00z Dec 8 Model Guidance

[tombo82685]

There wouldn't be much arctic air in the pattern; as you say, the cold air is being cut off from Canada and you can see that the cross-polar flow is occurring from the PV in Siberia towards Europe. All of the models are showing the PV currently over Canada retreating rapidly next week with a serious blocking ridge setting up over most of Canada. There'd be some low level cold air underneath the strong high pressure, so it's not quite as warm as it looks at 850mb, but still not the real arctic stuff. I'd think a lot of the CONUS would stay below average in temperatures though due to the high pressing southward and the low-level cold. Here is a good shot of the cross-polar flow being cut from the 12z ECM:

then why do we want a -ao so much? Granted it does force the colder air south towards us, but it rids canada of the cold air.To me a perfect pattern would be one in which the ao toggles back and forth between - and+

[Thunder Road]

497 thickness Tuesday... brrrr!

Imagine if we got a Clipper in that - 35:1 ratios!

[Voyager]

108

120

132

Forgive me if I'm wrong, but that looks to be a bit farther west than the 18z ensemble mean.

[isnice]

How is it possible that a model's ensembles differ so much from its OP less than 120 hours out?

[Chris L]

then why do we want a -ao so much? Granted it does force the colder air south towards us, but it rids canada of the cold air.To me a perfect pattern would be one in which the ao toggles back and forth between - and+

Tom, I think you would agree the perfect pattern would be last winter when we had a STJ and historic -AO, to keep us just cold ENOUGH for snow.

[EasternUSWX]

Forgive me if I'm wrong, but that looks to be a bit farther west than the 18z ensemble mean.

It's basically the same. Further SE early a bit west later.

[isnice]

Forgive me if I'm wrong, but that looks to be a bit farther west than the 18z ensemble mean.

You're right. I'm just pointing out the fact that the ensembles say "what cutter?" and take it up the coast. The op is definitely correct, it just sounds like the ensembles need a tune-up.

[Isotherm]

then why do we want a -ao so much? Granted it does force the colder air south towards us, but it rids canada of the cold air.To me a perfect pattern would be one in which the ao toggles back and forth between - and+

Last winter featured a severely -AO and although, yes, there wasn't much arctic air on the map, it was still plenty cold. In addition, the pattern is more favorable for east coast snows w/ a -AO. Abovve normal temps in Canada mean below normal down here for the most part. A +AO is conducive to severe cold in Canada, but what good does that do us if there's no mechanism to transport it into the Northeast?

[tombo82685]

Tom, I think you would agree the perfect pattern would be last winter when we had a STJ and historic -AO, to keep us just cold ENOUGH for snow.

yea, that most definitely would be. I just don't like how the block becomes so strong canada is left with stale, albeit cold air.....btw for people reading this im doing the euro in the gen forum thread...

[tombo82685]

Last winter featured a severely -AO and although, yes, there wasn't much arctic air on the map, it was still plenty cold. In addition, the pattern is more favorable for east coast snows w/ a -AO. Abovve normal temps in Canada mean below normal down here for the most part. A +AO is conducive to severe cold in Canada, but what good does that do us if there's no mechanism to transport it into the Northeast?

very true, but after a while you most definitely would want it to go back to positive to reload on the arctic air, then have it go negative again so it can come south.

[NJwinter23]

I'm not sure the MJO has been/will be much of a help in terms of forecasting this winter. It's been in phase 4 recently, and forecast to move into P5-6 which teleconnects to a warm CONUS and positive NAO. But obviously that has not been the case. We've gotten the -NAO/-AO and cold US without favorable MJO forcing. The position of the GOA low and the orientation of the NAO block are the big keys in this pattern IMO.

I believe there is a lag effect on the pattern like 1-2 weeks upon entering a different phase. With that said though, the current model preditions for the coming week to 10 days at least do not look like phase 4-5-6 across the conus.

[Isotherm]

very true, but after a while you most definitely would want it to go back to positive to reload on the arctic air, then have it go negative again so it can come south.

I'd agree with that. Which is partially why an autumn +NAO/AO is a good thing for winter prospects of a blocking.

[tombo82685]

I believe there is a lag effect on the pattern like 1-2 weeks upon entering a different phase. With that said though, the current model preditions for the coming week to 10 days at least do not look like phase 4-5-6 across the conus.

correct me if im wrong, but split the square in half everything to the right is not favorable, everything to the left is favorable for us?

[Chris L]

I'd agree with that. Which is partially why an autumn +NAO/AO is a good thing for winter prospects of a blocking.

Yes, but then its tough to get it established later on to a + to -NAO, right?

