Winter 2013-14 Pattern Discussion

[CAD_Wedge_NC]

The monthly CPC forecasts are out, and as usual, the graphics are showing EC for our area with a hint at drier than normal conditions. Most of the Mets that were on the warm train earlier have now changed their tune to a colder December. The record blocking event in the Aleutians and the -EPO that has led us into this cold pattern, looks to re-load as we head into December. If things line up right, we could be looking at a major cold air outbreak rivaling the 1983 Christmas outbreak sometime in the next 4-5 weeks.... After the dismal last couple of Decembers, this one holds some promise for winter weather fans.

[griteater]

I agree with Lindsaywx at the end of the Nov thread - the latest trends in the mid-long range are for the ridge axis to setup off the west coast.  The ridging up through Alaska is still there, but with the ridge axis setting up off the west coast, that favors the cold dumping moreso into the west, with the storm track to our north and west...and no sign of a -NAO thus far.  We'll have to see where we go from here...in the least, some of the coldest temperature anomalies in the Northern Hemisphere will be located in Canada and the U.S.

 

 

[Cold Rain]

Grit (or anyone), stupid question: What does the superensemble map represent? The top ten closest analogues to the predicted pattern (in your example, 12/2)? If so, what does each analogue date represent? A specific storm threat? A specific pattern? Something else? And the clusters of red and blue contours....I assume they are areas of cold and warm anomalies, with the number of contours representing the degree of predicted temp departure. Is that correct? Anything else? I appreciate the insight!

[CAD_Wedge_NC]

I agree with Lindsaywx at the end of the Nov thread - the latest trends in the mid-long range are for the ridge axis to setup off the west coast.  The ridging up through Alaska is still there, but with the ridge axis setting up off the west coast, that favors the cold dumping moreso into the west, with the storm track to our north and west...and no sign of a -NAO thus far.  We'll have to see where we go from here...in the least, some of the coldest temperature anomalies in the Northern Hemisphere will be located in Canada and the U.S.

 

 

Those are some cold analogs showing up. Especially 1983 and 1989.

[bobbitt]

yeah models has done a great job of showing cold here right ?after the 5th of dec, the connections are looking better for the east. http://t.co/V0lGpyTfXz

[griteater]

Grit (or anyone), stupid question: What does the superensemble map represent? The top ten closest analogues to the predicted pattern (in your example, 12/2)? If so, what does each analogue date represent? A specific storm threat? A specific pattern? Something else? And the clusters of red and blue contours....I assume they are areas of cold and warm anomalies, with the number of contours representing the degree of predicted temp departure. Is that correct? Anything else? I appreciate the insight!

Here's what I know...I believe the superensemble is an average of multiple runs of the GFS Ensemble.  My guess is that it's the average of the last 4 GFS Ensemble runs.  Theory being that the average of the last 4 runs is better than any single GFS Ens run for that forecast time range.  That map I posted is showing 500mb height anomalies, with the red contours representing above normal heights (ridging), and the blue contours showing below normal heights (troughing).  The more contours, the stronger the deviation from normal.  That map is a 5 day mean for the 6-10 day period, centered on day 8.  They also have one for days 8-14, centered on day 11.  The analog dates indicate the dates since 1950 that most closely match the 500mb pattern.  The first date listed is the best match, and the last one is the 10th best match.  The analog dates have to be within a 35 day window centered on the forecast date.  So, for the 12/2 map above, the analog dates are going to be within a period of mid-Nov to mid-Dec.  You won't see, for example, a Feb analog date that is a close pattern match for an early Dec forecast date.  The description on CPC says that the analog dates are based on a pattern match of the PNA region.  The PNA region is a vast domain from just west of the dateline in the Pacific, east to include all of North America - specifically, 175E to 60W, and 20N to 70N.  So, the area for the analog dates doesn't include the full domain of the NAO, but from what I've seen, it still seems to have good matches (i.e. analog dates that appear from prior -NAO episodes).    

 

They also have temperature and precip maps based on the analog dates:

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/gifs/sfc_count_sup610_temp.gif

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/gifs/sfc_count_sup610_prec.gif

[Cold Rain]

Here's what I know...I believe the superensemble is an average of multiple runs of the GFS Ensemble. My guess is that it's the average of the last 4 GFS Ensemble runs. Theory being that the average of the last 4 runs is better than any single GFS Ens run for that forecast time range. That map I posted is showing 500mb height anomalies, with the red contours representing above normal heights (ridging), and the blue contours showing below normal heights (troughing). The more contours, the stronger the deviation from normal. That map is a 5 day mean for the 6-10 day period, centered on day 8. They also have one for days 8-14, centered on day 11. The analog dates indicate the dates since 1950 that most closely match the 500mb pattern. The first date listed is the best match, and the last one is the 10th best match. The analog dates have to be within a 35 day window centered on the forecast date. So, for the 12/2 map above, the analog dates are going to be within a period of mid-Nov to mid-Dec. You won't see, for example, a Feb analog date that is a close pattern match for an early Dec forecast date. The description on CPC says that the analog dates are based on a pattern match of the PNA region. The PNA region is a vast domain from just west of the dateline in the Pacific, east to include all of North America - specifically, 175E to 60W, and 20N to 70N. So, the area for the analog dates doesn't include the full domain of the NAO, but from what I've seen, it still seems to have good matches (i.e. analog dates that appear from prior -NAO episodes).

