don't really have a nice vortex in the Atlantic in the proper position. Note in the the 500h forecasts for the Dec and Feb storms last year. Note the difference in the re areas over the Atlantic, the blocking is farther east and the vortex near nova scotia is weaker this year

http://voices.washin...nowy_par_1.html

and compare them with the same type of chart this year.

http://www.meteo.psu.edu/~gadomski/ENSHGTAVGNH_6z/f120.html

Blocking often tries to build back west and that is what the models are trying to do on the longer ranges. However, they have been too aggressive bringing the blocking high westward this winter and during westerly QBO years, the tendency is for a more eastward based negative NAO. Combine that with the LA Nina tendency towards a negative PNA pattern and getting a big snowstorm becomes tougher, not impossible, but tougher than a year like last year.

Or look at the D+10 500h pattern from last night.

This is tru about most Nina Years for the Mid atlantic, Not enough Glaam No STJ, hence storms move S-N not West to East.

In this pattern, the storm will make it's own southeast ridge.

[WhiteoutWX]

This is tru about most Nina Years for the Mid atlantic, Not enough Glaam No STJ, hence storms move S-N not West to East.

In this pattern, the storm will make it's own southeast ridge.

The opposite of it making its own cold air?

[Amped]

The opposite of it making its own cold air?

I'll try explain scientificly about how this happens.

Northern stream short waves over the Great Lakes allow cold air over New England to retreat. and the retrograding pattern allows shortwaves to go negative without gaining very much longitude. As the storm slows down it gives the ridge time to build ahead of it and bump the 50/50 low out of the way, or move it just enough to make room for an inland track.

[gil888]

This looks familiar--another crazy low -AO period, this time stronger than the last one?

[tacoman25]

This looks familiar--another crazy low -AO period, this time stronger than the last one?

So with all this extreme blocking going on so far, have your thoughts changed at all for the winter?

[okie333]

So with all this extreme blocking going on so far, have your thoughts changed at all for the winter?

Not sure about Gil, but my thoughts haven't changed one bit... except I may have been a bit too warm for January (and everyone else may have been way too warm for January).

[okie333]

This looks familiar--another crazy low -AO period, this time stronger than the last one?

Two of the ensemble members go off the chart... you can see one of them going back up a couple of days later. I wonder where that other one is heading...

[nzucker]

Two of the ensemble members go off the chart... you can see one of them going back up a couple of days later. I wonder where that other one is heading...

12z ECM shows a lot of blocking in the LR. Very high heights near the North Pole combined with an hellacious east based -NAO.

[BlizzardWx]

That block is unbelievable in Greenland. Just insane. Too bad its basically been going to waste for many with not much in the way of snow.

[VAwxman]

Absolutely.

It's nice to see an honest response to what's going on. A lot of the people claiming the Nina was going to overpower blocking this winter have been awfully quiet about what's been happening the past couple weeks...

Yeah I try to be a straight shooter. Time constraints with starting a new job have limited my posting for awhile, but I think it is pretty safe to say this blocking is surprising the vast majority of folks. I think Don S. posted a stat about never having a -AO this strong with a nina at -1.00 or colder... pretty astounding stuff, and I sure won't pretend like I have all the answers. It's fun to watch unfold though.

[NJwinter23]

Yeah I try to be a straight shooter. Time constraints with starting a new job have limited my posting for awhile, but I think it is pretty safe to say this blocking is surprising the vast majority of folks. I think Don S. posted a stat about never having a -AO this strong with a nina at -1.00 or colder... pretty astounding stuff, and I sure won't pretend like I have all the answers. It's fun to watch unfold though.

We watched it unfold last year with an established mod/strong nino (though a general -NAO/AO regime if I remember correctly was well signaled/forecasted by many for last winter?), and now it looks like were gonna get to see what happens when we have an established mod/strong nina, at least for the next couple weeks. Very interesting stuff.

[okie333]

Yeah I try to be a straight shooter. Time constraints with starting a new job have limited my posting for awhile, but I think it is pretty safe to say this blocking is surprising the vast majority of folks. I think Don S. posted a stat about never having a -AO this strong with a nina at -1.00 or colder... pretty astounding stuff, and I sure won't pretend like I have all the answers. It's fun to watch unfold though.

I posted a little further back in this thread with links and quotes of some of my past posts. The --AO and west-based ---NAO is definitely not a surprise to me... although current stratospheric developments may bring the -AO to a level I would consider surprising in around a month.

[VAwxman]

I posted a little further back in this thread with links and quotes of some of my past posts. The --AO and west-based ---NAO is definitely not a surprise to me... although current stratospheric developments may bring the -AO to a level I would consider surprising in around a month.

To be fair, you also claimed that the blocking last winter was a surprise, which it wasn't back then.

You also months ago vehemently said this la nina would never form and we'd stay tilted to the el nino side.

