December 2021

[NEG NAO]

15 minutes ago, RippleEffect said:

did you guys see the snowstorm for january 8th on the GFS? one can only dream

we are in the green

[mattinpa]

11 minutes ago, NEG NAO said:

we are in the green

Looks great. Maybe we can get excited if we start seeing more of these show up in the first 10 days of Jan.

[mattinpa]

Also, Merry Christmas/Happy Holidays to all. Too bad it will be another mild one. 

[qg_omega]

1 hour ago, dmillz25 said:

When did he say that? And by the way it just snowed last night lol

 

[dmillz25]

1 minute ago, qg_omega said:

 

Lmao he said the END of the month. He did say through the 20 will be meh

[BxEngine]

Whats that saying about glass houses and stones? if you have gotten every forecast correct, by all means. Criticize. But we all know how the forecasts around here have gone. 
 

Discuss the weather, not the person. Not dealing with hostility and *ssholeness on xmas eve. 

[hudsonvalley21]

2 hours ago, EasternLI said:

Somebody should just start a January thread soon. My mojo sucks, so somebody else lol

Don’t be so negative, even a broken clock is right twice a day. 

[donsutherland1]

Earlier today, Bridgeport, Islip, and New York City received their first measurable snowfall of the season. First measurable snowfall statistics for select cities:

Allentown: Normal: December 6; 2020-21: December 9
Bridgeport: Normal: December 3; 2020-21: December 16; 2021-22: December 24
Islip: Normal: December 10; 2020-21: December 16; 2021-22: December 24
New York City: Normal: December 13; 2020-21: December 16; 2021-22: December 24
Newark: Normal: December 9; 2020-21: December 9; 2021-22: November 28
Philadelphia: Normal: December 19; 2020-21: December 16

A very warm December is now nearing its conclusion. The remaining days of the month will be generally mild with only some modestly cooler days.

It will be a different story in the Pacific Northwest. Near record to record cold, along with snowfall, is possible during the closing days of December in such cities as Portland, Seattle, and Vancouver. In the South, near record and record warmth will prevail. Today, Houston reached 80° for a December record 11th day. The old record of 10 days was set in 2012.

January will likely commence with an AO-/PNA- pattern. That typically favors somewhat cooler than normal readings in the East. For NYC, the January 1-10, 1991-2020 mean temperature for such cases was 33.5° (normal: 34.8°).

The latest guidance suggests that temperatures could head toward seasonal levels and then periodically below seasonal levels as the first week of January progresses. The coldest air will likely remain confined to the Pacific Northwest, Northern Plains, and western and central Canada. No severe cold is likely through at least the first week of January. There are some hints that a milder pattern could begin to develop around mid-January.    

In the Midwest, through 4 pm CST today, Chicago has yet to receive its first measurable snowfall. The old record latest first measurable snowfall was December 20, 2012.

Following very wet July-September periods, winter (December-February) precipitation has typically been near or below normal. The most recent exception was winter 2018-19.

The ENSO Region 1+2 anomaly was -1.7°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 15. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.15°C and the ENSO Region 3.4 anomaly has averaged -0.93°C. La Niña conditions will likely persist through meteorological winter.

The SOI was +29.22 today.

The preliminary Arctic Oscillation (AO) figure was -1.420 today.

On December 22 the MJO was in Phase 7 at an amplitude of 2.514 (RMM). The December 21-adjusted amplitude was 2.342 (RMM).

Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal December (1991-2020 normal). December will likely finish with a mean temperature near 43.2° (4.1° above normal). That would rank 2021 as the 6th warmest December on record.

 

[EasternLI]

10 minutes ago, hudsonvalley21 said:

Don’t be so negative, even a broken clock is right twice a day. 

