AO Forecast to Plunge

[uncle W]

..The -AO gave Tampa Florida its coldest December on record...

http://www.tampabay.com/news/weather/december-coldest-on-record-for-tampa-bay-area/1143263

[Amped]

A second plunge may beat the first

[Yes_Probably_Maybe_No]

A second plunge may beat the first

expand the scale to -7 FTW

here's hoping the second half of january produces a KU or three

[Yes_Probably_Maybe_No]

Strong warming....looks like it's propagating downward as well

[mitchnick]

expand the scale to -7 FTW

here's hoping the second half of january produces a KU or three

that's right come to think of it

early last year and all year's prior, it only used to go to -4; I forgot about that

then they expanded it to accommodate the tanking last year

this is quite unreal

[Chinook]

I'm glad to see that the Europeans, Russians, Chinese, Japanese, and some of the Americans are getting frozen this winter.

[OKpowdah]

A couple of plots I put together. First is monthly AO v. QBO, the second one is monthly AO v. Nino3.4

[A-L-E-X]

Thanks for those plots! So it looks like, while extreme, it hasnt been the most extreme. Which months/years are at the extreme end of the scatter plot envelope?

[OKpowdah]

Thanks for those plots! So it looks like, while extreme, it hasnt been the most extreme. Which months/years are at the extreme end of the scatter plot envelope?

For the month of December, 2010 was definitely the most extreme. There are a few November, January and February points that rival as outliers. I'm only interested in the quadrant of Dec 2010 (i.e. III for AO v Nino3.4 and IV for AO v QBO)

I only have the AO v Nino3.4 data handy right now. The only outliers in quadrant III in the same league as Dec 2010 are perhaps November 1955, January 1985, February 1986, and January 1963. But especially with the AO v Nino3.4 data, December 2010 is nearly in a league of it's own as the most extreme case of a -AO during a mod-strong Nina state.

[nzucker]

-AO is batting a shut-out this winter:

[A-L-E-X]

For the month of December, 2010 was definitely the most extreme. There are a few November, January and February points that rival as outliers. I'm only interested in the quadrant of Dec 2010 (i.e. III for AO v Nino3.4 and IV for AO v QBO)

I only have the AO v Nino3.4 data handy right now. The only outliers in quadrant III in the same league as Dec 2010 are perhaps November 1955, January 1985, February 1986, and January 1963. But especially with the AO v Nino3.4 data, December 2010 is nearly in a league of it's own as the most extreme case of a -AO during a mod-strong Nina state.

November 1955 is interesting, as 55-56 was one of the analogs for this season.

[A-L-E-X]

-AO is batting a shut-out this winter:

Hmmm I wonder if we'll get close to the record neg ao in terms of consecutive days.

[pcbjr]

-AO is batting a shut-out this winter:

So with a positive PNA in the forecast, and a still very negative AO and negative NAO (which may go to neutral, but doesn't look like it goes positive for long, if at all), why are we modeled to get warm after the middle of the month? I would appreciate any insightful insights

Post Script -

[uncle W]

the blocking was similar to Dec. 1950 to January 51 but that blocking period ended around this time in January and didn't return until March...that year had a 3" snowfall while this year had a 20" one...all those 1950's analogs were during a long term drought...We are still in a long term wet spell...I like the 95-96 analog now...It doesn't mean I think we'll get 75" of snow...If Tuesday's storm is another biggie 50" is possible...

[das]

Why is this no longer pinned? This discussion will roll off quickly...

[nzucker]

So with a positive PNA in the forecast, and a still very negative AO and negative NAO (which may go to neutral, but doesn't look like it goes positive for long, if at all), why are we modeled to get warm after the middle of the month? I would appreciate any insightful insights

There's a bit of a SE ridge showing up on models which keeps Florida warmer. This is a strong La Niña winter, after all.

