December 2023

[lee59]

Heat island apparent tonight as temperatures in suburbs approach the teens in some places, NYC still in mid 30s.

[eduggs]

2 hours ago, BoulderWX said:

If you want any real chances of a snowstorm before February all bets point to the Rockies. Anything on the east coast including NE will be a thread the needle through timing situation. I think we have a few chances in February but I will go on record as saying I don’t see enough of a pattern shift to produce any meaningful snow along the east coast, particularly the 95 corridor until the last week of January into February. 
 

would love to be wrong and wilL admit if I am, but not seeing anything that gets me excited about a colD and snowy January 

Do you really have confidence that we can predict February weather 5+ weeks in advance. Other than February being further away from a snowless period, I see no compelling reason to think January couldn't be better than February.

[psv88]

21.8 now, coldest of this winter season 

[wdrag]

Not threading anything for the 27th-29th.  Ensembles offer NYC subforum around 1" of rain, give or take. River rises occur but generally within bank, except those that went to major a few days ago...those would rise back to minor flooding IF that rainfall occurs.  Think it best to wait this out. 

[bluewave]

11 hours ago, eduggs said:

My first post today was about next weekend i.e., about 180 hrs out. I pointed out that during this time period we briefly lose the western trof which you suggested was something we needed to get snow. 

My sense is that you are good at diagnosing the big picture. I prefer to look at the details, which I believe are critical for regional and particularly local snowfall. In truth I believe both scales are important. If the big picture is unfavorable, the details don't get you squat. 

Obviously, the raw ensemble output has gotten better at forecasting the general patterns especially day 1-5 and 6-10. But beyond that range for the general forecasts, I have been using bias correction to adjust the raw output. So this lead to seeing back in late November that the risks to the week 3 and 4 extended forecasts for mid to late December would be warmer than originally modeled which is what happened. 

The specifics in December flowed from the much warmer than average pattern coupled with the general storm tracks. Split flow patterns with a lack of cold usually don’t produce much snow which is what has happened in December.

The current general forecasts going forward are still lacking the ingredients which would lead to much improved snowfall outcomes for various reasons outlined already in this thread. So several challenges still remain. 

But even if they did begin to show a better general pattern for snowfall which matched past snowier outcomes, we would not expect models to have an accurate forecast for that until we got under 120 hrs. And even then, we don’t get a true idea of specific snowfall outcomes often until under 72 hrs. Some events like January 2016 and 2015 weren’t even modeled well for specific snowfall amounts 24 hrs out. So specific snowfall forecasting is probably one of the most difficult forecast challenges that we face.

[Allsnow]

EPS snow mean perked up for Jan 4/5 

[North and West]

Do you really have confidence that we can predict February weather 5+ weeks in advance. Other than February being further away from a snowless period, I see no compelling reason to think January couldn't be better than February.

I always say something this to my dad when he mentions that the iPhone weather app or TWC app has snow or ice more than five days out.

Basically, we can detect temperature patterns, as in it is likely enough to support snow at that timeframe, but there’s no way to know for sure precipitation other than there’s a broad signal but no specifics.


.

[bluewave]

Meanwhile, North America drops to unchartered territory for low snow cover heading into the holiday period. 

https://www.star.nesdis.noaa.gov/smcd/emb/snow/HTML/snow_extent_monitor.html

[snowman19]

7 minutes ago, bluewave said:

Meanwhile, North America drops to unchartered territory for low snow cover heading into the holiday period. 

https://www.star.nesdis.noaa.gov/smcd/emb/snow/HTML/snow_extent_monitor.html

It’s the worst since 1980, sea ice is equally as bad. Our source region is going to continue to be a huge problem as is true cold air as @NittanyWx has cautioned over and over 

[North and West]

Meanwhile, North America drops to unchartered territory for low snow cover heading into the holiday period. 

https://www.star.nesdis.noaa.gov/smcd/emb/snow/HTML/snow_extent_monitor.html

Do you think this is all CC-related, or patterns like El Niño amplifying CC to make it worse?

(Probably an open-ended question, but wanted the opinion of someone who knows what they’re talking about. Thanks!)


.

[bluewave]

1 minute ago, snowman19 said:

It’s the worst since 1980, sea ice is equally as bad. Our source region is going to continue to be a huge problem as is true cold as @NittanyWx has cautioned over and over 

So much mild Pacific air has flooded Canada, that any continental polar will get modified heading south. That’s why I think the long range models will continue to correct warmer as we get closer to the forecast period. Plus storm tracks with the fast split flow will also present challenges.

[the_other_guy]

1 minute ago, North and West said:

Do you think this is all CC-related, or patterns like El Niño amplifying CC to make it worse?

(Probably an open-ended question, but wanted the opinion of someone who knows what they’re talking about. Thanks!)


.

