December Model Discussion

[Paragon]

1 hour ago, Rittenhouse said:

The cold on that Euro run would be historic for NYC lol. The lows for the last four nights are all below zero. That has only happened once since 1869 (during the winter of 1917-1918). The last night gets down to -9, which would be the third coldest low temperature since 1869 (it got down to -15 in 1934 and -13 during that streak in 1917-1918).

wow that would be much more historic than a 20" snowstorm (on the same level as the 30" from Jan 2016)

Is the Euro prone to having a cold bias though?

 

[Paragon]

48 minutes ago, donsutherland1 said:

The coming severe cold could produce NYC’s coldest temperature sine February 14, 2016 when the temperature fell to -1 degree. That was the City’s last single digit reading. One more single digit readings remain likely before the pattern breaks near the end of the first week in January.

Don is there a moderate possibility that the cold could be as strong as what the Euro predicts and we all go below zero for a night or two?

 

[NEG NAO]

4 minutes ago, PB COLTS NECK NJ said:

 

This has become a N branched dominate feature now that is still in a sparser data region , but that doesn't mean this can't turn into a snowstorm on the EC.

This will be grabbed tomorrow by 12z and the models will get a better handle on what it is 

Right now all the solutions you are seeing in the numerical guidance is not to be taken too seriously because the models are probably undermodeling the N vort

Why? Well it's done it for the last 2 systems and has to correct to the stronger SW.

Secondly the WAR has been undermodeled in the mid range since November and every coastal has ended up closer than forecast.

These are 2 very big forecast fixes that change what you are looking at.

Its very hard to come in here at times and explain why the models could be wrong , why there was a never a SE ridge , why it was going to snow on the coast on the 10th and how most of you were going to snow on Christmas when the prevailing posts in here from 5 days ago was 60 and rain.

 

We don't look to why the model is right , we debate away why the model is wrong and what needs to catch up synoptically to make the forecast work.

This is not going to take much to produce a snowstorm here , so I would advise against difinititive statements 5 days out on the E/C .

Merry Christmas 

WPC does not agree with you

[NEG NAO]

1 minute ago, Paragon said:

Don is there a moderate possibility that the cold could be as strong as what the Euro predicts and we all go below zero for a night or two?

 

In snow covered areas much easier to get below zero - much more difficult in the city and surrounding areas that currently have no snow cover

[PB COLTS NECK NJ]

13 minutes ago, NEG NAO said:

WPC does not agree with you

 

 

Lets revisit in 2 days and take a look again 

[Paragon]

Just now, NEG NAO said:

In snow covered areas much easier to get below zero - much more difficult in the city and surrounding areas that currently have no snow cover

But by then we should all have some snowcover even if it's just a few inches.

 

Also, looking at climatology for our area and our biggest snow event could come right before the pattern breaks in the second week of January.

What do you think about that, Don?

 

 

 

[donsutherland1]

2 minutes ago, Paragon said:

Don is there a moderate possibility that the cold could be as strong as what the Euro predicts and we all go below zero for a night or two?

 

There are differences in what the ECMWF is forecasting. Several sites show subzero cold. At least one shows only low single digit cold. For now, as the peak of the cold is still 7-10 days out, I would take the more conservative warmer numbers.

[Paragon]

4 minutes ago, donsutherland1 said:

There are differences in what the ECMWF is forecasting. Several sites show subzero cold. At least one shows only low single digit cold. For now, as the peak of the cold is still 7-10 days out, I would take the more conservative warmer numbers.

I take it that even having just a few inches of snow on the ground would make a difference - even if we get just 2-4.

Do you think our biggest chances for a big snowstorm will come just before the pattern breaks around Jan 7?

 

[donsutherland1]

6 minutes ago, Paragon said:

But by then we should all have some snowcover even if it's just a few inches.

 

Also, looking at climatology for our area and our biggest snow event could come right before the pattern breaks in the second week of January.

What do you think about that, Don?

 

 

 

I believe we have a good chance of having snow cover. The pattern still has potential, so accumulating snow should not be written off. It's very difficult to forecast phased solutions from far out, as more often than not it is difficult for the guidance to resolve individual short waves with the necessary degree of precision. The moderate-borderline significant snow event on the ECMWF remains plausible. But much uncertainty still exists. Given the forecast pattern, I believe the 18z GFS idea of no accumulating snow for the City and nearby is less likely than the ECMWF solution. Several inches is probably more likely, but we'll have a better idea by Tuesday or Wednesday concerning the possible 12/30-31 event.

