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November 2019 General Discussions & Observations Thread


Rtd208
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Today, the temperature peaked at 53° in New York City's Central Park. That was New York City's warmest temperature since November 12 when the high temperature was 57°. Tomorrow could see a somewhat higher reading before colder air returns to the region.

Even as another shot of cooler air arrives, accumulating snow in such cities as Newark, New York, and Philadelphia remains a low probability scenario through the remainder of November.

The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was +0.8°C for the week centered around November 13. 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 +0.63°C. These recent conditions are consistent with a weak El Niño. Nevertheless, a neutral ENSO remains the base case for Winter 2019-20.

The SOI was -11.65 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 -2.250.

On November 20, the MJO was in Phase 8 at an amplitude of 1.156 (RMM). The November 19-adjusted amplitude was 1.442.

Even as the recent MJO progression through Phases 6, 7 and into 8 at high amplitude has typically preceded a mild December, there remains considerable uncertainty concerning the longer-term evolution of the teleconnections.

To date, November has an AO average of -1.225. The November 16-21 AO average is -1.661. Since 1950, there were five years that saw the AO average -1.000 or below in November and -1.500 or below during the second half of November. Out of the total of 15 months that followed, the AO averaged < 0 during 12 (80%) and -0.500 or below during 10 (67%). This data suggests that the potential for above average frequency of AO blocking for winter 2019-2020 has increased.

Based on sensitivity analysis applied to the latest guidance, New York City has an implied 97% probability of experiencing a colder than normal November.

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It’s not really worth looking at the models past 7 days.The Niña-like SE ridge keeps beating expectations from what is shown at day 10. So the main storm track in the fast Pacific split flow is through the Great Lakes.

New day 7 forecast 

58664498-51CC-4FA1-99B0-7D117E004778.thumb.png.f075e694f08f301fb21c5282e188c8f9.png

Old day 10 forecast 

 

A50293C0-6A0D-46DD-8961-CA674A464148.thumb.png.5388f6661e51026742731762d8569faa.png

Old day 11-15 forecast 

2CF724CE-8E4A-4305-A710-0DB1184B4B83.thumb.png.7ab4afabf65495738ea779cdb288152d.png

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1 hour ago, bluewave said:

It’s not really worth looking at the models past 7 days.The Niña-like SE ridge keeps beating expectations from what is shown at day 10. So the main storm track in the fast Pacific split flow is through the Great Lakes.

New day 7 forecast 

58664498-51CC-4FA1-99B0-7D117E004778.thumb.png.f075e694f08f301fb21c5282e188c8f9.png

Old day 10 forecast 

 

A50293C0-6A0D-46DD-8961-CA674A464148.thumb.png.5388f6661e51026742731762d8569faa.png

Old day 11-15 forecast 

2CF724CE-8E4A-4305-A710-0DB1184B4B83.thumb.png.7ab4afabf65495738ea779cdb288152d.png

What is so bad about the eps ? It still shows a negative Nao and negative EPO.  December should start out fun.

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12 minutes ago, Brasiluvsnow said:

Your lips to the Snow Gods Ears = still lots of time

Yeah, that’s why I agree with BW, we have seen this show a million times. Models look great in the long run only to default back to pattern recognition. We could get lucky and score an early season event but my money’s on the big show coming sometime in late January

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One big difference so far this year is that a true -NAO block and 50/50 low is developing. Although these will probably break down past the first week of December, it bodes well for a potential return during our January-February climo.

Another nice takeaway from the next ~2 weeks is that SE Canada will be building deep snow cover, so we'll have a close source region for cold low-level air moving forward.

 

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53 minutes ago, bluewave said:

The model forecasts from late last November got hopes up also. Very difficult to extrapolate an entire December pattern from a late November forecast for the first week.

A2D98CD6-7DC0-4F55-9E5D-510458B42110.png.6f1d3591928f35d66b805a6eff51fd79.png

 

Like sandpaper looking at that image.  Seems like a "wait-and-see"-type deal right now.  I'll become more invested if we see a decent look up top materialize for an appreciable period in December.  Usually that bodes well (as it did in 2013-14, for instance).

If we are going to battle a SE ridge yet again this year, are we better-armed with a -EPO or a -NAO?  IIRC, some SE ridging actually worked to our benefit during those magical -EPO winters of 13-14 and 14-15.....

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47 minutes ago, LongBeachSurfFreak said:

Yeah, that’s why I agree with BW, we have seen this show a million times. Models look great in the long run only to default back to pattern recognition. We could get lucky and score an early season event but my money’s on the big show coming sometime in late January

That is way too late. Are all the models wrong about blocking in early December ?

