January 2017 Discussion & Observations

[PB GFI]

 

 

 

 

Early  FEB is  driven by this 

 

 

 

 

Now the harder part of the forecast. 

 

 

 

 

The above could lead to the this for the second half . 

 

But this is very far off in the L/R and is not very clear. 

 

 

 

 

[bluewave]

Hopefully, we can take advantage of the late Jan into early Feb window of opportunity to produce some more snowfall.

EPS,CMC,GEFS all retrograde  the +PNA ridge back to the Aleutians toward day 15. That has been the preferred location of 

the ridge all season long.

 

 

Default seasonal 500 mb pattern

 

 

[PB GFI]

[PB GFI]

The GFS thinks the VORTEX pays a visit .

 

OBV an op run . 

 

[snowman19]

1 hour ago, bluewave said:

Hopefully, we can take advantage of the late Jan into early Feb window of opportunity to produce some more snowfall.

EPS,CMC,GEFS all retrograde  the +PNA ridge back to the Aleutians toward day 15. That has been the preferred location of 

the ridge all season long.

 

 

Default seasonal 500 mb pattern

 

 

If you look at the main signals we saw going into this winter, westerly QBO, modoki La Niña, low solar and a neutral PDO which has been a non factor this winter you knew this was coming. Predominant -PNA, +NAO and +AO has been the theme and will continue to be going into spring

[snowman19]

9 minutes ago, snowman19 said:

If you look at the main signals we saw going into this winter, westerly QBO, modoki La Niña, low solar and a neutral PDO which has been a non factor this winter you knew this was coming. Predominant -PNA, +NAO and +AO has been the theme and will continue to be going into spring

The big spike in geomag also played a role in keeping the NAO positive 

[Allsnow]

The trough is to Far East on the models for anything to slow down and amplify. I'm afraid we will be cold and dry when we have the pna spike. 

[Allsnow]

You see on the gefs we loose the pna and the southeast ridge pops. Only saving grace is the pv to our north with hopefully can beat down the ridge. If not it's same old same old 

[LongBeachSurfFreak]

12 minutes ago, Allsnow said:

You see on the gefs we loose the pna and the southeast ridge pops. Only saving grace is the pv to our north with hopefully can beat down the ridge. If not it's same old same old 

That's actually a great setup if we stay on the right side of the boundary. Just look at the last January's blizzard. It could also be an epic fail

[bluewave]

1 hour ago, snowman19 said:

If you look at the main signals we saw going into this winter, westerly QBO, modoki La Niña, low solar and a neutral PDO which has been a non factor this winter you knew this was coming. Predominant -PNA, +NAO and +AO has been the theme and will continue to be going into spring

Following the record negative to positive AO reversal back in the fall, all our winter storm opportunities were courtesy of the 2 -EPO drops.

Extreme volatility between those 2 indices with record daily highs and lows.

 

 

[donsutherland1]

The extended range of the 1/20/2017 12z GEFS goes even more strongly toward the February 1-15, 1989 500 mb pattern, not just over North America, but also Europe. The forecast pattern also closely resembles what one would see in the composite EPO-/PNA-/AO+ pattern for the February 1-15 period (1981-2010 climatology). That pattern has been the predominant one this winter.

Moreover, looking at the February 1-15 EPO-/PNA-/AO+ cases, the ridging that covers a large part of the southern U.S. extending into the central U.S. sometimes splits for a time with one ridge developing in the West and another along or just off the East Coast. However, at other times, the ridging repeatedly regenerates after weakening. Less frequent are cases where a strong trough develops in the East.

If the AO+ weakens dramatically early in February, trough development would become more likely. If not, then the predominant winter 2016-17 pattern may be difficult to break for any meaningful period of time. My guess is that we'll have a better idea about where things are headed by the middle of next week.

Meanwhile, to avoid posting just negative developments, the CFSv2 actually has cold February anomalies in parts of the East.

[SnowGoose69]

1 hour ago, donsutherland1 said:

The extended range of the 1/20/2017 12z GEFS goes even more strongly toward the February 1-15, 1989 500 mb pattern, not just over North America, but also Europe. The forecast pattern also closely resembles what one would see in the composite EPO-/PNA-/AO+ pattern for the February 1-15 period (1981-2010 climatology). That pattern has been the predominant one this winter.

