The PHL/NYC Medium Range Thread - Part 2

[Rainshadow]

Also, the GWO has come out of the circle for the first time in a while. It'll be interesting to see if it will go through a full 8-1-2-3-4 progression, or just dive back into the middle. The 8-1-2-3-4 is also a warm signal in the East, but I'm not holding my breath for anything to break the block down.

This is me just wondering aloud, but if the solar factor is driving the high latitude blocking, I wonder if the MJO and GWO data are contaminated by the 80s-00s and the Nina signals aren't well represented in winter? I have zero evidence to back this up, so feel free to tell me I'm an idiot if I am.

Well we did have one warm day yesterday, maybe this supported the lake cutter solution? They do have daily gwo stats going back to 1958, so it can be computed. As far as next weekend goes PHL has not had a 10" or greater snowfall when the global relative atmospheric angular momentum anomaly has been less than -1. I don't have that slide in front of me, but I don't think there have been many in the southwestern quadrant at all. That goes back to the winter of 1957-8. So this upcoming weekend possibly alot of gwo/nina climo and the operational models/real world may be coming to a head.

[Guest Patrick]

Well we did have one warm day yesterday, maybe this supported the lake cutter solution? They do have daily gwo stats going back to 1958, so it can be computed. As far as next weekend goes PHL has not had a 10" or greater snowfall when the global relative atmospheric angular momentum anomaly has been less than -1. I don't have that slide in front of me, but I don't think there have been many in the southwestern quadrant at all. That goes back to the winter of 1957-8. So this upcoming weekend possibly alot of gwo/nina climo and the operational models/real world may be coming to a head.

One more reason why this is thrilling regardless of what falls or doesn't fall IMBY. Any idea where to find global relative atmospheric angular momentum anomolies? I am clueless about that, but I am a statistician so I think I can have some fun with this.

[Rainshadow]

One more reason why this is thrilling regardless of what falls or doesn't fall IMBY. Any idea where to find global relative atmospheric angular momentum anomolies? I am clueless about that, but I am a statistician so I think I can have some fun with this.

I agree, no matter what transpires this pattern shows both end of the spectrum statements anyone related to meteorology should never utter:

"We never get."

"In this pattern it has to."

From 1958 they are listed here:

http://www.esrl.noaa...im/gwo.data.txt

The current is:

http://www.esrl.noaa...gcm/gwo_40d.gif

[Guest Patrick]

Thanks so much!

From 1958 they are listed here:

http://www.esrl.noaa...im/gwo.data.txt

The current is:

http://www.esrl.noaa...gcm/gwo_40d.gif

[Rainshadow]

The models are forecasting the -nao to weaken, if correct down the road, we'll need the Pacific to co-operate for cold air, aka more likely if the MJO can complete the circle.

[am19psu]

The models are forecasting the -nao to weaken, if correct down the road, we'll need the Pacific to co-operate for cold air, aka more likely if the MJO can complete the circle.

Yeah, the Euro ENS is even more bearish. Roundy's forecast shows the -OLR anomalies hitting a brick wall at 135E, too.

[Rainshadow]

Yeah, the Euro ENS is even more bearish. Roundy's forecast shows the -OLR anomalies hitting a brick wall at 135E, too.

Ok, I'll ask the dumb question I should probably know the answer to, who or what is Roundy?

[am19psu]

Ok, I'll ask the dumb question I should probably know the answer to, who or what is Roundy?

Paul Roundy at U of Albany. He's a tropical wave guy. Here is his website. Look around and ask questions if you have them.

[Akeem the African Dream]

I know most of the focus is on the potential storm this weekend, but is there anything else on the horizon for next week?

[HM]

Also, the GWO has come out of the circle for the first time in a while. It'll be interesting to see if it will go through a full 8-1-2-3-4 progression, or just dive back into the middle. The 8-1-2-3-4 is also a warm signal in the East, but I'm not holding my breath for anything to break the block down.

