The Winter 2010-11 NYC/PHL Medium Range Thread

[Analog96]

People see what they want to see and say what they want to say. Fact of the matter is the cold is exactly on time, Turkey Day. Not only that, people need to put down these NAO charts and LOOK at the 500 mb maps. A 550 block over greenland extending into the Davis Strait is a west based block, I don't need a computer to tell me that and its not east based.

Sometimes I wonder if we are too obsessed with figuring out a pattern instead of just seeing and reacting. Turkey Day and beyond most def. has the look of a west based NAO with either a split flow or possible western ridging with plenty of vortexes in the pipe line. That is good news with -10 850's hanging around a nice snow pack building over Southern Canada.

To add to that, it also seems like the Atlantic has continued to dominate this blocky pattern, which should be good news as we go into winter- another good reason NOT to just base seasonal forecasts entirely off ENSO.

[phlwx]

And it's going to be warm on Sunday, right? When NYC doesn't make 45 degrees. The GFS has been very consistent in advertising that Turkey Day is when the real cold gets here, and it actually has gotten colder (there are also a couple snow threats this run, but temps are easier to predict at that range). What I don't understand is why people think the cold is gettting pushed back, because it's not cold NOW? It was never supposed to be. The cold air and pattern change is perfectly on track!

If anything, it screams more to the temp swings we're going to see. Saturday was supposed to be cold a week ago...now it's going to be seasonal if not mild south of Philly. Remember the GFS late last week was humping this upcoming cold shot as 3-4 days...now it's a day at best before we moderate Saturday before a one day reversal Sunday (doubtful we get to 45 on Sunday...probably will be a nudge warmer, IMHO).

[Guest Kramer]

To add to that, it also seems like the Atlantic has continued to dominate this blocky pattern, which should be good news as we go into winter- another good reason NOT to just base seasonal forecasts entirely off ENSO.

oh, totally agree! Look at how blocky our pattern has been without a true -NAO, east or west. I am sure I will get slammed for this, but I buy the GFS' look over the ECM right now, it has been far more consistent in showing the strong block around Turkey day and it makes sense given our MJO progression and the history of the NAO over the past year +.

[Analog96]

oh, totally agree! Look at how blocky our pattern has been without a true -NAO, east or west. I am sure I will get slammed for this, but I buy the GFS' look over the ECM right now, it has been far more consistent in showing the strong block around Turkey day and it makes sense given our MJO progression and the history of the NAO over the past year +.

The GFS has actually been better so far this fall.

[earthlight]

Here's another graphical look at the favorable pattern the GFS develops in the extended. As NZucker mentioned, the Pacific pretty much breaks down by the time the Atlantic and polar areas become more favorable. That being said, we have gotten some snow historically in these types of ENSO events despite poor Pacific setups. The pattern as advertised on the GFS extended range does offer some hope...but it would definitely be threading the needle should we get any major snowfall in that setup.

[Guest Noreaster]

Here's another graphical look at the favorable pattern the GFS develops in the extended. As NZucker mentioned, the Pacific pretty much breaks down by the time the Atlantic and polar areas become more favorable. That being said, we have gotten some snow historically in these types of ENSO events despite poor Pacific setups. The pattern as advertised on the GFS extended range does offer some hope...but it would definitely be threading the needle should we get any major snowfall in that setup.

300 hour plots aren't worth very much, but the NAO being favorable better than a thread the needle situation. If you have the atlantic on your side then you at least are in the game. Having a favorable pac, favorable atlantic, and favorable pole situation is hard to do, so you gotta take what you have and go with it. Split flow can change this all.

[Analog96]

Here's another graphical look at the favorable pattern the GFS develops in the extended. As NZucker mentioned, the Pacific pretty much breaks down by the time the Atlantic and polar areas become more favorable. That being said, we have gotten some snow historically in these types of ENSO events despite poor Pacific setups. The pattern as advertised on the GFS extended range does offer some hope...but it would definitely be threading the needle should we get any major snowfall in that setup.

Isn't it always threading the needle in November?

[Guest Kramer]

The GFS has actually been better so far this fall.

really? that is good news! I haven't taken look at the model statistics

[Weathergun]

With the dominance of the Pacific on the pattern we might be able to coax a solid week but I don't think we're going to get a "locked" pattern that lasts 2-3 wks even though modeling is more favorable...last week was modeling a solid shot from this weekend on and that has melted down to a one day cold shot before we're back at/above average on Saturday. The average on the whole will probably be slightly below average but I don't foresee weeks of uninterrupted cold compared to average.

It'll be a fun ride this winter though -- lots of variety in the cards.

