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NYCweatherNOW

December 2019

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2 hours ago, White Gorilla said:

Any more winter storm opportunities for December on the horizon? 

There is a window of interesting disturbances and decent tellies Dec 11-16 give or take which while not screaming 'storm' holds some potential for a surprise.

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6 minutes ago, Ralph Wiggum said:

There is a window of interesting disturbances and decent tellies Dec 11-16 give or take which while not screaming 'storm' holds some potential for a surprise.

Dec 7 looks interesting on the gfs

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4 minutes ago, Snow88 said:

Dec 7 looks interesting on the gfs

Too progressive still but that wave you mention transitions to ridging upstream and slows things down for the period I am looking at.

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14 minutes ago, Ralph Wiggum said:

Too progressive still but that wave you mention transitions to ridging upstream and slows things down for the period I am looking at.

Warm calls might be in trouble if the gfs is right 

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16 minutes ago, Snow88 said:

Warm calls might be in trouble if the gfs is right 

Warm Dec calls are losing steam quickly it appears. Many of the tellies those forecasters were keying on haven't evolved nor had any staying power yet. Too early to say tho but next 10 days....yeah. takes us to almost kid Dec and no torch.

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12 minutes ago, Ralph Wiggum said:

Warm Dec calls are losing steam quickly it appears. Many of the tellies those forecasters were keying on haven't evolved nor had any staying power yet. Too early to say tho but next 10 days....yeah. takes us to almost kid Dec and no torch.

Indications were for a cooler start to December. That much has been obvious for a while. The make or break period for December departures has been mid to late month in recent times. That portion of the forecast is still outside reliable range. Plus long range modeling has been very poor with the raging Pacific split flow.

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Gee,  I wonder if we'll get some snow on the 10th,  EURO is boasting a high of 67* now!      Then it flips 45 degrees!!.

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9 minutes ago, bluewave said:

Indications were for a cooler start to December. That much has been obvious for a while. The make or break period for December departures has been mid to late month in recent times. That portion of the forecast is still outside reliable range. Plus long range modeling has been very poor with the raging Pacific split flow.

There were quite a few that had early Dec mild and the tail end turning favorable as of 2 or 3 weeks ago. Now we are hearing just the opposite from several sources. I try and base my expectations on day 10 and under. I've learned that sure you can get clues past day 10 but predictability is rather low. Now we continue to see 10 day and under progs hanging on to a general cooler look and holding off any firehose/torch out past day 10. The delay keeps reoccurring for now anyway and HL blocking (AO/EPO/some NAO) keeps popping up mid range. Any warmth looks transient next 10 days in advance of arctic fropa. We will see how much longer the delay in pattern flip to 'blah' continues. I'm happy where we are for now and with some of the recurring tellies that are showing up as possible background state.

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1 hour ago, Snow88 said:

Warm calls might be in trouble if the gfs is right 

EPS disagrees and it holds more merit than the GFS op runs.

Doesn't look like a nonstop torch but it should overall be mild with transient cool shots thrown in.

One caveat is the blocking Bluewave described and to an extent the +PNA, that should mitigate the warmth somewhat.

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12 minutes ago, SnoSki14 said:

EPS disagrees and it holds more merit than the GFS op runs.

Doesn't look like a nonstop torch but it should overall be mild with transient cool shots thrown in.

One caveat is the blocking Bluewave described and to an extent the +PNA, that should mitigate the warmth somewhat.

If the MJO is right , it's not getting warm.

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1 hour ago, bluewave said:

There is also another consideration. The record breaking open water in the Chukchi Sea. It’s a continuation of the record low sea ice extent in that region this fall. You can see how the the blocking there wasn’t forecast very well by the day 10 EPS. So the 5 day EPS is stronger on the blocking now in that region. This helps to buckle the fast Pacific flow with  a progression of ridges and troughs moving east. Whether the ridging continues to build there after day 10 remains to be seen. Beyond that, the MJO looks to stay put in phase 2-3 during the first half of this month with the record +IOD. We would normally see an eventual moderation in temperatures this time of year with those phases. But that could be mitigated to some extent by stronger blocking continuing north of Alaska.

EA904C6D-E135-426E-9C66-F9EF84D45574.thumb.png.5aa51ee2a2069e23c0d8d76b6860dc83.png
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5B2093A9-78D0-445A-B78C-E9BF4B0166A5.png.c4c0b7c4a74b36fecae887cd4df4ee3b.png

Not sure I agree with the Chukchi Sea driving the EPO ridge. Chicken/egg argument. The PDO is likely more of a factor on why the EPO has been such a feature more than not the last 8 years to a decade. That ridge is leading to warmth and yes the open waters where you mentioned. But such a relatively small body of water is doubtful to be one of the main reasons for the repeated ridging in the area. Also, note that ridging  in the EPO is actually  being fed across the pole from old western Russia over the Pole then down into the EPO region. 

