Medium-long range thread

[phlwx]

I just went through the "normal" Octobers with weak/mdt ninas and then looked at temps for the ensuing Novembers. Only 1 of 12 were "warm" in PHL.

2008-9 btw fell in the normal third.

My guess would be '99 as the 'warm' one.

[snowlurker]

Just going off of weenie Wundermap (God, I love that site), the GFS shows a Southern Slider OTS on Friday that completely misses the Mid Atlantic, a Lakes Fizzler on the 9th, and a large, elongated area of SW->NE oriented low pressure that sweeps across the Eastern half of the nation on the 15th-18th+. It appears that the exit of the last event might sweep in a shot of cold. Until then, it appears that the GFS wants to keep us dry and seasonal.

But...that's the Third Place GFS. I only have 180 hours out on the Euro and don't have access to the Ukie.

[snowlurker]

as others have stated i dont see a porlonged shot of cold till mid month or better shot around t giving. The gfs and euro are starting to show some hints of a -nao building in at the end of the periods on some of the runs. The mjo, looks to be a in a favorable phase in about a couple weekes as it goes from phase 2-3 back to 7-8. The ao looks to push negative at the end of the 4 day period also. Given models usually try to rush things i think around the t giving timeframe is when we start looking for sustained cold. We need a big lake cutter to jump start a -nao

I remember from many discussions here and elsewhere that a move of the MJO to phases 7/8 is good for wet (whether liquid or frozen) weather for us, but I don't remember if there's a time lag between a jump to a 7/8 MJO and wet sensible weather or if the two coincide.

Anyone want to educate us?

[NaoPos]

Just going off of weenie Wundermap (God, I love that site), the GFS shows a Southern Slider OTS on Friday that completely misses the Mid Atlantic, a Lakes Fizzler on the 9th, and a large, elongated area of SW->NE oriented low pressure that sweeps across the Eastern half of the nation on the 15th-18th+. It appears that the exit of the last event might sweep in a shot of cold. Until then, it appears that the GFS wants to keep us dry and seasonal.

But...that's the Third Place GFS. I only have 180 hours out on the Euro and don't have access to the Ukie.

With a pretty -PNA and no upstream blocking, expect above seasonal to seasonal weather. Don't even have to look at the models till about mid month. SE ridge taking over 2/3rds November.

[snowlurker]

Maybe the thread subtitle can be changed. I hardly doubt we'll see any more tropical action this year...

[Feb]

http://www.meteo.psu...z/mrfloop2.html

Yes i'm a weenie but the 18z gfs at 384 hours looks delicious.

[tombo82685]

The gfs and euro continue to show a colder pattern change towards the mid and late november. Both the 12z gfs and euro ens show a strong indication for blockiness to develop and sending a cold air mass down western canada into the mid west. As i said previusly we need to route for a strong cutter to jump start the -na0. This is exactly what the 12z gfs is doing which sends a strong low into the lakes which pumps a ton of mild air up into greend land and baffin island. The 12z gfs ensembles are not as forth going in developing this pattern as majority show a +pos to neutral nao, while the operational is a full blown -nao

At hr 240 on the euro you can see some of the higher hgts starting to work towards greenland area, while cross polar flow comes pouring onto our side of the globe into western canada. One thing i would like to see, that would really help getting things cold is a +pna, which none of the models show right now. This all coming about the same time the mjo is heading towards the 7/8 phase, though some ensemble guidance takes it into the circle of death while others push it into phase 1.

12z gfs hr 264

324

384

euro ens hr 240

[phlwx]

^Given modeling is sometimes too quick with pattern changes, I'd time the change for around Thanksgiving weekend give or take a couple of days.

[am19psu]

I remember from many discussions here and elsewhere that a move of the MJO to phases 7/8 is good for wet (whether liquid or frozen) weather for us, but I don't remember if there's a time lag between a jump to a 7/8 MJO and wet sensible weather or if the two coincide.

Anyone want to educate us?

It depends on the wavelengths. If the heart of winter, P8 is great for developing a trough in the East, setting the stage for potential Nor'easters.