This is me just wondering aloud, but if the solar factor is driving the high latitude blocking, I wonder if the MJO and GWO data are contaminated by the 80s-00s and the Nina signals aren't well represented in winter? I have zero evidence to back this up, so feel free to tell me I'm an idiot if I am.

Hey, didn't see this post but all the GWO/AAM data goes back to the 1950s so the La Niñas of the 80s/90s shouldn't contaminate. Also, the GWO/AAM data has plenty of neutral years too (and even warm events) where the GWO/AAM were acting like La Niña.

There is strong negative tendency now with the phase 5 response to forcing and the picture looks very similar to the mid OCT wave. During that period, the NAO generally rose to a positive peak by Halloween. I suspect something similar will happen this go-around but no doubt December's NAO monthly number will be in the tank. The medium range data is finally breaking this pattern down for Christmas with a completion of the -NAO block retrograding. Will another block form?

[am19psu]

Hey, didn't see this post but all the GWO/AAM data goes back to the 1950s so the La Niñas of the 80s/90s shouldn't contaminate. Also, the GWO/AAM data has plenty of neutral years too (and even warm events) where the GWO/AAM were acting like La Niña.

There is strong negative tendency now with the phase 5 response to forcing and the picture looks very similar to the mid OCT wave. During that period, the NAO generally rose to a positive peak by Halloween. I suspect something similar will happen this go-around but no doubt December's NAO monthly number will be in the tank. The medium range data is finally breaking this pattern down for Christmas with a completion of the -NAO block retrograding. Will another block form?

The reforecast ensembles from yesterday showed a trough west/ridge east pattern, which makes sense given the MJO moving into Phase 6. Assuming the MJO dies at 135E, you'd (well, I'd) think other forcing will take over, which seems to have defaulted to blocking this winter, but that's more of a persistence forecast than anything else.

Thanks for the reply, by the way. Don't be a stranger in this thread.

[HM]

The reforecast ensembles from yesterday showed a trough west/ridge east pattern, which makes sense given the MJO moving into Phase 6. Assuming the MJO dies at 135E, you'd (well, I'd) think other forcing will take over, which seems to have defaulted to blocking this winter, but that's more of a persistence forecast than anything else.

Thanks for the reply, by the way. Don't be a stranger in this thread.

I don't want to be a stranger to my own subforum region but usually I only have time to zip through each region/main forum. Unfortunately, people are going to use this period of time to belittle the MJO's effects down-the-road. While it may appear that it has no effect on the pattern, it actually did significantly. The development of a huge Aleutian High was directly related to the forcing. The -EPO/propagating -daam/dt anomaly from late November began the domino-effect on the NAO region. Once you get that machine going, it is hard to stop and I tried to stop it at the first relaxation period in early Dec. In all actuality, the NAO did go positive/neutral for a while there but the block quickly came back toward 12/10 due to the leftover closed lows in the further south Latitudes.

The wavelengths are still pretty shorter than normal although the Pacific is growing more wintry over the last 5 days. As these continue to expand with the Aleutian High/BOA low, this will allow the CONUS to relax a bit.

I am not so sold on the -NAO coming back like others are but maybe I'm not the best person right now to ask. haha...

[Rainshadow]

I don't want to be a stranger to my own subforum region but usually I only have time to zip through each region/main forum. Unfortunately, people are going to use this period of time to belittle the MJO's effects down-the-road. While it may appear that it has no effect on the pattern, it actually did significantly. The development of a huge Aleutian High was directly related to the forcing. The -EPO/propagating -daam/dt anomaly from late November began the domino-effect on the NAO region. Once you get that machine going, it is hard to stop and I tried to stop it at the first relaxation period in early Dec. In all actuality, the NAO did go positive/neutral for a while there but the block quickly came back toward 12/10 due to the leftover closed lows in the further south Latitudes.

The wavelengths are still pretty shorter than normal although the Pacific is growing more wintry over the last 5 days. As these continue to expand with the Aleutian High/BOA low, this will allow the CONUS to relax a bit.

