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December Mid-Long Range Discussion


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Yea, not great or even good but at least not impossible. Sometimes little storms just sneak up on us. I suppose other than having a weak wave traverse the conus and glide south we could get some sort of trailing energy lagging on a front that passes with one of the cutters. That's another way we could get "something". So far I haven't seen anything indicative of that but that sort of thing generally doesn't appear until d5+/-.

The 264hr gfs threat doesn't even bear watching (not that we should watch fine details in that range anyway). The fact that the storm before and after both track to our west isn't exactly indicative of a good pattern. lol

Not true. Step down pattern. Each wave progressively moves east. A few lakes cutters make the trough then a storm comes up the coast. It has happened many times before.

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Not true. Step down pattern. Each wave progressively moves east. A few lakes cutters make the trough then a storm comes up the coast. It has happened many times before.

what do you make of the CFSV2 model JB tweets about?...the model has quite the snow cover from DC north on three of the four members and snow cover on all of them same region 24 - 29 Dec...is it just snake oil and voodoo.

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what do you make of the CFSV2 model JB tweets about?...the model has quite the snow cover from DC north on three of the four members and snow cover on all of them same region 24 - 29 Dec...is it just snake oil and voodoo.

3 days ago it had the same week warmer than normal. It's really been jumping around and on average I think it has been too cool but that's just my perception from looking at it recently.

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what do you make of the CFSV2 model JB tweets about?...the model has quite the snow cover from DC north on three of the four members and snow cover on all of them same region 24 - 29 Dec...is it just snake oil and voodoo.

that same CFS2 model has this for a DEC temp forecast so take the snow forecast w/a grain of salt

usT2mMonInd1.gif

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It's dec forecast verifying warm is a lock after this next week. As to the longer range, it has really been waffling on its week3 and 4 forecasts. Besides that if you look at the last panel of the GEFS and look at the spaghetti plots, there is little agreement amoung members across our area. I'm not saying there is no chance of a storm and those weeks ending cold but they also may not and to me the pattern still doesn't look that good and the 364 hr look to the ens mean looks worse on the 18Z run than the 12Z not that it matters much out that far.

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Been too busy to really look at guidance but from a quick glance it looks like both the gfs and euro retrograde the pac ridge west (d10ish) and an area of lower heights and associated trough take it's place. A bit convoluted down stream but with a -nao asserting itself we would potentially get some sort of overrunning event with any energy that tracks through the 4 corners area. Would have to think that any type of closed ull or surface low would track west of us. Maybe an open wave can just glide to the south of us. I'm probably reaching here but the pattern doesn't look "impossible".

0Z GFS is trying to show something like this for the 22nd-23rd time frame. Just an open wave overrun event. But its still a bit north. That time frame is looking like there is a possibility of something at least. It will be interesting to see how it evolves on the models.

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For what it is worth, Fantasy land on the GFS ensemble has a decent look to it. Upstream it has strong Aleutian ridging building into western Alaska and a trough in the Gulf of Alaska. It has good placement of ridging in the western US with a trough on the east coast. The NAO is also negative and west based with higher heights reaching toward the northern plains. Looking over the previous day of runs they have also hinted at a similar setup as well. I think if I were to see this type of setup within 5-7 days I would start getting a little excited.

post-1191-0-69652500-1354961210_thumb.gi

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For what it is worth, Fantasy land on the GFS ensemble has a decent look to it. Upstream it has strong Aleutian ridging building into western Alaska and a trough in the Gulf of Alaska. It has good placement of ridging in the western US with a trough on the east coast. The NAO is also negative and west based with higher heights reaching toward the northern plains. Looking over the previous day of runs they have also hinted at a similar setup as well. I think if I were to see this type of setup within 5-7 days I would start getting a little excited.

Aleutian ridging and GOA troughing is the exact opposite of what is the ideal combo to get the E US cold. So, it is hard for me to get excited about cold with that setup. Terrible Pacific!