I also believe we will have a few shots at accumulating snow before the pattern breaks. Moreover, I believe the break will likely be temporary (1-2 weeks in duration).

For NYC to get below zero, the City will need very strong cold air advection. Radiational cooling won't cut it for the City.

[Paragon]

2 minutes ago, donsutherland1 said:

I believe we have a good chance of having snow cover. The pattern still has potential, so accumulating snow should not be written off. It's very difficult to forecast phased solutions from far out, as more often than not it is difficult for the guidance to resolve individual short waves with the necessary degree of precision. The moderate-borderline significant snow event on the ECMWF remains plausible. But much uncertainty still exists. Given the forecast pattern, I believe the 18z GFS idea of no accumulating snow for the City and nearby is less likely than the ECMWF solution. Several inches is probably more likely, but we'll have a better idea by Tuesday or Wednesday concerning the possible 12/30-31 event.

I also believe we will have a few shots at accumulating snow before the pattern breaks. Moreover, I believe the break will likely be temporary (1-2 weeks in duration).

For NYC to get below zero, the City will need very strong cold air advection. Radiational cooling won't cut it for the City.

Don does snow cover aid CAD also, or is it more of a catalyst for dropping temperatures more quickly for radiational cooling?

I was thinking it helps both, but radiational cooling moreso than CAD?

I've noticed on radiational cooling nights, the city's temps stop dropping an hour or two after midnight.

 

[donsutherland1]

1 minute ago, Paragon said:

Don does snow cover aid CAD also, or is it more of a catalyst for dropping temperatures more quickly for radiational cooling?

I was thinking it helps both, but radiational cooling moreso than CAD?

I've noticed on radiational cooling nights, the city's temps stop dropping an hour or two after midnight.

 

Yes, it helps CAA, too.

[sferic]

I have also noticed that for NYC to go to zero or below Winds have to be NNW, if there is a more westerly component (WNW) it moderates the cold.

I believe most of NYC zero or below mornings  had strong, strong winds too as opposed to light and variable

[donsutherland1]

27 minutes ago, NEG NAO said:

WPC does not agree with you

A note of caution may be in order. Today's product might be automated output given the Christmas holiday. It looks almost identical to the GEFS for the relevant timeframe, albeit a somewhat smoothed version (e.g., all area with < 0.05" QPF are assigned < 0.01").

[Yaz]

4 hours ago, White Gorilla said:

A wild and juicy OP run gets hopes up too much despite knowing deep inside that such resolutions at such a time distance rarely pan out.  The disappointments happen as a function of human nature despite repeated lessons. 

Very well stated.

[LongBeachSurfFreak]

1 minute ago, sferic said:

I have also noticed that for NYC to go to zero or below Winds have to be NNW, if there is a more westerly component (WNW) it moderates the cold.

I believe most of NYC zero or below mornings  had strong, strong winds

I would say more straight north with a direct drain down the Hudson. This limits downslope warming to pretty much nil as the Hudson is near sea level till way upstate.

[SnowGoose69]

9 minutes ago, sferic said:

I have also noticed that for NYC to go to zero or below Winds have to be NNW, if there is a more westerly component (WNW) it moderates the cold.

I believe most of NYC zero or below mornings  had strong, strong winds too as opposed to light and variable

It’s possible on a light due north wind if there is snow cover.  There was a day in 1994 after the -1 morning where it got to 0 with a very light north wind 

[Paragon]

24 minutes ago, sferic said:

I have also noticed that for NYC to go to zero or below Winds have to be NNW, if there is a more westerly component (WNW) it moderates the cold.

I believe most of NYC zero or below mornings  had strong, strong winds too as opposed to light and variable

If the Appalachians did not exist I believe that NYC would get both more snow and colder weather.  Similar to Pittsburgh in cold (similar latitude and elevation) but with more snow (from coastals).  Probably average around 40" of snow per winter.

 

 

[Paragon]

20 minutes ago, SnowGoose69 said:

It’s possible on a light due north wind if there is snow cover.  There was a day in 1994 after the -1 morning where it got to 0 with a very light north wind 

-2 the first morning 0 the next...had a high of 10 degrees barely missing single digits..... Jan 1985's high of 7 after a low of -2 which was the last time we had a single degree high.  Jan 1985 remains the coldest arctic outbreak I've ever experienced.  I don't remember Jan 1977 don't know if it had a colder one.

Wasn't there a second arctic outbreak later in Jan where they got to 0 again?

And 32 by midnight the next night with a strong cutter the next day with temps in the mid 50s and a gale warning lol.

