January 2023 Mid-Long Range Disco

[cbmclean]

31 minutes ago, DarkSharkWX said:

From Dec 15(around time when we were expected to go into a favorable pattern) - Dec 24(latest date available) there doesn't seem to be any sign of a -PNA/SER at all. The PNA not being east enough(not over the Rockies) and the lack of 50/50 are one of the factors that contributed into the pattern not doing well.

Interesting that in that composite no WAR really shows up, but we know it was there when it counted.  You can also see that the mean trough is much further west compared to say Dec 2010 or March 2018 which itself hints of higher heights in the SE.

[DarkSharkWX]

Just now, cbmclean said:

Interesting that in that composite no WAR really shows up, but we know it was there when it counted.  You can also see that the mean trough is much further west compared to say Dec 2010 or March 2018 which itself hints of higher heights in the SE.

Yeah most of the cold was placed in the Central US because of the lack of a 50/50 low and the ridge not being east enough over the Rockies. Had we had those 2 factors, this December could have gone a lot better

[nj2va]

2 hours ago, CAPE said:

Interesting that the EPS is building +heights into the NAO domain across Greenland around the 10th, sooner than the GEFS and CMC ens, both of which have - h5 anomalies there at that point.

That’s a look that works in prime climo for sure.

[Weather Will]

WB latest EURO weeklies 

[Heisy]

Just posting an example of something to root for or look ahead. The hopeful “ridge killer” gets a little help from the N stream on the 18z GFS. It then leads to a decent confluence setup over SE Canada. La La land but something to keep an eye on as we get this time frame under 8-10 days.

First image is the N stream dipping south combining with S vort to help usher in some colder air and knock down ridge.

Second image is the setup it creates, which is pretty optimal imo. Note the tight isobars draped across the Lakes through NE







.

[psuhoffman]

3 hours ago, Maestrobjwa said:

And that -PNA....The more neutral/slightly positive look being shown on guidance a couple weeks ago never really verified, did it?

You gonna yell at me again if I answer? 

[frd]

26 minutes ago, Weather Will said:

WB latest EURO weeklies 

Isn't that climo based for a 46 day snowfall forecast. I have seen double that amount without any snow in my area during the next 46 days. 

[cbmclean]

18 minutes ago, psuhoffman said:

You gonna yell at me again if I answer? 

Actually it did verify to some extent as seen in the composite posted by DarkSharkWX.  But as he noted the ridge axis was considerably further west than ideal.

Edit: And yes I know the MA used to not always need perfect ridge axis placement for snow. 

[Weather Will]

18 minutes ago, frd said:

Isn't that climo based for a 46 day snowfall forecast. I have seen double that amount without any snow in my area during the next 46 days. 

The latest weeklies are not that impressive to my nonexpert eye…but they are not a torch after the first week of January.  Seems like we will have a better handle on January after the torch period.  Patience will be required.  Not much happening the next 10 days unless you like mild and rainy weather.

[CAPE]

21 minutes ago, psuhoffman said:

You gonna yell at me again if I answer? 

This seems like a passive-aggressive thing lol.

[Maestrobjwa]

32 minutes ago, psuhoffman said:

You gonna yell at me again if I answer? 

Hahaha Fair, lol Nah you good 

[psuhoffman]

3 hours ago, DarkSharkWX said:

From Dec 15(around time when we were expected to go into a favorable pattern) - Dec 24(latest date available) there doesn't seem to be any sign of a -PNA/SER at all. The PNA not being east enough(not over the Rockies) and the lack of 50/50 are one of the factors that contributed into the pattern not doing well.

 

3 hours ago, cbmclean said:

Interesting that in that composite no WAR really shows up, but we know it was there when it counted.  You can also see that the mean trough is much further west compared to say Dec 2010 or March 2018 which itself hints of higher heights in the SE.

What CBM said. The low heights on the mean are from two bowling bowls that progressed through after cutters. As both shortwaves were approaching the critical area there was a WAR and full latitude eastern ridge in front. 

[frd]

This is interesting from Don S.  

Unlike in New York City where no measurable snowfall through December 31st is uncommon and has a strong correlation with January snowfall, in Washington, DC such outcomes are more common. There is also a lower correlation with the January outcomes. 

For the 23 prior cases with no measurable snowfall through December 31st, mean January snowfall was 6.1" and median January snowfall was 3.3". However, 5/23 (22%) January cases saw 10" or more snowfall. January 1987 had the most with 20.8". 3/23 (13%) January cases had no measurable snowfall.

