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Talking Winter 2012-2013


wederwarrior

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The ECMWF monthly forecast came in with a lot of near normal temps for the winter. With the el-nino more than likely being weak instead of moderate that changes the analog list considerabily. It's hard to find a good match for a week el-nino after back to back nina seasons with the PDO negative. Many of the week el-ninos have been mild and snowless ex. 04-05. While the moderate el-ninos ended up being cold and snowy ex. 02-03 in recent years. This will be a tough winter forecast. Short term indices (AO, NAO etc.) will play a larger role than normal this winter.

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The ECMWF monthly forecast came in with a lot of near normal temps for the winter. With the el-nino more than likely being weak instead of moderate that changes the analog list considerabily. It's hard to find a good match for a week el-nino after back to back nina seasons with the PDO negative. Many of the week el-ninos have been mild and snowless ex. 04-05. While the moderate el-ninos ended up being cold and snowy ex. 02-03 in recent years. This will be a tough winter forecast. Short term indices (AO, NAO etc.) will play a larger role than normal this winter.

04-05 was a decent slightly above normal snowfall winter locally

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04-05 was a decent slightly above normal snowfall winter locally

That winter featured a pretty tight gradient across S/CNJ. Near normal snowfall around PHL but I had well above normal w/ 45-50" in Monmouth, cashing in on a lot of the Miller B's. PHL SW tends to do better in Miller A dominant years like DCA and BWI.

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The ECMWF monthly forecast came in with a lot of near normal temps for the winter. With the el-nino more than likely being weak instead of moderate that changes the analog list considerabily. It's hard to find a good match for a week el-nino after back to back nina seasons with the PDO negative. Many of the week el-ninos have been mild and snowless ex. 04-05. While the moderate el-ninos ended up being cold and snowy ex. 02-03 in recent years. This will be a tough winter forecast. Short term indices (AO, NAO etc.) will play a larger role than normal this winter.

Whereas in the very short term (say since 2002), it, indeed, hasn't worked out, I assume that you realize that the longer term shows that weak Ninos have been colder than moderate ON AVG for much of the E US. This has especially been the case for those following Ninas. (I'm not addressing snow.) This includes cold weak Nino winters like 1976-7, 1963-4, 1939-40, 1911-2, and 1904-5. Also, 1968-9 was pretty chilly, itself. 1951-2 is admitedly a warm exception, but it is in the minority.

Edit: By the way, how confident are you that the PDO won't turn + in time for the DJF avg. and on what are you basing this? I ask this because of the following very cold winter weak Nino analogs that followed a Nina that had a sharp PDO reversal:

- 1904-5: had a similarly strongly negative PDO to 2012 the preceding summer and switched to a +PDO by the autumn that persisted through the winter

- 1939-40: Aug.-Nov. all were solidly -PDO months and were immediately followed by a DJF that had the 5th most +PDO for the period 1900-2012

- 1976-7: the entire period 1/1975-6/1976 had a solidly -PDO. By 8/1976, it had already turned to a solidly +PDO, which persisted through 3/1977. The strong +PNA pattern started during 9/1976 and persisted through the rest of fall and in the winter.

By the way, 1911-12 had a -PDO for the DJF avg. and it followed back to back Nina seasons.

General Q about the PDO: is there somewhat of a chicken-egg situation with the +PNA/+PDO?

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Whereas in the very short term (say since 2002), it, indeed, hasn't worked out, I assume that you realize that the longer term shows that weak Ninos have been colder than moderate ON AVG for much of the E US. This has especially been the case for those following Ninas. (I'm not addressing snow.) This includes cold weak Nino winters like 1976-7, 1963-4, 1939-40, 1911-2, and 1904-5. Also, 1968-9 was pretty chilly, itself. 1951-2 is admitedly a warm exception, but it is in the minority.

Edit: By the way, how confident are you that the PDO won't turn + in time for the DJF avg. and on what are you basing this? I ask this because of the following very cold winter weak Nino analogs that followed a Nina that had a sharp PDO reversal:

- 1904-5: had a similarly strongly negative PDO to 2012 the preceding summer and switched to a +PDO by the autumn that persisted through the winter

- 1939-40: Aug.-Nov. all were solidly -PDO months and were immediately followed by a DJF that had the 5th most +PDO for the period 1900-2012

- 1976-7: the entire period 1/1975-6/1976 had a solidly -PDO. By 8/1976, it had already turned to a solidly +PDO, which persisted through 3/1977. The strong +PNA pattern started during 9/1976 and persisted through the rest of fall and in the winter.