[VAwxman]

There's a bit of a SE ridge showing up on models which keeps Florida warmer. This is a strong La Niña winter, after all.

That's not why models are showing warmer trends though, and in fact the SE ridge really isn't there yet anyway, relative to normal. The change is all about Alaska, as models say the ridge there now goes over to Asia and is replaced with a vortex, which bring mild Pacific air into North America. I think this does occur, but wonder if models are rushing it. We shall see.

[nzucker]

That's not why models are showing warmer trends though, and in fact the SE ridge really isn't there yet anyway, relative to normal. The change is all about Alaska, as models say the ridge there now goes over to Asia and is replaced with a vortex, which bring mild Pacific air into North America. I think this does occur, but wonder if models are rushing it. We shall see.

I don't completely agree with this...sure we're probably going to lose the AK block in the next couple of weeks with the ridging migrating towards Siberia, but much of the Northeast remains below average on many of the operational models. I think the reason for the lack of cold air in Florida is that the trough isn't particularly deep and we have some higher heights trying to sneak into the subtropical regions with a gradient pattern evolving across the CONUS.

I don't really mind if we switch from a -EPO/-NAO/neutral PNA pattern to a +PNA/+EPO/-NAO...the temperatures would start to moderate a few days after the arctic unloads, but a +PNA can give us very good storm threats in the east with the energy diving down the backside of the western ridge axis. We also look to stay in average to slightly below average temperatures for a while, which is plenty cold in mid-January to get some decent snows. Even slightly above average wouldn't be terrible.

[VAwxman]

I don't completely agree with this...sure we're probably going to lose the AK block in the next couple of weeks with the ridging migrating towards Siberia, but much of the Northeast remains below average on many of the operational models. I think the reason for the lack of cold air in Florida is that the trough isn't particularly deep and we have some higher heights trying to sneak into the subtropical regions with a gradient pattern evolving across the CONUS.

I don't really mind if we switch from a -EPO/-NAO/neutral PNA pattern to a +PNA/+EPO/-NAO...the temperatures would start to moderate a few days after the arctic unloads, but a +PNA can give us very good storm threats in the east with the energy diving down the backside of the western ridge axis. We also look to stay in average to slightly below average temperatures for a while, which is plenty cold in mid-January to get some decent snows. Even slightly above average wouldn't be terrible.

I was assuming he was talking about nationally, not just his location in FL, but maybe I"m wrong. The reason for the removal of strong cold nationally is all due to the AK situation, as I outlined. That's what's being modeled at least. We'll see if it is real. And no, I never said that ends winter threats.

[pcbjr]

I was assuming he was talking about nationally, not just his location in FL, but maybe I"m wrong. The reason for the removal of strong cold nationally is all due to the AK situation, as I outlined. That's what's being modeled at least. We'll see if it is real. And no, I never said that ends winter threats.

No, I was not being Florida specific. Of course, my neck of the woods always interests me, but I was looking at models showing a generally milder set of conditions throughout the south east and into the mid-Atlantic, and was wondering why with a positive PNA forcasted (which I understand to mean: "The positive phase of the PNA pattern is associated with above-average temperatures over western Canada and the extreme western United States, and below-average temperatures across the south-central and southeastern U.S." - CPC), and with the AO still negataive, and the NAO rising but looking like it may not go very positive, if at all, then why the teleconnections don't support at least cool to cooler than normal temps for the next 15 - 20 days for the east and southeast in general.

I've gotten an answer, thanks to you all, and of course, solicit even more info/education if anyone is inclined.

Thanks!

[wxmx]

I'm on the other side of the fence. Looks like a real threat for a high amplitude MJO wave and anomalous (non Niña like) area of tropical forcing, with -OLR anomalies near the dateline. If the wave is nearly as strong as progged, I really doubt the Pacific will become unfavorable for cold, specially for east of the Rockies. Yes, there will be a moderation of the -AO/-NAO, but come on, that's a given looking how we are at near record levels...And the PV in all levels is rather weak, and I doubt it will strengthen enough to keep it from spilling more cold air masses to the south. As a matter of fact, there's a window of opportunity for a significant snow event in the East coast for late Jan to early Feb.

