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November 2019 General Discussions & Observations Thread


Rtd208
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7 minutes ago, bluewave said:

Looks like the Arctic air mass that dominated the first half of November will be replaced by more of a Pacific one. So any cold we get should be much less intense. Probably have to wait for the next big -EPO drop to see Arctic air again. 
 

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Looks like the end of the month would have a small -epo. NAO looks to stay somewhat negative. Even though PNA is negative would think we could score with that look in mid to late December

4indices.thumb.png.125bb15b10cb9521dc50f40c17edb6a0.png

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4 hours ago, EastonSN+ said:

Looks like the end of the month would have a small -epo. NAO looks to stay somewhat negative. Even though PNA is negative would think we could score with that look in mid to late December

 

It was a very impressive first half of November for early record snow and cold. You can see the beginning of the -EPO relaxation with the North American snow extent peaking. We’ll have to see how the record +IOD interacts with the MJO and El Niño. Even weak El Niño patterns like we have now are usually back-loaded winters with mild Decembers. The one exception to that is getting a -NAO. But we have been in a mild December +NAO streak since 2011.

038AC330-CA7C-4F72-B68F-E9568E3C8B2F.png.9784dd192983a2b7cf33c4e5c5166b98.png

Daily EPO

2019 10 23  -43.21
2019 10 24  -36.14
2019 10 25  -49.33
2019 10 26 -193.78
2019 10 27 -286.38
2019 10 28 -273.06
2019 10 29 -225.04
2019 10 30 -191.46
2019 10 31 -179.78
2019 11 01 -191.50
2019 11 02 -233.94
2019 11 03 -260.13
2019 11 04 -268.09
2019 11 05 -261.25
2019 11 06 -237.61
2019 11 07 -181.25
2019 11 08 -150.84
2019 11 09 -175.85
2019 11 10 -217.23
2019 11 11 -197.04
2019 11 12  -92.56
2019 11 13  -67.49
2019 11 14  -10.10
2019 11 15   42.49
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Frigid air brought some additional record low temperatures to northern New England. Burlington tied its daily record low temperature of 7°, which had been set in 1924. At Caribou, the temperature fell to -1°, breaking the record low of 4°, which was set in 1943. More impressively, that is the earliest subzero temperature on record for Caribou. The prior earliest such reading occurred on November 21, 1959 with a temperature of -1°.

On parts of the West Coast, record heat prevailed. Records included: Camarillo, CA: 94°(old record: 92°, 1932); Los Angeles: 93° (old record: 91°, 1949); Redding, CA: 87° (old record: 83°, 1895 and 1936); San Diego: 88° (tied record set in 1976); and, San Francisco: 74° (old record: 73°, 1989 and tied in 2008).

As an anecdote, the following cases among the years cited above for which California's heat records were tied and broken, 1932, 1936, 1949, and 2008 saw a cold November and warm December in the East. 1976 and 1989 saw a continuation of the cold in December. In short, one cannot rule out a pattern change that results in a milder December, even if the guidance does not yet show such an outcome.

A strong coastal storm will pass offshore tonight and tomorrow bringing some showers and perhaps periods of rain to the region, along with gusty winds. Most of the region will likely pick up less than 0.50" rain. Some coastal flooding is likely at times of high tide.

With a high temperature of 78°, Key West's record stretch of 234 consecutive days (from March 28 through November 16) with high temperatures of 80° or above came to an end. The prior record was 225 consecutive days, which was set in 1965.

The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was +0.5°C for the week centered around November 6. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.68°C and the ENSO Region 3.4 anomaly has averaged +0.58°C. A neutral ENSO is currently the base case for Winter 2019-20.

The SOI was -9.17 today.

An SOI reading of -30 or below, as occurred on November 4-5, also occurred during three prior years in the November 1-10 timeframe. All three cases featured a warmer than normal December. The average temperature for those three cases was 2 degrees warmer than normal.

Today, the preliminary Arctic Oscillation (AO) figure was -1.364.

The guidance continues to show the AO remaining negative to strongly negative through at least late November. With the AO having become the dominant element shaping the Hemispheric 500 mb pattern, the base case is now a widespread cool anomaly (perhaps 1°-2° below normal).

On November 16, the MJO was in Phase 8 at an amplitude of 1.337 (RMM). The November 15-adjusted amplitude was 1.283.

The recent MJO tendencies suggest that December could wind up at least somewhat warmer than normal overall. The MJO had spent three days in Phase 6 at an amplitude of 1.500 or above. Since 1974, five years saw the MJO in Phase 6 at an amplitude of 1.500 or higher for two or more days during the 1974-2018 period: 1985, 1987, 1996, 1998, and 2018. Only 1985 with a mean temperature of 34.2° was colder than normal during December.

It also spent three days in Phase 7 at an amplitude of 1.500 or above. All five years (1986, 1990, 1996, 1999, and 2016) that saw the MJO in Phase 7 at an amplitude of 1.500 or above during the November 10-20 period went on to record a warmer than normal December. The recent record cold outbreak (11/12-13) coincided closely with the timing of a similar magnitude Arctic outbreak in 1986 (11/13-14). The December 1986 mean temperature in New York City was 39.0°.