[isnice]

I believe there is a lag effect on the pattern like 1-2 weeks upon entering a different phase. With that said though, the current model preditions for the coming week to 10 days at least do not look like phase 4-5-6 across the conus.

It isn't much of a forecast then is it? It's more like some sort of measure of progression.

[Yorkpa25]

I've always been a follower, first time posting, tombo you said you are posting the 0z euro in the gen thread? Which thread is that?

[Analog96]

Last winter featured a severely -AO and although, yes, there wasn't much arctic air on the map, it was still plenty cold. In addition, the pattern is more favorable for east coast snows w/ a -AO. Abovve normal temps in Canada mean below normal down here for the most part. A +AO is conducive to severe cold in Canada, but what good does that do us if there's no mechanism to transport it into the Northeast?

I can't consider last year a classic winter, however, because IMO, every "classic" winter needs to have one true Arctic outbreak.

[soadforecaster]

I can't consider last year a classic winter, however, because IMO, every "classic" winter needs to have one true Arctic outbreak.

i agree with you on that, there were historic storms, but there wasnt any artic outbreaks

[tombo82685]

I've always been a follower, first time posting, tombo you said you are posting the 0z euro in the gen thread? Which thread is that?

just click the gen forums button then wx forecasting and discussion on the top of the page...here http://www.americanwx.com/bb/index.php?/forum/20-weather-forecasting-and-discussion/

[Yorkpa25]

Okay, thank you

[SnowGoose69]

I can't consider last year a classic winter, however, because IMO, every "classic" winter needs to have one true Arctic outbreak.

Last winter was a whisker away from being 97-98, but on average surface temps and mid level temps during those storms were 5-10 degrees cooler this time around...remember 97-98 had a raging negative AO and perfect storm tracks all winter but no snow because of lack of cold air...last winter was oh so close to that again but since it went so extreme the other way nobody really noticed it.

[tombo82685]

Last winter was a whisker away from being 97-98, but on average surface temps and mid level temps during those storms were 5-10 degrees cooler this time around...remember 97-98 had a raging negative AO and perfect storm tracks all winter but no snow because of lack of cold air...last winter was oh so close to that again but since it went so extreme the other way nobody really noticed it.

if i remember correctly, the day time temps were below normal, but what killed us and really skewed the monthy temperature avgs were the night time lows which were warm.

[nzucker]

then why do we want a -ao so much? Granted it does force the colder air south towards us, but it rids canada of the cold air.To me a perfect pattern would be one in which the ao toggles back and forth between - and+

A -AO doesn't necessarily mean Canada is warm. For example, if you had a block over Alaska extending towards the North Pole and a block over Greenland, Canada would be bitterly cold with the PV sitting over Hudson Bay in all probability. This would promote lots of arctic air over the Canadian Prairies and down into Ontario/Quebec. It's really a question of where the PV sets up when it is displaced by high-latitude block. In the case of next week, the PV is retreating to Siberia and setting up strong cross-polar flow into Europe, but not on the North American side.

[SnowGoose69]

For those bummed by this Nina, DT just posted on SV the MEI for November rose from -1.91 to -1.60...it may not be a guarantee the Nina is dying but its a possibility.

[Edge Weather]

Surprised no one is talking about it. Shows possibly a couple of inches on Monday into NYC. Maybe a little more than that in Northern NJ.

[Ericjcrash]

Surprised no one is talking about it. Shows possibly a couple of inches on Monday into NYC. Maybe a little more than that in Northern NJ.

me too, GFS east DGEX east

[SnowGoose69]

Surprised no one is talking about it. Shows possibly a couple of inches on Monday into NYC. Maybe a little more than that in Northern NJ.

It may show that but its not legit....yet....the surface low has to pass east of NYC for there to really be any chance of wraparound snows...a track that passes either to the west, directly over, or even slightly east is usually going to result in too much of a downslope component to any precip trying to wraparound the low....both off the Poconos and the higher terrain of NJ and even the initiation of the bands as they attempt to wrap westerly over the Catskills. In addition there is going to have to be a due north or NNW motion to the low center...many of the models indicate this would be the case as the trough takes on a negative tilt...we still need about a 50-100 mile shift east from what the UKMET and GFS show and alot more from what the Euro has....the Euro's 00Z track does a bit too much mountain tracking as I complained the GFS was doing before its last run which was more logical, I do think the Euro comes east of the mountains at 12Z.

[CooL]

dgex was interesting, the primary doesnt get passed Tenn, and then fiddles out. Allowing a coastal hugging secondary to ride up the coast with decent wrap around snows it looks like. If the dgex/gfs/euro trend 50-100 miles more to the east, then we can talk big city snow.