Winter 2013-14 medium range discussion

[Ginx snewx]

The predictions for the breakdown of the EPO ridge have greatly diminished very similar how the early November Euro ENS predictions evolved . Any breakdown is transient on Ens. Cold waves continued to be modeled.

[Isotherm]

The predictions for the breakdown of the EPO ridge have greatly diminished very similar how the early November Euro ENS predictions evolved . Any breakdown is transient on Ens. Cold waves continued to be modeled.

 

 

This winter would fall into the minority of cases if we do in fact see a complete reversal of the EPO regime for the rest of the season. The statistical correlations and analogs for late autumn suggest that the odds favor the -EPO in the overall sense for DJF with transient breaks to be expected.

[Isotherm]

True. We are seeing a much different pattern this year as the ridge in that location is keeping the temperatures cooler.

The raging +EPO in 2012 just flooded the lower 48 with record warmth.

 

YearTDeptUS.png

 

12.png

 

AnnDec12TDeptUS.png

 

 

Yep, absolutely hideous temp regime across much of the US. Amazing the difference one year can make.

[Ginx snewx]

This winter would fall into the minority of cases if we do in fact see a complete reversal of the EPO regime for the rest of the season. The statistical correlations and analogs for late autumn suggest that the odds favor the -EPO in the overall sense for DJF with transient breaks to be expected.

my thoughts are in line with yours

[donsutherland1]

Cold Air Now Arriving in the Pacific Northwest, Does Snow Lie in the Future?

 

At 10 pm PST, the temperature at Seattle stood at 37° and is likely to approach or reach freezing by morning. Even colder readings will occur during the following days.

 

Now that the much anticipated cold air is arriving, the all-important question concerns whether it will snow. Both the 12/2 18z and 12/3 0z runs of the GFS have suggested the potential for an extended snowfall event. The GFS Forecast and Reforecast ensembles have both had a precipitation signal for some time.

 

 

In addition, the December 2008 cold outbreak, which has shown up in multiple runs of the GFS ensembles' objective analogs and in the partial teleconnection cases, featured two weeks of cold, along with snow. From December 13 through December 26, 13.9" snow fell. The biggest storm dumped 6.6" during the 12/20-22 timeframe.

 

The synoptic pattern is very likely to feature an EPO-/PNA- combination through at least the first two weeks of December. Such a pattern accounts for the overwhelming share of Seattle's 6" or greater snowstorms. The AO, which is highly important when it comes to Mid-Atlantic snowstorms is much less of a factor in the Pacific Northwest.

 

Below are a scatter diagram, AO/PNA and EPO/PNA charts for Seattle's 6" or greater snowstorms.

 

 

Needless to say, such a pattern does not guarantee snowfall, but it is the kind of pattern that is most favorable for such events. Odds probably favor at least some accumulation of snow in Seattle and Spokane and possibly Portland before the cold period ends.

[bluewave]

Yep, absolutely hideous temp regime across much of the US. Amazing the difference one year can make.

 

That huge -EPO ridge has resulted in the warmest SST's in that region south of Alaska that we have ever seen this time of year.

 

[donsutherland1]

You're avoiding the key question: what are your error bars, and why don't you report them?

I agree with you that the professionals are not that much better than random chance; my argument is that you are worse than they are, I.e., that, reported rigorously, your method has no skill beyond what someone with a very basic knowledge of meteorology could do. Your arguments against the traders apply to you too, and more so. The market is very good, but not perfect, at valuation; the odds of anyone actually beating the market is very low indeed. If you think the market is not skilled, then the null hypothesis is that your forecasts are worthless.

 

 

Several points:

 

1. There is no requirement that members who participate in the wide-ranging discussions at AmericanWx or any other weather forum for that matter post error bars.

 

2. The issue of natural gas traders was brought up strictly based on the statement in the message that was subsequently deleted that my having gone mild in parts of the East would be wrong and essentially because the traders were going cold there. There are no guarantees when it comes to monthly forecasting and no slam dunks of any kind. One can only know at the end of the month and we'll see where things stand then.

 

3. I've made no claims of any kind regarding superior methods/techniques for extended range forecasting. I've noted repeatedly my healthy respect for uncertainty and the challenges involved. I've had my share of hits and misses and such is the nature when one expresses thoughts/opinions about future events.

 

Some things have been measured here and elsewhere and I'll let the numbers speak for themselves:

 

AmWx Monthly Anomalies Guesses:

http://www.americanwx.com/bb/index.php/topic/38076-december-2012-forecast-contest-temperatures/page-2?hl=%2Bcontest#entry1978291

 

AmWx Global Temperature Anomalies Guesses:

http://www.americanwx.com/bb/index.php/topic/38718-guess-the-2013-global-temperature-anomalies/

 

NE Wx Snowfall Contests:

http://newx-forecasts.com/contest_winners.html

 

As is the case in any forum, one is free to agree/disagree with me or any other member on any of the thoughts we express. Reasonable people don't always reach the same conclusions even when presented with the same information.