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42 minutes ago, purduewx80 said:

One big difference so far this year is that a true -NAO block and 50/50 low is developing. Although these will probably break down past the first week of December, it bodes well for a potential return during our January-February climo.

Another nice takeaway from the next ~2 weeks is that SE Canada will be building deep snow cover, so we'll have a close source region for cold low-level air moving forward.

 

A nao block is developing right now. Eps breakdown down the NAO block but replaces it with an epo block. That's another way  we can stay cold in December. 

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15 minutes ago, Eduardo said:

Like sandpaper looking at that image.  Seems like a "wait-and-see"-type deal right now.  I'll become more invested if we see a decent look up top materialize for an appreciable period in December.  Usually that bodes well (as it did in 2013-14, for instance).

If we are going to battle a SE ridge yet again this year, are we better-armed with a -EPO or a -NAO?  IIRC, some SE ridging actually worked to our benefit during those magical -EPO winters of 13-14 and 14-15.....

you want "some" SE ridge-that's often the storm track along the northern edge of the ridge.   Too much blocking and it's southern sliders and mid-altantic specials.      93-94 had a weak to moderate SE ridge which got us multiple moderate snow and ice events almost every week.

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5 minutes ago, Snow88 said:

That is way too late. Are all the models wrong about blocking in early December ?

I wrote we could get lucky with an early season event. It’s still a little early for the coast just look at past storm numbers, so it’s going to be thread the needle. Cold has to be timed right and readily available or it’s 33 and rain at the coast will inland cashes in. 

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3 hours ago, bluewave said:

It’s not really worth looking at the models past 7 days.The Niña-like SE ridge keeps beating expectations from what is shown at day 10. So the main storm track in the fast Pacific split flow is through the Great Lakes.

New day 7 forecast 

58664498-51CC-4FA1-99B0-7D117E004778.thumb.png.f075e694f08f301fb21c5282e188c8f9.png

Old day 10 forecast 

 

A50293C0-6A0D-46DD-8961-CA674A464148.thumb.png.5388f6661e51026742731762d8569faa.png

Old day 11-15 forecast 

2CF724CE-8E4A-4305-A710-0DB1184B4B83.thumb.png.7ab4afabf65495738ea779cdb288152d.png

If you Loop the EPS starting from hour 72 from last night's run and go back to the 240 hour forecast it missed the n a o block completely still have 3 days to verify but that's a positive sign going forward that models maybe under estimating the block in the high latitudes this year

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3 minutes ago, binbisso said:

If you Loop the EPS starting from hour 72 from last night's run and go back to the 240 hour forecast it missed the n a o block completely still have 3 days to verify but that's a positive sign going forward that models maybe under estimating the block in the high latitudes this year

The -NAO blocks this time of year have been fleeting. We had a big -NAO drop at the same time last year. Our best recent success with more sustained -NAO blocking has been later in the season.

https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.index.b500101.current.ascii

2018 11 19 -0.274
2018 11 20 -0.826
2018 11 21 -0.726
2018 11 22 -0.348
2018 11 23 -0.369
2018 11 24 -0.804
2018 11 25 -1.373
2018 11 26 -1.404
2018 11 27 -1.144
2018 11 28 -0.872
2018 11 29 -0.440
2018 11 30 -0.133


 

 

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21 minutes ago, bluewave said:

The -NAO blocks this time of year have been fleeting. We had a big -NAO drop at the same time last year. Our best recent success with more sustained -NAO blocking has been later in the season.

https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.index.b500101.current.ascii

It's interesting to look back at how that evolved last year on http://www.esrl.noaa.gov/psd/data/composites/day/ - it appears that dip last year was from a ridge that was transient and only closed off for a couple of days. The hemispheric wave pattern was also quite a bit different this time last year.

2018

compday._p5W2J_5oO.gif.36c2e4cfb5388f2a55648529834f6b95.gif

2019 EPS fcst:

m500z_f090_bg.png.03e8f36ee5c750cba83b76baa846e6f4.png

Certainly will be interesting to see how this evolves over the next few weeks.

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18 minutes ago, purduewx80 said:

It's interesting to look back at how that evolved last year on http://www.esrl.noaa.gov/psd/data/composites/day/ - it appears that dip last year was from a ridge that was transient and only closed off for a couple of days. The hemispheric wave pattern was also quite a bit different this time last year.

2018

 

2019 EPS fcst:

 

Certainly will be interesting to see how this evolves over the next few weeks.

The fly in the ointment this year has been the unusually strong low over the SW US. So the SE ridge corrects stronger the closer we get to the forecast period.

https://ktar.com/story/2850504/hail-falls-across-the-phoenix-area-but-storms-are-heading-out-of-town/

 

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