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A change to a wintry pattern emerging after November?


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The models have been hinting at an emerging pattern change for the end of November and into December for the past few days.

One feature that the models all agree on is the Aleutian ridge this is currently building and looks to remain in place for at least the next couple of weeks, some models have this forming a cut-off block, pushing its way poleward and splitting the upper-level PV.

Additionally, the NAO looks to return to its negative phase in the next few days, perhaps locking in for a while IF the PV displacement produced by the AK block establishes a new PV over E Canada as the GGEM and GFS are forecasting at D+10: The ECMWF has been waffling the past couple of days on it's end-of-run solutions. While yesterday's 12z run produced a strong cutoff AK block, today's 0z took it out entirely and only has the Aleutian ridge remaining in place.

Should this AK block cutoff and push its way to the NP and a -NAO redevelops, the possibility of our first real surge of arctic air pushing down to our region greatly increases.

6z GFS @ 240hrs:

jhzUf.gif

0z GGEM @ 240hrs:

ap0gD.gif

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The models have been hinting at an emerging pattern change for the end of November and into December for the past few days.

One feature that the models all agree on is the Aleutian ridge this is currently building and looks to remain in place for at least the next couple of weeks, some models have this forming a cut-off block, pushing its way poleward and splitting the upper-level PV.

Additionally, the NAO looks to return to its negative phase in the next few days, perhaps locking in for a while IF the PV displacement produced by the AK block establishes a new PV over E Canada as the GGEM and GFS are forecasting at D+10:

6z GFS @ 240hrs:

0z GGEM @ 240hrs:

I sure hope goofy is correct ;) Dr. No isn't sure this will happen, but does show the possibility. Interesting times as we head into met winter and I'm looking forward to the first real threat of some winter precip for the se crew.

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I sure hope goofy is correct wink.png Dr. No isn't sure this will happen, but does show the possibility. Interesting times as we head into met winter and I'm looking forward to the first real threat of some winter precip for the se crew.

I just added a revision to mention the waffling the ECMWF has done for the past few runs. The Euro ensemble, however, do maintain a strong Aleutian block and -NAO, along with a mean trough over the East...

3SJbc.gif

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Wow, nice to get some weather posts from you. I know you must bust your butt on the tech & business ends of the site but, I enjoy your thoughts when you do post them. As has been stated in the other threads.....That we are at least seeing potential even if it is med. range is a big win over last winter already! Looking forward to the evolution of this in the coming days.

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I just added a revision to mention the waffling the ECMWF has done for the past few runs. The Euro ensemble, however, do maintain a strong Aleutian block and -NAO, along with a mean trough over the East...

The EC continues to want to hold back the energy from the west, but it's known for doing things like this. It certainly has my interest :lol: It would be nice to track the possibility.....it's been a long time ;)

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I will call it a toss up where the arctic ball will drop. We are still 10 days out but the thing to take away from it right now is the presence of a significant blocking episode taking place. Either way it is looking good. If it does hang back west it will eventually head east as long as the blocks in place hold - that is, holding the AO/NAO negative.

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While the operational models are still figuring out where to drop the PV as it moves southward near the end of the month, the ensembles still maintain a mean trough over the east, the block over the bering sea, and ridge extending into Greenland.

12z Euro ENS at 240 hrs:

oApgi.gif

12z GEFS @ 240 hrs:

mC5I5.gif

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The 18z GFS pops a +PNA ridge and hooks up with the AK block. Of course, beyond 240 it deflects a huge emerging Greenland block and breaks it all down but if the Greenland block does form and force the PV Down to SE Canada then December will be (dare I say) rockin'.

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While the operational models are still figuring out where to drop the PV as it moves southward near the end of the month, the ensembles still maintain a mean trough over the east, the block over the bering sea, and ridge extending into Greenland.

12z Euro ENS at 240 hrs:

oApgi.gif

12z GEFS @ 240 hrs:

mC5I5.gif

Lovely cross polar flow.

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So many times we end up with a sideswipe hit and run, in the early days of winter.... it would be nice to see a full on attack into the deep south. Climo down here, it usually seems. speaks against a full assult, but there is always the odd winter out smile.png T

December 2000 comes to mind. It got cold early and stayed that way until after new years. I had snow on the ground at least half of the month and it snowed new years eve at 16 degrees. It looked like powdered sugar.

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The 18z GFS pops a +PNA ridge and hooks up with the AK block. Of course, beyond 240 it deflects a huge emerging Greenland block and breaks it all down but if the Greenland block does form and force the PV Down to SE Canada then December will be (dare I say) rockin'.

Looking at 18z it looked like it really wanted to pop something out of the GOM but then just goes fizzle and turns into a really weak front. Either way I think it's safe to say someone on the EC is probably going to get something the first week of December.

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Looking at 18z it looked like it really wanted to pop something out of the GOM but then just goes fizzle and turns into a really weak front. Either way I think it's safe to say someone on the EC is probably going to get something the first week of December.

Models might be having a hard time with the potential setup. Looks like around day ten things will start to get interesting. Maybe around Thanksgiving we'll have something to track. For right now each new model run may/will show dramatic differences (..more than normal); like today's 12z GFS compared to GFS 18z.

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Looking at 18z it looked like it really wanted to pop something out of the GOM but then just goes fizzle and turns into a really weak front. Either way I think it's safe to say someone on the EC is probably going to get something the first week of December.

I haven't even started looking at individual shortwaves yet. Step 1 will be sniffing out the new pattern which lies ahead. If the elements we need to obtain a favorable winter pattern does emerge then once we are within the 5 to 6 day window we can look at what storms may be of interest to us.

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