Option 2. El Niños are always bad, and it’s amplified with CC

[bluewave]

12 minutes ago, North and West said:

Do you think this is all CC-related, or patterns like El Niño amplifying CC to make it worse?

(Probably an open-ended question, but wanted the opinion of someone who knows what they’re talking about. Thanks!)


.

It’s a combination of several factors. El Niño coupled with warm MJO phases plus the warming climate. Warmer SSTs in the WPAC slow an amplify forcing there. So instead of a vanilla El Niño pattern which has the warm focused in Canada, this is one of the warmest Canadian and Northern Tier Decembers on record. So the El Niño and MJO give us the geographic locations of the warmest anomalies. But the magnitude of the warmth is where the warming climate contributes. 

 

 

[North and West]

It’s a combination of several factors. El Niño coupled with warm MJO phases plus the warming climate. Warmer SSTs in the WPAC slow an amplify forcing there. So instead of a vanilla El Niño pattern which has the warm focused in Canada, this is one of the warmest Canadian and Northern Tier Decembers on record. So the El Niño and MJO gives us the geographic locations of the warmest anomalies. But the magnitude of the warmth is where the warming climate contributes. 
 
 

Yikes. (I appreciate the straightforward explanation!)


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[snowman19]

10 minutes ago, bluewave said:

So much mild Pacific air has flooded Canada, that any continental polar will get modified heading south. That’s why I think the long range models will continue to correct warmer as we get closer to the forecast period. Plus storm tracks with the fast split flow will also present challenges.

When we saw all the arctic air displaced to the other side of the pole in Eurasia, that was a dead giveaway that there were going to be major snow and ice cover issues in our source region. This isn’t just simply low snowcover and ice cover it’s record breaking low. I agree 100%. Without snowcover and ice, the air masses are going to be passing over bare ground and open waters and modifying. Extremely likely that the models are way overdoing the surface/boundary layer cold and will end up correcting warmer as we get closer in time. And the models are definitely going to struggle with the very fast split-flow

[Allsnow]

The one thing I will say about snow cover is it can change quickly once we establish more of a cross polar flow. Next week the Midwest is getting a huge snowstorm to start things off…

[donsutherland1]

35 minutes ago, bluewave said:

It’s a combination of several factors. El Niño coupled with warm MJO phases plus the warming climate. Warmer SSTs in the WPAC slow an amplify forcing there. So instead of a vanilla El Niño pattern which has the warm focused in Canada, this is one of the warmest Canadian and Northern Tier Decembers on record. So the El Niño and MJO give us the geographic locations of the warmest anomalies. But the magnitude of the warmth is where the warming climate contributes. 

 

 

In addition, as is the case with many stations with long periods of record, whether 2023 finishes as the warmest year on record or not, 7 of Milwaukee's 10 warmest years will have occurred since 2000. Records there go back to 1871.

[Dark Star]

Another Festivus miracle!  Graupel and or sleet!  It wasn't really bouncing, so I assumed it was graupel?  Just as forecasted.

[Dark Star]

1 hour ago, snowman19 said:

When we saw all the arctic air displaced to the other side of the pole in Eurasia, that was a dead giveaway that there were going to be major snow and ice cover issues in our source region. This isn’t just simply low snowcover and ice cover it’s record breaking low. I agree 100%. Without snowcover and ice, the air masses are going to be passing over bare ground and open waters and modifying. Extremely likely that the models are way overdoing the surface/boundary layer cold and will end up correcting warmer as we get closer in time. And the models are definitely going to struggle with the very fast split-flow

Absolutely true.  I remember a lot of warm winters, but it seems we were always on the wrong side of the trough and/or ridge; or a zonal flow.  But even in those years, there ALWAYS seemed to be arctic air trapped in Canada, never NO cold air anywhere between us and the north pole?

[Sey-Mour Snow]

9 hours ago, eduggs said:

IMO you are a little loose with your terminology. People get so used to certain phrases that they start taking them for granted. Terms like "nail" and "lock into place" are subjective. The parameters and spatial scale in question as well as your criteria for assessing model accuracy are not clear. Even the term "pattern" is only vaguely defined. It's easy to rationalize having a good handle on something if details and definitions are kept fuzzy.

The magnitude and orientation of 500mb height values at the continental scale are modestly predictable out to about 10 days. But the point I've been trying to make is that regional weather forecasting at and beyond this time frame requires model accuracy that exceeds the current average error. Even if longwave trofs and ridges are roughly predictable, local sensible weather is highly dependent on fine-scale features and evolution that is outside the scope of model skill and only modestly correlated to large-scale features. It's hard enough to see a regional cold snap coming 10 days out. To detect a snowstorm at that range is really hard. And while everybody is looking far into the future for the perfect pattern, a decaying lake effect streamer could drop an inch or two almost without warning.

