December 2019 Forecasts and Discussions

[HarrisonSasquatchWx]

You always forecast this type of pattern.

Jrs. getting angry @ El Nito.

[AbbyJr]

Jrs. getting angry @ El Nito.

People don't typically laugh when they are angry.

[HarrisonSasquatchWx]

Gumps slyty was looking for you but he had to slip out.

[HarrisonSasquatchWx]

People don't typically laugh when they are angry.

Sorry Jr. my cell was upside down.

[wetcoast91]

You always forecast this type of pattern.

Because we have seen this pattern take hold during recent NDJ periods (aside from 2016-17). Most of the South Coast cold airmasses have come with retrogression of the WCR -leading to backdoor intrusions at best. Blocky winters are hit or miss but often suck in the 2000's due to the persistent +PNA. And it's no coincidence we have seen an alarming decrease in the number of coastal storms in the NDJ period this decade with a meandering split jet.

In my opinion...JFM has been a more interesting period weatherwise recently.

[HarrisonSasquatchWx]

Because we have seen this pattern take hold during recent NDJ periods (aside from 2016-17). Most of the South Coast cold airmasses have come with retrogression of the WCR -leading to backdoor intrusions at best. Blocky winters are hit or miss but often suck in the 2000's due to the persistent +PNA. And it's no coincidence we have seen an alarming decrease in the number of coastal storms in the NDJ period this decade with a meandering split jet.

In my opinion...JFM has been a more interesting period weatherwise recently.

Actually agree.

[Typeing3]

Because we have seen this pattern take hold during recent NDJ periods (aside from 2016-17). Most of the South Coast cold airmasses have come with retrogression of the WCR -leading to backdoor intrusions at best. Blocky winters are hit or miss but often suck in the 2000's due to the persistent +PNA. And it's no coincidence we have seen an alarming decrease in the number of coastal storms in the NDJ period this decade with a meandering split jet.

In my opinion...JFM has been a more interesting period weatherwise recently.

Wouldn't agree with January being more interesting recently. It's been a +PNA/+EPO fest over the better part of the past two decades. We haven't seen a relatively cold or snowy January since 1993. This was something that would occur on a much more frequent basis in the 20th century.

[AbbyJr]

Because we have seen this pattern take hold during recent NDJ periods (aside from 2016-17). Most of the South Coast cold airmasses have come with retrogression of the WCR -leading to backdoor intrusions at best. Blocky winters are hit or miss but often suck in the 2000's due to the persistent +PNA. And it's no coincidence we have seen an alarming decrease in the number of coastal storms in the NDJ period this decade with a meandering split jet.

In my opinion...JFM has been a more interesting period weatherwise recently.

Good explanation.

It would be interesting to find out what is driving this persistent +PNA pattern that used to be much less dominant. That said, it remains to be seen what happens this winter. I think if we fail to score anything in the late December early January period, then we may be out of luck but of course its impossible to say that with any kind of reliable confidence this early.

By the way, does the SSW effect the state of the PNA or does the state of the PNA effect the outcome of the SSW?

[AbbyJr]

Wouldn't agree with January being more interesting recently. It's been a +PNA/+EPO fest over the better part of the past two decades. We haven't seen a relatively cold or snowy January since 1993. This was something that would occur on a much more frequent basis in the 20th century.

There have been some decent Januarys though. Ex: 2005, 2007, 2009, 2011, and 2012.

[Forrest Gump]

It's still 10° out

[Weather101]

It's still 10° out

9c so I win

[Forrest Gump]

9c so I win

Nito would beg to differ.

[Monty]

6.8C and dry. Just 0.5mm from this system here so far

[Catnip]

https://twitter.com/albrechtjay/status/ ... 08161?s=21

[Antares]

Good explanation.

It would be interesting to find out what is driving this persistent +PNA pattern that used to be much less dominant. That said, it remains to be seen what happens this winter. I think if we fail to score anything in the late December early January period, then we may be out of luck but of course its impossible to say that with any kind of reliable confidence this early.

By the way, does the SSW effect the state of the PNA or does the state of the PNA effect the outcome of the SSW?

Higher atmospheric CO2 concentrations obviously.