My Winter Outlook 2011-12

[Isotherm]

Can be found on my website:

http://www.lightinthestorm.com/archives/420

Past winter/summer outlooks are also archived on there.

[griteater]

Awesome write-up. As well thought out and written as any I've ever seen for a winter outlook.

[HM]

Awesome write-up. As well thought out and written as any I've ever seen for a winter outlook.

I agree. I love how succinct it is and thought out. He skips the nonsense!

Isotherm, I agree about more of a ridge in the south this winter than the last 2. Some of these monthly departure maps are going to look funny. Who would ever predict a monthly departure map that looks like Dec 1954?

When the western Canadian vortex takes over and we lose the block, it won't just be a SE ridge warm shot either. It will be many people who go above normal. It is a good thing for cold and snow lovers that the IMF is still weak.

[tacoman25]

So just out of curiousity, why did you choose to make January warmer and February cooler than last winter (in the East)?

[Bob Chill]

Good writeup. Enjoyed it very much. Everything I've been looking at too points to a cold to very cold December in the E.

One thing that concerns me is no mention of soil moisture.

[Redmorninglight]

Great job, Tom. I gained a better understanding about the cycles of the sun and the impacts on the winter weather. I assume you are looking for the PNA to be rather negative given the maps posted. It has been amazing what the NOA/AO couplet has compensated for over the past 2 winters.

[usedtobe]

I agree, really a nice write up. I'm not good enough to know which month will be the warmest between jan and feb but your reasoning to me is good. Your december cold certinaly would fit HM's 50 mb qbo signal idea.

[uncle W]

good luck!... I hope it works out...

[OKpowdah]

Nice write up!! Our January temp maps certainly look very different, but I think it comes down to timing and magnitude of the thaw.

I really don't understand any of the solar stuff. I keep meaning to try to read up on some of it, but it never happens lol. I love reading your outlooks though, because here and there I can pick up a few things, and the originality of your methods is a great addition to long range forecasting.

One quick question: why is there a 1 to 1.5 year lag in the NAO-geomagnetic correlation?

One nit picky thing: you mention the negative AAO this summer may suggest a similar pattern in the NH this winter, but last summer, the AAO was near record positive levels, prior to a near record negative AO the next winter, which you used as your greatest example of applying the geomagnetic correlation.

[bluewave]

Tom, very nice write up and presentation. It will be interesting to see how things work out this winter.

[Ginx snewx]

Excellent writeup. Picky question no EPO discssion, what are your thoughts on the EPO and its relativity to NAO

[Isotherm]

Thank you everyone for the kind words!

I agree. I love how succinct it is and thought out. He skips the nonsense!

Isotherm, I agree about more of a ridge in the south this winter than the last 2. Some of these monthly departure maps are going to look funny. Who would ever predict a monthly departure map that looks like Dec 1954?

When the western Canadian vortex takes over and we lose the block, it won't just be a SE ridge warm shot either. It will be many people who go above normal. It is a good thing for cold and snow lovers that the IMF is still weak.

Thanks HM! And I agree about the departure map. I think especially for January and February, part of each month will be very warm in the East while another part will be quite cold. To be honest I'm actually concerned I went to warm for Feb w/ near normal in the NYC area; I see Jan with potentially a 2 week blowtorch period.

So just out of curiousity, why did you choose to make January warmer and February cooler than last winter (in the East)?

Thanks! Looking at tropical forcing I felt the period late Jan-mid Feb was favorable for another negative NAO and storminess in the East. The timing of it IMO may cut February literally in half, with the first 15 days cold and the second half much warmer. Should be interesting.

I agree, really a nice write up. I'm not good enough to know which month will be the warmest between jan and feb but your reasoning to me is good. Your december cold certinaly would fit HM's 50 mb qbo signal idea.

Thanks a lot! Your forecast is always one I love to read, and think your LR skills are some of the best I've seen.

