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December Forecast Discussion


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With the -PNA where do you think the boundary will set up for the storm track? Southern NC or further north?

I have no idea. It depends a lot on how strong the NAO is. I think for now most storms will be rain but I could see one or two small events for the upper south/Mtns with some weak overrunning events. This is by no means a blockbuster type pattern on the ensembles but I really like the NAO and AO staying negative. If we could just get a few +pna spikes watch out!

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12z Euro has block moving west toward Greenland. But the Pacific looks awful. Cold air appears to be heading back over the pole.

What good is a new pattern if it leads to the same crapppy weather as the old pattern?

Europe has greatly benefited from the Greenland blocking while the Pacific has been fighting hard to keep any real arctic air from moving down south of Canada. A very persistent -PDO/-PNA structure has been holding winter back from us quite well and looks to continue for a time..

gFW2D.gif

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Europe has greatly benefited from the Greenland blocking while the Pacific has been fighting hard to keep any real arctic air from moving down south of Canada. A very persistent -PDO/-PNA structure has been holding winter back from us quite well and looks to continue for a time..

gFW2D.gif

If that scenario occurs, then we'll be talking AT LEAST another week or more after 10 days from now before there's even the possibility of winter starting in this part of the world. That's if things play out like the Euro is showing.

I am starting to agree with those who have punted December altogether (not implying that I'm expecting a torch). If in a few days we still the west based -NAO in the 7-15 day frames, not making it under a week consistently, and if we continue to see the -PNA/+EPO repeating, then I'll jump ship on December.

The important thing is that it's only December 6. But equally important is the fact that although the models have been trying to step us in the right direction, they keep coming back to delaying the -NAO while maintaining the -PNA. And I think until we see better evidence and more consistency, then the wisest course is to maintain the expectation of the absence of winter for the foreseeable future.

And if all the cold goes back to the other side of the world, then we can probably tack on another few weeks.

Fortunately, the models have been rather inconsistent, so I expect tomorrow, we will be looking at a different solution.

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I'm not trying to be mean or anything but I just felt like your comment was useless and lacked any substance. Looking at the last few runs of the GFS I would say the NE is probably in play just before the 17th.

They might be...something to watch.

If we are just going to overlook the next 11 days...(taking out 35% of what is left of December)...the title of the thread should probably be renamed to Looking for December Snow Chances. I think its meaningful for people to know how long we may be in the clear for...

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Better to bake on occasion now than to bake near Christmas I guess...better climatology favored for snow anyway...with a chance of below normal temps after a pattern change...will this year feature another white Christmas?

cfs_snow_max_conus_2012120600_81_thumb.png

This map just updated today...just goes to show the lack of snow cover compared to last winter. The snow depth does appear deeper in southern Canada tho...

67612_518482638171619_1431969126_n.png

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Okay, I got a few minutes so here we go GFS Ensemble mean.

240 hours next one block over Greenland the other in the Gulf of Alaska. (no more vortex)

http://raleighwx.ame...nomalyNH240.gif

Roll forward to 300 hours Greenland block retrograding west connection almost there.

http://raleighwx.ame...nomalyNH300.gif

Now out to 384 hours The Greenland block is over eastern Canada (west based -NAO and it's starting to hook up with the block over Alaska. Just in time for the Holidays so Santa can bring us some snow!!!

http://raleighwx.ame...nomalyNH384.gif

Great post man, you should insert the images next time instead of links, I enjoy your posts. Anyway, I especially like your mention of the blocks interacting, it's like what's happening and will continue to happen in Europe as a met mentioned today (not going to mention who, for politics sake). It would be awesome if that came to fruition here for obvious reasons, but seeing it modeled a good start. I don't know a lot about how sustainable that is, or what it's officially called, I just know it will lock in the cold we need in Canada and things would be very interesting for the eastern US. All of the 3 latest runs of the GFS ENS had this interaction as well, now we just have to get the Euro on the table.

dLGej.gif

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Great post man, you should insert the images next time instead of links, I enjoy your posts. Anyway, I especially like your mention of the blocks interacting, it's like what's happening and will continue to happen in Europe as a met mentioned today (not going to mention who, for politics sake). It would be awesome if that came to fruition here for obvious reasons, but seeing it modeled a good start. I don't know a lot about how sustainable that is, or what it's officially called, I just know it will lock in the cold we need in Canada and things would be very interesting for the eastern US. All of the 3 latest runs of the GFS ENS had this interaction as well, now we just have to get the Euro on the table.

dLGej.gif

Are those two height anomilies hooking up what's called a cross polar flow? I hear that alot but I'm trying to figure out what it is. Thanks for everybody's patience as I try to understand what we're all looking at.