With the AO currently serving as the "king" of the Northern Hemisphere pattern, weakening of the AO domain blocking, could provide the first tangible evidence that a pattern change toward milder weather is imminent. For now, even as a milder than normal December appears more likely than not, the timing of the necessary pattern change remains uncertain.

Based on sensitivity analysis applied to the latest guidance, New York City has an implied 92% probability of experiencing a colder than normal November. November 2019 could finish with a monthly average temperature that could be the coldest since 2012 (43.9°) or perhaps even 1996 (43.0°) in New York City.

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25 minutes ago, donsutherland1 said:

Frigid air brought some additional record low temperatures to northern New England. Burlington tied its daily record low temperature of 7°, which had been set in 1924. At Caribou, the temperature fell to -1°, breaking the record low of 4°, which was set in 1943. More impressively, that is the earliest subzero temperature on record for Caribou. The prior earliest such reading occurred on November 21, 1959 with a temperature of -1°.

On parts of the West Coast, record heat prevailed. Records included: Camarillo, CA: 94°(old record: 92°, 1932); Los Angeles: 93° (old record: 91°, 1949); Redding, CA: 87° (old record: 83°, 1895 and 1936); San Diego: 88° (tied record set in 1976); and, San Francisco: 74° (old record: 73°, 1989 and tied in 2008).

As an anecdote, the following cases among the years cited above for which California's heat records were tied and broken, 1932, 1936, 1949, and 2008 saw a cold November and warm December in the East. 1976 and 1989 saw a continuation of the cold in December. In short, one cannot rule out a pattern change that results in a milder December, even if the guidance does not yet show such an outcome.

A strong coastal storm will pass offshore tonight and tomorrow bringing some showers and perhaps periods of rain to the region, along with gusty winds. Most of the region will likely pick up less than 0.50" rain. Some coastal flooding is likely at times of high tide.

With a high temperature of 78°, Key West's record stretch of 234 consecutive days (from March 28 through November 16) with high temperatures of 80° or above came to an end. The prior record was 225 consecutive days, which was set in 1965.

The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was +0.5°C for the week centered around November 6. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.68°C and the ENSO Region 3.4 anomaly has averaged +0.58°C. A neutral ENSO is currently the base case for Winter 2019-20.

The SOI was -9.17 today.

An SOI reading of -30 or below, as occurred on November 4-5, also occurred during three prior years in the November 1-10 timeframe. All three cases featured a warmer than normal December. The average temperature for those three cases was 2 degrees warmer than normal.

Today, the preliminary Arctic Oscillation (AO) figure was -1.364.

The guidance continues to show the AO remaining negative to strongly negative through at least late November. With the AO having become the dominant element shaping the Hemispheric 500 mb pattern, the base case is now a widespread cool anomaly (perhaps 1°-2° below normal).

On November 16, the MJO was in Phase 8 at an amplitude of 1.337 (RMM). The November 15-adjusted amplitude was 1.283.

The recent MJO tendencies suggest that December could wind up at least somewhat warmer than normal overall. The MJO had spent three days in Phase 6 at an amplitude of 1.500 or above. Since 1974, five years saw the MJO in Phase 6 at an amplitude of 1.500 or higher for two or more days during the 1974-2018 period: 1985, 1987, 1996, 1998, and 2018. Only 1985 with a mean temperature of 34.2° was colder than normal during December.

It also spent three days in Phase 7 at an amplitude of 1.500 or above. All five years (1986, 1990, 1996, 1999, and 2016) that saw the MJO in Phase 7 at an amplitude of 1.500 or above during the November 10-20 period went on to record a warmer than normal December. The recent record cold outbreak (11/12-13) coincided closely with the timing of a similar magnitude Arctic outbreak in 1986 (11/13-14). The December 1986 mean temperature in New York City was 39.0°.

With the AO currently serving as the "king" of the Northern Hemisphere pattern, weakening of the AO domain blocking, could provide the first tangible evidence that a pattern change toward milder weather is imminent. For now, even as a milder than normal December appears more likely than not, the timing of the necessary pattern change remains uncertain.

Based on sensitivity analysis applied to the latest guidance, New York City has an implied 92% probability of experiencing a colder than normal November. November 2019 could finish with a monthly average temperature that could be the coldest since 2012 (43.9°) or perhaps even 1996 (43.0°) in New York City.

“With the AO currently serving as the "king" of the Northern Hemisphere pattern, weakening of the AO domain blocking, could provide the first tangible evidence that a pattern change toward milder weather is imminent. For now, even as a milder than normal December appears more likely than not, the timing of the necessary pattern change remains uncertain.”

