Jan. 19-20th, 2024 | Winter Storm Speculation

[Lazman]

8 hours ago, so_whats_happening said:

All good.

So when I mentioned temps at the surface and 925mb in my previous post that is solely to state that temps can go as high as that but still have reasonable snow ratios above 10:1, more likely they will end up closer to 10:1 though. The NWS post is spot on and those are the most important factors to consider. The best way to describe it is there is a balance between moisture and temperature, the more moisture but warmer temp the further left you go in the snowflake chart. It can still accumulate well but you use up more moisture and that hurts the potential of maximizing snowfall output. Now when you have a scenario like we have coming up where there is less moisture available so the temps become rather important but it is the temps aloft that are the important part not at the surface. 

Surface temps are correlated to how much cold air is pressing into the region so if we have extremely cold temps aloft the surface temps will be notably colder but then we get issues of moisture availability and irregular snowflakes think micro flakes in that scenario. They fall the ground gets coated but you get hours and hours of that and maybe only accumulate 1-2". As time goes on more moisture pushes into the region from warmer areas (think of warm air advection) the upper levels warm up to a more suitable level and there is more moisture availability to allow for near perfect conditions for snow growth. If you add too much moisture we start to slide left on the scale and then get heavy wet snows but all the while this is happening surface temps could stay the same. It is aloft that matters notably from 850 to about 600mb that matters the most. 

It is a big reason why when we get coastal storms the area NW of 95 into the mountains tend to get the most snow because the balance between moisture and temps with strong lift is near perfect while closer to 95 and the Jersey shore tend to still get snow but it is an extremely heavy wet snow. Both areas may have the same amount of QPF lets use 1" as an example so Jersey and 95 corridor get 6-10" with that there snow ratios are about 6:1 to about 10:1 while areas NW get 12-16" so there ratios are more along the line of 12:1-16:1 the biggest reason the temps aloft are colder NW and get to more suitable levels for good dendritic growth. It is rather rare to stay at one specific snow ratio the whole storm though and they tend to only happen with these weaker systems that throw moisture in. 

Temps in the column of 850-700mb may only be closer to say -6 closer to 95 while NW gets closer to -10 or -12. If we start to go colder ratios go up of course but the accumulation rate tends to weaken as the flakes become irregular and the dendritic growth zone moves out of the best lifting region. Less moisture also shows up in colder temps but if lift is strong enough it can overcome that issue and still produce think clippers in that scenario. It really is a fine balance though and surface temps only play a role in moisture availability and stickage. You want low levels (surface-850mb) moist so that when your lifting mechanism gets to you there is enough moisture to produce but you don't want too much or it hurts growth potential.

Thanks for your time and weather speak. Much appreciated. 

[Snowadelphia]

About an inch and a half on the ground right now. Snow has picked up considerably in the last 15 minutes or so. Roads are covered.

[clm]

18 minutes ago, Chris2333 said:

Reason 203 why you can’t trust weather apps (even weather underground). Yes I put the obligatory grill in the photo  

 

You're the only one getting Fog.  Do you know how much Fog you're going to get?  🤪

[Rheino]

Our grill shot. 3+ today. Snizzle atm, waiting to see if pivot produces more. Bowie md

[Undertakerson2.0]

Just now, Rheino said:

Our grill shot. 3+ today. Snizzle atm, waiting to see if pivot produces more. Bowie md

Nekid grills!

[Wtkidz]

[clm]

1 minute ago, Rheino said:

Our grill shot. 3+ today. Snizzle atm, waiting to see if pivot produces more. Bowie md

I always had a problem grilling eggs.  They just kept falling down.

[Sentinel]

12 minutes ago, Undertakerson2.0 said:

Kind of OT, somewhat related though

This is Jim who, waaaay back in Accu Days was known to us as a 16y.o. aspiring met - went by OSUWx2 or some such. We named him Poster of the Year one year (same year Jesse kicked him off the forums LOL) He is now an actual Met out of NWS Cleveland 

So... Get him over here... 😎

[eddygeeme]

5 hours ago, Rheino said:

Bernie, Bernie, Bernie lol

He nailed it 

[Sentinel]

8 hours ago, so_whats_happening said:

All good.

So when I mentioned temps at the surface and 925mb in my previous post that is solely to state that temps can go as high as that but still have reasonable snow ratios above 10:1, more likely they will end up closer to 10:1 though. The NWS post is spot on and those are the most important factors to consider. The best way to describe it is there is a balance between moisture and temperature, the more moisture but warmer temp the further left you go in the snowflake chart. It can still accumulate well but you use up more moisture and that hurts the potential of maximizing snowfall output. Now when you have a scenario like we have coming up where there is less moisture available so the temps become rather important but it is the temps aloft that are the important part not at the surface. 

Surface temps are correlated to how much cold air is pressing into the region so if we have extremely cold temps aloft the surface temps will be notably colder but then we get issues of moisture availability and irregular snowflakes think micro flakes in that scenario. They fall the ground gets coated but you get hours and hours of that and maybe only accumulate 1-2". As time goes on more moisture pushes into the region from warmer areas (think of warm air advection) the upper levels warm up to a more suitable level and there is more moisture availability to allow for near perfect conditions for snow growth. If you add too much moisture we start to slide left on the scale and then get heavy wet snows but all the while this is happening surface temps could stay the same. It is aloft that matters notably from 850 to about 600mb that matters the most. 