It's all semantics at this point, it seems like you agree with what we are saying, but are arguing otherwise.  Long story short, long wave patterns are generally forecastable 8-12 days in advance by ensembles.  Whether or not it produces the exact result we want or suspect is a different story.. 

[forkyfork]

1 hour ago, the_other_guy said:

Option 2. El Niños are always bad, and it’s amplified with CC

1952 1957 1963 1969 2002 2009

[WX-PA]

If your looking for a solid medium forecast looks like day 5-7 are solid now. Thats a big change from 20 years ago. 7-12 day forecasts on the ensembles can show the right pattern but details are hard .12-16 days forecast even on the ensemles  can be inaccurate. And the weeklies especailly after week 3 are not good.But it sure beats the 70's when 3 day forecasts were inaccurate.

[the_other_guy]

27 minutes ago, forkyfork said:

1952 1957 1963 1969 2002 2009

List the ones that were bad. We did this already.

 

You got your Nino reset. Lets hope it plays out like you want. Id like to see AN snow.

[eduggs]

2 hours ago, North and West said:

I always say something this to my dad when he mentions that the iPhone weather app or TWC app has snow or ice more than five days out.

Basically, we can detect temperature patterns, as in it is likely enough to support snow at that timeframe, but there’s no way to know for sure precipitation other than there’s a broad signal but no specifics.


.

Totally agree about the weather apps. 

In terms of forecasting temperatures 40 days out. In general it's basically a coin flip whether a particular day will be warmer or colder than "average." Average is of course a moving target. In recent years I would always hedge warmer than average for future forecasts. So maybe 60-40 warmer than average bet. A "snow supporting column" might be slightly easier to forecast in advance than surface temperatures, but at 40 days out it's essentially impossible to accurately predict.

[Eduardo]

2 hours ago, bluewave said:

So much mild Pacific air has flooded Canada, that any continental polar will get modified heading south. That’s why I think the long range models will continue to correct warmer as we get closer to the forecast period. Plus storm tracks with the fast split flow will also present challenges.

I agree with this, although as we get into January, it becomes more possible to sneak in an event with a marginal airmass.  Something has to break our way at some point, right?….. Right? 

[EastonSN+]

53 minutes ago, forkyfork said:

1952 1957 1963 1969 2002 2009

I think the other guy meant El ninos of this strength. 1982, 1997, 2015. 

[EastonSN+]

1 hour ago, Dark Star said:

Absolutely true.  I remember a lot of warm winters, but it seems we were always on the wrong side of the trough and/or ridge; or a zonal flow.  But even in those years, there ALWAYS seemed to be arctic air trapped in Canada, never NO cold air anywhere between us and the north pole?

I have to believe Canada looked the same w/r/t cold air as well in 97/98, as the vortex off the WC continuously flooded the continent for an extended period. 

[SACRUS]

 

28 to 38 with clouds and some scattered shower/flurries.

 

 

[eduggs]

57 minutes ago, Sey-Mour Snow said:

It's all semantics at this point, it seems like you agree with what we are saying, but are arguing otherwise.  Long story short, long wave patterns are generally forecastable 8-12 days in advance by ensembles.  Whether or not it produces the exact result we want or suspect is a different story.. 

I think I mostly agree, but with caveats. If you go back 10 days and compare the ensemble forecasted 10-day 500mb chart to, say, last night's 6hr GFS 500mb chart (or the actual 500mb interpolated analysis) you'll see some of the features match up well and others not so well. Whether or not we can say a model correctly forecasted a "pattern" is completely subjective and dependent on the spatial scale in question, criteria for defining a "pattern," and reference thresholds for accuracy.

People living in regions where the ensemble 10-day 500mb heights were poorly forecast would disagree that a model nailed a "pattern." In these areas, the airmass and surface features are drastically different than predicted 10-days ago. Since we never know for sure in advance which areas will be more accurately modeled and which less, it's very difficult to have confidence in even general "pattern" features at this range. What I have observed for many years on this forums is that posters (including meteorologists) confidently proclaim a particular "pattern" coming 10-15 days or more in advance but the realization rate of those prediction is much less than would be warranted based on the confidence in the original claim.

People instinctively clamor for understanding and predictability. There is desperation to see the light at the end of the tunnel. We cling to a simplistic understanding of the relationships between climate and regional weather. But we're collectively just not (yet) as good at seeing into the future as we think we are. And we rationalize it away instead of using honest assessment to understand our limitations.

[EastonSN+]

For those who want to see how a vortex off the west Coast can and has (now and in the past) flood Canada with PAC air, run the loop of the latest EPS.

In the image below, see that deep blue, that spin is rapidly pushing warm PAC air into Canada (like a river from SW to NE). A problem with stronger El ninos. 

https://www.tropicaltidbits.com/analysis/models/?model=eps&region=nhem&pkg=z500a