Moreover, looking at the February 1-15 EPO-/PNA-/AO+ cases, the ridging that covers a large part of the southern U.S. extending into the central U.S. sometimes splits for a time with one ridge developing in the West and another along or just off the East Coast. However, at other times, the ridging repeatedly regenerates after weakening. Less frequent are cases where a strong trough develops in the East.

If the AO+ weakens dramatically early in February, trough development would become more likely. If not, then the predominant winter 2016-17 pattern may be difficult to break for any meaningful period of time. My guess is that we'll have a better idea about where things are headed by the middle of next week.

Meanwhile, to avoid posting just negative developments, the CFSv2 actually has cold February anomalies in parts of the East.

I believe there was a SSW in February 89.  That month was a relatively good one snow wise for the MA and SE I believe but we missed out on several suppressed events here.  I know the cold mostly focused over the Plains though.

[donsutherland1]

18 minutes ago, SnowGoose69 said:

I believe there was a SSW in February 89.  That month was a relatively good one snow wise for the MA and SE I believe but we missed out on several suppressed events here.  I know the cold mostly focused over the Plains though.

I remember that winter. It was very snowy in places like Norfolk and Atlantic City picked up a foot of snow in a late February snowstorm while nothing fell up in NYC.

[psuhoffman]

Curious your take on this so reposting it from mid atl forum. 

"Friend just linked me to a Jb post on the weeklies because he thought it sounded like what I said. I just read it and I hate hate hate to agree with him but he did just say exactly what I did last night. That it looks very odd and a bit confusing that it builds a western ridge and rushing over the top with a negative AO but yet no response over the us. Just higher heights across all of North America. It's not like most of winter where the trough is stuck in the west or where we're flooded with PAC air because of a vortex over AK. With ridging in the west and AK we shouldn't be flooded with a PAC firehouse. And with a higher heights in the AO space we shouldn't have a roided se ridge. I've given my best guess to the possible cause. But I'm honestly curious what anyone else's take is. I so wish we could see the members. "

I had opined earlier that perhaps there are divergent clusters. That one has a -AO and some modest lower heights over the conus. The other smaller cluster has a more neutral AO and a torch at h5. Then the washed out mean of those two has ridging up where we want it yet still higher heights over basically the whole conus. But I'm curios if anyone has a better explanation. It's rare I'm baffled by something but that run had be shaking my head.

[donsutherland1]

26 minutes ago, psuhoffman said:

Curious your take on this so reposting it from mid atl forum. 

"Friend just linked me to a Jb post on the weeklies because he thought it sounded like what I said. I just read it and I hate hate hate to agree with him but he did just say exactly what I did last night. That it looks very odd and a bit confusing that it builds a western ridge and rushing over the top with a negative AO but yet no response over the us. Just higher heights across all of North America. It's not like most of winter where the trough is stuck in the west or where we're flooded with PAC air because of a vortex over AK. With ridging in the west and AK we shouldn't be flooded with a PAC firehouse. And with a higher heights in the AO space we shouldn't have a roided se ridge. I've given my best guess to the possible cause. But I'm honestly curious what anyone else's take is. I so wish we could see the members. "

I had opined earlier that perhaps there are divergent clusters. That one has a -AO and some modest lower heights over the conus. The other smaller cluster has a more neutral AO and a torch at h5. Then the washed out mean of those two has ridging up where we want it yet still higher heights over basically the whole conus. But I'm curios if anyone has a better explanation. It's rare I'm baffled by something but that run had be shaking my head.

First, a negative AO is not the most likely outcome into at least early February. In fact, the guidance has been trending toward a more strongly positive AO in recent days in a fashion similar to what occurred in late January-early February 1989.

A sufficiently strongly positive AO essentially overwhelms the pattern, with the trough migrating northward into Canada, ridging spreading across much of CONUS, and the PNA/EPO ridge retrograding. It appears that February will begin with an EPO-/PNA-/AO+ pattern. The only question is whether the AO will be sufficiently positive to overwhelm the pattern.