[donsutherland1]

That huge -EPO ridge has resulted in the warmest SST's in that region south of Alaska that we have ever seen this time of year.

 

post-564-0-00130600-1386024910.gif

That's an extremely impressive map and it speaks well of why the EPO has had a dominant influence on the late autumn/early winter hemispheric pattern.

[bluewave]

That's an extremely impressive map and it speaks well of why the EPO has had a dominant influence on the late autumn/early winter hemispheric pattern.

 

I agree, Don. This is an extension of the strong ridge parked over the s region during 2013. The rapid SST increase  over the 

summer was also extremely impressive event in response to the strong height rises there.

 

http://bobtisdale.files.wordpress.com/2013/08/animation-3.gif

[Absolute Humidity]

Several points:

 

1. There is no requirement that members who participate in the wide-ranging discussions at AmericanWx or any other weather forum for that matter post error bars.

 

2. The issue of natural gas traders was brought up strictly based on the statement in the message that was subsequently deleted that my having gone mild in parts of the East would be wrong and essentially because the traders were going cold there. There are no guarantees when it comes to monthly forecasting and no slam dunks of any kind. One can only know at the end of the month and we'll see where things stand then.

 

3. I've made no claims of any kind regarding superior methods/techniques for extended range forecasting. I've noted repeatedly my healthy respect for uncertainty and the challenges involved. I've had my share of hits and misses and such is the nature when one expresses thoughts/opinions about future events.

 

Some things have been measured here and elsewhere and I'll let the numbers speak for themselves:

 

AmWx Monthly Anomalies Guesses:

http://www.americanwx.com/bb/index.php/topic/38076-december-2012-forecast-contest-temperatures/page-2?hl=%2Bcontest#entry1978291

 

AmWx Global Temperature Anomalies Guesses:

http://www.americanwx.com/bb/index.php/topic/38718-guess-the-2013-global-temperature-anomalies/

 

NE Wx Snowfall Contests:

http://newx-forecasts.com/contest_winners.html

 

As is the case in any forum, one is free to agree/disagree with me or any other member on any of the thoughts we express. Reasonable people don't always reach the same conclusions even when presented with the same information.

100% Agree Don.

[donsutherland1]

Verification:

November 22-30, 2013 Period (#40, 11/13)

 

As was noted in the message about the East:

 

11/13/2013 0z run of the GFS was cold for the eastern U.S. in the extended range. That fits with the extended range of the earlier run of the GFS ensembles. It also matches up well with the objective analogs (based off the GFS ensembles) rolled forward to be centered on 11/26 and the temperature anomalies for the 11/22-30 period resulting from the combination of ENSO and the forecast teleconnection indices.

 

The charts from that message were:

 

The actual outcome was:

 

[donsutherland1]

With regard to the unfolding cold in the Pacific Northwest and Northern Plains, the following are the lowest readings now showing up on the 12z MEX MOS for select cities:

 

Portland: 18°

Seattle: 20° (with one subfreezing high)

Spokane: -1° (with a high temperature as low as 13°)

 

Parts of Montana will likely experience recordbreaking cold. The following are the MEX MOS forecasts for Havre and Jordan with records for lowest daily maximum and minimum temperatures in parentheses. 

 

Havre:

12/5: High: -14° (-12°, 1880); Low: -27° (-27°, 1956)

12/6: High: -17° (-15°, 1972); Low: -32° (-31°, 1972)

12/7: High: -6 (-19°, 1927); Low: -37° (-33°, 1927)

 

Jordan:

12/5: High: -11° (-12°, 1880); Low: -29° (-27°, 1956)

12/6: High: -17° (-15°, 1972); Low: -40° (-31°, 1972)

12/7: High: -8 (-19°, 1927); Low: -37° (-37°, 1927)

 

Jordan has had only 5 prior readings of -40° or below in December, the last of which occurred on December 31, 1992 (-40°F)

[donsutherland1]

To put the coming cold for parts of the Northern Plains into perspective, the MEX MOS shows the following lowest maximum and lowest minimum temperatures for Havre, MT and Jordan, MT:

 

Havre:

Lowest Maximum: -17°

Lowest Minimum: -37°

 

Jordan:

Lowest Maximum: -17°

Lowest Minimum: -40°

 

Below is a chart showing the lowest December maximum and minimum temperatures beginning in 2000:

 

[tacoman25]

Dec 2009 was a very impressive cold event for the West, but this could very well surpass it.

[donsutherland1]

Morning thoughts...

 

1. The well-modeled cold has now moved into the Pacific Northwest and Northern Plains

 

2. In the extended range, the AO and PNA look to remain locked in what has been their predominant state through the late fall into early winter: AO+ and PNA-. The ensemble guidance continues to indicate a relaxation of the EPO-.

 

3. Consistent with the forecast teleconnections, there are growing indications on the ensembles of a milder pattern in the long-range after mid-month (~12/20 +/- a few days might be reasonable timing) for the CONUS while Canada remains cold for the most part. This progression is also consistent with the evolution of the composite pattern associated with predominant EPO-/AO+ regimes (1950-2012).