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Are those two height anomilies hooking up what's called a cross polar flow? I hear that alot but I'm trying to figure out what it is. Thanks for everybody's patience as I try to understand what we're all looking at.

I know when two PVs ( polar vortex) connect and cross back and forth over the pole it's cross polar flow, I wasn't sure what two + heights not quite crossing the pole was called. Didn't know if the feature had a name.

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It's called how to get cold out west. The ridge over the Bering Sea has to move east to bring above avg heights to AK and the west coast in order for we folk to get the goods.

The talk among some is the block over Greenland to retrograde westward and promote arctic air buildup over SE Canada. While this is a good sign if it comes to pass, we have to cut off the Pacific hose as it has beaten the Greenland block back already. There will be a temp. reprieve in the next week so hopefully we'll get a chance to trend in the right direction.

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It's called how to get cold out west. The ridge over the Bering Sea has to move east to bring above avg heights to AK and the west coast in order for we folk to get the goods.

The talk among some is the block over Greenland to retrograde westward and promote arctic air buildup over SE Canada. While this is a good sign if it comes to pass, we have to cut off the Pacific hose as it has beaten the Greenland block back already. There will be a temp. reprieve in the next week so hopefully we'll get a chance to trend in the right direction.

Yes a +pna is preferred, but we have not had the solid west based nao that was modeled before. it's been more east based. If the pna stays - and the nao backs west then the heights in the east will collapse. Especially if we get the active southern stream storms will be forced under the block I.E overrunning events, and this is what the GFS ensembles are showing along with the CMC and the euro ensemble mean is not as gung ho. By the way check out the 18z gfs op, It tanks the NAO!!

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I doubt it will amount to anything but the GFS leave a little piece of energy behind after swinging the front thru. The CMC is totally different and has a cutter at this time.

http://raleMaighwx.ame...00mbvort144.gif

The 18z GFS kept the Trailing energy post front it also trended a little stronger with it to even throw some moisture into the upper south. Temps were just a little to warm but they were very close at 850 for the mtns. Maybe on future runs something more will pop.
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18z gfs delivers some vodka cold day 10 - 15. If your bored and miss seeing fantasy cold frozen precip opportunities then log into Allan site and enjoy the movie. The conus goes in the deep freeze.

Edit: went back and checked the individual ensemble members 500mb and was very surprised

With the agreement save all but 2members.

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That there would be another ridge up the Bering Strait with a -PNA trough over the west. That is similar to what happened a couple of weeks ago.

Yep, the further south and east one is, the more important that pna be positive.

Dallas, Memphis, Nashville can all get snow with a negative pna but that's about as far south as it can get. Troughs just can't get deep enough unless a cold core vortex closes off and sits in indiana.

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Thanks Jon, I don't like to post maps because it takes a while sometimes to load a page when viewing from a phone. I really hoping the west based Davis Strait -nao comes, if not it's will be Christmas in short sleeves with a few rounds of golf. Would rather have the sleds waxed and the snowpack building. Anyone know where weathernc is? he has been absent of late.

Great post man, you should insert the images next time instead of links, I enjoy your posts. Anyway, I especially like your mention of the blocks interacting, it's like what's happening and will continue to happen in Europe as a met mentioned today (not going to mention who, for politics sake). It would be awesome if that came to fruition here for obvious reasons, but seeing it modeled a good start. I don't know a lot about how sustainable that is, or what it's officially called, I just know it will lock in the cold we need in Canada and things would be very interesting for the eastern US. All of the 3 latest runs of the GFS ENS had this interaction as well, now we just have to get the Euro on the table.

dLGej.gif

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Not surprised there is no post on the 0z Euro -- gorgeous block east of Greenland is wasted by horrible Pacific setup. Bulk of the cold air is retreating back over the pole. If this is accurate, it will be weeks and weeks before we see a significant arctic outbreak (if at all).

