Hints of a Pattern Change to Start Near Mid-November

[donsutherland1]

Among the Halloween candy are some wrapped hints of a pattern change that could begin to evolve around mid-month.

First, the Southern Oscillation Index (SOI) has stormed to a strongly positive reading in recent days:

October 29: +3.20
October 30: +20.30
October 31: +23.00

Considering how strongly positive it has swung and the likelihood it will remain positive or strongly positive for 5 or more days, this is a sign that the a more amplified pattern could begin to evolve around mid-month, give or take a few days.

While that happens, there are also strong hints that the NAO could be negative at that time.

The below animation shows an area of above normal heights that has developed broadly speaking from the Arctic Ocean to the Barents Sea in very recent days. Notice how the deviation has been increasing relative to normal.

<img src="http://www5.wright-weather.com/bb/attachment.php?s=&postid=122126">

This could--emphasis on "could"--be the first seed of new blocking that could develop and retrograde.

Moreover, there is support for just such a development. The GFS ensembles suggest that the NAO will be negative by mid-month or thereabouts. At the same time, they show significant blocking retrograding toward Iceland and Greenland between November 10-15.

The PNA is a tougher call. There are some hints it could be positive or trending positive by mid-month. The slow progression of above normal heights (now currently located in the vicinity of the Gulf of Alaska) also tends to support the idea that the PNA will rebound in the longer-range.

Consequently, during the November 13-18 period, I believe one will see decent amplification and at this point the current configuration of a trough in the West/ridge in the East will be giving way to one that will ultimately lead to a ridge in the West/trough in the East. I don't believe the amplification will immediately give way to that configuration. It might take a few days to perhaps another week or so for that transition to be complete.

So, enjoy the early November warmth in the East. Some shots of cooler air lie ahead as the calendar advances toward mid-month. Then, a pattern change will likely get underway that will bring an end to the general tendency of above normal temperatures that should predominate during the November 1-15 period.

Another treat to be unwrapped is the recent buildup of Northern Hemisphere snowcover. At this time, snowcover has expanded to above normal levels after a very slow start:

<img src="http://www.ssd.noaa.gov/PS/SNOW/ARCHIVE/NHem/ims2003304.gif">

October 2003 is probably at least comparable to October in the following years: 1974, 1977, 1978, 1982, 1985, 1993, 1996, and 1998.

50% of those were snowy winters in the East.

Throw in the ENSO (N or N/W-) and one is left with: 1977, 1978, 1985, 1993, and 1996.

60% of those were snowy winters in the East.

Finally, throw in the QBO (E or E-to-W) and one is left with: 1977, 1993, and 1996.

67% of those were snowy winters in the East.

All said, the recent buildup of snowcover indicates that things remain on track for a winter with normal-to-somewhat above normal snowfall and probably normal-to-somewhat below normal readings in the Mid-Atlantic/Northeast.

Finally, in the last Halloween candy wrapper is Dr. D'Aleo's <b>excellent discussion</b> pertaining to the recent solar activity.

Notice how the recent period of the current solar flux cycle matches closely with that of solar flux cycle 20:

<img src="http://www.intellicast.com/DrDewpoint/Library/1413/CYCLES1923.jpg">

Assuming that this holds true, the recent explosion of solar activity should diminish. Although there might be a gradual rise in solar activity through the winter, it probably should not be so high that the sun would turn out to be the grinch who stole winter as was the case in 2001-02.

For now, enjoy the candy and the sweet warmth of early November. Hints that the warmth will fade, particularly after mid-month are growing as quickly as the leaves are falling.

[wx247]

Thanks for the technical update!

[Stormsfury]

This is an excellent discussion, Don. Something that I base a decision on in the long range has to come from experience. Looking at the setup in the short term, it certainly looks possible that some daily record highs may fall by the wasteside with the setup. There also looks to be a lot of variability (discussed on another thread), or flip-flopping.

If the pattern interchanges quite a bit (the variability), and with the current warm air intrusion across the East, upstream would lead me to believe someone else is experiencing (or will experience) some record cold down the road (That is if we can get a highly amplified ridge/trough couplet).

The month of November, IMHO (but not professional) opinion could end being quite a roller coaster ride.

SF

[StormCrazyIowan]

Well, my October was a roller coaster, will I settle down, or ride again?

[Guest]

Well, my October was a roller coaster, will I settle down, or ride again?

Get ready to ride again Jacki but i think with a bit more in the way of cold temps and Yes Snow!!!!!!!

[wx247]

Speaking of snow I was just noticing how much the snowcover has advanced south into the US since the last map I looked at earlier this week.

[Stephanie]

It's great to see the snow pack building up the way it is.

Those analog years that you were displaying for comparison Don is alittle scary to say the least. It contained 1993 & 1996!

[donsutherland1]

Stephanie,

I should note that the sample for years concerning October snowfall is based on the snowcover map. The text figure for millions of square kilometers of snowcover is not yet out.

Overall, I believe that the recent buildup of snowcover--aided in part by the recent Pacific jet stream bringing moisture into expanding cold air in Canada and now the northern USA--is just another hint that a decent winter is ahead as discussed previously.

Barring some major changes, I don't believe it will be as snowy as last winter but it certainly should be much snowier than 2001-02.

[Colin]

Excellent discussion, Don! This might mean some cold temperatures and maybe even some snow for the East, at least that's what I get out of your discussion.

Thanks, and keep up the excellent work here at Storm2K!

[donsutherland1]

Colin,

I believe that by month's end, you will likely have seen at least a small accumulation of snow. Even cities along the I-95 Corridor from NYC to Boston might well experience at least a trace of snow before November ends and perhaps a little more based on a combination of analogs and the early indications that a pattern evolution could commence around the 11/13-18 period with the new pattern possibly in place by 11/16-25. There can be some shots of cool air before the pattern change, but those will probably be brief in nature and not very harsh.

How quickly the SE Ridge is beaten down will be important, particularly the farther south and east one goes. I believe that will happen before November is finished; it's just a matter of timing.

[Colin]

Thanks for the awesome news Don! I hope you are right! I'm kind of getting out of the winter spirit in this 75° to 80° weather.

But now you got me right back into it!

[therock1811]

what do you see for OH/KY? I hope for snow before Thanksgiving...

[donsutherland1]

Therock1811,

I believe that there is a reasonable chance that Ohio and perhaps parts of Kentucky will have seen a little snow or flurries before Thanksgiving.