But right now, with the wavelengths still a bit longer, P8 is mostly blah.

Here is a link to RaleighWx's H5/MJO correlations by month: http://raleighwx.americanwx.com/MJO.html

With a pretty -PNA and no upstream blocking, expect above seasonal to seasonal weather. Don't even have to look at the models till about mid month. SE ridge taking over 2/3rds November.

Yep

[snowlurker]

It depends on the wavelengths. If the heart of winter, P8 is great for developing a trough in the East, setting the stage for potential Nor'easters.

But right now, with the wavelengths still a bit longer, P8 is mostly blah.

Here is a link to RaleighWx's H5/MJO correlations by month: http://raleighwx.ame...wx.com/MJO.html

Yep

Thanks for the information. I assume that the wavelength varies with the time of the year - I had thermodynamics, physics, and chemistry last century but still don't have a handle on the different types of waves mentioned in meteorological discussions). BTW, that's a sweet page that RaleighWx put out.

[am19psu]

Thanks for the information. I assume that the wavelength varies with the time of the year - I had thermodynamics, physics, and chemistry last century but still don't have a handle on the different types of waves mentioned in meteorological discussions). BTW, that's a sweet page that RaleighWx put out.

Yes, the wavelengths of mid-latitude planetary Rossby waves are dependent on the total hemispheric baroclinicity (IOW, the pole-to-equator temperature gradient). In summer, when the pole-to-equator temperature gradient is weak, wavelengths are longer, and vice versa.

[phlwx]

the cold shot that the GFS was hyping up for the 20th on is muting a bit in the last couple of runs. Cold centers in Plains and Rockies.

[easternsnowman]

the cold shot that the GFS was hyping up for the 20th on is muting a bit in the last couple of runs. Cold centers in Plains and Rockies.

Gfs 15 days out.....enough said.

[phlwx]

Gfs 15 days out.....enough said.

naw...I thought it was supposed to be taken as gospel, especially the 18z runs.

FWIW, 0z's run last night does bring the cold shot in around the 20th....quick hitter for a couple of days before bouncing out around Turkey Day.

Probably gets delayed a few more days and hits over Turkey Day weekend.

Until then, generally dry through mid month (even Thursday's showers look pretty uneventful)...maybe some rain around 16th.

[tombo82685]

the euro ens and op continue to build a solid -nao towards the end of the period...still looks like around t giving for pattern change.,

[NaoPos]

the euro ens and op continue to build a solid -nao towards the end of the period...still looks like around t giving for pattern change.,

on the op its a weird set up. nice blocking going on @ the davis straights, but a split PV in BC Canada opens the pacific flood gates..

[Feb]

JB said all the signs point toward a very wintry period Northern Plains and East coast Thanksgiving through Christmas.

[tombo82685]

12z euro shows huge arctic outbreak coming into the midwest and pushing east at the end of the period. Sub 504 thicknesses in northern mn...Has -nao but not classic one into the bering straights, its more east based than west based...though the pna looks like its about to swing to positive with thr trof moving into the center of the country

[Rainshadow]

the cold shot that the GFS was hyping up for the 20th on is muting a bit in the last couple of runs. Cold centers in Plains and Rockies.

As long as the MJO has legs an overall colder pattern should be arriving just before Thanksgiving.

[phlwx]

12z euro shows huge arctic outbreak coming into the midwest and pushing east at the end of the period. Sub 504 thicknesses in northern mn...Has -nao but not classic one into the bering straights, its more east based than west based...though the pna looks like its about to swing to positive with thr trof moving into the center of the country

0z does not show this and keeps the cold shot locked in Canada.

[easternsnowman]

0z does not show this and keeps the cold shot locked in Canada.

It's the 0z euro...just wait it will change again!

[Rib]

I think we are seeing what our at least early December pattern will look like with the trough in the plains and a strong se ridge. It's typical.

[NaoPos]

I think we are seeing what our at least early December pattern will look like with the trough in the plains and a strong se ridge. It's typical.

Just went over some of the models and Ensembles from last night. The pacific pattern is ugly. Its allowing that SE ridge to just rebuild after everytime it's bout to get squashed. Trough after troubling diving out west.