I like to say that's the only time I've ever experienced a low of 0 F and a high of 0 C lol

[Rjay]

The Korean looks amped at hr 72

 

[SnowGoose69]

12 minutes ago, Rjay said:

The Korean looks amped at hr 72

I haven’t looked up this way but the German ICON was very amplified down in the SE US

[Tatamy]

33 minutes ago, Paragon said:

If the Appalachians did not exist I believe that NYC would get both more snow and colder weather.  Similar to Pittsburgh in cold (similar latitude and elevation) but with more snow (from coastals).  Probably average around 40" of snow per winter.

 

 

If the Appalachians did not exist then you could say good bye to the cold air damming that frequently sets up to the east of the mountains during winter events.  As they say you would want to be careful what you wish for.

[Paragon]

45 minutes ago, Tatamy said:

If the Appalachians did not exist then you could say good bye to the cold air damming that frequently sets up to the east of the mountains during winter events.  As they say you would want to be careful what you wish for.

Isn't cold air damming more for icing events? I find that our big blockbuster storms usually have air that is plenty cold enough, cold air damming is more for marginal events (and more important down south).

 

[Paragon]

1 hour ago, SnowGoose69 said:

I haven’t looked up this way but the German ICON was very amplified down in the SE US

I never understood why each nation has its own model.  Physics is universal, shouldn't there theoretically be just one system?

 

[sferic]

1 hour ago, Paragon said:

-2 the first morning 0 the next...had a high of 10 degrees barely missing single digits..... Jan 1985's high of 7 after a low of -2 which was the last time we had a single degree high.  Jan 1985 remains the coldest arctic outbreak I've ever experienced.  I don't remember Jan 1977 don't know if it had a colder one.

Wasn't there a second arctic outbreak later in Jan where they got to 0 again?

And 32 by midnight the next night with a strong cutter the next day with temps in the mid 50s and a gale warning lol.

I like to say that's the only time I've ever experienced a low of 0 F and a high of 0 C lol

Close for Jan 21st 1985  high of 9 as per http://thestarryeye.typepad.com/weather/2013/01/baby-its-cold-outside-a-history-of-single-digit-temperatures-in-new-york-city.html

[snow1]

DT throwing in the towel on this upcoming threat! 

[David-LI]

GFS's next week arctic shot is brutal.

[WeatherFeen2000]

54 minutes ago, David-LI said:

GFS's next week arctic shot is brutal.

U mean this week

[Rjay]

The Euro trended towards something a bit more impactful.   Very close to bringing a major snow storm to our subforum instead if just LI.

 

 

[The Plowsman]

My Holly early this am on late week...
LONG TERM /WEDNESDAY THROUGH MONDAY/... Arctic high pressure continues to build into the region with temperatures some 15-20 degrees below normal for most of this week. Highs top off in the teens across the Poconos and northern NJ, low to mid 20s for most of southeast PA and central and southern NJ, and in the mid to upper 20s across the Delmarva Wednesday through Friday, with the coldest day being Thursday. Overnight lows during this time will range from the single digits to the teens, and as a result, the corresponding lowest wind chills will range from as low as 15 below zero in the Poconos, and from the single digits to as low as 5 below elsewhere. Conditions will be dry through Thursday night, and then the high moves offshore. Low confidence in the forecast from Friday through Sunday. There are stark differences between the 00Z operational GFS and the 00Z ECMWF. The GFS has a weak clipper system passing through the region Friday, and then low pressure forms well offshore Friday night. High pressure then builds into the region Saturday, followed by another weak clipper system Saturday night, and then low pressure forms off the Southeast U.S. Sunday night and Monday. The ECMWF, however, is slower to bring the clipper system on Friday, and does not bring it into the region until late Friday night. With a deeper and sharper upper trough, a secondary low forms off the Mid-Atlantic coast and phases with the approaching clipper system to produce a more significant coastal low over the area Saturday and Saturday night. The CMC- GDPS is dry through Friday, and then the clipper system passes through on Saturday and intensifies offshore on Sunday. As a result, in terms of sensible weather, will forecast slight chance/low chance PoPs for Friday, and then chance PoPs Friday night and Saturday, with PoPs lowering into Sunday. Will keep forecast relatively similar to previous forecast due to this low confidence. Stay tuned, as there is the potential for development late in the week/over the weekend. High pressure then returns for the start of the new week with cold and dry conditions with temperatures again some 15-20 degrees below normal.

[MJO812]

Gfs still loves the 2nd wave for NyE