To be fair, at the beginning of November you wrote chances of an above normal November were likely (70 percent if I recall) was strong consensus of warmth to possibly really warm in the second half of this month.
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there is uncertainty with the long range AO forecast today...at the end of the forecast period half the members are just over positive while the other half is negative...there are many more negative members than yesterdays forecast...the nao had three members popping into positive levels while the others get quite negative...this is also an improvement over yesterdays nao forecast...the nao has been mostly positive this month while the ao mostly negative...

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47 minutes ago, qg_omega said:

“With the AO currently serving as the "king" of the Northern Hemisphere pattern, weakening of the AO domain blocking, could provide the first tangible evidence that a pattern change toward milder weather is imminent. For now, even as a milder than normal December appears more likely than not, the timing of the necessary pattern change remains uncertain.”

To be fair, at the beginning of November you wrote chances of an above normal November were likely (70 percent if I recall) was strong consensus of warmth to possibly really warm in the second half of this month.

Here's what I wrote, which is at the beginning of this thread:

Since 1974, there were 3 cases that saw the MJO in Phase 2 at an amplitude of 1.500 or above for at least 3 days during the October 15-25 period, as occurred this year: 1990, 2011, and 2015. All three cases featured a warmer than normal November in New York City and readings that were 3° or more above normal during the second half of November. For that reason, the base case remains a warmer than normal November, but any warm anomaly will likely be much smaller than the October one.

The initial sensitivity analysis suggests that New York City has an implied 40% probability of having a warmer than normal November.

At the time, I noted the colder guidance, but had not expected the AO to assert itself in the way that has happened. The basic premise was that the MJO would continue to play a leading role in shaping the November outcome. That assumption proved incorrect leading to a bad November forecast.

At present, there is considerable uncertainty about the AO's state in the extended range. One also cannot be sure when its predominant influence will wane and multiple factors, including but not limited to the MJO, will exert a greater influence.

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The -EPO relaxation and loss of  the record breaking Arctic air mass is right on schedule. This has been one of our famous 2010’s repeating weather patterns. Record cold in November followed by a moderation as we head into December. So we have probably seen our last -20 degree departure for a while in NYC. The only months to feature them in the 2010’s have been November, January, and February.

All NYC -20 or lower days since January 2010

Data for NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.
Date
Avg Temperature Departure 
2016-02-14 -28.0
2015-02-20 -25.6
2019-01-31 -24.1
2015-02-16 -23.4
2018-01-06 -23.3
2019-01-21 -23.3
2018-11-22 -23.2
2015-02-24 -23.0
2018-11-23 -21.8
2014-01-22 -21.4
2014-02-28 -21.4
2014-01-07 -21.2
2018-01-07 -21.2
2016-02-13 -20.9
2015-02-15 -20.7
2015-02-13 -20.4
2018-01-01 -20.4
2019-11-13 -20.1
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16 minutes ago, Brian5671 said:

That last Euro image looks like coast to coast cold could develop especially with some blocking

That big ridge north of Hawaii isn’t a great look if it verifies like shown. The air mass is largely Pacific in origin. Since the NAO has been verifying more positive recently than long range forecasts, the SE Ridge May correct stronger the closer in we get.

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2 minutes ago, bluewave said:

That big ridge north of Hawaii isn’t a great look if it verifies like shown. The air mass is largely Pacific in origin. Since the NAO has been verifying more positive recently than long range forecasts, the SE Ridge May correct stronger the closer in we get.

yeah, the SE ridge definitely makes appearances on all the guidance. really not much point in talking about what one set of model runs shows in 10+ days this time of year (or any?). there has been a lot of volatility in the ops and ensembles.

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2 minutes ago, bluewave said:

That big ridge north of Hawaii isn’t a great look if it verifies like shown. The air mass is largely Pacific in origin. Since the NAO has been verifying more positive recently than long range forecasts, the SE Ridge May correct stronger the closer in we get.

Just like last year, if  correct. Then, as you mention the response, just like last December , especially post 12/20/19, was the growing SE ridge.    

You believe this is a feedback,  or is the cause for the shift in ridging further away form the West coast of NA the location of the warmer water?  ( Being located further away form the West Coast )  The warm waters are not close like they were in the winter of 2014-15 I believe. 

Granted ,we are not talking extreme warm waters off the West Coast / the warm blob, etc., but there is an anomaly  of warmer waters North of the Hawaii ridge. Seems like the anomaly has been shifting West with time. 

Also of note, is the Pac Jet coming in fast on the West coast of Canada, again similar to last year, when NA snow cover took a big hit up there. Even though that loss came more so during mid December 2019 period.  

 

 

 

 

 

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3 hours ago, purduewx80 said:

yeah, the SE ridge definitely makes appearances on all the guidance. really not much point in talking about what one set of model runs shows in 10+ days this time of year (or any?). there has been a lot of volatility in the ops and ensembles.

Yeah, the  post day 10 performance has been pretty poor from the ensembles. This is often the case as their useful limit is about 7-10 days depending on the pattern. Once in  a while we get lucky and day 11-15 shows more skill. But they have been forecasting too much -NAO recently. If we lose the -EPO pattern  for Arctic cold, then SE Ridge has found a way to sneak in the closer we get. 
 

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