The January cases with 10" or more snowfall were:

1912: 16.9"
1987: 20.8"
2000: 14.5"
2016: 18.8"
2022: 12.3"

 

 

[AtlanticWx]

i would 100% take another repeat of jan 2022 last year. so many storms to track and while Jan 3 did bust pretty badly here, it was such a fun tracking period with storm after storm

[DarkSharkWX]

3 hours ago, psuhoffman said:

 

What CBM said. The low heights on the mean are from two bowling bowls that progressed through after cutters. As both shortwaves were approaching the critical area there was a WAR and full latitude eastern ridge in front. 

Fair enough - I can see what you mean; still wouldn't say pattern was dominated by SER/-PNA, and as others have said sometimes its just luck(if the frontend was colder for just a bit longer or it snowed for a bit longer in the right areas we would have gotten accumulating snow)

[cbmclean]

Gonna be pretty quite for a while as we wait for the vortex to retrograde.  Anyone care to spend a paragraph to explain the way in which patterns of geopotential height controls the flow of airmasses and storm systems?  I'm having trouble finding that level of detail on easily available internet resources.  The closest I can find is a mention on the Wikipedia articel about geopotential height:

"Geophysical sciences such as meteorology often prefer to express the horizontal pressure gradient force as the gradient of geopotential along a constant-pressure surface, because then it has the properties of a conservative force. For example, the primitive equations which weather forecast models solve use hydrostatic pressure as a vertical coordinate, and express the slopes of those pressure surfaces in terms of geopotential height."

So if this is accurate patters of gph are actually equivalent to patterns in plain air pressure gradient force.  This intrigues me but I do not understand how it is so.

Anyone feeling didactic tonight?

[Terpeast]

8 minutes ago, cbmclean said:

Gonna be pretty quite for a while as we wait for the vortex to retrograde.  Anyone care to spend a paragraph to explain the way in which patterns of geopotential height controls the flow of airmasses and storm systems?  I'm having trouble finding that level of detail on easily available internet resources.  The closest I can find is a mention on the Wikipedia articel about geopotential height:

"Geophysical sciences such as meteorology often prefer to express the horizontal pressure gradient force as the gradient of geopotential along a constant-pressure surface, because then it has the properties of a conservative force. For example, the primitive equations which weather forecast models solve use hydrostatic pressure as a vertical coordinate, and express the slopes of those pressure surfaces in terms of geopotential height."

So if this is accurate patters of gph are actually equivalent to patterns in plain air pressure gradient force.  This intrigues me but I do not understand how it is so.

Anyone feeling didactic tonight?

Couple of things. 

First, for the models to work well, they use pressure as a vertical coordinate system instead of height. Instead of 2,000 feet 4,000 ft 10,000 ft and so on, you have 900mb 800mb 700mb all the way up to 10 mb. It’ll be too complicated for the models/equations otherwise. 

Second, geopotential height patterns tells you where the warm air masses and cold air masses are. The higher the geopotential height at the 500mb pressure surface (think coordinate system), the warmer the airmass. The lower the geopotential height is, the colder the air mass. 

Now, when you have a cold and warm airmass butting up against each other, there is wind… and the stronger the temperature gradient between the air masses, the stronger the wind is. And it is that wind that controls the flow and track of storm systems.

Took me three paragraphs to explain it. Maybe someone else can do it in one. 

[cbmclean]

4 minutes ago, Terpeast said:

Couple of things. 

First, for the models to work well, they use pressure as a vertical coordinate system instead of height. Instead of 2,000 feet 4,000 ft 10,000 ft and so on, you have 900mb 800mb 700mb all the way up to 10 mb. It’ll be too complicated for the models/equations otherwise. 

Second, geopotential height patterns tells you where the warm air masses and cold air masses are. The higher the geopotential height at the 500mb pressure surface (think coordinate system), the warmer the airmass. The lower the geopotential height is, the colder the air mass. 

Now, when you have a cold and warm airmass butting up against each other, there is wind… and the stronger the temperature gradient between the air masses, the stronger the wind is. And it is that wind that controls the flow and track of storm systems.

Took me three paragraphs to explain it. Maybe someone else can do it in one. 

Thank you for taking the time to explain this.  Can you help me understand how blocking works?  I am particularly trying to understand why a 50/50 low makes a -NAO more effective as a blocking agent.

[DarkSharkWX]

5 minutes ago, cbmclean said:

Thank you for taking the time to explain this.  Can you help me understand how blocking works?  I am particularly trying to understand why a 50/50 low makes a -NAO more effective as a blocking agent.

