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2/10-2/12 Winter Storm Threat


The Iceman
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Just now, RedSky said:

Water expands when it freezes then break it into little pieces 1:1 feels like being short changed

 

I never liked how sleet was added to snowfall makes no sense....its not snow. I also dont like padding winter snowfall with fluke April snows. The latter I can accept moreso than the sleet thing but that's just me being picky. 

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5 minutes ago, RedSky said:

Water expands when it freezes then break it into little pieces 1:1 feels like being short changed

 

Maybe the 3:1 is the melted down liquid equivalent. I see it as frozen just denser than snow. Same goes for wet snow vs dry snow, it is what it is when it comes to measuring what's fallen.

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Okay I'll break down Berks County on the NAM.

 

Snow comes in around 9pm Monday evening and goes until 5am Tuesday before any mixing. Total snow around 4".

 

Sleet starts to mix around 5am Tuesday and lasts until noon or 1pm. Total qpf from sleet around 0.4" or so. That would come out to a little over an inch of sleet.

 

Total from wave one and wave 2: 5-6" of snow and 1.2" of sleet.

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2 hours ago, famartin said:

Kamu said I needed to provide some guidance on sleet here. Without reading the whole thread, can someone bring me up to speed?

I think we more or less sorted it out, but to summarize:

Is sleet counted as snow for snowfall totals, and at a 1 to 1 ratio? E.g., 3" of snow followed by 0.5" of sleet would be 3.5" of snow (especially if measured separately, as opposed to snow depth).

What is the LE ratio for sleet, about 3:1? Newman seems to have it nailed down at around 3.5:1.

There are the model output (snowfall map) issues where sleet may be added to total snowfall as if it was snow at a 10:1 ratio, but I think that can be sorted out by looking at soundings, upper air temps, qpf, snow depth maps, etc.

Thanks in advance Ray!

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16 minutes ago, KamuSnow said:

I think we more or less sorted it out, but to summarize:

Is sleet counted as snow for snowfall totals, and at a 1 to 1 ratio? E.g., 3" of snow followed by 0.5" of sleet would be 3.5" of snow (especially if measured separately, as opposed to snow depth).

What is the LE ratio for sleet, about 3:1? Newman seems to have it nailed down at around 3.5:1.

There are the model output (snowfall map) issues where sleet may be added to total snowfall as if it was snow at a 10:1 ratio, but I think that can be sorted out by looking at soundings, upper air temps, qpf, snow depth maps, etc.

Thanks in advance Ray!

3:1 or 3.5:1 is about right. Model snow map output continues to have issues discriminating. In any mix scenario I would always look closely at thermals for myself.

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1 hour ago, anthonyweather said:

 

 


In your head maybe

6d2cf2a1a1a5ff0b7c17e6f7eac1c1ec.jpg


.

 

 

That is an inside joke sir. Most here know what it means to be NAM'd. Regardless that is poor practice to be using a kuchera based snowfall map in what looks to be quite an IP and fzra for parts of the interior.

I strongly suggest you pull up a skew-t and take a look around the region at thermal soundings from the 18z. A larger part of the event now shows sub 850s this run with a warm tongue and LOTS of sleet. So yes while that map you posted is likely more accurate for snowfall it is extremely misleading irt the IP/fzra potential with this CAD situation.

If you put the 10:1 snow map next to that map you posted the difference is mostly IP and that my friend is a big red flag. Again most people here (the group of like 10 of us that post here) know that is not all snow. Your subforum is going to have alot of ice issues.

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