But yes, the EPO is certainly helping to buckle the flow. We just disagree on what the catalyst is for said ridging. I believe the state of the PDO keeping the Aleutian low in play is more the reason than the small pool of open waters N of Alaska. The atmosphere affected the waters/ssts not the other way around imo.

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A storm continues to bring some snow to the region this evening. Storm total accumulations include: Albany: 17.3"; Binghamton: 10.6"; Bridgeport: 0.7"; East Glenville, NY: 25.2"; Hartford: 5.5"; Highland Lakes, NJ: 10.5"; Islip: 0.2"; New York City: 1.0"; and, Newark: 1.4".

The ENSO Region 1+2 anomaly was +0.4°C and the Region 3.4 anomaly was +0.4°C for the week centered around November 27. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.43°C and the ENSO Region 3.4 anomaly has averaged +0.62°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 +6.80 today.

Today, the preliminary Arctic Oscillation (AO) figure was +1.749. The preliminary PNA value was -0.108.

Daily MJO data was unavailable. Outgoing long-wave radiation is currently unavailable according to Australia's Bureau of Meteorology (BOM). The BOM is working on the issue.

After a generally cold first week of December, warmer conditions will likely return. There is a chance that the second week of December could see one or more days with much above normal readings topping out in the 50s and perhaps even near 60° in the northern Mid-Atlantic region. Overall, December will likely finish somewhat warmer than normal to warmer than normal across the region.

When it comes to New York City's 4" or greater snowstorms the PNA is more important than the AO during the first half of December. Since 1950, December 1-15 has seen 10 storms bring 4.0" or more snow to New York City. 50% occurred with an AO- or AO+. However, 80% occurred when the PNA was positive. All 6" or greater snowstorms during this timeframe occurred when the PNA was positive. During the second half of December, larger snowstorms have occurred with a negative PNA.

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The next 8 days are averaging 39degs., or just about Normal.

32* here at 6am, flurries.        34* by Noon.        37* by 2pm.

All the major models have Rain with a temperature blow off to near 60* by the 10th., then a sharp drop---with some backend snow by the 12th.

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9 hours ago, donsutherland1 said:

A storm continues to bring some snow to the region this evening. Storm total accumulations include: Albany: 17.3"; Binghamton: 10.6"; Bridgeport: 0.7"; East Glenville, NY: 25.2"; Hartford: 5.5"; Highland Lakes, NJ: 10.5"; Islip: 0.2"; New York City: 1.0"; and, Newark: 1.4".

The ENSO Region 1+2 anomaly was +0.4°C and the Region 3.4 anomaly was +0.4°C for the week centered around November 27. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.43°C and the ENSO Region 3.4 anomaly has averaged +0.62°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 +6.80 today.

Today, the preliminary Arctic Oscillation (AO) figure was +1.749. The preliminary PNA value was -0.108.

Daily MJO data was unavailable. Outgoing long-wave radiation is currently unavailable according to Australia's Bureau of Meteorology (BOM). The BOM is working on the issue.

After a generally cold first week of December, warmer conditions will likely return. There is a chance that the second week of December could see one or more days with much above normal readings topping out in the 50s and perhaps even near 60° in the northern Mid-Atlantic region. Overall, December will likely finish somewhat warmer than normal to warmer than normal across the region.

When it comes to New York City's 4" or greater snowstorms the PNA is more important than the AO during the first half of December. Since 1950, December 1-15 has seen 10 storms bring 4.0" or more snow to New York City. 50% occurred with an AO- or AO+. However, 80% occurred when the PNA was positive. All 6" or greater snowstorms during this timeframe occurred when the PNA was positive. During the second half of December, larger snowstorms have occurred with a negative PNA.

Don, do you think the rest of the month, starting with next Monday will be above normal and pretty snowless?

 

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December looks to be following in the footsteps of November where a very negative departure for the first 15 days may be hard to overcome. We are below normal the rest of this week and then warm up briefly Monday and Tuesday before the next arctic front comes in later next week. that should take us through the 15th and will probably be negative 5 in the departure that's tough to overcome but we will see

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5 minutes ago, binbisso said:

December looks to be following in the footsteps of November where a very negative departure for the first 15 days may be hard to overcome. We are below normal the rest of this week and then warm up briefly Monday and Tuesday before the next arctic front comes in later next week. that should take us through the 15th and will probably be negative 5 in the departure that's tough to overcome but we will see

I see in the NE forum they are saying that the Euro brings back the deep cold later in the period with more snow chances.

Friday is a day to look out for snow also.

 

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31 minutes ago, LibertyBell said:

Don, do you think the rest of the month, starting with next Monday will be above normal and pretty snowless?

 

No. I believe there will be transient cold shots and perhaps one or more opportunities for snowfall. Whether the closing week of the month turns colder remains to be seen.