That's not yet assured (favored by one cluster of ensemble members with a separate cluster keeping the AO+ weaker). If that does, in fact, occur, the strong trough that will develop for a time in the East next week could prove transient. The 6z and especially 12z GEFS have the 500 mb pattern evolving into one that is remarkably similar to the predominant February 1-15, 1989 pattern and reasonably similar to the 500 mb pattern in the means that has defined winter 2016-17 to date.

 

[uncle W]

until the AO goes negative I'm not expecting any KU events...It can get very cold with a very positive AO like what happened in January 1957...I'm still holding out hope that February will see a more negative ao like what we saw in 1993...Feb. and march 93 were quite wintry...

[bluewave]

9 minutes ago, uncle W said:

until the AO goes negative I'm not expecting any KU events...It can get very cold with a very positive AO like what happened in January 1957...I'm still holding out hope that February will see a more negative ao like what we saw in 1993...Feb. and march 93 were quite wintry...

The AO has become much more positive following the record March 2013 drop. That extreme event for March really flipped the pattern to more Pacific based blocking since then.

[psuhoffman]

19 minutes ago, donsutherland1 said:

First, a negative AO is not the most likely outcome into at least early February. In fact, the guidance has been trending toward a more strongly positive AO in recent days in a fashion similar to what occurred in late January-early February 1989.

A sufficiently strongly positive AO essentially overwhelms the pattern, with the trough migrating northward into Canada, ridging spreading across much of CONUS, and the PNA/EPO ridge retrograding. It appears that February will begin with an EPO-/PNA-/AO+ pattern. The only question is whether the AO will be sufficiently positive to overwhelm the pattern.

That's not yet assured (favored by one cluster of ensemble members with a separate cluster keeping the AO+ weaker). If that does, in fact, occur, the strong trough that will develop for a time in the East next week could prove transient. The 6z and especially 12z GEFS have the 500 mb pattern evolving into one that is remarkably similar to the predominant February 1-15, 1989 pattern and reasonably similar to the 500 mb pattern in the means that has defined winter 2016-17 to date.

 

Btw I love your posts. Always excellent. I don't disagree with any of your analysis. My comment was regarding the euro weeklies run last night and their look in the feb 10 on look.  It's not even regarding any sensible weather just was a puzzling look. I would post if I could but from about feb 10 on they have ridging in the west and western Canada and a -AO but still higher heights across the whole conus. 

[uncle W]

3 minutes ago, bluewave said:

The AO has become much more positive following the record March 2013 drop. That extreme event for March really flipped the pattern to more Pacific based blocking since then.

we've been lucky getting above normal snow with the ao being not as negative since then...last year the ao almost hit -5...anytime that happens we get a major cold wave or snowstorm that year...

[bluewave]

5 minutes ago, uncle W said:

we've been lucky getting above normal snow with the ao being not as negative since then...last year the ao almost hit -5...anytime that happens we get a major cold wave or snowstorm that year...

Yeah, last year was the exception with the strong AO block and historic blizzard. We got lucky that the Kara block built back to Greenland and tanked  the AO.

Like you mentioned, most of our other snow events in recent years have been driven by Pacific side blocking. But for me personally, none of those snowstorms since

13-14 driven by the Pacific could match the -AO blizzard last January.

 

[donsutherland1]

30 minutes ago, psuhoffman said:

Btw I love your posts. Always excellent. I don't disagree with any of your analysis. My comment was regarding the euro weeklies run last night and their look in the feb 10 on look.  It's not even regarding any sensible weather just was a puzzling look. I would post if I could but from about feb 10 on they have ridging in the west and western Canada and a -AO but still higher heights across the whole conus. 

It's possible that rapid changes are taking place and the weekly mean is skewed.

[donsutherland1]

The GFS kept the PNA+ going; its ensembles don't. The former would, typically be snowier in the February 1-15 period.

[bluewave]

First time that JFK had over 10 inches of snow for January while being in the top ten warmest Januaries.

Top 10 warmest Januaries at JFK and monthly snowfall:

40.5...1950...T

39.6...1998...0.1

39.4...1990...1.4

39.1...2006...2.1

38.9...2002...4.1

37.9...1975...0.1

37.8...2017...11.1

37.8...1995...0.1

2007...37.3...1.7

2012...37.2...1.6

 

[PB GFI]

1 hour ago, bluewave said:

First time that JFK had over 10 inches of snow for January while being in the top ten warmest Januaries.