I'm thinking the cold doesn't come after thanksgiving like myself and others were thinking. It's gonna be delayed till mid december at least. La Nina driven type pattern in the meantime.

(this is no means a winter cancel)

[tombo82685]

Just went over some of the models and Ensembles from last night. The pacific pattern is ugly. Its allowing that SE ridge to just rebuild after everytime it's bout to get squashed. Trough after troubling diving out west.

I'm thinking the cold doesn't come after thanksgiving like myself and others were thinking. It's gonna be delayed till mid december at least. La Nina driven type pattern in the meantime.

(this is no means a winter cancel)

la nina driven patterns are always cold in december though, and warmer in jan and esp feb.

[am19psu]

Don't forget about the MJO guys

[VAwxman]

Don't forget about the MJO guys

It's interesting, as I could use the MJO and the rapid snowcover buildup to say that models might be missing some cold, and they have in fact trended "colder" for next week (in quotes since it still isn't all that cold), and the day 7-9 progs show a nice Bering Sea high anomaly and some NAO assistance, albeit not nearly as good as last year. Makes me wonder if we escape so easily and warm so strongly in the 11-15 day. That said, the Eurasian wave train is almost opposite of what it needs to be in order to maintain the Bering high, which is probably why models kill the good NPAC setup.

[am19psu]

It's interesting, as I could use the MJO and the rapid snowcover buildup to say that models might be missing some cold, and they have in fact trended "colder" for next week (in quotes since it still isn't all that cold), and the day 7-9 progs show a nice Bering Sea high anomaly and some NAO assistance, albeit not nearly as good as last year. Makes me wonder if we escape so easily and warm so strongly in the 11-15 day. That said, the Eurasian wave train is almost opposite of what it needs to be in order to maintain the Bering high, which is probably why models kill the good NPAC setup.

Nice to have you back, Brian. Feel free to pop in here whenever.

I was talking more about post-Thanksgiving. I don't see a chance for sustained cold until we get the MJO back around to the IO around that time.

[Rainshadow]

It's interesting, as I could use the MJO and the rapid snowcover buildup to say that models might be missing some cold, and they have in fact trended "colder" for next week (in quotes since it still isn't all that cold), and the day 7-9 progs show a nice Bering Sea high anomaly and some NAO assistance, albeit not nearly as good as last year. Makes me wonder if we escape so easily and warm so strongly in the 11-15 day. That said, the Eurasian wave train is almost opposite of what it needs to be in order to maintain the Bering high, which is probably why models kill the good NPAC setup.

Brian,

Its nice to have you back.

[VAwxman]

Nice to have you back, Brian. Feel free to pop in here whenever.

I was talking more about post-Thanksgiving. I don't see a chance for sustained cold until we get the MJO back around to the IO around that time.

Gotcha. That's what I get for jumping in after a long hiatus and not reading enough lol.

Seems post T-day is the more likely time for anything notable. I worry the forecast could still trend a little colder in the day 8-15 time frame compared to some of the forecasts out there, but it's not "noteworthy" cold by any means yet. More just removing some of the strong warmth and adding a little variability. Long term, hard not to like the buildup of cold in western Canada. While it doesn't have to invade the U.S, I'd be surprised if we don't hear from it at some point as we roll toward early Dec.

[CoastalWx]

Gotcha. That's what I get for jumping in after a long hiatus and not reading enough lol.

Seems post T-day is the more likely time for anything notable. I worry the forecast could still trend a little colder in the day 8-15 time frame compared to some of the forecasts out there, but it's not "noteworthy" cold by any means yet. More just removing some of the strong warmth and adding a little variability. Long term, hard not to like the buildup of cold in western Canada. While it doesn't have to invade the U.S, I'd be surprised if we don't hear from it at some point as we roll toward early Dec.

It's doing what it should this time of year....laying the foundation down to help refrigerate the airmass.

I'm on the post T-day train as well, but looks like we may get a transient shot or two of some cold. I did notice the trend in some of the runs to bring the first wave of cold in the 18-20th timeframe.