Medium Range Discussion Winter 2011-12

[nzucker]

For those who are interested, the dreary CFSv2 forecast for February 2012 is below:

At this point in time, the CFSv2 has frequently demonstrated a degree of skill with regard to the following month's forecast.

Looks very cold globally but the PV is going to shift over to Asia, which will leave Canada torched as all models show.

[wxmx]

Don, great work. It looks like our concerns (you me Adam and others) for the warmth to return as we start February is becoming legitimate. Having said that, the PNA spike may allow for a brief window of cold / wintry weather Superbowl Weekend. We'll see how the tropical forcing behaves over the next week to see if any push out of the phase 4-6 area will allow for a better assault at the PV in Alaska.

I was too fast with the cold return, as I thought it would make a reappearance by very late Jan into early Feb.., but I still think there's a good chance the warmth will be short-lived. Tropical forcing in the IO region is going to die out, with a rather strong wave moving over the Indonesia region, and probably a dampened one will make it's way to the dateline. That will probably weaken the Aleutian high a good deal, and allow the Alaskan PV to be scoured, allowing for fresh arctic air to replenish the Canadian prairies. But just before that, modeling is showing a nice +PNA pattern, and if the -EPO and +PNA overlap, that would bring a 180 degrees turnaround to the current winter in some places, especially the eastern half.

The GFS (both the op and the ens) modeling is being a bit more adamant showing the above scenario in the 10+ days timeframe, though confidence is low wrt AK PV moving out of the way.

MJO gaining substantial amplitude in most models and making progress towards phase 8 is looking good...but can it make it? The Nina wall might have a word, though a KW moving thru (is there one?) could give credence to the forecast.

Finally, the CFS CHI forecasts don't show that much orange in the Pac basin, as it has been showing most of the winter:

[usedtobe]

FWIW, the Euro weeklies are showing a shot for the Northeast in Week 2 (Feb 6-12), coincident with the expected response from tropical convection heading to 160-170E around the same period. Weeks 3 and 4 are ugly though.

I think the 6-12 period looks reasonable but think I can already see signs of the PNA pattern getting ready to retrograde back to a negative PNA. That's what the CFS2 does.

[am19psu]

I think the 6-12 period looks reasonable but think I can already see signs of the PNA pattern getting ready to retrograde back to a negative PNA. That's what the CFS2 does.

Yeah, Weeks 3-4 are +EPO/-PNA all over again.

[usedtobe]

Yeah, Weeks 3-4 are +EPO/-PNA all over again.

But we have feb 5-11 which is looking interesting.

[donsutherland1]

But we have feb 5-11 which is looking interesting.

I agree. The initial look at the February 8-15 timeframe overall is providing me with more cold scenarios for the East than warm ones. I'll post my thoughts for that period on Saturday or Sunday. But it is a welcome change to see data hinting at a cold outcome. There remains some significant uncertainty with respect to the AO, so nothing is cast in stone at present. The month as a whole still looks warmer than normal.

[CoastalWx]

But we have feb 5-11 which is looking interesting.

That could be the best period where the entire East Coast, or a good chunk of it may be vulernable to a storm. The other times may feature more Miller B redevelopers or clippers, but that timeframe seems to want to develop some sort of potential from RIC-DC on north. As usual, details TBD.

[usedtobe]

I agree. The initial look at the February 8-15 timeframe overall is providing me with more cold scenarios for the East than warm ones. I'll post my thoughts for that period on Saturday or Sunday. But it is a welcome change to see data hinting at a cold outcome. There remains some significant uncertainty with respect to the AO, so nothing is cast in stone at present. The month as a whole still looks warmer than normal.

I agree about the month as a whole but do like the look of the feb 5 or 6 to the feb 11 or 12 period.