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Aleutian ridging and GOA troughing is the exact opposite of what is the ideal combo to get the E US cold. So, it is hard for me to get excited about cold with that setup. Terrible Pacific!

I thought the overnight models looked pretty bad. Good news is they probably change back in two or three days. Maybe we can progressively get to better patterns modeled which might eventually lead to an actual better pattern happening.

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Aleutian ridging and GOA troughing is the exact opposite of what is the ideal combo to get the E US cold. So, it is hard for me to get excited about cold with that setup. Terrible Pacific!

But it does suggest more heavy rain for northern California/SFO. To me the ens runs didn't look good with the 240 hr cutter on the euro and I think 06Z gefs. Pretty much what we'e been dealing with. The D+11 still looks bad but at least a number of its analogs based strictly on the 5 day mean pattern were from dec 1978 for what little that is worth (probably nothing except fantasies.

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You would think that a flip to a much better pattern would at least be possible down the road. The PNA index has been negative continuously since about Nov 4 and negative predominantly since about Aug. Thats one impressive stretch. It would seem that it becomes more likely to go pos with each passing day unless it's going to stay neg forever. And with Wes and Bob saying the Dec AO number is often the predictor of the winter AO, maybe the two hook up and give us a better pattern later.

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Earlier I had looked at the D+11 and it was an old version. The new one is not quite as bad. Still horrid in the Pacific but with a neg NAO far enough west to keep our temps near to slightly below normal during the 5 days centered on the mean.

post-70-0-48921800-1354980135_thumb.gif

The strong pacific flow is going to do it's work again beyond the 5 day period as you can see the warmth expand eastward between the composite based on the day of the centered mean.

post-70-0-54909900-1354980259_thumb.gif

and 2 days later

post-70-0-73782800-1354980327_thumb.gif

By 3 days later we are again above normal according to the composites. However, not all the analogs evolved the same as one showed snow at D+4 and another at D+5 a solution that seems unlikely with all the pac air coming east. However by Day 5 the analogs were again colder than normal over our area so this D+11 is a change from the any we've seen earlier this month. There alsowas a one inch event 1 day prior to the centered mean. To me the pattern still looks unlikely to produce any snow before Dec 21 but as Ji like to note, I have been wrong in the past.

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Is it possible that the trough off of the west coast ends up so far out in the Pacific that it pumps up a small ridge in the western US? It almost looks like some of the ens are doing a bit of that.

That's what we need to root for. It might be happening a bit on the ensemble mean in the long range. The ensembles forecast the MJO to move strongly into Phase 1 in the next several days and that should shake things up. Right now, the pattern is almost opposite of what we'd expect in Phase 1 in December, but it starts looking more similar in the long range.

First image is ensemble mean 500mb anomalies at 360hr and second is the mean anomalies for Phase 1 in December. They definitely look similar in our area, and while the Pac is still quite different, it's getting closer with the Aleutian ridge getting beat down a little between the two troughs.

12zgfsensembles500mbHeightAnomalyNH360.gif

DecemberPhase1500mb.gif

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the next 23 days are gone IMO here is to hoping we can get the PAC to relax in mid Jan

IF the CFS is to believed, our winter weather will come in JAN-MAR

interesting to note that it has Europe well below normal tempwise in DEC but it continues to heat Europe in JAN-MAR, which is a good "sign"

whether that "sign" results in anything of substance only time will tell

here's the link to the CFS2 monthlies for Europe http://origin.cpc.nc...euT2me3Mon.html

I guess I should mention that as the CFS2 started warming NA for DEC, it was cooling down Europe, so that's the basis for my optimism

it's certainly possible Europe and NA could be +normal, but relatively speaking to DEC the CFS2 is cooling us for JAN-MAR which is consistent w/an above normal Europe. Here's the NA monthly temp link http://origin.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/htmls/usT2me3Mon.html

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