The Winter 2010-11 NYC/PHL Medium Range Thread

[Rainshadow]

The Aleutian High pattern can be GREAT with a -NAO...while the brunt of the cold is still to the west, you certainly get more of the cold than you normally would, and the -NAO would help to squash the SE ridge...that would lead to a GREAT gradient pattern, and we'd be off to the races!!

The only problem is that if you don't get the -NAO, it could be an ugly pattern.

What I've noticed is that the modeling day 7 to 10 deterministic forecasts seem to verify better in the Pacific than the Atlantic and this becomes the rub with -NAO. The Euro has a tendency to love these Greenland ridges which doesn't make the beyond day 7 outlooks too easy. Overall it could be worse for cold.

[usedtobe]

What I've noticed is that the modeling day 7 to 10 deterministic forecasts seem to verify better in the Pacific than the Atlantic and this becomes the rub with -NAO. The Euro has a tendency to love these Greenland ridges which doesn't make the beyond day 7 outlooks too easy. Overall it could be worse for cold.

Tony,

I posted something on the impact of the NAO versus negative PNA on U.S. temps during November. The Pacific tends to rule even with a negative NAO. That's certainly what the D+10 euro and GFS is saying. When you get into winter, the impact of a NAO is larger.

[Rainshadow]

Tony,

I posted something on the impact of the NAO versus negative PNA on U.S. temps during November. The Pacific tends to rule even with a negative NAO. That's certainly what the D+10 euro and GFS is saying. When you get into winter, the impact of a NAO is larger.

Wes,

Your point is well taken if the nao usually switches signs from Oct to the winter and Oct and the winter temps are better correlated, then the nao can't be the dominate feature in the autumn.

I missed the one stop (thread page) shopping days of Eastern. Then again I'm always behind the times. I'm still waiting to apply to my space.

At anyrate it does look just based on the s.d. that the biggest uncertainty (least confidence) beyond day 7 is between us and Greenland.

[tombo82685]

Wes,

Your point is well taken if the nao usually switches signs from Oct to the winter and Oct and the winter temps are better correlated, then the nao can't be the dominate feature in the autumn.

I missed the one stop (thread page) shopping days of Eastern. Then again I'm always behind the times. I'm still waiting to apply to my space.

At anyrate it does look just based on the s.d. that the biggest uncertainty (least confidence) beyond day 7 is between us and Greenland.

you need a facebook account, i believe mike has one but he hates me and wont confirm me as a friend.

[tombo82685]

Tony,

I posted something on the impact of the NAO versus negative PNA on U.S. temps during November. The Pacific tends to rule even with a negative NAO. That's certainly what the D+10 euro and GFS is saying. When you get into winter, the impact of a NAO is larger.

wes, is this a true -nao though? It seems more east based then anything. The heights are centered mainly over greenland, not towards baffin island. East based -nao usually don't do much for us, so it would make sense that the -pna would override that. I wonder what it would look like if we had a strong west based block combine that with -pna, which would win.

[Rainshadow]

you need a facebook account, i believe mike has one but he hates me and wont confirm me as a friend.

Facebook, I'm still trying to sell my typewriter on e-bay.

I'm not Wes even on my best day so that said the whole pattern for our area strikes me as eh, it could be worse.

[Analog96]

Tony,

I posted something on the impact of the NAO versus negative PNA on U.S. temps during November. The Pacific tends to rule even with a negative NAO. That's certainly what the D+10 euro and GFS is saying. When you get into winter, the impact of a NAO is larger.

I believe we had a -NAO/-PNA combo in the winter of 1993-94, which is why it took until after Christmas to get the real cold going,

[Isotherm]

I believe we had a -NAO/-PNA combo in the winter of 1993-94, which is why it took until after Christmas to get the real cold going,

Actually it was the opposite, a +NAO/+PNA winter. Great looking Pacific, terrible Atlantic, but a favorable PV placement near Hudson Bay which kept surface cold locked in across the nern tier.

[Rainshadow]

Actually it was the opposite, a +NAO/+PNA winter. Great looking Pacific, terrible Atlantic, but a favorable PV placement near Hudson Bay which kept surface cold locked in across the nern tier.

We also a tremendously deep snow pack over Eastern Canada. November 1993 had the second greatest geographic NH snow and ice extent on record since 1973.

[tombo82685]

this is way out in la la time, but this is a ture -nao west based block

[Guest PDIIREDUX]

this is way out in la la time, but this is a ture -nao west based block

actually that block is just getting to be west based and it still more east than west. When the highest heights are right over greenland into the davis straits (strait block) now you are talking west based. There is also a feedback mechanism with the PV and the block. The block, in theory, will continue to move west as the PV spins into the 50/50 position.

[phlwx]

this is way out in la la time, but this is a ture -nao west based block

the "cold" is just 15 days away... lol

Unfortunately it looks like the much talked about weekend cold shot is becoming much more transient...I thought we would have seen things drop off a bit sooner rather than later...instead it's going to be about average through Turkey Day with the cold dumping into the Midwest instead. "Might" go colder for the holiday weekend but we've seen this game before in the day 15 range with cold shots that end up transient.