No way. Started a storm thread once and it almost immediately evaporated lol

[brooklynwx99]

46 minutes ago, qg_omega said:

 

Unfortunately, although the anomalous -NAO/-EPO couplet did develop, it is impossible to overcome a record breaking -PNA. If the PNA was negative but not completely unprecedented (which is what I wrongly predicted), then this month would’ve turned out much differently.

Nobody could’ve have seen the PNA being that overpowering, as it was literally a historical event, and there was no indication that an event of such magnitude would unfold. A “normal” -PNA would have been easily overcome by the -NAO, not a -3 sigma trough.

So yes, there was a complete pattern change, but we got very unlucky and I’d be lying if I said I wasn’t a bit frustrated about it.

[psv88]

1 minute ago, brooklynwx99 said:

Unfortunately, although the anomalous -NAO/-EPO couplet did develop, it is impossible to overcome a record breaking -PNA. If the PNA was negative but not completely unprecedented (which is what I wrongly predicted), then this month would’ve turned out much differently.

Nobody could’ve have seen the PNA being that overpowering, as it was literally a historical event, and there was no indication that an event of such magnitude would unfold. A “normal” -PNA would have been easily overcome by the -NAO, not a -3 sigma trough.

So yes, there was a complete pattern change, but we got very unlucky and I’d be lying if I said I wasn’t a bit frustrated about it.

To be honest, and I hate to say it, certain posters have been harping on the overpowering -PNA for a month but they were mocked and laughed at. 
 

We all know who these posters are, but to say that nobody saw it coming is just false 

[brooklynwx99]

12 minutes ago, psv88 said:

To be honest, and I hate to say it, certain posters have been harping on the overpowering -PNA for a month but they were mocked and laughed at. 
 

We all know who these posters are, but to say that nobody saw it coming is just false 

My original disagreement with those posts was that, at the time of my post, the -PNA was not nearly at the strength that it was. Therefore, I was claiming that the 3 SD ridge over Greenland would overpower the -PNA, which happens an overwhelming majority of the time.

However, we ended up getting 510dam heights over Seattle, which is something that nobody could predict more than a few days in advance, let alone more than 10 days. I did anticipate the -PNA, but there was no way that anybody could see its record breaking nature at that lead time, which is what fully overwhelmed the pattern. 

Look, LR forecasting is hard, and I did not want to derail my intuition based on the slight possibility that an unprecedented event would occur. It would be just as bad if I said there would be a blizzard over the metro if there was a mean trough over the E US at 180 hours. Everyone makes mistakes though, the weather humbles everyone.

[lee59]

38 for a high temperature here today. Little colder than I thought it would be.

[Allsnow]

10 minutes ago, brooklynwx99 said:

My original disagreement with those posts was that, at the time of my post, the -PNA was not nearly at the strength that it was. Therefore, I was claiming that the 3 SD ridge over Greenland would overpower the -PNA, which happens an overwhelming majority of the time.

However, we ended up getting 510dam heights over Seattle, which is something that nobody could predict more than a few days in advance, let alone more than 10 days. I did anticipate the -PNA, but there was no way that anybody could see its record breaking nature at that lead time, which is what fully overwhelmed the pattern. 

Look, LR forecasting is hard, and I did not want to derail my intuition based on the slight possibility that an unprecedented event would occur. It would be just as bad if I said there would be a blizzard over the metro if there was a mean trough over the E US at 180 hours. Everyone makes mistakes though, the weather humbles everyone.

Great stuff! I was wrong as well about the magnitude of the pna. Unfortunately, the 11-15 day can over smooth the anomalies but when we get closer certain signals trend stronger. 
 

I completely agree, if this pna was just normal and centered over the Rockies it would have been a completely diff outcome for our area. The only thing the nao is doing is keeping it from being 70 degrees every day. If we didn’t have the nao currently we would be breaking record highs daily 

[wdrag]

Not threading the patchy icing that will occur in NNJ by sunrise and extensively further north in CT/se NYS.  