It is a big reason why when we get coastal storms the area NW of 95 into the mountains tend to get the most snow because the balance between moisture and temps with strong lift is near perfect while closer to 95 and the Jersey shore tend to still get snow but it is an extremely heavy wet snow. Both areas may have the same amount of QPF lets use 1" as an example so Jersey and 95 corridor get 6-10" with that there snow ratios are about 6:1 to about 10:1 while areas NW get 12-16" so there ratios are more along the line of 12:1-16:1 the biggest reason the temps aloft are colder NW and get to more suitable levels for good dendritic growth. It is rather rare to stay at one specific snow ratio the whole storm though and they tend to only happen with these weaker systems that throw moisture in. 

Temps in the column of 850-700mb may only be closer to say -6 closer to 95 while NW gets closer to -10 or -12. If we start to go colder ratios go up of course but the accumulation rate tends to weaken as the flakes become irregular and the dendritic growth zone moves out of the best lifting region. Less moisture also shows up in colder temps but if lift is strong enough it can overcome that issue and still produce think clippers in that scenario. It really is a fine balance though and surface temps only play a role in moisture availability and stickage. You want low levels (surface-850mb) moist so that when your lifting mechanism gets to you there is enough moisture to produce but you don't want too much or it hurts growth potential.

 

7 hours ago, so_whats_happening said:

Another important thing I wanna throw out here is snowfall intensity, this is based off of visibility. 

Heavy snow is 1/4 mile or less

Moderate snow is above a 1/4 mile but less than or equal to 5/8ths of a mile (typically shown at 1/2 mile at ASOS)

Light snow is considered above 5/8ths of a mile (typically shown 3/4 mile or above at ASOS).

 

So when you see a station reporting 3/4mile visibility this is still considered light snow. 1/2 mile gets switched to moderate snow. and 1/4 mile is heavy snow.

You tend to get snowfall rates of 1" per hour around 1/2 mile visibility and less than 1" per hour with 3/4 mile visibility. 1/4 mile and less visibility pushes you closer to 2"+ per hour rates.

This is all just from my experience of working at the airport for snowfall rates.

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[Tater]

2 minutes ago, Wtkidz said:

Snow doesn't seem to be making it out of WV into VA. Seems like the mountains often wring it out and we don't get much from snow coming from the west.

We got 1.25" overnight, and it's been mood flakes all morning that haven't amounted to anything.

[clm]

On 1/18/2024 at 8:53 AM, stormsurf said:

Im so happy to have found you all again.  

You may not remember me from the Accu days, mostly a lurker, but always enjoyed this bunch.

I dont add much to the discussion, although you think I would have learned more over the years 😜....mostly just zingers here and there.

Glad to be back and around so much weather knowledge....the boards I have tried were super BORING.  

Agree on that.  I joined one forum last year and posted and no responses.  7 months later I got a welcome response.  The moderator said something to the effect of welcome, this is a relaxed forum compared to others.  I figured, yeah 7 months for a response is extremely relaxed.  Needless to say I never went back again.

[Sentinel]

On 1/18/2024 at 8:53 AM, stormsurf said:

Im so happy to have found you all again.  

You may not remember me from the Accu days, mostly a lurker, but always enjoyed this bunch.

I dont add much to the discussion, although you think I would have learned more over the years 😜....mostly just zingers here and there.

Glad to be back and around so much weather knowledge....the boards I have tried were super BORING.  

Welcome! 

[Chris2333]

8 minutes ago, clm said:

You're the only one getting Fog.  Do you know how much Fog you're going to get?  🤪

Some damn thick fog here in the form of small white flake things…

[Undertakerson2.0]

Back to snowing moderately again. 

(looks at clock) Oh man, time to go measure? Again? (sighs deeply puts on Uncle Buck hat and heads towards door) 

Edited January 19 by Undertakerson2.0

[Snowadelphia]

7 minutes ago, eddygeeme said:

He nailed it 

Wouldn’t say he nailed it - but he absolutely had the right idea. 

[mikeysed]

Mt Holly went backwards and upped totals: In the last 12 hours they've shifted a lot of 4-6 to 2-4 now 3-4".

 

I am assuming they feel the heavier echos will make it more north.

 

Edited January 19 by mikeysed

[mikeysed]

Yet Upton lowered amounts:

 

[Sentinel]

1 minute ago, mikeysed said:

Mt Holly went backwards and upped totals: In the last 12 hours they've shifted a lot of 4-6 to 2-4 now 3-4".

 

I am assuming they feel the heavier echos will make it more north.

 

Wherever the cut off is on those bands, those just S and E will receive a nice thump. 

[mikeysed]

1 minute ago, Uscg Ast said:

Wherever the cut off is on those bands, those just S and E will receive a nice thump. 

Yep. ALMOST to me, 3 towns away about 15 miles to my south :

 

[Undertakerson2.0]

10:30 report

SN; 26.5F

W - Calm

SN Ttl: 1.75"

[woodyelm]

Carlisle, PA  10:38 am.  30 degrees F.  81% humidity IMBY.  Accumulation 1-57/64 of an inch.  Pretty snowfall.  Light, but keeping the street free of white mud.  

[Undertakerson2.0]

Just now, woodyelm said:

Carlisle, PA  10:38 am.  30 degrees F.  81% humidity IMBY.  Accumulation 1-57/64 of an inch.  Pretty snowfall.  Light, but keeping the street free of white mud.  

1-57/64 of an inch

LOVE IT!

[DLisa]

JUST started snowing here.  Supposed to get 4-6 but looks like just around 3.  But, I'm not complaining! 😊

Edited January 19 by DLisa

[Bucikaroo]

6 minutes ago, mikeysed said:

Mt Holly went backwards and upped totals: In the last 12 hours they've shifted a lot of 4-6 to 2-4 now 3-4".

 

I am assuming they feel the heavier echos will make it more north.

 

Yea they up our totals again