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Rainshadow

Winter 2017-18 Outlook Discussion, The Pool Is Cooler

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In his latest blog Cohen notes that the AO- troposphere is currently uncoupled from strong stratosphere PV. There is no strat disturbance in sight currently. He gives three options: 1) they stay uncoupled, 2) the strat PV eventually weakens or 3) PV remains strong and couples with troposphere. 1 or 2 could lead to a good winter here. 3 would torch.

aerFigure10_14.png

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25 minutes ago, Chubbs said:

In his latest blog Cohen notes that the AO- troposphere is currently uncoupled from strong stratosphere PV. There is no strat disturbance in sight currently. He gives three options: 1) they stay uncoupled, 2) the strat PV eventually weakens or 3) PV remains strong and couples with troposphere. 1 or 2 could lead to a good winter here. 3 would torch.

aerFigure10_14.png

Yup, its a what PV? disaster area out there:

f12.gif.9eca2818649d4cec0699967c6ac71158.gif

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With November likely to be below normal, the region has salvaged half of the winter predictands:

From Mark: October mean minimum temperature and the November mean maximum temperature explained approximately 51
percent of the variance in mean winter temperature.  That is equivalent to a .7 correlation of I have my statistics info correct.

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Updated IRI outlook: slight retrogression of the pattern it seems from October outlook.

DJF18_NAm_tmp.gif.6708cd3f3a9c2e2838b9d4ae4c42365f.gif

DJF18_NAm_pcp.gif.12aa6b906cf47000202a2f3ca43d7899.gif

 

And CPC's outlook:

page2.gif.079c777670e5b3541e4f07ea792c9a36.gif

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Weather.us also has the latest euro seasonal forecast. Looks like 2010/11 with a NAO- start, a stormy january and a feb warm-up.

us_season-en-087-0_modezseason_2017110100_1_5436_528.png

us_season-en-087-0_modezseason_2017110100_2_5436_528.png

us_season-en-087-0_modezseason_2017110100_2_5436_527.png

us_season-en-087-0_modezseason_2017110100_3_5436_528.png

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24 minutes ago, Rainshadow said:

Definitely did not get the corroboration of the October pattern this November as we did last November. 

Help me out here I don't know the reference can you expand?

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3 minutes ago, susqushawn said:

Help me out here I don't know the reference can you expand?

Last November we had the screaming Pacific jet in the eastern Pacific that knocked the stuffing out of an extremely positive PDO; this November a blockier (-wpo / -epo) flow has kept the PDO from tanking.  The PDO value is too close to zero to guarantee it will remain positive for the winter, but the November Pacific pattern is not hurting it.  Positive PDO winters tend to be colder here.

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45 minutes ago, Rainshadow said:

Definitely did not get the corroboration of the October pattern this November as we did last November. 

Locally, we could end up with one of our bigger Oct-->Nov T reversals

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21 minutes ago, Chubbs said:

Locally, we could end up with one of our bigger Oct-->Nov T reversals

Yup.  2007 had 18.8F, 1995 18.3F, 1879 17.8F, 1971 17.4F; eyeballing a few.  Carl probably has a top ten list ready to go.  

BTW I was looking at the warmest third of all winters (23) since 1950 & the greatest Oct/Nov combination temp was a normal October followed by a warm November (7 times).  Second was a warm October followed by a normal November (5 times), after a warm October, if the ensuing November is a bottom third, there were only three occurrences.  A Bottom third November is < 45.5F.

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29 minutes ago, Rainshadow said:

Yup.  2007 had 18.8F, 1995 18.3F, 1879 17.8F, 1971 17.4F; eyeballing a few.  Carl probably has a top ten list ready to go.  

BTW I was looking at the warmest third of all winters (23) since 1950 & the greatest Oct/Nov combination temp was a normal October followed by a warm November (7 times).  Second was a warm October followed by a normal November (5 times), after a warm October, if the ensuing November is a bottom third, there were only three occurrences.  A Bottom third November is < 45.5F.

several of these years have been tossed around already

1947 - 19.1

2007 - 18.8

1995 - 18.3

1879 - 17.8

1951 - 17.7

1971 - 17.4

1984 - 16.9

1910 - 16.9

1882 - 16.5

1920 - 16.4

 

 

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9 hours ago, colonel_kurtz said:

several of these years have been tossed around already

1947 - 19.1 - neutral / 30.6F / 31.7"

                       averaged exactly 0.0C, can't get more enso neutral than that

2007 - 18.8 - strong nina / 36.8F /  6.3"

1995 - 18.3 - weak nina / 31.9F / 65.5"

1879 - 17.8 -  weak nina / 39.7F / n/a

1951 - 17.7 - weak nino /  38.0F / 16.2"

1971 - 17.4 - weak nina / 36.3F / 12.2"

1984 - 16.9 - moderate nina / 34.8F / 16.5"

1910 - 16.9 - moderate nina / 34.1F /  28.9"

1882 - 16.5 - neutral negative / 34.6F / n/a

1920 - 16.4 - weak nina / 37.8F / 13.7"

Average: 35.5F / 23.9"

Median: 35.6F / 16.4"

Current Normals: 35.4F / 22.4"

We are sitting at 15.2F right now.

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Response I wrote to the other Tom on facebook:

It is a step down from October (ok would have been tough to be a step up). There is also the random element that the NAO could go negative, which really was never the case last winter. Since 1950 the warmest winter combos were an average October / warm November which happened 7 times; in second place was a warm October / average November which happened 5 times. Warm October / cold November combo produced a top third winter 3 times and those winters were weak nino and a pair of enso neutral negatives. So getting this November toward or below 45.5F has some merit for a colder winter. Month to date for PHL currently is 48.7F.

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Cohen discusses his winter forecast in his latest blog. One positive for the east coast is unusually low sea ice near Alaska which will tend to favor ridging.

 

seaice2.png

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Since 1950 the coldest winter following a warm October and November was 1985-86 @ 32.7F.  2010-11 was second @ 33.1F.  The coldest winter following a warm October and average November (we are going there) was 2013-14 @ 33.0F.

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