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October 2020 General Discussions & Observations Thread

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The storm responsible for heavy snow in the Northern Rockies tonight and tomorrow will bring a near-record to record cold air mass into the Northern Rockies and Northern Plains. Numerous single-digit low temperatures will be likely on Sunday morning in parts of Montana, North Dakota, South Dakota, and Wyoming. A few locations could even experience subzero low temperatures. The cold will then expand into the Central Plains for Monday and Tuesday. However, much of this cold air will likely remain confined west of the Middle Atlantic and southern New England regions until the closing days of this month.

A brief but fairly sharp shot of cooler air could arrive during the weekend in the Northeast. During the closing days of the the month, some of the cold air from out West will spill into the region. November could commence on a cool note.

The ENSO Region 1+2 anomaly was -1.2°C and the Region 3.4 anomaly was -1.4°C for the week centered around October 14. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.85°C and the ENSO Region 3.4 anomaly has averaged -1.10°C. La Niña conditions will likely prevail at least into mid-winter.

The SOI was +9.22.

Today, the preliminary Arctic Oscillation (AO) figure was +1.021.

On October 22 the MJO was in Phase 5 at an amplitude of 2.543 (RMM). The October 21-adjusted amplitude was 2.469.

Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO.

From that larger pool of 10 La Niña winters that followed El Niño winters, there were four cases where October saw the MJO in Phases 4-6 for 20 days or more, as was the case this year: 1983-84, 1988-89, 1998-99, and 2016-17. All four cases featured an EPO+/AO+ winter.

Both 1988-89 and 1998-99 saw the MJO in Phase 5 with an amplitude of 2.000 or above as has occurred this year.  Both those winters featured below to much below normal snowfall in the Middle Atlantic and southern New England areas. Select snowfall seasonal snowfall totals were:

1988-89:
Boston: 15.5"
New York City: 8.1"
Philadelphia: 11.2"

1998-99:
Boston: 36.4"
New York City: 12.7"
Philadelphia: 12.5"

This is not cast in stone. However, this is a plausible scenario should things evolve toward an EPO+/AO+ winter as is suggested on some of the current seasonal guidance.

Based on sensitivity analysis applied to the latest guidance, there is an implied 84% probability that New York City will have a warmer than normal October. October will likely finish with a mean temperature near 58.5°.

 

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4 minutes ago, donsutherland1 said:

The storm responsible for heavy snow in the Northern Rockies tonight and tomorrow will bring a near-record to record cold air mass into the Northern Rockies and Northern Plains. Numerous single-digit low temperatures will be likely on Sunday morning in parts of Montana, North Dakota, South Dakota, and Wyoming. A few locations could even experience subzero low temperatures. The cold will then expand into the Central Plains for Monday and Tuesday. However, much of this cold air will likely remain confined west of the Middle Atlantic and southern New England regions until the closing days of this month.

A brief but fairly sharp shot of cooler air could arrive during the weekend in the Northeast. During the closing days of the the month, some of the cold air from out West will spill into the region. November could commence on a cool note.

The ENSO Region 1+2 anomaly was -1.2°C and the Region 3.4 anomaly was -1.4°C for the week centered around October 14. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.85°C and the ENSO Region 3.4 anomaly has averaged -1.10°C. La Niña conditions will likely prevail at least into mid-winter.

The SOI was +9.22.

Today, the preliminary Arctic Oscillation (AO) figure was +1.021.

On October 22 the MJO was in Phase 5 at an amplitude of 2.543 (RMM). The October 21-adjusted amplitude was 2.469.

Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO.

From that larger pool of 10 La Niña winters that followed El Niño winters, there were four cases where October saw the MJO in Phases 4-6 for 20 days or more, as was the case this year: 1983-84, 1988-89, 1998-99, and 2016-17. All four cases featured an EPO+/AO+ winter.