By the way, 1911-12 had a -PDO for the DJF avg. and it followed back to back Nina seasons.

General Q about the PDO: is there somewhat of a chicken-egg situation with the +PNA/+PDO?

While there is a leaning here for where Mitch was posting, but not a slam dunk : 13 of 21 winters colder than long term median in weak nina winters for PHL area. Surprising, only 8 of 19 were snowier than average. Moderate el ninos were warmer, but they were also snowier. For us as long as the nino or nina is not off the charts strong, its how far from neutrality will the NAO be; last three winters proved that.

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While there is a leaning here for where Mitch was posting, but not a slam dunk : 13 of 21 winters colder than long term median in weak nina winters for PHL area. Surprising, only 8 of 19 were snowier than average. Moderate el ninos were warmer, but they were also snowier. For us as long as the nino or nina is not off the charts strong, its how far from neutrality will the NAO be; last three winters proved that.

**I'm not addressing snowfall in this post**

The good news for cold chances is that we're almost definitely going to have a weak Nino peak this fall /winter and we already know it followed a Nina. Now, if I want the best shot at a very cold winter for the E US during a weak Nino that follows a Nina, I'd certainly hope for a +PDO for DJF (along with a -AO/-NAO, of course) as these charts illustrate well:

+PDO weak Nino winters that followed a Nina (all three cold to very cold):

post-882-0-80908300-1347656529_thumb.png

-PDO weak Nino winters that followed a Nina (3 of 4 cool to cold; only 1951-2 stank):

post-882-0-25020200-1347656823_thumb.png

-PDO weak Nino winters that followed a Nina excluding 1951-2:

post-882-0-05356700-1347656842_thumb.png

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The ECMWF monthly forecast came in with a lot of near normal temps for the winter. With the el-nino more than likely being weak instead of moderate that changes the analog list considerabily. It's hard to find a good match for a week el-nino after back to back nina seasons with the PDO negative. Many of the week el-ninos have been mild and snowless ex. 04-05. While the moderate el-ninos ended up being cold and snowy ex. 02-03 in recent years. This will be a tough winter forecast. Short term indices (AO, NAO etc.) will play a larger role than normal this winter.

04-05 had 30" of snow and was right near the current 30 yr average on temps. Are you thinking of 94-95?

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04-05 had 30" of snow and was right near the current 30 yr average on temps. Are you thinking of 94-95?

I'm thinking he might have looked at either 2003-4 or 2005-6 that were both close to normal snow-wise. I won't see him til the end of the next week. Then again today's CFS2 run brings us to mdt el nino territory. Tomorrow's... :unsure:

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Latest PDO is still strong negative. http://jisao.washington.edu/pdo/PDO.latest

04-05 is the winter I thought of. Only 33% of normal snow fell where I was in 04-05, Lexington, KY that winter. However I guess by the posts it was a much snowier winter here. Also this would add more to the idea Feb may be the worse month for snowy cold weather this winter.

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For entertainment purposes only this morning I put toghter an analog package. QBO and the usual teleconnections will have a role as well. If the QBO flips to + then 94-95 would be triple weighted. However if it stays - then 86-87 would be double weighted.

PDO 51-52, 01-02, 94-95 ENSO 51-52, 76-77, 86-87, 94-95, 02-03, 04-05, 06-07

Overall Dec and Jan are really warm with a colder Feb. I'd like to see the PDO flip to have the best shot at a cold snowy winter. Although the average is warm a few winters on the list such as 76-77, 02-03 were cold/snowy. These are my personal thoughts and not that of that the NWS.

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Agree with what you have so far, Mitchell. If it's going to be snowy this year, I think it is back-weighted.

I'm going to secretly work on getting the nao negative for Dec & Jan. :pimp:

Ok semi-serious. I'm assuming there is something cyclical to the cfs2 outlooks, because the recent members are trending enso neutral positive while the "older" ones were mdt el nino.

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