Nice write up!! Our January temp maps certainly look very different, but I think it comes down to timing and magnitude of the thaw.

I really don't understand any of the solar stuff. I keep meaning to try to read up on some of it, but it never happens lol. I love reading your outlooks though, because here and there I can pick up a few things, and the originality of your methods is a great addition to long range forecasting.

One quick question: why is there a 1 to 1.5 year lag in the NAO-geomagnetic correlation?

One nit picky thing: you mention the negative AAO this summer may suggest a similar pattern in the NH this winter, but last summer, the AAO was near record positive levels, prior to a near record negative AO the next winter, which you used as your greatest example of applying the geomagnetic correlation.

Thanks! Yeah the timing I thought w. tropical forcing and nao periods favored the bulk of Jan being warmer, and the next cold period lasting a good deal of Feb.

Re the AAO, although last winter the correlation didn't work, I've found that most years since 1980 which featured a -AAO summer (in the sern hemishere) featured a -NAO/AO in the ensuing nern hem winter. Like any correlation, its not perfect, but I'd estimate about a 0.6-0.65 correlation with it.

[Isotherm]

Excellent writeup. Picky question no EPO discssion, what are your thoughts on the EPO and its relativity to NAO

Thanks! I expect a fairly strong Aleutian High this winter given the -ENSO/-PDO; however, it should be similar to last winter in that tis displaced further northeast than normal for a mod+ Nina year. The nern hemispheric blocking (-NAO/AO) could connect with the Alaskan block at times, particularly December and late Jan into Feb, when a cross polar flow may develop.

[hiker]

Isotherm,

This is a superbly logical, easily understood write-up.

Thanks!

[Lee]

Good overall scientific writeup. However, a couple questions for you. Given the analogues you used, just curious to why you extended the warmth further north and east to cover the entire SE and up into the lower MA as those composites suggest normal to slightly below for much of said area.

Are you thinking the blocking will be weaker than last winter, as many are,and thus your warmer outlook for the southern tier?

My other question is, would not a weaker Nina than last winter's negate the weaker blocking(if that's your reasoning) and therefore pretty much balance out and produce something akin to last winter?

[Matt Rogers]

Excellent forecast discussion! I agree that blocking looks more favorable than not. 2008-09 DJF NAO was only -0.1, so it was quite a close call that particular year.

I noticed that when you showed your top three analogs, you compared against a 1950-1995 normal benchmark instead of the 1981-2010 latest NOAA 30Y normal. I believe you may find a colder answer against the new normals, particularly for the Deep South too (0 to +1 instead) unless maybe your DJF national map is also against the 1950-95 baseline?

[phlwx]

Excellent forecast discussion! I agree that blocking looks more favorable than not. 2008-09 DJF NAO was only -0.1, so it was quite a close call that particular year.

I noticed that when you showed your top three analogs, you compared against a 1950-1995 normal benchmark instead of the 1981-2010 latest NOAA 30Y normal. I believe you may find a colder answer against the new normals, particularly for the Deep South too (0 to +1 instead) unless maybe your DJF national map is also against the 1950-95 baseline?

Have they reformulated the NAO index at some point? The first link below and second link have different values (looks like the ESRL link has a more "intense" variation than the CPC link...I'm just curious when that was done).

http://www.esrl.noaa...lation/nao.data

http://www.cpc.ncep....ent.ascii.table

[Matt Rogers]

Interesting! I hadn't seen the ESRL data set there.

Well, I agree it was a -NAO year, but just not as strong as the other cases:

[Isotherm]

Isotherm,

This is a superbly logical, easily understood write-up.

Thanks!

Thanks for the nice compliment!

Good overall scientific writeup. However, a couple questions for you. Given the analogues you used, just curious to why you extended the warmth further north and east to cover the entire SE and up into the lower MA as those composites suggest normal to slightly below for much of said area.

Are you thinking the blocking will be weaker than last winter, as many are,and thus your warmer outlook for the southern tier?