Both 1988-89 and 1998-99 saw the MJO in Phase 5 with an amplitude of 2.000 or above as has occurred this year.  Both those winters featured below to much below normal snowfall in the Middle Atlantic and southern New England areas. Select snowfall seasonal snowfall totals were:

1988-89:
Boston: 15.5"
New York City: 8.1"
Philadelphia: 11.2"

1998-99:
Boston: 36.4"
New York City: 12.7"
Philadelphia: 12.5"

This is not cast in stone. However, this is a plausible scenario should things evolve toward an EPO+/AO+ winter as is suggested on some of the current seasonal guidance.

Based on sensitivity analysis applied to the latest guidance, there is an implied 84% probability that New York City will have a warmer than normal October. October will likely finish with a mean temperature near 58.5°.

 

Amazing Don, those 3rd week in October single digit lows may be lower than the lowest CPK reading for our entire cold season. Serves us right for having an affair with a warm ocean. As always ....

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6 minutes ago, rclab said:

Amazing Don, those 3rd week in October single digit lows may be lower than the lowest CPK reading for our entire cold season. Serves us right for having an affair with a warm ocean. As always ....

Great Falls could even dip below zero.

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The last 8 days of October are averaging 55deg., making it 50degs., or about -3.0.

Month to date is  60.4[+2.3].        Oct. should end at about 57.7[+0.8].

62*(97%RH) here at 6am, overcast.         64*(94%RH) by Noon.          68* between 2pm-5pm with a bit of sun and falling RH, now 68% at 5pm.        54*(55%RH} by 10pm.

Tropics:   36.7N  62.3W.

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Morning thoughts...

A strong cold front will sweep across the region today. Ahead of the front, today will be partly to mostly cloudy and still mild. Likely high temperatures around the region include:

New York City (Central Park): 68°

Newark: 71°

Philadelphia: 74°

Tomorrow will be sharply colder with the temperature struggling just to reach the lower 50s in many parts of the region.

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For those watching the progress of the cold and snow in the Northern Rockies, Great Falls, MT set daily records for the minimum temperature and snowfall yesterday. Yesterday’s low temperature was 3 degrees (old record” 10 degrees, 1957). Daily snowfall was 4.0” (old record: 2.8”, 1954).

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1 hour ago, donsutherland1 said:

Morning thoughts...

A strong cold front will sweep across the region today. Ahead of the front, today will be partly to mostly cloudy and still mild. Likely high temperatures around the region include:

 

Tomorrow will be sharply colder with the temperature struggling just to reach the lower 50s in many parts of the region.

You forgot to mention the mist and drizzle, this is just an extension of the last four dreary days so far.

Hopefully it will be really dry with a breeze to dry things out, it's too soggy to even do anything outside in the yard :( 

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54 minutes ago, donsutherland1 said:

For those watching the progress of the cold and snow in the Northern Rockies, Great Falls, MT set daily records for the minimum temperature and snowfall yesterday. Yesterday’s low temperature was 3 degrees (old record” 10 degrees, 1957). Daily snowfall was 4.0” (old record: 2.8”, 1954).

I would imagine, Don, that it is in the realm of possibility, that the one 3rd week in  October MT temperature and snowfall totals could outdo CPK for the coming cold season. It. nearly outdid the last entire cold season. I may go to the roof and start sprinkling holy water in the direction of the south east ridge. As always .....

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3 minutes ago, rclab said:

I would imagine, Don, that it is in the realm of possibility, that the one 3rd week in  October MT temperature and snowfall totals could outdo CPK for the coming cold season. It. nearly outdid the last entire cold season. I may go to the roof and start sprinkling holy water in the direction of the south east ridge. As always .....

That may well occur. Things aren’t currently looking very good for snowfall and a warmer than normal winter is likely.

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Is it me or is the GFS parallel fraught with the sometimes NAM meso modeling steroids as the model gets extended in time and buys too heavy into the short waves.??