My point is not to criticize.. We all have misses. But the main theme is that there are things that have been going on that are very different these days, which has been making long term forecasting more difficult than it already was.

[Snow Wizard]

To be fair, you also claimed that the blocking last winter was a surprise, which it wasn't back then.

You also months ago vehemently said this la nina would never form and we'd stay tilted to the el nino side.

My point is not to criticize.. We all have misses. But the main theme is that there are things that have been going on that are very different these days, which has been making long term forecasting more difficult than it already was.

What are your thoughts about the NW finally getting something worthwhile?

[okie333]

To be fair, you also claimed that the blocking last winter was a surprise, which it wasn't back then.

You also months ago vehemently said this la nina would never form and we'd stay tilted to the el nino side.

My point is not to criticize.. We all have misses. But the main theme is that there are things that have been going on that are very different these days, which has been making long term forecasting more difficult than it already was.

While I busted on the La Niña strength (said it would be neutral or weak Niña, turned out moderate or borderline strong), the La Niña has still not gone west-based as Chuck and others vehemently said it would. However, I made it perfectly clear that the AO/NAO would be the main driver of the winter pattern, not the ENSO. I never claimed that we would remain in an El Niño. Last winter's blocking was unexpected by pure ENSO reasoning since any strong ENSO (whether positive or negative) has a tendency to bring the AO to a positive state. In addition, the SST's did not support a -NAO, as they do this winter. The AO looks to be more prone to negativity this year than last, as very small stratospheric warmings are producing a larger effect than even I would expect. It will be interesting to see what a major SSW could do, if and when one occurs. Lastly, I'll say that the CFS temperature forecast is a joke right now (no surprise; they busted royally on the summer as well); I really don't see any way that December turns out 4-5 degrees F (2-3 degrees C) above average for my area.

[VAwxman]

What are your thoughts about the NW finally getting something worthwhile?

Be on watch toward the last 10 days of the months. There are some hints given the MJO + Asian pattern that we might push the GOA trough inland and build pressures to the north which could give the NW another round of cold. Mind you, confidence level isn't particularly high, but I think that's the next period to watch for. How did you do up there in the November cold outbreak?

[VAwxman]

While I busted on the La Niña strength (said it would be neutral or weak Niña, turned out moderate or borderline strong), the La Niña has still not gone west-based as Chuck and others vehemently said it would. However, I made it perfectly clear that the AO/NAO would be the main driver of the winter pattern, not the ENSO. I never claimed that we would remain in an El Niño. Last winter's blocking was unexpected by pure ENSO reasoning since any strong ENSO (whether positive or negative) has a tendency to bring the AO to a positive state. In addition, the SST's did not support a -NAO, as they do this winter. The AO looks to be more prone to negativity this year than last, as very small stratospheric warmings are producing a larger effect than even I would expect. It will be interesting to see what a major SSW could do, if and when one occurs. Lastly, I'll say that the CFS temperature forecast is a joke right now (no surprise; they busted royally on the summer as well); I really don't see any way that December turns out 4-5 degrees F (2-3 degrees C) above average for my area.

The bolded part is good. I recall you saying something different about ENSO, but whatever, the fact that you pointed more to the AO is working for now... not taking that away from you.

You could not be more wrong about last winter. Almost every factor pointed to blocking, from the orientation of ENSO, to stratosphere, to QBO, to snowcover, and on and on. Extratropical SSTs do not and have not explained the NAO state on seasonal time scales. Long term, sure they can add some impact, and if strong enough, play a small role on the seasonal time scale, but in no way should someone use those as a basis for a seasonal forecast since the atmosphere is going to do the dictating.

[Snow Wizard]

Be on watch toward the last 10 days of the months. There are some hints given the MJO + Asian pattern that we might push the GOA trough inland and build pressures to the north which could give the NW another round of cold. Mind you, confidence level isn't particularly high, but I think that's the next period to watch for. How did you do up there in the November cold outbreak?

For once I was in one of the better areas. I live about 30 miles SE of Seattle and had 6 inches of snow and a low of 8 degrees. Amazingly it was already down to 11 by 9pm on one day and then the clouds moved in a few hours later. Could have gotten near zero if it had stayed clear.

[Yes_Probably_Maybe_No]

Looks like the -NAO goes bye bye in early Jan. Anyone have any ENSO/GWO/MJO ideas that blowtorch us for January?

[tacoman25]

What are your thoughts about the NW finally getting something worthwhile?

You just had a historic Arctic outbreak and snowstorm a couple weeks ago!

[Snow Wizard]

You just had a historic Arctic outbreak and snowstorm a couple weeks ago!

That was then and this is now.

[tacoman25]

That was then and this is now.

Ok...but your post made it seem like the PNW has been waiting up until now for something good to happen. Spokane saw their snowiest November ever, and Seattle/Portland saw their third greatest Nov Arctic outbreak on record.

I think January is your time to really shine again.