Here is a PPT that explains the significance of a 50/50 low(shows examples and explains more in detail), it prevents storms from cutting inland, strengthens the block, and locks high pressure in place

5050low.ppt

[Terpeast]

9 minutes ago, cbmclean said:

Thank you for taking the time to explain this.  Can you help me understand how blocking works?  I am particularly trying to understand why a 50/50 low makes a -NAO more effective as a blocking agent.

Remember that the wind controls the flow and track of a storm system. 

To understand blocking, let’s think of the opposite scenario:

Cold airmass (low geopotential height) over Greenland and a warm airmass (high geopotential height) over the west Atlantic. This is a +NAO.

The temp gradient in between the two air masses are going to be pretty damn steep. So we should expect very strong winds going between the two air masses. 

An incoming storm is going to follow the wind and traverse between the two air masses. Since the wind is moving fast, the storm will race through there.

Now, lets flip the air masses around and get a -NAO. 50/50 low in the western atlantic with a greenland high. Now the temp gradient will be much flatter. Wind will be moving very slowly, and may even reverse. 

An incoming storm approaches, and then because of weaker winds, it has nowhere to go. It gets “blocked”, hence the term. Sometimes it goes under the block, which means further south bringing more cold air south, which means snow for our location. 

[DarkSharkWX]

20 minutes ago, Terpeast said:

Couple of things. 

First, for the models to work well, they use pressure as a vertical coordinate system instead of height. Instead of 2,000 feet 4,000 ft 10,000 ft and so on, you have 900mb 800mb 700mb all the way up to 10 mb. It’ll be too complicated for the models/equations otherwise. 

Second, geopotential height patterns tells you where the warm air masses and cold air masses are. The higher the geopotential height at the 500mb pressure surface (think coordinate system), the warmer the airmass. The lower the geopotential height is, the colder the air mass. 

Now, when you have a cold and warm airmass butting up against each other, there is wind… and the stronger the temperature gradient between the air masses, the stronger the wind is. And it is that wind that controls the flow and track of storm systems.

Took me three paragraphs to explain it. Maybe someone else can do it in one. 

Paraphrased:
Models use pressure as a vertical coordinate system(500mb, 750mb, etc.) rather than height(10000 ft, 20000 ft, etc.) to work well. Geopotential height patterns at the 500mb pressure surface show where warm and cold air masses are located, with higher geopotential heights indicating warmer air masses and lower geopotential heights indicating colder air masses. When cold and warm air masses meet, wind is produced, with the strength of the wind being determined by the strength of the temperature gradient between the air masses. This wind controls the flow and track of storm systems.

[Terpeast]

3 minutes ago, DarkSharkWX said:

Paraphrased:
Models use pressure as a vertical coordinate system(500mb, 750mb, etc.) rather than height(10000 ft, 20000 ft, etc.) to work well. Geopotential height patterns at the 500mb pressure surface show where warm and cold air masses are located, with higher geopotential heights indicating warmer air masses and lower geopotential heights indicating colder air masses. When cold and warm air masses meet, wind is produced, with the strength of the wind being determined by the strength of the temperature gradient between the air masses. This wind controls the flow and track of storm systems.

Thank you. 

And did you use ChatGPT by any chance?

[DarkSharkWX]

7 minutes ago, Terpeast said:

Thank you. 

And did you use ChatGPT by any chance?

yeah lmao, chat gpt is pretty good with stuff like this(as long as it is given proper set of directions/data), i just changed a few parts

[pazzo83]

lol

 

[Solution Man]

6 minutes ago, pazzo83 said:

lol

 

[DarkSharkWX]

GFS fantasy run

[IUsedToHateCold]

4 minutes ago, DarkSharkWX said:

GFS fantasy run

Just looked… that’s going to make some people happy 

[Ji]

Just looked… that’s going to make some people happy 

Blue....and didn't have to pay 8 dollars

[Heisy]

Seeing better confluence for this time period showing up. We just had the GFS fantasy run, CMC looks better as well. Probably not enough confluence/cold air but trending right direction at least?



.

[cbmclean]

I see Ji would be happy at around Hr 300 on the 00z GFS.  That aside that GFS run does not amuse me.  Way too much blue at H5 around Alaska all the way to 384.  At 384 perhaps the merest hint of a nascent -EPO building in the Yukon.  I know op at range worse than useless.  But if people can  be happy about the blue I can be sad about the other blue.