I haven't looked yet but if that's true, that's about the second run in a row that's showed a similar scenario. Now, several runs ago, it was showing a much more favorable pattern evolving, which of course didn't pan out. But you know this one will end up being right.

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Just took a quick look myself. Certainly nothing winter to get a postive feeling about. The Pacific is what to watch as it is so strong, its firehose is continuing to beat everything else down.

Hopefully here is just some variability in play right now that will smooth out in winter's favor for the week of December 21st.

If the Pacific beats down the last 2 weeks of December also, then the first half on January is at risk also with 2/3 of good winter down the tubes.

No slant at all towards individuals that work very very hard on seasonal advance outlooks, but long range forecasting still has a very long way to go (if ever can be answered).

Counting on the last 2 weeks of December to deliver!

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Just took a quick look myself. Certainly nothing winter to get a postive feeling about. The Pacific is what to watch as it is so strong, its firehose is continuing to beat everything else down.

Hopefully here is just some variability in play right now that will smooth out in winter's favor for the week of December 21st.

If the Pacific beats down the last 2 weeks of December also, then the first half on January is at risk also with 2/3 of good winter down the tubes.

No slant at all towards individuals that work very very hard on seasonal advance outlooks, but long range forecasting still has a very long way to go (if ever can be answered).

Counting on the last 2 weeks of December to deliver!

I was going to make a long post but I figured it was pointless. Anyways, you should be on the lookout (especially in your neck of the woods more so than mine) for a sneaky event midweek. Might be rain or dry but is has potential. I don't get the whole talk of tossing Dec and then the first two weeks of Jan. Have you been looking at any of the ensembles, or just following the long range Euro op?

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I was going to make a long post but I figured it was pointless. Anyways, you should be on the lookout (especially in your neck of the woods more so than mine) for a sneaky event midweek. Might be rain or dry but is has potential. I don't get the whole talk of tossing Dec and then the first two weeks of Jan. Have you been looking at any of the ensembles, or just following the long range Euro op?

It seems so many are hanging their hat on the Euro Op. How has it been doing as of late?

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Not surprised there is no post on the 0z Euro -- gorgeous block east of Greenland is wasted by horrible Pacific setup. Bulk of the cold air is retreating back over the pole. If this is accurate, it will be weeks and weeks before we see a significant arctic outbreak (if at all).

The Pacific is killing us. It doesn't matter how much better the players on the filed this winter are compared to last winter. If the Pacific is too strong, it doesn't matter. West coast got no love for the East coast.

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It seems so many are hanging their hat on the Euro Op. How has it been doing as of late?

I really can't tell you, I don't follow the op runs very much unless there is a storm on the way. I did look at the Euro op off of Allan's site it's not the death run it was a few days ago. Here is the hour 240, the Pacific is horrible but look, -nao blocking over Greenland and eastern Canada and lower heights over the consensus. That would keep us below normal with chances, with an active southern stream. This is all verbatim, it is a 10 day op prog and I'm sure it's wrong with many features.

http://raleighwx.americanwx.com/models/euro/00zeuro500mbHeightAnomalyNH240.gif

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I really can't tell you, I don't follow the op runs very much unless there is a storm on the way. I did look at the Euro op off of Allan's site it's not the death run it was a few days ago. Here is the hour 240, the Pacific is horrible but look, -nao blocking over Greenland and eastern Canada and lower heights over the consensus. That would keep us below normal with chances, with an active southern stream. This is all verbatim, it is a 10 day op prog and I'm sure it's wrong with many features.

http://raleighwx.ame...nomalyNH240.gif

With the forecasted -NAO and -AO, you would have to feel somewhat confident in winter towards the last ten days of the month. I know the Pacific sucks, but I'm sure we've had winter weather when not every planet is aligned in our favor. I guess that explains more of a step down in temps.

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I was going to make a long post but I figured it was pointless. Anyways, you should be on the lookout (especially in your neck of the woods more so than mine) for a sneaky event midweek. Might be rain or dry but is has potential. I don't get the whole talk of tossing Dec and then the first two weeks of Jan. Have you been looking at any of the ensembles, or just following the long range Euro op?

My comment was directed to last night's operationals.

The ensembles do look more promising. We just need to see some good members deliver to fruition.

Patience will have to prevail until at least the 17th until things can firm up for week of the 21st.

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