I'm watching this GFS-P closely in the eastern USA as well as the ICON in the Atlantic tropics.  For those that have been monitoring... my initial thought is the GFS-P seems too strong after 4 or 5 days... and the ICON is nice to have but not necessarily any better than any other global model.  

Any thoughts?

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58 minutes ago, donsutherland1 said:

That may well occur. Things aren’t currently looking very good for snowfall and a warmer than normal winter is likely.

I wouldn't mind another mild snow-free winter. Lower bills, no traffic jams/accidents, no shoveling, no frigid weather. 

Not a bad ask.

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2 hours ago, donsutherland1 said:

That may well occur. Things aren’t currently looking very good for snowfall and a warmer than normal winter is likely.

Too early to say . Look what happened last winter.

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1 hour ago, SnoSki14 said:

I wouldn't mind another mild snow-free winter. Lower bills, no traffic jams/accidents, no shoveling, no frigid weather. 

Not a bad ask.

Could we get at least one area wide 5-8" event or so in this mild winter? I'd hate to be shut out for two consecutive seasons.

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5 hours ago, MJO812 said:

Too early to say . Look what happened last winter.

Yes. It still is early. Unfortunately, things look worse than they did a few weeks ago. Hopefully, things will change down the road.

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6 hours ago, MJO812 said:

Too early to say . Look what happened last winter.

I don’t trust any experts wha ever the experts say I go with the opposite!

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In the wake of a strong cold front that is clearing the region, tomorrow will be sharply colder. Readings in the Middle Atlantic and southern New England regions will struggle to reach the lower 50s. Parts of the region will see high temperatures in the 40s. Some showers or sprinkles are possible tomorrow.

Snowfall totals from the storm that brought record early-season snowfall to parts of Montana included:

Great Falls: 10.0"
Helena (1 SSW): 20.5"
Helena (2 W): 20.0"

As the snowstorm departs, near-record to record cold is likely in the Northern Rockies tonight. Numerous single-digit low temperatures will be likely tomorrow morning in parts of Montana, North Dakota, South Dakota, and Wyoming. A few locations could even experience subzero low temperatures. The cold will then expand into the Central Plains for Monday and Tuesday. However, much of this cold air will likely remain confined west of the Middle Atlantic and southern New England regions until the closing days of this month.

During the closing days of the the month, some of the cold air from out West will spill into the region. November could commence on a cool note. The first week of November will likely be cooler than normal.

The ENSO Region 1+2 anomaly was -1.2°C and the Region 3.4 anomaly was -1.4°C for the week centered around October 14. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.85°C and the ENSO Region 3.4 anomaly has averaged -1.10°C. La Niña conditions will likely prevail at least into mid-winter.

The SOI was +1.16.

Today, the preliminary Arctic Oscillation (AO) figure was +1.365.

On October 23 the MJO was in Phase 5 at an amplitude of 2.285 (RMM). The October 22-adjusted amplitude was 2.537.

Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. A predominant EPO+/AO+ pattern is likely for winter 2020-21. In response, it is likely that the Middle Atlantic and southern New England areas will see a warmer than normal winter with potentially below normal snowfall.

Based on sensitivity analysis applied to the latest guidance, there is an implied 83% probability that New York City will have a warmer than normal October. October will likely finish with a mean temperature near 58.3°.

 

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21 minutes ago, David-LI said:

Can anyone please explain this to me?

 

gfs_asnow_scus_18.png

Amarillo is going to get clobbered!  They always do well early in the season. I’m hyped about this winter I think we’ll do very well

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Finally got a little taste of sun today, for about 20-30 minutes in Central Jersey. Car thermometer got up to 75, which was the highest temp reading between Long Island and southern Virginia. Lowest was 66 just north of Richmond, temp shot up to 73 in the UHI.

Fall foliage in Central Jersey and even swaths of South Jersey and Delaware is further along than in NYC and Long Island, shockingly. Maryland outside of Baltimore and DC looked like NYC/LI.

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