My other question is, would not a weaker Nina than last winter's negate the weaker blocking(if that's your reasoning) and therefore pretty much balance out and produce something akin to last winter?

Thanks, and re the deviation from analog years; I expect the southern ridge to be more bullish overall this year, with Jan and Feb both being fairly mild months in the SE. While the Nina will be weaker than last winter, I think it'll still be moderate intensity. Also recall last January had a +PNA which allowed the Southeast to end up fairly cold, and December 2011 had a strong -NAO/AO. This winter I don't anticipate the prolonged +PNA surge in January. Given a -PNA, it's much more difficult to get sustained cold from the lower middle atlantic southward.

So it's not that I think blocking will be much weaker, but January as feb should be warm (unlike last winter) from the lower mid atlantic southward.

Excellent forecast discussion! I agree that blocking looks more favorable than not. 2008-09 DJF NAO was only -0.1, so it was quite a close call that particular year.

I noticed that when you showed your top three analogs, you compared against a 1950-1995 normal benchmark instead of the 1981-2010 latest NOAA 30Y normal. I believe you may find a colder answer against the new normals, particularly for the Deep South too (0 to +1 instead) unless maybe your DJF national map is also against the 1950-95 baseline?

Thanks for the kind words!

I just prefer using the 1950-1995 baseline as I think comparing to the 1980-2010 averages skews the composite a bit too cold. The 1950-1995 period is also a longer time frame and encompasses more of each decadal phases (+PDO, -PDO, +AMO, -AMO, etc).

[ineedsnow]

wow great job and nice effort!!

[mattie g]

Excellent writeup, Isotherm. It was very easy for a complete novice like me to understand, yet I'm sure the more experienced and learned weather types will feel like your method and explanation scratch the itch that is their scientific curiosity.

One little nitpick for MBY...you state that the I-95 corridor is looking at above-normal snowfall, yet you note below that your call for DC is 13-18". That's essentially normal (or even below normal, in IAD's case). Again...just a small nitpick in an otherwise fantastic writeup.

[NYsnowlover]

I think that he is expecting that there will be a strong snowfall gradient this winter.

Excellent writeup, Isotherm. It was very easy for a complete novice like me to understand, yet I'm sure the more experienced and learned weather types will feel like your method and explanation scratch the itch that is their scientific curiosity.

One little nitpick for MBY...you state that the I-95 corridor is looking at above-normal snowfall, yet you note below that your call for DC is 13-18". That's essentially normal (or even below normal, in IAD's case). Again...just a small nitpick in an otherwise fantastic writeup.

[Isotherm]

wow great job and nice effort!!

Thanks!

Excellent writeup, Isotherm. It was very easy for a complete novice like me to understand, yet I'm sure the more experienced and learned weather types will feel like your method and explanation scratch the itch that is their scientific curiosity.

One little nitpick for MBY...you state that the I-95 corridor is looking at above-normal snowfall, yet you note below that your call for DC is 13-18". That's essentially normal (or even below normal, in IAD's case). Again...just a small nitpick in an otherwise fantastic writeup.

Thanks. To be honest that range was forecasted with the mindset DCA usually underreports / is the lowest station in the area in terms of snowfall. I expect most of the DC/BWI area to be 18"+ and IAD likely in the 23-28" range.

[CoastalWx]

Nice forecast isotherm. Really put together well. Good luck!

[Lee]

Thanks for the nice compliment!

Thanks, and re the deviation from analog years; I expect the southern ridge to be more bullish overall this year, with Jan and Feb both being fairly mild months in the SE. While the Nina will be weaker than last winter, I think it'll still be moderate intensity. Also recall last January had a +PNA which allowed the Southeast to end up fairly cold, and December 2011 had a strong -NAO/AO. This winter I don't anticipate the prolonged +PNA surge in January. Given a -PNA, it's much more difficult to get sustained cold from the lower middle atlantic southward.

