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Pittsburgh/Western PA WINTER ‘25/‘26


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just out of curiosity, i started to look at the soundings of the nam to see what is going on in those areas of sleet or fzr. Can someone explain how the entire column can be relatively comfortable below freezeing ( -3°C) and yet it is still showing fzr? Any ideas?

Screenshot 2026-01-23 at 10.50.13 PM.png

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On 1/19/2026 at 9:47 PM, RitualOfTheTrout said:

No need to nickel and dime...

</Optimism> Once the weekend storm slows down a little more allowing a clean phase with that northern stream piece dropping into the dakotas, the storm will move back north hammering us with 16 inches. </Optimism>

This post seems to be ageing well. :lol:

Given that, Ill stick to my original call for 16 imby.

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3 minutes ago, MikeB_01 said:

just out of curiosity, i started to look at the soundings of the nam to see what is going on in those areas of sleet or fzr. Can someone explain how the entire column can be relatively comfortable below freezeing ( -3°C) and yet it is still showing fzr? Any ideas?

 

maybe because it is too dry in the DGZ? Just throwing some thoughts against the wall

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2 minutes ago, MikeB_01 said:

maybe because it is too dry in the DGZ? Just throwing some thoughts against the wall

I don't know if the map shows as sleet despite there being only a few pellets of sleet. Maybe programmed to show as sleet any time no matter how much it really is sleeping even if only a few pellets. 

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1 minute ago, colonel717 said:

I don't know if the map shows as sleet despite there being only a few pellets of sleet. Maybe programmed to show as sleet any time no matter how much it really is sleeping even if only a few pellets. 

Could be... Any way, I view that as a positive.  The entire column stays below freezing all the way down to morgantown on that NAM - Even if it is showing up as a mix

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11 minutes ago, colonel717 said:

I don't know if the map shows as sleet despite there being only a few pellets of sleet. Maybe programmed to show as sleet any time no matter how much it really is sleeping even if only a few pellets. 

Chat GTP basically told me it’s “typical NAM behavior” and that it holds on to partially melted particles even if the warm layer was very shallow or gone.

Disclaimer: I’m posting this snippet  for entertainment purposes, and we know that the NAM does in many cases sniff this out. But could be something to this: 

  • Ignore NAM sleet if:
    • 850–700 mb is ≤ –2°C
    • No >0°C layer ≥ ~30 mb
    • Other models (GFS is snow
  • Use NAM for:
    • QPF placement
    • Thermal trends
    • Frontogenesis / banding signals
  • But not for dominant p-type in marginal cold events.
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Chat GTP basically told me it’s “typical NAM behavior” and that it holds on to partially melted particles even if the warm layer was very shallow or gone.

Disclaimer: I’m posting this snippet  for entertainment purposes, and we know that the NAM does in many cases sniff this out. But could be something to this: 
  • Ignore NAM sleet if:
    • 850–700 mb is ≤ –2°C
    • No >0°C layer ≥ ~30 mb
    • Other models (GFS is snow
  • Use NAM for:
    • QPF placement
    • Thermal trends
    • Frontogenesis / banding signals
  • But not for dominant p-type in marginal cold events.

Awesome use of AI!

So perhaps the NAM is not as north as we thought. More in line with the 3k


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