 

Given how far out that possible change is, it is still within the speculative realm. Nevertheless, it is perhaps something to watch for in subsequent guidance, especially as it is consistent with the evolution of past EPO-/AO+ regimes. It is also not dissimilar to the evolution of the late November/December 2008 pattern that has provided insight in recent weeks. 2008 also continues to show up among the GFS ensemble analogs (Day 8 and Day 11).  

[Ottawa Blizzard]

It's looking like this cold/snow outbreak is going to be most impressive in western Canada and the western U.S. The cold frankly does not look all that impressive for southern Ontario and Quebec. This may be a case similar to 2009-2010 when the U.S. was having one of its coldest and snowiest winters of recent decades while Toronto had its least snowiest winter on record.

[donsutherland1]

It's looking like this cold/snow outbreak is going to be most impressive in western Canada and the western U.S. The cold frankly does not look all that impressive for southern Ontario and Quebec. This may be a case similar to 2009-2010 when the U.S. was having one of its coldest and snowiest winters of recent decades while Toronto had its least snowiest winter on record.

There's little doubt that western Canada will wind up with far colder anomalies than eastern Canada. However, the 12/5-15 period does look colder than normal for the greater Toronto area. Afterward, the overall December outcome will depend on how much warmth develops toward latter part of the month. Canada will likely warm more slowly than the CONUS, so one can't dismiss the possibility of December turning out somewhat colder than normal.

[Jonger]

The GFS has shown a warming pattern after 300+ hours, but this has remained in the 300+ hr mark for the last few days, might be a false signal. Anyhow, lets hope for a more favorable AO, because this -EPO can't last forever.

[donsutherland1]

Growing Hints of an EPO Flip...

 

As had been noted previously (#197), historical experience argued that one should watch for the EPO's possibly shifting to positive by mid-December +/- 1 week. The longest stretch during which the EPO had remained negative after such a regime commenced in November was 45 days. The second and third longest such streaks were 33 and 32 days respectively.Through today, the EPO has been negative for 26 consecutive days.

 

The latest guidance is now showing the EPO rising toward 0 in the extended range. Some individual ensemble members take it positive.

 

Below is the latest reforecast ensemble mean forecast from CDC:

 

 

Such an outcome, particularly if the AO remains positive, would have potential implications. It would tend to favor milder weather across at least parts of the CONUS and, depending on the overall pattern evolution, possibly on a widespread basis. The composite EPO/AO combinations for the December 16-31 period are below:

 

[Heisy]

Thanks for the great news Don!

 

Is there any glimmer of hope when it comes to the AO? 

[SnoSki14]

So if the EPO fades and the AO remains positive, which as of now looks to be the case, then we can potentially kiss winter goodbye either partially or completely right?

[donsutherland1]

So if the EPO fades and the AO remains positive, which as of now looks to be the case, then we can potentially kiss winter goodbye either partially or completely right?

It's uncertain how long that pattern would last, so it would be premature to do so.

[donsutherland1]

Thanks for the great news Don!

 

Is there any glimmer of hope when it comes to the AO? 

Not right now on the ensembles, but that's in the extended range, so things can still change.

[donsutherland1]

It will be interesting to see if the retrogression of the -EPO ridge that the models are showing

is a hint of the January and February pattern. The 8 closest December composite since 1950

featured westward shift in the ridge position closer to the Aleutians during January and February.

 

DEC.png

 

JF.png

I agree. I suspect that it is a hint of sorts and that we're in the latter stages of the transition toward what will become the predominant winter pattern. It will be interesting to see how things evolve.

[Jonger]

The PNA looks like its going to plung negative.

Long range GFS has been trending colder and colder, the previously depicted warm-up has been replaced by cold in the east.

[donsutherland1]

The PNA looks like its going to plung negative. Long range GFS has been trending colder and colder, the previously depicted warm-up has been replaced by cold in the east.

Hopefully, the 0z won't reverse and the ensembles will trend in that direction.

[pcbjr]

The PNA looks like its going to plung negative. Long range GFS has been trending colder and colder, the previously depicted warm-up has been replaced by cold in the east.

Don't we want a +PNA for cold in the east?

[Jonger]

The PNA looks like its going to plung negative. Long range GFS has been trending colder and colder, the previously depicted warm-up has been replaced by cold in the east.

Don't we want a +PNA for cold in the east?

Makes me think the EPO isn't going to change then.

[tacoman25]

DEN hit -13 this evening. Previously the coldest temp on record before Dec 5 was -8.

[donsutherland1]

DEN hit -13 this evening. Previously the coldest temp on record before Dec 5 was -8.

This is certainly among the coldest air masses so early in the season in Denver.

 

However, the -5° figure is from Denver International Airport, but the record only goes back to 1995 there. At Stapleton Airport, where records used to be kept (records go back to 1948 there), there were 7 dates prior to December 5 when the temperature fell below -5°, including November 9-10, 1950 with a temperature of -8°. The lowest Denver area record prior to December 5 per Threadex is -18° on November 29, 1877.