The models and ensembles never really showed a 500mb pattern that locked cold air in the East for the 20th. They still had PV up Northern Canada and the -NAO block wasn't mature enough. After thanksgiving, the current guidance bring PV down to the SE Canada and develop and mature and west based based -NAO block develops.

There are some signs on the ensembles that the cross-polar flow relaxes over the CONUS a bit the week after Thanksgiving. But Alletuian/Siberia ridge begins building back up again by day 10 and we see more cold air buid up in Alaska and NW Canada along with west -NAO still in place. So I right think we see temp return to normal or slightly above between 11/30-12/3. And then another major cold shot around 12/4-12/6.

[Guest Noreaster]

Isn't it always threading the needle in November?

LOL. Getting snow is always difficult, if it were easy, we would all average 100 inches. Wish we could retire the term thread the needle.

[Analog96]

LOL. Getting snow is always difficult, if it were easy, we would all average 100 inches. Wish we could retire the term thread the needle.

It's not nearly as difficult in February, this isn't RIC. In Feb, things don't have to be quite perfect. But in November, they do.

[Guest Noreaster]

It's not nearly as difficult in February, this isn't RIC. In Feb, things don't have to be quite perfect. But in November, they do.

agreed. Even still, this is a pretty decent pattern we are approaching.

[am19psu]

really? that is good news! I haven't taken look at the model statistics

D8

D10

[Weathergun]

Here's another graphical look at the favorable pattern the GFS develops in the extended. As NZucker mentioned, the Pacific pretty much breaks down by the time the Atlantic and polar areas become more favorable. That being said, we have gotten some snow historically in these types of ENSO events despite poor Pacific setups. The pattern as advertised on the GFS extended range does offer some hope...but it would definitely be threading the needle should we get any major snowfall in that setup.

I think the Pacific pattern would HAVE to break down at some point get a cold air pattern over the Atlantic side. And the Alleutian/Siberian ridge starts returning at the end there. So I'm not really worried about it.

[Rainshadow]

Since the GFS was upgraded this summer, the skill gap between the Euro and GFS has narrowed. Interesting test coming up around Thanksgiving between the Euro and GFS as to how the cold air seeps east and how precip is impacted.

[Guest Kramer]

Since the GFS was upgraded this summer, the skill gap between the Euro and GFS has narrowed. Interesting test coming up around Thanksgiving between the Euro and GFS as to how the cold air seeps east and how precip is impacted.

It will all come down to to who handles the NAO the best. If the GFS is right and the block gets truly west based and then some, then congratulations to the GFS.

If EUROPEAN is correct and its merely East based, then SW flow from hell here it comes.

[SnowGoose69]

It will all come down to to who handles the NAO the best. If the GFS is right and the block gets truly west based and then some, then congratulations to the GFS.

If EUROPEAN is correct and its merely East based, then SW flow from hell here it comes.

Again its all coming down to the NAO....the GFS continues to be overly aggressive in putting the trough too far east in the long range beyond Day 10 or so but if the NAO is negative the East will have a chance for cold and snow in December....I still don't think we're going to see any sort of sustained eastern trough with this La Nina even with a raging -NAO, but we could get a 93-94 type setup or December 08 regime like we saw around the 3rd week where the gradient setup was far enough south for NYC to be cold and have a chance for snow....but odds are though even if we get a very strong west based Davis Strait block going we're still going to see the mean trough positioned west of the Mississippi.

[jm1220]

Again its all coming down to the NAO....the GFS continues to be overly aggressive in putting the trough too far east in the long range beyond Day 10 or so but if the NAO is negative the East will have a chance for cold and snow in December....I still don't think we're going to see any sort of sustained eastern trough with this La Nina even with a raging -NAO, but we could get a 93-94 type setup or December 08 regime like we saw around the 3rd week where the gradient setup was far enough south for NYC to be cold and have a chance for snow....but odds are though even if we get a very strong west based Davis Strait block going we're still going to see the mean trough positioned west of the Mississippi.

It's not a terrible thing if we're far enough north. Setups like that are definitely overrunning and latitude based, but the block being far enough SW could save us from lousy changeover scenarios while Boston cashes in. The SST profile in the Atlantic right now definitely argues for a favorable NAO once in a while. The question is how horrible the PAC jet will be in trying to blast it away.