MJO forecast, rather impressive because of the consensus and being mostly based on ensembles.

Indonesia goes from -OLR to mostly +OLR...that will probably help the STJ

[Big O]

I'm on the other side of the fence. Looks like a real threat for a high amplitude MJO wave and anomalous (non Niña like) area of tropical forcing, with -OLR anomalies near the dateline. If the wave is nearly as strong as progged, I really doubt the Pacific will become unfavorable for cold, specially for east of the Rockies. Yes, there will be a moderation of the -AO/-NAO, but come on, that's a given looking how we are at near record levels...And the PV in all levels is rather weak, and I doubt it will strengthen enough to keep it from spilling more cold air masses to the south. As a matter of fact, there's a window of opportunity for a significant snow event in the East coast for late Jan to early Feb.

MJO forecast, rather impressive because of the consensus and being mostly based on ensembles.

Indonesia goes from -OLR to mostly +OLR...that will probably help the STJ

What does this translate to in terms of sensible weather? Does this have any effect on the AO, NAO, EPO, or PNA? Thanks in advance, Jorge.

[wxmx]

What does this translate to in terms of sensible weather? Does this have any effect on the AO, NAO, EPO, or PNA? Thanks in advance, Jorge.

Most likely, the main effects will be felt in the Pacific side. Tropical forcing near the dateline promotes an Aleutian low, which will enhance a ridge down wind, that is, in the Pac coast of North America... so the main index affected will be those of Pacific origin, PNA for example and, to a lesser degree, the EPO. Also a more active STJ is possible.

The AO and NAO are not as strongly correlated, and even then, they have been more strongly affected by other factors this year, which will persist, and I think will inhibit any extreme change of the pattern in the high latitudes to distinctly positive in both indices. My thinking is that high latitude ridging will subside a bit, but then have a new go for negative, starting late Jan.

[donsutherland1]

A record courtesy of the blocking:

000
NOUS41 KCAR 100626
PNSCAR
MEZ001>006-010-011-015>017-029>032-101830-

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CARIBOU ME
130 AM EST SUN JAN 10 2011

...LATEST DATE FOR BELOW ZERO TEMPERATURE READINGS AT CARIBOU ME...

HISTORICALLY...THE RECORD LATEST DATE FOR THE CARIBOU ME AREA TO
EVER REACH ZERO DEGREES FAHRENHEIT OR COLDER WAS JANUARY 4, 2002
WHEN THE MERCURY DROPPED TO MINUS 3 DEGREES FAHRENHEIT. WITH NO
PROSPECTS OF DROPPING INTO THE NEGATIVE REALM IN THE NEAR
FUTURE...THAT RECORD HAS BEEN BROKEN WITH A POSITIVE ONE DEGREE
READING ON DECEMBER 18, 2010 BEING THE COLDEST CARIBOU HAS SEEN TO
DATE.

ALSO TO NOTE...THE WINTER OF 2009-2010 WAS A RECORD YEAR FOR THE
LEAST NUMBER OF DAYS WITH A MINIMUM TEMPERATURE LESS THAN OR EQUAL
TO ZERO WITH A TOTAL OF 17 DAYS FOLLOWED BY THE WINTER OF 2001-2002
WITH 18 DAYS.

THE EARLIEST THAT CARIBOU HAS SEEN THE TEMPERATURE DROP BELOW ZERO
WAS NOVEMBER 21 1959 WITH A MORNING LOW OF -1F. THE HIGHEST NUMBER
OF DAYS WITH TEMPERATURES AT OR BELOW ZERO OCCURRED IN THE WINTER OF
1971-1972 WHEN THE MARK WAS REACHED A TOTAL OF 64 TIMES.