Trends regarding the modeling seem to be colder as we draw closer to these events. I am not closing to the door on developments the next 4 weeks.  It seems like some changes are coming... and that blocking across the pole into northern Canada is going to become broad and fairly strong.  Implications keep seasonable cold here for at least two weeks, if not longer and those seasonable temps can be cold enough for snow-timing-timing-timing. 

 

29/25 as of this 928PM writing here in Wantage NJ... going to be difficult to avoid icing here early Christmas day. 

[LibertyBell]

1 hour ago, psv88 said:

To be honest, and I hate to say it, certain posters have been harping on the overpowering -PNA for a month but they were mocked and laughed at. 
 

We all know who these posters are, but to say that nobody saw it coming is just false 

You can still get minor snowfalls with a -PNA like this (we just had one today). As the season goes on and if this stays the way it is we could still get minor events.  People get way too spoiled with double digit snowfalls.  Keep your expectations in check, and you can get 1-4" inch type snowfalls in ANY kind of pattern.  We had a lot of those in the 80s when it was much worse than it is now.

 

[LibertyBell]

1 hour ago, brooklynwx99 said:

Unfortunately, although the anomalous -NAO/-EPO couplet did develop, it is impossible to overcome a record breaking -PNA. If the PNA was negative but not completely unprecedented (which is what I wrongly predicted), then this month would’ve turned out much differently.

Nobody could’ve have seen the PNA being that overpowering, as it was literally a historical event, and there was no indication that an event of such magnitude would unfold. A “normal” -PNA would have been easily overcome by the -NAO, not a -3 sigma trough.

So yes, there was a complete pattern change, but we got very unlucky and I’d be lying if I said I wasn’t a bit frustrated about it.

chin up, we can still get minor snowfalls in a pattern like this, we just had one this morning

stop expecting double digit snowstorms every season those should be a once in a decade event

 

[MJO812]

Gefs still likes January 2nd 

 

[MJO812]

Geps!!

 

Alot colder than the op which was a warm coastal.

 

[gravitylover]

I've got light rain falling and it's 29°. Everything not covered with snow was glazed in the first 2 minutes. Looks like fun 

[snowman19]

9 hours ago, bluewave said:

The difference between the 12z and 18z GEFS is a great example of how small changes in the Pacific can make a big difference in our area. The 12z run was more like the Euro with height rises north of Alaska. 18z has a stronger Aleutians ridge and a deeper -PNA pattern. So we’ll want to see the EPS idea win out for an improved Pacific. When we have such a strong Aleutians Ridge and -PNA, it’s important to see post day 10 changes move up to the day 6-10 range. It’s always a big confidence booster when an  11-15 day forecast can survive to the 6-10 day range.

18z

12z

 

Same old song since late November….models grossly underestimating the -PNA until we get to the medium range. This is a good explanation of the upcoming pattern for early January: 

 

[EasternLI]

I've been thinking a little bit about that record -PNA business. I think it's actually possible that the QBO could be contributing to the Pacific ridge directly. I remember reading that the QBO actually has a surface reflection. In the form of North Pacific high pressure. But only in EQBO and la Niña. I'll have to dig around for that.

[snowman19]

Just now, EasternLI said:

I've been thinking a little bit about that record -PNA business. I think it's actually possible that the QBO could be contributing to the Pacific ridge directly. I remember reading that the QBO actually has a surface reflection. In the form of North Pacific high pressure. But only in EQBO and la Niña. I'll have to dig around for that.

HM wrote an article back in early 2012 showing that -QBO/Niña strongly supports a flat Aleutian ridge while +QBO/Niña strongly supports a poleward Aleutian ridge

[EasternLI]

2 minutes ago, snowman19 said:

HM wrote an article back in early 2012 showing that -QBO/Niña strongly supports a flat Aleutian ridge while +QBO/Niña strongly supports a poleward Aleutian ridge

Yes, I remember that. There was a specific height level of the QBO he focused on for that. I wish I could remember exactly. It doesn't seem to be online anymore. What I'm talking about is something else though. I'm just speculating that maybe the QBO aided the amplitude of the ridge somewhat directly. So we see a record -PNA episode as a result. Just a hypothesis. I'd have to find the paper on that and read it again. 