[CoastalWx]

I agree. The initial look at the February 8-15 timeframe overall is providing me with more cold scenarios for the East than warm ones. I'll post my thoughts for that period on Saturday or Sunday. But it is a welcome change to see data hinting at a cold outcome. There remains some significant uncertainty with respect to the AO, so nothing is cast in stone at present. The month as a whole still looks warmer than normal.

The NAO is likely staying at least neutral to positive. Other than a hint of ridging here or there, I don't see it going negative anytime soon. This seems to be all PNA driven. I noticed the euro ensembles do try to squeeze in some faint ridging in ne Greenland, but that's a stretch.

[Ottawa Blizzard]

JB seems to be hinting at a big comeback for winter for February and March. Personally I think he's grasping at straws, just as he did in 2001-2002. DT seems to think JB's outlook is a joke and that he's just seeing what he wants to see. This winter could very well rank up in the top 5 snowless in Toronto.

[Feb]

JB seems to be hinting at a big comeback for winter for February and March. Personally I think he's grasping at straws, just as he did in 2001-2002. DT seems to think JB's outlook is a joke and that he's just seeing what he wants to see. This winter could very well rank up in the top 5 snowless in Toronto.

That's ironic since DT had to change his underwear the other week after the 12z GFS showed snowstorm after snowstorm with arctic cold air for the east. That was back when DT was still on the cold bandwagon. He was seeing what he wanted to see. Now he accuses others of doing what he has ALL winter.

[HM]

I was too fast with the cold return, as I thought it would make a reappearance by very late Jan into early Feb.., but I still think there's a good chance the warmth will be short-lived. Tropical forcing in the IO region is going to die out, with a rather strong wave moving over the Indonesia region, and probably a dampened one will make it's way to the dateline. That will probably weaken the Aleutian high a good deal, and allow the Alaskan PV to be scoured, allowing for fresh arctic air to replenish the Canadian prairies. But just before that, modeling is showing a nice +PNA pattern, and if the -EPO and +PNA overlap, that would bring a 180 degrees turnaround to the current winter in some places, especially the eastern half.

I agree that the MJO progression beyond phase 7 is becoming more and more likely, too.

[CoastalWx]

I agree that the MJO progression beyond phase 7 is becoming more and more likely, too.

Impressed with what the models showed today.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

[Ottawa Blizzard]

That's ironic since DT had to change his underwear the other week after the 12z GFS showed snowstorm after snowstorm with arctic cold air for the east. That was back when DT was still on the cold bandwagon. He was seeing what he wanted to see. Now he accuses others of doing what he has ALL winter.

You know, I have to say that DT isn't a very diplomatic person. While I know JB can sometimes bash the NWS, I don't think he's ever bashed another met by name like DT has.

I should add that while I think JB may be grasping at straws, I do not think he's a joke, like DT has publically announced on FB.

[CoastalWx]

While all models agree on the PNA spike, we just have to make sure that the amplitude doesn't start to diminish as we get closer, thanks to the AO. The PV is modeled to retrograde, but something to watch going forward. So far, it seems all models are pretty bullish with this ridge across NAMR.

[easternsnowman]

You know, I have to say that DT isn't a very diplomatic person. While I know JB can sometimes bash the NWS, I don't think he's ever bashed another met by name like DT has.

I should add that while I think JB may be grasping at straws, I do not think he's a joke, like DT has publically announced on FB.

I like to see dt call jb a joke to his face!

[wxmx]

While all models agree on the PNA spike, we just have to make sure that the amplitude doesn't start to diminish as we get closer, thanks to the AO. The PV is modeled to retrograde, but something to watch going forward. So far, it seems all models are pretty bullish with this ridge across NAMR.

I think the key will be the tropical forcing. It looks like there will be a high amplitude MJO wave that will move past Indonesia. That would enhance the Aleutian trough and pump a ridge downstream. By that time we already have a +PNA ridge, so it would morph it into a very high amplitude ridge into AK (-EPO), assaulting and finally scouring the AK low, establishing a cross polar flow, with frigid air in our part of the world. 12z GFS shows this very well, with cold after cold and a huge area of -30C 850mb in Canada.