They also have temperature and precip maps based on the analog dates:

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/gifs/sfc_count_sup610_temp.gif

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/gifs/sfc_count_sup610_prec.gif

Thanks man. That's a very good explanation and it helps a lot!

[Cold Rain]

Retreat or reload? That's the question for today's LR update. Both the operational GFS and Euro gradually moderate the current pattern and show increasingly milder conditions as we approach day 10 (after the upcoming event and subsequent cold blast). None of the teleconnections look favorable in the LR: AO rises rapidly, the NAO is neutral/positive, and the PNA drops. The MJO is also forecast by many models to become more of a factor, although models differ as to the phase in which it will emerge from the COD...so there remains an incoherent signal there.

H5 shows a general trough west with more ridging east in the day 10 time frame. The good news is, there is plenty of cold in Canada, and the snowpack continues to look good. Strong HPs continue to generate and migrate into the US.

Beyond Day 10, there is a lot of uncertainty, as usual. The look of the pattern has the look of a reload, but it remains to be seen.

Is this going to be another year where we have no trouble with blocking in non-winter months, but in winter we can't buy a block? I hope not.

[SnowNiner]

Retreat or reload? That's the question for today's LR update. Both the operational GFS and Euro gradually moderate the current pattern and show increasingly milder conditions as we approach day 10 (after the upcoming event and subsequent cold blast). None of the teleconnections look favorable in the LR: AO rises rapidly, the NAO is neutral/positive, and the PNA drops. The MJO is also forecast by many models to become more of a factor, although models differ as to the phase in which it will emerge from the COD...so there remains an incoherent signal there.

H5 shows a general trough west with more ridging east in the day 10 time frame. The good news is, there is plenty of cold in Canada, and the snowpack continues to look good. Strong HPs continue to generate and migrate into the US.

Beyond Day 10, there is a lot of uncertainty, as usual. The look of the pattern has the look of a reload, but it remains to be seen.

Is this going to be another year where we have no trouble with blocking in non-winter months, but in winter we can't buy a block? I hope not.

 

 

That's what is ironically laughable to me.  We go through last winter with the blocks on the models just around the corner, just around the corner, then they finally show up in mid March when it's too warm to snow.  We get blocked over the head all spring and summer.  Now going in to the fall, we have all the cold air and even an STJ, but no blocking what so ever.  It's almost like there's someone out there with a weather remote being a jerk who hates the southeast, cutting blocks on and off just to get hopes up then to cruelly crush them. 

 

With that said, I can live without the blocking this winter, I just hope the pacific keeps the trough in the east most of the time. 

[Marion_NC_WX]

Can you say Cross-Polar flow?

 

[griteater]

Yeah, it looks like wow and franklin ran the 00z GFS...full conus trough, most of U.S. in the freezer...let's see if it holds.  It's going to get real cold somewhere in the U.S. with that big ridge going up

[CAD_Wedge_NC]

Can you say Cross-Polar flow?

 

 

That map is a thing of beauty. Atlantic looks pretty good as well. Notice the ridge pushing into Greenland. Not too shabby. Let's hope this will be the predominant pattern for the winter.

[NCCatawba]

Joe Bastardi ‏@BigJoeBastardi14h

We are showing clients how pattern day 10-20 resembles great arctic outbreak of dec 19-28. Showing up on analogs

 

Joe Bastardi ‏@BigJoeBastardi5h

@RyanMaue The negative WPO and ridge over Alaska argues for widespread cold centered near and just EAST of trough Similar to Dec 1983!

[superjames1992]

 

Joe Bastardi ‏@BigJoeBastardi14h

We are showing clients how pattern day 10-20 resembles great arctic outbreak of dec 19-28. Showing up on analogs

 

Joe Bastardi ‏@BigJoeBastardi5h

@RyanMaue The negative WPO and ridge over Alaska argues for widespread cold centered near and just EAST of trough Similar to Dec 1983!

 

 

Which Arctic outbreak is "Dec 19-28"?  Or is he trying to say December 1928?

[Blue_Ridge_Escarpment]

I'm not sure what he was trying to say but on Dec 19, 2009 we received about 16 inches of snow here and struggled to get out of the teens and 20's for at least a week. May be what he is referring to? Just a guess

[Heisy]

EURO dumps the PV into the NW lol...ensembles aren't as crazy as that, but we will see a warmup during first week of Dec, what happens once that cold spreads east is what we need to watch for . Could get a gradient type pattern that sets up, the strength of the cold in that gradient should come down to whether or not we get a +PNA

[NCSNOW]

Which Arctic outbreak is "Dec 19-28"?  Or is he trying to say December 1928?