Canada, at least, looks cold...should help build some snowpack in the Great White North.

[Guest PDIIREDUX]

the "cold" is just 15 days away... lol

Unfortunately it looks like the much talked about weekend cold shot is becoming much more transient...I thought we would have seen things drop off a bit sooner rather than later...instead it's going to be about average through Turkey Day with the cold dumping into the Midwest instead. "Might" go colder for the holiday weekend but we've seen this game before in the day 15 range with cold shots that end up transient.

Canada, at least, looks cold...should help build some snowpack in the Great White North.

patience, its only November. The ridiculous calls for Thanksgiving and end of November snow were a pipe dream. It will be a gradual process and come December when it is supposed to snow it will.

[Rainshadow]

the "cold" is just 15 days away... lol

Unfortunately it looks like the much talked about weekend cold shot is becoming much more transient...I thought we would have seen things drop off a bit sooner rather than later...instead it's going to be about average through Turkey Day with the cold dumping into the Midwest instead. "Might" go colder for the holiday weekend but we've seen this game before in the day 15 range with cold shots that end up transient.

Canada, at least, looks cold...should help build some snowpack in the Great White North.

Looks like we're going to be close to the battleground area after this week. The -EPO is going to deliver the cold air into NOAM then forecast to fade/retrograde which leaves us with the positioning of the -NAO as to how blocked the cold air will be from leaving. The MJO is cycling toward colder anomalies for us. The -PNA forecasts also point to the SE ridge being a player, all looks like a problem with "the angle of the cold" and a rollercoaster ride in the model runs and temperatures in general.

[CoastalWx]

Looks like we're going to be close to the battleground area after this week. The -EPO is going to deliver the cold air into NOAM then forecast to fade/retrograde which leaves us with the positioning of the -NAO as to how blocked the cold air will be from leaving. The MJO is cycling toward colder anomalies for us. The -PNA forecasts also point to the SE ridge being a player, all looks like a problem with "the angle of the cold" and a rollercoaster ride in the model runs and temperatures in general.

It's going to be interesting to see how you guys fair down there. Like you said, I think you guys will be in the "battle ground". The euro ensembles post D10 still have a pretty massive -nao, but lower heights out west will probably help flax the se ridge now and then. Even so, it does show east coast troughing with colder air getting down towards the MA during the last week of November. We'll see how it goes.

[earthlight]

The strength of this Aleutian Ridge is just ridiculous

[Dsnowx53]

^^

The strength of that ridge is pretty much equivalent to that god-send -NAO block we had last winter. What's with these years and hugely historic +500mb anomalies?

I also hope the Euro isn't overdoing the strength of its -NAO block down the road...New England should definitely be fine in the pattern post-Thanksgiving, but if the block is too east-based, we will be right in the transition zone and may deal with some painfully close changeovers.

[Dsnowx53]

Also, the better the Pacific looks, the easier it is to get away with an "easty" block. I'm glad the timing of this seems to have been delayed to around Thanksgiving, seeing as the Atlantic doesn't have a great influence in November, anyway.

Sometimes when you get a -NAO block that's so strong, it can actually help the Pacific Pattern look a bit better because of how much it can slow down the flow and buckle it. Maybe December is a bit too early for a -NAO block to do that kind of thing, but I'm still not in love with what I see from the Pacific. I do see some improvements with the Pacific post-Thanksgiving, but I don't think we're going to have a great Pacific pattern. Hopefully, it's good enough with this block that the models seem so insistent on having.

[jm1220]

Also, the better the Pacific looks, the easier it is to get away with an "easty" block. I'm glad the timing of this seems to have been delayed to around Thanksgiving, seeing as the Atlantic doesn't have a great influence in November, anyway.

Sometimes when you get a -NAO block that's so strong, it can actually help the Pacific Pattern look a bit better because of how much it can slow down the flow and buckle it. Maybe December is a bit too early for a -NAO block to do that kind of thing, but I'm still not in love with what I see from the Pacific. I do see some improvements with the Pacific post-Thanksgiving, but I don't think we're going to have a great Pacific pattern. Hopefully, it's good enough with this block that the models seem so insistent on having.

The Pacific does have more of an effect, simply based on the fact that our weather moves from west to east. The NAO can offer a stop to an overly aggressive Pacific dominated regime, but during a Nina it's hard to imagine the roaring Pacific jet not taking over eventually. It's probably going to be more of a battle than in past recent Nina years, given the excellent SST configuration for -NAOs, and the recent history of -NAO. Hopefully that can at least salvage December. I can see it going crazily back and forth around here and us having some interesting R/S battles. Whenever -NAOs are around, hopefully they can at least force any cutters to redevelop and give us a shot at something.