I am not so sold on the -NAO coming back like others are but maybe I'm not the best person right now to ask. haha...

Howdy and thank-you for the insight.

[A-L-E-X]

I actually discussed that in the sne thread. I wonder what the phase composites would look like if we included the 50's and 60's during the -nao decadal cycle. Again, maybe it doesn't make much difference, but you have to wonder.

It probably makes a huge difference.  We stereotype whats supposed to happen in specific ENSO signals but we dont have a large enough sample size.  Include data from 1903-04, 1909-10, 1916-17 and 1917-18 also-- there is no logical reason we shouldnt try to expand the sample size as much as possible or else we wont be aware of the full range of possibilities that can happen.

[Rainshadow]

It probably makes a huge difference. We stereotype whats supposed to happen in specific ENSO signals but we dont have a large enough sample size. Include data from 1903-04, 1909-10, 1916-17 and 1917-18 also-- there is no logical reason we shouldnt try to expand the sample size as much as possible or else we wont be aware of the full range of possibilities that can happen.

Alex,

Whatever does or does not happen this upcoming weekend aside, I am not of the belief that there are many absolutes in meteorology, you know the this can't happen here because statements. There are climatological foundations that may make it more difficult to occur, so even including records as far back as we can tell will add more history but would never cover all of the bases. Even in specific enso patterns, the atmosphere might not be in that mode at that time, the listed I posted earlier, there were heavy snows with positive nao(s) (ok index number) and the list can go on and on.

[A-L-E-X]

Alex,

Whatever does or does not happen this upcoming weekend aside, I am not of the belief that there are many absolutes in meteorology, you know the this can't happen here because statements. There are climatological foundations that may make it more difficult to occur, so even including records as far back as we can tell will add more history but would never cover all of the bases. Even in specific enso patterns, the atmosphere might not be in that mode at that time, the listed I posted earlier, there were heavy snows with positive nao(s) (ok index number) and the list can go on and on.

Exactly, Tony.  It's all a matter of probabilities, and under the right circumstances it can still happen.  Of course, the chances might be like 5% but if that 1 in 20 chance verifies you wont remember that lol.

[am19psu]

I don't want to be a stranger to my own subforum region but usually I only have time to zip through each region/main forum. Unfortunately, people are going to use this period of time to belittle the MJO's effects down-the-road. While it may appear that it has no effect on the pattern, it actually did significantly. The development of a huge Aleutian High was directly related to the forcing. The -EPO/propagating -daam/dt anomaly from late November began the domino-effect on the NAO region. Once you get that machine going, it is hard to stop and I tried to stop it at the first relaxation period in early Dec.

I hear you, man. I was guilty there, too. Kinda taking a beating at work for it, since I am the only MJO-believer in the office.

The wavelengths are still pretty shorter than normal although the Pacific is growing more wintry over the last 5 days. As these continue to expand with the Aleutian High/BOA low, this will allow the CONUS to relax a bit.

I am not so sold on the -NAO coming back like others are but maybe I'm not the best person right now to ask. haha...

Well, I didn't think we'd have such sustained blocking to begin with, so I'm a little gun shy in thinking we go NAO neutral or slight positive heading into New Years'. That said, am I wrong to think that all of the major forcings outside of solar and NATL SSTAs signal less blocking through the rest of winter?

[am19psu]

I don't want to be a stranger to my own subforum region but usually I only have time to zip through each region/main forum. Unfortunately, people are going to use this period of time to belittle the MJO's effects down-the-road. While it may appear that it has no effect on the pattern, it actually did significantly. The development of a huge Aleutian High was directly related to the forcing. The -EPO/propagating -daam/dt anomaly from late November began the domino-effect on the NAO region. Once you get that machine going, it is hard to stop and I tried to stop it at the first relaxation period in early Dec. In all actuality, the NAO did go positive/neutral for a while there but the block quickly came back toward 12/10 due to the leftover closed lows in the further south Latitudes.