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28 minutes ago, bluewave said:

That warming hole positive feedback was the topic of a recent paper. 

https://www.nature.com/articles/s41598-019-41682-4

Conclusion

We showed that a warm hole over the Pacific sector was responsible for the cold 2017–18 winter in the mid-latitudes, in addition to the effect of the semi-permanent ice retreat in the Barents Sea. The warm hole symbolizes the historically largest ice-free ocean in the Bering and Chukchi Seas because the shape of the ice-free ocean appears as a hole with overlying warm air. Analyses focusing on the area of the Pacific sector also showed that there was a positive feedback mechanism between the warm hole, underlying ocean, and overlying atmosphere. This feedback process made the Arctic upper air warm, which caused the jet stream to push northward. Furthermore, we showed that the coincidence of the two events – pre-existing warm holes in late autumn and the occurrence of the sporadic strong and moist northward wind events that are strong enough to move thin ice, such as an atmospheric river, – could initiate and develop the positive feedback system. In addition, the poleward penetration of atmospheric rivers can induce sea ice melt or prevent its formation through enhanced downwelling longwave radiation. The positive feedback between the large ice-free ocean, the atmospheric rivers, and the ocean current actively pushed the jet northward. In reaction to this northward meander, large southward jet stream pathways formed over Asia and America, allowing cold air to spread into Asia and the southern areas of North America. We therefore conclude that the warm hole apparing in the Pacific side of the Arctic is responsible for the anomalous jet meander. The positive feedback system does not operate in isolation within the Arctic. Rather there are contributions from external lower-latitude forcings, such as atmospheric rivers16. Deepening the knowledge of the extra-Arctic processes that control long-term variations of atmospheric rivers is beneficial for long-range winter weather forecasts. Examining the reasons why the warm hole appeared is also beneficial because the sea-ice hole serves as a predictor. The positive feedback could provide Eastern Eurasia and North America with cold winters in the new era of the warm hole. Whether the positive feedback is strong or not must be tested by examining detailed data analyses, together with high-resolution numerical simulations of both the atmosphere and ocean. This study showed an upscale effect, i.e., influence of narrow-width atmospheric rivers upon global-scale jet streams, suggesting that a fine-mesh numerical model that resolves atmospheric rivers is needed to predict the global-scale climate change associated with future global warming.

So open arctic waters = blocking/ridging patterns with displaced jet streams? That is some interesting stuff. So if a hole formed in the Arctic Circle near the N Pole should we expect a -AO? I'm not seeing how such a small scale feature would cause the entire jet structure to buckle and 'meander' North. The nature.com article may not be inaccurate as the biblio shows they drew heavily on legit sources. But I cant see how that small area has more say in driving the patterns than the entire Pac/PDO influence. Interesting discussion tho.

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18 minutes ago, EasternLI said:

Interesting that some guidance is hinting at a piece of the TPV making a run through SE Canada. Ensembles don't necessarily disagree with that notion.

The ensembles are also getting colder. Warm december forecasts might be in trouble. 

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1 minute ago, bluewave said:

It’s not that area of open water with reduced sea ice working in isolation. The paper goes on to discuss how it can interact with tropical forcing to influence the overall pattern. Another recent paper studied how the warming Arctic can lead to a rapid warming of Pacific Ocean. So the relationship between the Arctic and Tropics is an ongoing area of research.

The NAO and AO is a whole different story. A paper back in 2009 found greater swings from one phase to another. But one phase  was not favored over another. So we get both record highs and lows with as the planet continues to warm. This is perhaps why the Siberian October snow signal didn’t work out for the NAO and AO in recent years.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL077325

Plain Language Summary

The effect of projected Arctic sea ice loss on the global climate system is investigated using a state‐of‐the‐art coupled climate model. This study shows that the tropics respond to the ice loss within two to three decades via dynamical ocean processes and air‐sea interaction. This tropical response in turn modifies the atmospheric circulation and precipitation responses over the North Pacific. This fast response indicates that ocean dynamics needs to be represented for an accurate picture of the global impact of Arctic sea ice loss.

https://www.sciencedaily.com/releases/2009/01/090113101200.htm

Using a 218-year-long temperature record from a Bermuda brain coral, researchers have created the first marine-based reconstruction showing the long-term behavior of one of the most important drivers of climate fluctuations in the North Atlantic.
 

Anthropogenic (human-related) warming does not appear to be altering whether the NAO is in a positive or negative phase at multi-decadal time scales,” said WHOI paleoclimatologist Konrad Hughen. “It does seem to be increasing variability. Clearly, this has implications for the future.”

“As temperatures get warmer, there’s potential for more violent swings of the NAO — the phases becoming even more positive and even more negative,” Hughen added. “If the NAO locks more into these patterns, intense storms will become more intense and droughts will become more severe.”

 
 

 

what about the connection between AGW and more frequent occurrences of super el nino events, Chris?

 

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some analogs have a warm up the second week of December...then it gets colder the last 10 days or so with some snow...if we get into the 50's before mid month it would be a normal occurrence...

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11 minutes ago, uncle W said:

some analogs have a warm up the second week of December...then it gets colder the last 10 days or so with some snow...if we get into the 50's before mid month it would be a normal occurrence...

even 60 would be pretty common, even in our snowier/colder winters

 

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