CLIMATOLOGICALLY...THE COLDEST PART OF THE WINTER IS
APPROACHING...WITH A NORMAL MINIMUM TEMPERATURE OF -1F FROM JANUARY
13 TO FEBRUARY 1. THE LOWEST DAILY AVERAGE TEMPERATURE OF 9F IS
NORMALLY BETWEEN JANUARY 11 AND JANUARY 29. THE NORMAL MAXIMUM
TEMPERATURE OF 19F IS FOUND BETWEEN JANUARY 7 AND 28...ALTHOUGH
THERE IS LITTLE THREAT TO THESE NORMALS BEING SKEWED DOWNWARD WITH
FORECAST TEMPERATURES TO RANGE FROM MID TO UPPER 20S FOR HIGHS AND
TEENS FOR LOWS FOR THE NEXT 4-5 DAYS.

RESCHKE/RAHE

[BucksCO_PA]

A record courtesy of the blocking:

000
NOUS41 KCAR 100626
PNSCAR
MEZ001>006-010-011-015>017-029>032-101830-

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CARIBOU ME
130 AM EST SUN JAN 10 2011

...LATEST DATE FOR BELOW ZERO TEMPERATURE READINGS AT CARIBOU ME...

HISTORICALLY...THE RECORD LATEST DATE FOR THE CARIBOU ME AREA TO
EVER REACH ZERO DEGREES FAHRENHEIT OR COLDER WAS JANUARY 4, 2002
WHEN THE MERCURY DROPPED TO MINUS 3 DEGREES FAHRENHEIT. WITH NO
PROSPECTS OF DROPPING INTO THE NEGATIVE REALM IN THE NEAR
FUTURE...THAT RECORD HAS BEEN BROKEN WITH A POSITIVE ONE DEGREE
READING ON DECEMBER 18, 2010 BEING THE COLDEST CARIBOU HAS SEEN TO
DATE.

ALSO TO NOTE...THE WINTER OF 2009-2010 WAS A RECORD YEAR FOR THE
LEAST NUMBER OF DAYS WITH A MINIMUM TEMPERATURE LESS THAN OR EQUAL
TO ZERO WITH A TOTAL OF 17 DAYS FOLLOWED BY THE WINTER OF 2001-2002
WITH 18 DAYS.

THE EARLIEST THAT CARIBOU HAS SEEN THE TEMPERATURE DROP BELOW ZERO
WAS NOVEMBER 21 1959 WITH A MORNING LOW OF -1F. THE HIGHEST NUMBER
OF DAYS WITH TEMPERATURES AT OR BELOW ZERO OCCURRED IN THE WINTER OF
1971-1972 WHEN THE MARK WAS REACHED A TOTAL OF 64 TIMES.

CLIMATOLOGICALLY...THE COLDEST PART OF THE WINTER IS
APPROACHING...WITH A NORMAL MINIMUM TEMPERATURE OF -1F FROM JANUARY
13 TO FEBRUARY 1. THE LOWEST DAILY AVERAGE TEMPERATURE OF 9F IS
NORMALLY BETWEEN JANUARY 11 AND JANUARY 29. THE NORMAL MAXIMUM
TEMPERATURE OF 19F IS FOUND BETWEEN JANUARY 7 AND 28...ALTHOUGH
THERE IS LITTLE THREAT TO THESE NORMALS BEING SKEWED DOWNWARD WITH
FORECAST TEMPERATURES TO RANGE FROM MID TO UPPER 20S FOR HIGHS AND
TEENS FOR LOWS FOR THE NEXT 4-5 DAYS.

RESCHKE/RAHE

Don - Caribou recorded their warmest winter on record last season, around +8?

unfortunately they're ahead of that pace as we close in on the half-way point of Met winter, +8.8 for DEC & +12.9 through JAN

[Kennethb]

AO forecasted to get close to 0 before tanking again.