Top 10 warmest Januaries at JFK and monthly snowfall:

40.5...1950...T

39.6...1998...0.1

39.4...1990...1.4

39.1...2006...2.1

38.9...2002...4.1

37.9...1975...0.1

37.8...2017...11.1

37.8...1995...0.1

2007...37.3...1.7

2012...37.2...1.6

 

 

Amazing , every airport from EWR on E has AN snow to date and most are prob plus 3 since Dec 1 .

 

Side note , the 6z GEFS day 15  , 500 and 2 M anomalies look good enough .

Thats a nice barroclinic zone with frigid air N of the Mason Dixon line .

 

However the day 15 EPS really wants to take another break .

 

 

[bluewave]

13 minutes ago, PB GFI said:

 

Amazing , every airport from EWR on E has AN snow to date and most are prob plus 3 since Dec 1 .

 

Side note , the 6z GEFS day 15  , 500 and 2 M anomalies look good enough .

Thats a nice barroclinic zone with frigid air N of the Mason Dixon line .

 

However the day 15 EPS really wants to take another break .

 

 

 

The interesting thing about the EPS weeklies was how far in advance it picked out the +PNA spike coming up from near the start of January.

But the last run started to back away from the duration of +PNA it was showing in earlier runs. We then had the EPS day 11-15 runs since then

start to show even more of a relaxation relative to what the very last weekly run was showing toward day 15. So I guess we'll just have to

keep monitoring and see what the next batch of weeklies does Monday evening. The latest EPS runs seem to want to retrogress that +PNA

ridge back to the Aleutians like we have seen all season long.

[donsutherland1]

This morning's AO figure was +1.376. This is the 45th day on which the AO has been positive, assuring that it will have been positive for 50% or more of meteorological winter. The ensemble forecast shows a strongly positive AO in the medium-term with an increasing likelihood that the pattern will evolve toward the February 1-15, 1989 pattern at 500 mb. The 6z GFS took a step in that direction and the GFS ensembles continue to show such a pattern evolution.

[frd]

4 minutes ago, donsutherland1 said:

This morning's AO figure was +1.376. This is the 45th day on which the AO has been positive, assuring that it will have been positive for 50% or more of meteorological winter. The ensemble forecast shows a strongly positive AO in the medium-term with an increasing likelihood that the pattern will evolve toward the February 1-15, 1989 pattern at 500 mb. The 6z GFS took a step in that direction and the GFS ensembles continue to show such a pattern evolution.

Don , regarding the SSW event that took place in Feb 1989,  as well as the late month Atlantic City and Norfolk snowstorm, do you know if the sequence of events leading up to that mimics this year so far?

In regards to the forecasted rising AO , and the portrayed 500 mb pattern that you metion above with the progression of the pattern like 1989 do you think it is possible that the upcoming SSW ( depending of course on the final outcomes ) could cause a similiar event later this Feb., or early March.

Thanks

 

[bluewave]

36 minutes ago, donsutherland1 said:

This morning's AO figure was +1.376. This is the 45th day on which the AO has been positive, assuring that it will have been positive for 50% or more of meteorological winter. The ensemble forecast shows a strongly positive AO in the medium-term with an increasing likelihood that the pattern will evolve toward the February 1-15, 1989 pattern at 500 mb. The 6z GFS took a step in that direction and the GFS ensembles continue to show such a pattern evolution.

It would be great to know specifically how the record -AO in March 2013 appears to have shifted the AO to a more positive state. I guess there is much about

the AO that we just don't understand yet. The 46 month period from June 2009 to March 2013 featured 30 out of 46 months with a -AO. The most recent

46 month stretch from April 2013 to January 2017 has experienced 29 out of 46 months with a +AO.

[uncle W]

1988-89 had a positive ao every day except for 12/25 and 3/4...it reached +5.582 on 1/14...we could see a +4 ao next week...we can only hope the ao finally goes negative in February and stays that way a while like what happened in 1993...

[CIK62]

Next 8 days, including today,  still running at a toasty +12.5degs.   I estimate a positive surplus of 192 degrees or +6.8degs. by the morning of the 29th.   If last 3 days are normal, we could end month about +6.2degs.