[wdrag]

Pattern looks like it's evolving a little more favorably for wintry mixes all of our area I78 northward. Not threading Monday-Tuesday (yet), but it's looking messy to me.  

Meanwhile, the NAEFS is showing signs of much below normal cold intruding through the northern Plains into the upper midwest by early January and ensemble snow depth is modeled to increase there. That allows colder boundary layer temps to be less distant.

Already many models are/were MUCH too warm at the surface for yesterdays first measurable snow in NYC and for this mornings ice event north of I80.  I think the same is ahead this coming week. Suggest following the colder surface temps of GGEM/RGEM and EC through Wednesday.  My expectations below for early this coming week. 

I think we're looking at a period of snow Monday changing to periods of sleet or freezing rain Tuesday that may linger as mixed wintry precipitation into Wednesday. It's complex but I have little doubt that more hazardous wintry weather is coming early this coming week to at least portions of the I84 corridor and even down to Easton-Phillipsburg-Chester near I78 (PA/NJ). Long Island probably escapes the icy stuff (maybe not the period of snow Monday).

 

[CIK62]

The last 7 days of December are averaging  41degs.(38/45),or +7>>>+4 nowadays.

Month to date is  43.7[+3.8].      December should end at  43.1[+4.0].

Reached 44 here yesterday.

Today: 44-47, wind variable e. s. w. nw., rain till 3pm.

First 10 days of January could be near normal overall, say about 27/38.

42*(90%RH) here at 6am.{was 40* overnite}     3pm-6pm 49*.       53* at 8pm.

[bluewave]

1 hour ago, EasternLI said:

Yes, I remember that. There was a specific height level of the QBO he focused on for that. I wish I could remember exactly. It doesn't seem to be online anymore. What I'm talking about is something else though. I'm just speculating that maybe the QBO aided the amplitude of the ridge somewhat directly. So we see a record -PNA episode as a result. Just a hypothesis. I'd have to find the paper on that and read it again. 

Yeah, I can remember the discussion of this paper a while back. So it’s possible the QBO could be a piece of the puzzle. The +500 mb height anomaly south of the Aleutians driving the -PNA is on track to be the strongest on record for December. 
 

https://agupubs.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1002%2F2017GL076929&file=grl57089-sup-0001-2017GL076929-SI.docx

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL076929

Storm tracks, defined as the preferred regions of extratropical synoptic-scale disturbances, have remarkable impacts on global weather and climate systems. Causes of interannual storm track variation have been investigated mostly from a troposphere perspective. As shown in this study, Northern Hemisphere winter storm tracks are significantly modulated by the tropical stratosphere through the quasi-biennial oscillation (QBO). The North Pacific storm track shifts poleward during the easterly QBO winters associated with a dipole change in the eddy refraction and baroclinicity. 
 

 

[donsutherland1]

Morning thoughts…

It will be mostly cloudy and mild today. There will be some showers and periods of light rain. High temperatures will likely reach mainly the upper 40s and lower 50s in most of the region. Likely high temperatures around the region include:

New York City (Central Park): 49°

Newark: 53°

Philadelphia: 59°

Normals:

New York City: 30-Year: 41.9°; 15-Year: 42.8°

Newark: 30-Year: 42.4°; 15-Year: 43.5°

Philadelphia: 30-Year: 43.7°; 15-Year: 44.7°

The remainder of December will see generally above normal temperatures.

[crossbowftw3]

It’s like living in Groundhog Day, another rainy and foggy Christmas morning. 
 

At least there’s no wind to deal with today. 

[bluewave]

New Aleutians ridge and -PNA record for this time of year.