[Guest Kramer]

Again its all coming down to the NAO....the GFS continues to be overly aggressive in putting the trough too far east in the long range beyond Day 10 or so but if the NAO is negative the East will have a chance for cold and snow in December....I still don't think we're going to see any sort of sustained eastern trough with this La Nina even with a raging -NAO, but we could get a 93-94 type setup or December 08 regime like we saw around the 3rd week where the gradient setup was far enough south for NYC to be cold and have a chance for snow....but odds are though even if we get a very strong west based Davis Strait block going we're still going to see the mean trough positioned west of the Mississippi.

maybe, maybe not. The big question will be is the trough positioned so that the waves of LP still go under us? I think a big key here is that if Greenland over to central canada are blocked up and we can sustain a cross polar cold air feed, we may be seeing a bunch of over running events that are pretty much all frozen even with a crappy PAC. If nothing wraps up too much, that could be a good equation.

[phlwx]

Again its all coming down to the NAO....the GFS continues to be overly aggressive in putting the trough too far east in the long range beyond Day 10 or so but if the NAO is negative the East will have a chance for cold and snow in December....I still don't think we're going to see any sort of sustained eastern trough with this La Nina even with a raging -NAO, but we could get a 93-94 type setup or December 08 regime like we saw around the 3rd week where the gradient setup was far enough south for NYC to be cold and have a chance for snow....but odds are though even if we get a very strong west based Davis Strait block going we're still going to see the mean trough positioned west of the Mississippi.

Very good post.

One of things people are riding is Nina climo where December = cold. Doesn't always work that way in strong Nina events...January and February can be plenty cold and December can be volatile but mild.

We could see some pretty wild swings in temp over the next 2-3 weeks. Fun times ahead.

[nzucker]

I think the Pacific pattern would HAVE to break down at some point get a cold air pattern over the Atlantic side. And the Alleutian/Siberian ridge starts returning at the end there. So I'm not really worried about it.

Huh? You can have a -EPO/+PNA in conjunction with the -NAO. We don't want the Pacific to break down as the Atlantic is becoming favorable because the pattern limits cold air moving into Canada.

Also, an Aleutian ridge is not a good thing for NYC metro. It just guarantees that the trough will be in the West (-PNA). That's why we're getting screwed right now with above average temperatures. You want the blocking ridge to be farther east over Alaska or the Yukon.

[Allsnow]

Huh? You can have a -EPO/+PNA in conjunction with the -NAO. We don't want the Pacific to break down as the Atlantic is becoming favorable because the pattern limits cold air moving into Canada.

Also, an Aleutian ridge is not a good thing for NYC metro. It just guarantees that the trough will be in the West (-PNA). That's why we're getting screwed right now with above average temperatures. You want the blocking ridge to be farther east over Alaska or the Yukon.

Better now...then later........nate. I could care less about snow in november...

[tombo82685]

12z euro has huge west based nao and pos pna. Polar vortex dropped down from santa claus land and is about 300 miles north of north dakota.

[SnowGoose69]

12z euro has huge west based nao and pos pna. Polar vortex dropped down from santa claus land and is about 300 miles north of north dakota.

There have been some Euro ensemble members the last several days that have shown a 1976 like setup with the NW territory and Davis Strait blocks nearly merging to force the PV very close to the lower 48 but I'll believe it when I see it, that has not happened much the last 25 years despite it being depicted numerous times in the medium-long range.

[tombo82685]

There have been some Euro ensemble members the last several days that have shown a 1976 like setup with the NW territory and Davis Strait blocks nearly merging to force the PV very close to the lower 48 but I'll believe it when I see it, that has not happened much the last 25 years despite it being depicted numerous times in the medium-long range.

thats almost what it has. The block extends from greenland to almost the nw territories of canada. Im not sure how long that pattern would last on the euro though. Day 10 shows a GOA low moving in days 11-15 which chopping down the pos pna. The se ridge is still pretty prevalent. It wedges in between the polar vortex in south central canada, and a 50/50 low

[phlwx]

thats almost what it has. The block extends from greenland to almost the nw territories of canada. Im not sure how long that pattern would last on the euro though. Day 10 shows a GOA low moving in days 11-15 which chopping down the pos pna. The se ridge is still pretty prevalent. It wedges in between the polar vortex in south central canada, and a 50/50 low

Congrats Winnipeg?

Interesting to see the 850 line barely budge south of Philadelphia after day 8.

[tombo82685]

Congrats Winnipeg?

Interesting to see the 850 line barely budge south of Philadelphia after day 8.

yea the se ridge is here to stay

[Guest Noreaster]

yea the se ridge is here to stay

LOL. Models are having trouble resolving a little impulse at hour 54, you are worried about day 8?

[Analog96]

yea the se ridge is here to stay

That much SE Ridge, and no more, is a good thing in the heart of winter.

[tombo82685]

LOL. Models are having trouble resolving a little impulse at hour 54, you are worried about day 8?

Then don't read this thread. Im pretty sure the topic reads day 7 and beyond discussion...