It gets more likely that we'll get past phase 7 at a decent amplitude, that's where the fireworks begin:

[bluewave]

We have a shot at the first La Nina winter since 1950 in which each month has a positive PNA.

Though DEC/JAN 2001 was more strongly positive, February finally entered slightly

negative territory. The models kept backing off the negative forecasts.

[Srain]

I think the key will be the tropical forcing. It looks like there will be a high amplitude MJO wave that will move past Indonesia. That would enhance the Aleutian trough and pump a ridge downstream. By that time we already have a +PNA ridge, so it would morph it into a very high amplitude ridge into AK (-EPO), assaulting and finally scouring the AK low, establishing a cross polar flow, with frigid air in our part of the world. 12z GFS shows this very well, with cold after cold and a huge area of -30C 850mb in Canada.

It gets more likely that we'll get past phase 7 at a decent amplitude, that's where the fireworks begin:

I agree, Jorge. I still believe from the Intermountain West and points E, winter has not ended and in fact, the boring pattern will transition to an active regime, albeit brief, and will deliver the goods.

[winterymix]

Does the image below reflect the discussion immediately above?

If so, the east trough moderates quickly in later periods so therefore,

this seems to be a quick shot of cold along with blocking and then the

zonal flow tries to come back.

[wxmx]

Does the image below reflect the discussion immediately above?

If so, the east trough moderates quickly in later periods so therefore,

this seems to be a quick shot of cold along with blocking and then the

zonal flow tries to come back.

Well, there's ridging in AK, and a 1050+mb high coming down at that time...it's a setup for cold shallow and overruning pattern.

[winterymix]

Well, there's ridging in AK, and a 1050+mb high coming down at that time...it's a setup for cold shallow and overruning pattern.

Sounds about right. Winter tries to assert itself with partial success. It still seems that on the East coast,

we're really simply having three seasons this year, spring, summer and late fall-early spring.

[wxmx]

Another tease/false hope (especially from the Atlantic side)?

[CoastalWx]

EC op is probably too strong with that block, and no surprise that an hr 240 op prog is weenie-ish. The ensembles did have a little more of -NAO ridging than its previous runs.

[donsutherland1]

Today, the AO had fallen to -3.230. That is its lowest reading since January 12, 2011 when the AO was -3.297. The decline of the AO to -3.000 or below offers an indication that the AO will likely average < 0 in February. Since 1950, there have been 7 cases on which the AO fell to -3.000 or below for the first time in January on or after January 20. In 6/7 (86%) of those cases, the February AO averaged < 0. In 4/7 (57%) of those cases, the February AO averaged < -1.

Unfortunately, those outcomes do not necessarily indicate a cold February is in store for the East, much less across the U.S. and most of southern Canada. For five of those cases, the January AO averaged above -1. January 2012 will represent the sixth such case. Through January 28, the AO has averaged +0.231. The five prior cases in question were: 1952, 1954, 1986, 2003, and 2005. The composite for those five cases was milder anomalies across almost the entire CONUS and southern Canada.

Of course, a caveat is that the sample size is very small.

[Ottawa Blizzard]

Don, what do you think of JBs thoughts for a cold February?

From his twitter page:

http://www.weatherbell.com/saturday-summary--january-28-2012

[TNE]

The -AO and increasing +PNA might be a good combo for Cold Air in the East. Latest GFS is showing a sustained Upper Trough over the East from the 6-13 of February. Could be the first one of this winter and might be a strong signal for Cold Air when another Cut-Off tries to make it up the East Coast.

[Nic]

ILN

.LONG TERM /TUESDAY THROUGH SATURDAY/...

