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December Mid-Long Range Discussion


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What Bob said. There was a ~24hr period a few days ago when the modeling all looked quite good. That was preceeded by several days of generally warm-looking runs, and that was preceeded by when we still thought December would be really cold. The warm-look model runs have been winning.

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I was messing around with my various data lists looking at the -ao / -pna combo. I was trying to find a enso neutral year with a similar pac ridge that seems all but imminent now and I came across 1961. It's not a perfect fit but compare the h5 anom map for the first half of Dec 1961 to the progs on the gfs and euro. Definitely similar in some important ways:

Dec 1961 was pretty warm along the ec during the first half of the month. A lot of the + departures were erased because the pattern flipped nicely during the second half:

You can never find perfect matches but the first half of 61 has some distinct similarities to the progged pattern. 1961 was on my -ao list and had a Dec monthly of -1.668. PNA came in at -1.24 for the month.

From everything I've been reading from met posts is that this Dec prob won't flip but I don't think we can simply rule it out at this point. Especially late in the month.

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Bob, 11/61 had 3.2" and 12/61 had 7.2" at BWI

hmmmm, I don't think those 60's analogs work very well, and I mean any of them because of the change in everything

Just an exercise in pattern recognition. I don't like the 60's too much either.

1961 and 1996 both featured the relatively unusual combo of a -ao/nao/pna. 61 seemed to have the best match in the pac so it a decent comparison. .

Just because I'm bored and there is nothing to chase I put together an animation of Dec 61. Kinda weird evolution because it's in six 5 day panels but the general idea is there.

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Just an exercise in pattern recognition. I don't like the 60's too much either.

1961 and 1996 both featured the relatively unusual combo of a -ao/nao/pna. 61 seemed to have the best match in the pac so it a decent comparison. .

Just because I'm bored and there is nothing to chase I put together an animation of Dec 61. Kinda weird evolution because it's in six 5 day panels but the general idea is there.

Bob can you link me to the site that allows you to plot that map? The link I have only allows me to do back to 1980

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Bob can you link me to the site that allows you to plot that map? The link I have only allows me to do back to 1980

No prob:

http://www.esrl.noaa...composites/day/

Be careful though. This site is a SERIOUS time suck. lol

There are a bunch of free gif animators online so if you plot a time series that you like you can easily put it in motion without having to learn anything complicated.

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No prob:

http://www.esrl.noaa...composites/day/

Be careful though. This site is a SERIOUS time suck. lol

There are a bunch of free gif animators online so if you plot a time series that you like you can easily put it in motion without having to learn anything complicated.

Bob, thanks.

I plotted this year Nov. 15 to Dec. 3, then used the CPC analogs of 1966 and 1970 to plot those Nov. 15 to Dec. 15 and then the corresponding Dec. 15 to Feb 15. Both years switched to a colder pattern. They also used 1973 as an analog. It is of note that all 3 years were good snow years in Winchester (for the data that I have). I also did your 1961-1962 same time period. I am going to post the images, and since I'm not smart enough to know how to post them in one post, I'll post them in seperate posts.

Here's this year from Nov 15

post-178-0-06685900-1354667664_thumb.jpg

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Not sure if I'm reading these correctly...but as of the latest available, that's showing a high probability of above average 2m temps right? And slightly above normal chances of above normal precip? For January.

It does. And if you click on the "Weekly mean forecast" at the bottom of the page you can get the weekly forecast for the next 4 weeks. As of 2-3 days ago it was showing the end of December colder than normal and now the past couple of days it has backed off.

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Gfs end means take those higher heights and push them closer to the west coast and connect the low heights from western Canada all the way through to the Atlantic much like what happened in those analog years I posted. Euro trying to do the same, just not there yet.

The euro has some serious cold up in Canada. Like to see some of it get loose.

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Gfs end means take those higher heights and push them closer to the west coast and connect the low heights from western Canada all the way through to the Atlantic much like what happened in those analog years I posted. Euro trying to do the same, just not there yet.

The euro has some serious cold up in Canada. Like to see some of it get loose.

yep

click on this link to see it thru Day 10 on the Euro

http://www.ecmwf.int...2120500!!!step/

wonder what happens after that (if it's right, of course)

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I'm skeptical about the gfs. -pna in place and big ridge basically in the same place on the pac. It's all -nao driving and that's a monster -nao. Guidance looking like -3 sd's.

If the blocking in gl is weaker or a bit further east then we still stuck with relatively flat flow and raging pac jet. Not saying the gfs is wrong but with the unfavorable ridge place in the pac too much can go wrong.

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gotta' admit, they look awfully close Bob

can we cash in like that winter is the big question....the answer to which I have a strong "hunch" lol

Playing along in the game, unless my quick look was too quick, DCA had 15" that winter and Baltimore had 35". I can't remember when BWI became the official station so not sure where that 35 was recorded.

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gotta' admit, they look awfully close Bob

can we cash in like that winter is the big question....the answer to which I have a strong "hunch" lol

Who knows right? I only care about getting us out of the current pattern into something with more potential. Most importantly getting far away from 70 degree afternoon highs. It's tough to get snow in that pattern.

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Looking more and more like the key to this winter is going to be getting the PNA/EPO to behave. The placement and strength of the ridge in the Pacific is driving the pattern right now. Just too much jet pounding into the west coast, and when it gets east immediately erases the southern edge of any eastern trough that develops.

I know the second half of Dec looks good on the models, but I'm not falling for any eastern trough while there's still a misbehaving Pac ridge on those maps. Get that thing to set up over the Rockies and then we'll be in business.

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Looking more and more like the key to this winter is going to be getting the PNA/EPO to behave. The placement and strength of the ridge in the Pacific is driving the pattern right now. Just too much jet pounding into the west coast, and when it gets east immediately erases the southern edge of any eastern trough that develops.

I know the second half of Dec looks good on the models, but I'm not falling for any eastern trough while there's still a misbehaving Pac ridge on those maps. Get that thing to set up over the Rockies and then we'll be in business.

Without strong ENSO signal, other factors will play a big riole, and it's looking like the (bad) Pacific is taking over for now. A big negative AO and NAO will help, but the Pacific is really flexing its muscles right now.

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I'm skeptical about the gfs. -pna in place and big ridge basically in the same place on the pac. It's all -nao driving and that's a monster -nao. Guidance looking like -3 sd's.

If the blocking in gl is weaker or a bit further east then we still stuck with relatively flat flow and raging pac jet. Not saying the gfs is wrong but with the unfavorable ridge place in the pac too much can go wrong.

Bob, what I was saying is that the ens of both models seem to try and move those pos height anomalies closer to the west coast. That would have to help I would think. That boomerang of neg height anomalies from western Canada across the US and the Atlantic shown in your 1961 analog is exactly what the GFS end shows beyond about 10 days.

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