The wavelengths are still pretty shorter than normal although the Pacific is growing more wintry over the last 5 days. As these continue to expand with the Aleutian High/BOA low, this will allow the CONUS to relax a bit.

I am not so sold on the -NAO coming back like others are but maybe I'm not the best person right now to ask. haha...

Also, when you look at the propagating -dAAM/dt anomalies, at what latitude do they start having an effect on the mid-latitude pattern? I can clearly see the the anomaly you're talking about, but in a real time setting, I wouldn't really know how to use it. If that's infringing on your IP, don't worry about it.

[Rainshadow]

Paul Roundy at U of Albany. He's a tropical wave guy. Here is his website. Look around and ask questions if you have them.

Thanks for the link.

[tombo82685]

This would be interesting to see if this pans out this way. But look at the gfs 500mb, the block starts to fade then refires again later in the run

http://www.meteo.psu.edu/~gadomski/ENSHGTAVGNH_0z/ensloopmref.html

[Rainshadow]

It looks like the MJO has faded again. The Anomalous ridge over Canada should keep heights lower over the conus, but the flow looks more zonal on average. So while not a blowtorch, it looks as though the trend should be closer to normal temps and given the fast flow much numerical modeling angst.

[MJO812]

Euro monthly

http://www.accuweather.com/blogs/anderson/story/43105/updated-computer-forecast-for-the-winter-1.asp

Doesn't look like a blowtorch winter to me.

[LVblizzard]

18z GFS shows a dream white Christmas scenario. Snow on Christmas morning. It's backed up by the 18z DGEX but I'm not sure I want that model on my side.

[am19psu]

There are going to be some positive d(AAM)/dt anomalies propagating into the mid-latitudes this week and next, which looks to manifest mainly in a +EPO signal across the Pacific. However, after the brief warm up around New Years, Atlantic blocking will get started again. It looks like the first half of January will be cold, but the primary storm track will be west of our area, meaning cold and dry for the most part with rain storms coming from the west.

[A-L-E-X]

As per Don:

Earlier in this thread, I posted dismal snowfall statistics for moderate/strong La Niña winters when December had little or no snowfall. A snowy December improves the odds of a generally snowy winter, with significant snows (10" or more) usually returning either in February or March. April often had at least some accumulation of snow.

Some quick stats:

Boston: Moderate/Strong La Niña cases (1871-2009): 9" or more December snowfall:

- 4/5 (80%) cases had 50" or more seasonal snowfall

New York City: Moderate/Strong La Niña cases (1871-2009): 3" or more December snowfall:

- 8/9 (89%) cases had 20" or more seasonal snowfall

- 5/9 (56%) cases had 30" or more seasonal snowfall

-2/2 (100%) cases with 10" or more December snowfall had 30" or more seasonal snowfall

He also said there is an enhanced chance of getting another KU event later in the winter.

Those two analogs were 1886-87 and 1916-17, the latter analog gets brought up often with this season with how cold and now snowy its been.... it was the first of back to back 50 inch plus snow fall seasons for NYC (both of which were mod-strong la ninas) and still the only back to back 50 inch plus snowfall seasons.

[RowanBrandon]

So when is our next snow threat?

[am19psu]

When the Euro freebies come out, check out the battle between the Nina ridge and the -NAO at hour 216. It ought to be interesting to see how this plays out after New Years.

EDIT: The GFS shows the same battle, but has the -NAO winning, whereas the Euro pumps up the WAA across the country. Two very different solutions after 168.

[tombo82685]

not a bad look on the 10 day from the euro ens....looks like weak -nao with a ridge out west

[earthlight]

The long range pattern looks like it might support a gradient and/or overrunning event by Day 7 after the big cutter given the elongated ridge on the west coast and nice greenland -nao block. But we're going to need a well timed s/w

http://www.meteo.psu.edu/~gadomski/ENSHGTAVGNH_12z/f204.gif

[RowanBrandon]

Too soon to start tracking?

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_pcp_192l.gif