-- Changed Discussion --

PERIOD BEGINS WITH REGION IN SLY FLOW ON THE BACKSIDE OF HIGHPRESSURE. MODELS ARE CONSISTENT IN SWINGING A CDFNT OUT OF THEPLAINS TUESDAY NIGHT. THE FRONT WILL PRODUCE AN AREA OF SHOWERS TUENIGHT INTO EARLY WED AS IT SWINGS THRU. THE 12Z ECMWF HAS COME INMUCH SLOWER IN ENDING THE PCPN ON WED AS IT LINGERS PCPN MUCH OF THEDAY WED AS IT WORKS A SECONDARY TROF THRU. THIS LOOKS OVER DONE.PREFER THE QUICKER 12Z GFS AND NAM/00Z ECMWF SOLUTION.MODELS DIVERGE QUICKLY FOR THURSDAY. THE 12Z GFS BUILDS IN A WEAKAREA OF HIGH PRESSURE. THE 00Z ECMWF AND THE 12Z CMC HEMISPHERICDEVELOP A WAVE ON THE FNT IN KY AND PUSH AN AREA OF PCPN ACROSS THEREGION. THE 12Z ECMWF NOW HAS HIGH PRESSURE ACROSS THE REGION AFTERLINGERING THE PCPN LONGER ON WED. THE 00Z EC SOLUTION LOOKS THE MOSTREASONABLE SO WENT CHC POP ON THURSDAY.MODELS DEVELOP A H5 TROF OVER THE ROCKIES LATE IN THE WEEK...AND ASFC LOW DEVELOPS IN THE LOWER MS VALLEY IN RESPONSE. MODELS DIFFERIN HOW FAR NORTH THE PCPN WITH THIS SYSTEM WILL WORK...SO KEPTTHINGS DRY FOR NOW.RAN A BLEND OF GFS AND HPC TEMPERATURES THROUGH THE PERIOD. THISKEEPS TEMPERATURES ABOVE NORMAL AND WARM ENUF FOR RAIN THROUGH THEPERIOD.

-- End Changed Discussion --

Ok ILN you can't have all these cold fronts and troughs with above normal temps. Choose one or the other. lol

This discussion makes no sense to me.

[WestMichigan]

ILN

Ok ILN you can't have all these cold fronts and troughs with above normal temps. Choose one or the other. lol

This discussion makes no sense to me.

Read it again - They use words like "this looks overdone", "trof over the Rockies"

Do you still have questions?

[BethesdaWX]

Today, the AO had fallen to -3.230. That is its lowest reading since January 12, 2011 when the AO was -3.297. The decline of the AO to -3.000 or below offers an indication that the AO will likely average < 0 in February. Since 1950, there have been 7 cases on which the AO fell to -3.000 or below for the first time in January on or after January 20. In 6/7 (86%) of those cases,

the February AO averaged < 0. In 4/7 (57%) of those cases, the February AO averaged < -1.

Unfortunately, those outcomes do not necessarily indicate a cold February is in store for the East, much less across the U.S. and most of southern Canada. For five of those

cases, the January AO averaged above -1.

January 2012 will represent the sixth such case. Through January 28, the AO has averaged +0.231. The five prior cases in question were: 1952, 1954, 1986, 2003, and 2005. The composite for those five cases was milder

anomalies across almost the entire CONUS and southern Canada.

Of course, a caveat is that the sample size is

very small.

Most of those years show up quite dissimilar to this one, in progression. I've liked the colder February idea this year due to systematic progression coherent with the Sun, while contrary to statistically based methods, I feel it probably could have been seen above the fray if systematic progression had been weighted higher than dissimilar analogs were weighted.

2005/06, 2006/07, 1967/68, and 1898/99 have followed a similar progression broad scale, in my eyes. 3/4 of those were -ENSO, and all had low geomagnetic activity by a big margin.

Now the +PNA looks to set up shop, along with the -AO suggests a colder than avg period is in store for the east, with a -NAO possible further down the road. MJO wave into octant 8 and maybe onward seems to reinforce confidence.