[phlwx]

If the 12z GFS is right and that lobe drops down the West Coast around hr 180 it's going to kick up a pretty decent storm for the Midwest next Tuesday-Wednesday. Could be pretty epic if everything breaks right.

[tombo82685]

12z euro doesnt look to great in the long term either. Granted a huge east based -nao, but the pacific is blah. We start with a -pna then when that kicks out, it seems like the pacific jet is just blasting right in the western US

[Nikolai]

12z euro doesnt look to great in the long term either. Granted a huge east based -nao, but the pacific is blah. We start with a -pna then when that kicks out, it seems like the pacific jet is just blasting right in the western US

Since when was a block directly over Greenland an East-based -NAO?!? I don't know where people have gotten this idea, but from what I've always read it is very clearly west-based... east-based is over Iceland or Scandinavia.

And yes, the 12z EURO is rather tragic given we're wasting such an amazing block... and we have an abysmal SE ridge. Hopefully it doesn't verify.

[tombo82685]

Since when was a block directly over Greenland an East-based -NAO?!? I don't know where people have gotten this idea, but from what I've always read it is very clearly west-based... east-based is over Iceland or Scandinavia.

And yes, the 12z EURO is rather tragic given we're wasting such an amazing block... and we have an abysmal SE ridge. Hopefully it doesn't verify.

i always assumed a true west based -nao is one that has the center of its heights or close to it near baffin island...

[Weathergun]

12z/14 Ensemble Mean starts to form a true -west based NAO block at day 10. The stronger heights begin shifting over Baffin Island and the PV enlongated SE over Hudson Bay. The SE ridge gets crushed faster and it begins turning colder over again over the Northeast and Mid-Atlantic the day before Thanskgiving.

[Rainshadow]

12z euro doesnt look to great in the long term either. Granted a huge east based -nao, but the pacific is blah. We start with a -pna then when that kicks out, it seems like the pacific jet is just blasting right in the western US

Today's 12z OP GFS/Euro run was almost a textbook example of what Wes posted about the Pacific trumping the Atlantic in November.

[tombo82685]

Today's 12z OP GFS/Euro run was almost a textbook example of what Wes posted about the Pacific trumping the Atlantic in November.

tony where do you need the higher then normal heights centered to be considered a west based block? I have heard some say back towards baffin island, others say greenland...

[ORH_wxman]

tony where do you need the higher then normal heights centered to be considered a west based block? I have heard some say back towards baffin island, others say greenland...

You want the core of the highest height anomalies to be over Davis Straight/Baffin Island and even back toward Hudson Bay region for a west based block. If you look at the image posted above, you can see the core of the high anomalies are E of Greenland with a closed off contour out toward Iceland. That's definitely a more east based -NAO.

[earthlight]

Medium range guidance definitely is trending towards a more east based -NAO, which just isn't going to cut it in this pattern. The huge ridge over the Aleutians has insane height anomaly departures on almost all ensembles. That thing means business and the -PNA is going to really take control with the huge trough on the west coast. The result will likely be a building Southeast Ridge..and the -NAO, although east based, is the only reason why we wouldn't torch in that setup. Hopefully we can get some better luck in the longwave pattern by the time December starts.

[nzucker]

Medium range guidance definitely is trending towards a more east based -NAO, which just isn't going to cut it in this pattern. The huge ridge over the Aleutians has insane height anomaly departures on almost all ensembles. That thing means business and the -PNA is going to really take control with the huge trough on the west coast. The result will likely be a building Southeast Ridge..and the -NAO, although east based, is the only reason why we wouldn't torch in that setup. Hopefully we can get some better luck in the longwave pattern by the time December starts.

Yes, exactly...the Aleutian ridge is not bleeding far enough east to give us the classic -EPO; it's instead forming a strong -PNA pattern that causes high heights to develop in the East. Earlier model runs had shown the block becoming more permanent and eventually encompassing all of Alaska, but that doesn't seem likely to happen anymore as the GoA low comes back in the long range and all the cold air gets trapped behind that system. Meanwhile, the arrival of the GoA low means that the PV is redeveloping over Siberia, causing Canada to lose all of its bitter cold anomalies. The -NAO is too east based to fight the SE ridge, which is dominant by default in a strong Niña. This worries me as the Niña looks set to intensify more in coming weeks with AAM going very negative and trade winds across most of the ENSO regions.

[mattinpa]

Medium range guidance definitely is trending towards a more east based -NAO, which just isn't going to cut it in this pattern. The huge ridge over the Aleutians has insane height anomaly departures on almost all ensembles. That thing means business and the -PNA is going to really take control with the huge trough on the west coast. The result will likely be a building Southeast Ridge..and the -NAO, although east based, is the only reason why we wouldn't torch in that setup. Hopefully we can get some better luck in the longwave pattern by the time December starts.

Hi, earthlight - Pacific still doesn't look great in the long range on the 00z GFS, but it looks colder. In fact, around hr. 240 it looks close to snow. Is this due to a west-based -NAO?