So it's not that I think blocking will be much weaker, but January as feb should be warm (unlike last winter) from the lower mid atlantic southward.

Thanks for the kind words!

I just prefer using the 1950-1995 baseline as I think comparing to the 1980-2010 averages skews the composite a bit too cold. The 1950-1995 period is also a longer time frame and encompasses more of each decadal phases (+PDO, -PDO, +AMO, -AMO, etc).

Thanks Tom.

I'm still unclear on why you think the PNA will be more neg. this winter than last.( I agree whole heartily about the PNA and how hard it is to get the cold into the se. with it in the neg. phase). You mentioned a similar north pacific setup will be the case this winter. So, why would you think the PNA is more likely to be negative than last?

I agree that it should be mainly negative given the pacific setup and that last year's rather unusual +PNA duration under this setup would be unlikely to repeat. If that's your reasoning then that's basically all I'm asking as I'm just trying to decipher different forecasters ideas, logic, etc..

[mattie g]

Thanks. To be honest that range was forecasted with the mindset DCA usually underreports / is the lowest station in the area in terms of snowfall. I expect most of the DC/BWI area to be 18"+ and IAD likely in the 23-28" range.

Gotcha - makes sense.

Good luck with the forecast!

[Isotherm]

Nice forecast isotherm. Really put together well. Good luck!

Thank you!

Thanks Tom.

I'm still unclear on why you think the PNA will be more neg. this winter than last.( I agree whole heartily about the PNA and how hard it is to get the cold into the se. with it in the neg. phase). You mentioned a similar north pacific setup will be the case this winter. So, why would you think the PNA is more likely to be negative than last?

I agree that it should be mainly negative given the pacific setup and that last year's rather unusual +PNA duration under this setup would be unlikely to repeat. If that's your reasoning then that's basically all I'm asking as I'm just trying to decipher different forecasters ideas, logic, etc..

Lee, I think the PDO will be more negative this winter compared to 10/11. Values for the past few months are fairly significantly lower than 2010 at this time. Last winter hovered around -1 for the PDO; I'm expecting -1.5 to -2 this winter. A more strongly negative PDO almost seals the deal for very infrequent +PNA surges, making the pattern this winter more unfavorable for the SE US. Hopefully that helps answer your question.

Gotcha - makes sense.

Good luck with the forecast!

Thanks!

[Lee]

Thank you!

Lee, I think the PDO will be more negative this winter compared to 10/11. Values for the past few months are fairly significantly lower than 2010 at this time. Last winter hovered around -1 for the PDO; I'm expecting -1.5 to -2 this winter. A more strongly negative PDO almost seals the deal for very infrequent +PNA surges, making the pattern this winter more unfavorable for the SE US. Hopefully that helps answer your question.

Thanks!

Appreciate it Tom! Does make sense. Even if we were to get extreme blocking the storm track would most likely be further north in response to the enhanced -PDO. Good work man!

[Tropical]

You failed both last winter and this past summer. And coincidentally this forecast looks almost identical to those failed two.

[andyhb]

You failed both last winter and this past summer. And coincidentally this forecast looks almost identical to those failed two.

Coming from you?

Need I remind you of this?

I'm gonna say this winter will be mild and relatively snowless.

There are two reasons I'm going this route:

1) Leaves are changing color rapidly and already dropping. 07-08, 08-09, and 10-11 autumns had late leaf drop ... collection was extended up to Thanksgiving because the trees would not release the leaves. I was looking over pictures from 2009 and the trees in my backyard were 100% green on October 10th. Today they are completely yellow and half bare.

"When leaves fall early it will be a mild fall and winter."

2) Wooly bears have a large orange stripe this fall. Almost no black on the ones I've seen thus far.

"If there is a narrow orange band in the middle of the Woolly Bear caterpillar, it warns of heavy snow."

If I'm wrong, I'm wrong, but this is my guess for the winter. Time for someone to go against analogs and ENSO and throw something else on to the plate.