Not sure. But I would think he is referencing Dec 19-28, 1983. That was one of the all time great Artic outbreaks. Been a great November imo. 2 pesky events and cold.

[Cold Rain]

This morning's AO forecast continues to show a steady ascent.  Longer term, there is spread, as expected, with most members continuing to show a positive value.  There is no help from the NAO which continues to be shown positive, while the PNA drops substantially negative.  The most common forecast for the MJO is for it to emerge from the COD into Phase 2, propogating to Phase 3.  The CFS continues to show a normal to slightly below normal reading for December in the temp department, while a somewhat drier than normal signal has developed.  Canada is forecast to remain in the icebox.

 

As previously described the operational GFS eventually brings a full CONUS trough, after a mild period, and the operational Euro clearly shows the cold centered out west at 240.  However, the ridging off the west coast is pushing east toward the end of the run, so it appears that the pattern is somewhat progressive, indicating a shift toward a colder East is likely after a warm-up (as echoed above).

 

Does anyone know how, without cutting and pasting graphs, where you can get the AO, NAO, and PNA graphics all together in one image?  I don't know if that's possible.  But if it is, it would be useful for posting here.

[MichaelJ]

Bastardi's latest December forecast pretty much agrees with what I think is going to happen next month. The cold will be centered in the Midwest and the SE ridge will block most of our (cold) weather with some occasional cool periods followed by rapid warm-ups in the SE. Normal to slightly above normal temps are likely in the SE but much colder temps for the Midwest and interior NE. Now this could change if a -NAO develops and holds but right now that does not look likely according to long range projections (which to be fair are notoriously fickle)

[Brick Tamland]

Well, it figures we get colder than normal temps in November, but not cold enough for snow here, and then it warms up in December.

[Cold Rain]

Well, it figures we get colder than normal temps in November, but not cold enough for snow here, and then it warms up in December.

Well, so far, we've seen no evidence of any sustained SE ridge. It could change, but it's good that it hasn't been showing up yet.

[nchighcountrywx]

Headlines from WeatherBell:

 

Upper Ridge Over Alaska, Strong Negative WPO Set Stage for Historic Cold Threat Weeks 2 and 3

[Cold Rain]

Headlines from WeatherBell:

Upper Ridge Over Alaska, Strong Negative WPO Set Stage for Historic Cold Threat Weeks 2 and 3

Any idea where the historic cold threat will be?

[tnweathernut]

I know it's hard to accomplish, but I can see an almost coast to coast cold scenario for some time in December, except for the deep south.  The air masses this year have been the real deal and the one projected to come into the US further down the road are the types that like to spread out.  We saw a couple of these in the 80's.  The cold air is finally on our side of the globe.  I agree with Cold Rain in that we see forecasts of a strengthening SE ridge, but it never materializes.  Don't be surprised if we see modeling change throughout the coming week or so and dampen the effects of a SE ridge.

[griteater]

This morning's AO forecast continues to show a steady ascent.  Longer term, there is spread, as expected, with most members continuing to show a positive value.  There is no help from the NAO which continues to be shown positive, while the PNA drops substantially negative.  The most common forecast for the MJO is for it to emerge from the COD into Phase 2, propogating to Phase 3.  The CFS continues to show a normal to slightly below normal reading for December in the temp department, while a somewhat drier than normal signal has developed.  Canada is forecast to remain in the icebox.

 

As previously described the operational GFS eventually brings a full CONUS trough, after a mild period, and the operational Euro clearly shows the cold centered out west at 240.  However, the ridging off the west coast is pushing east toward the end of the run, so it appears that the pattern is somewhat progressive, indicating a shift toward a colder East is likely after a warm-up (as echoed above).

 

Does anyone know how, without cutting and pasting graphs, where you can get the AO, NAO, and PNA graphics all together in one image?  I don't know if that's possible.  But if it is, it would be useful for posting here.

 

I kind of like these regular CR long range updates, especially since they are free  

[Cold Rain]

I kind of like these regular CR long range updates, especially since they are free

Thanks! But if we go through long periods of bad patterns, I might stop. It's too depressing.

[Cold Rain]

Thanks. That's kinda what I figured. If it was to be in the east, no doubt they would have said it in the text. Thanks for posting it!

[tnweathernut]

Impressive cold, all blocked up and nowhere to go. Should continue to bleed east, putting most of the nation in the icebox. Now the real question is........is it going to happen? Lol

[pcbjr]

Impressive cold, all blocked up and nowhere to go. Should continue to bleed east, putting most of the nation in the icebox. Now the real question is........is it going to happen? Lol

 

Not without some sort of block on the east and a big west ridge....

 

[pcbjr]

And DT says: