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MLK Weekend Event - Making Lemonade Out of Lemons


Bob Chill
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11 minutes ago, high risk said:

a friendly reminder that when the NAM accumulated snow depth and Ferrier (from the nest) maps show much less than the 10:1 "snow" accumulation map, then the model is not predicting the snowfest that you think it is.....

Sanity check, 2.5 hrs of snow isn't going to give you 6-10"

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7 minutes ago, Amped said:

NAM ICON RGEM all have the same trend, lower heights out ahead of the storm and a further southeast track.

Seems like all of our trends are a day late and a buck short.

Yea...the lower hieghts are a nice change . Also.. with the anomalous artic cold lurking so close by . Models have trended much quicker with the cold plunge  starting with 18z suite. Sunday early morning now with the crash

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25 minutes ago, high risk said:

a friendly reminder that when the NAM accumulated snow depth and Ferrier (from the nest) maps show much less than the 10:1 "snow" accumulation map, then the model is not predicting the snowfest that you think it is.....

What's really off is the midlevels aren't even marginal. Not even close to a sleet sounding either but the snowmaps pile it up hour after hour. TT is using the JB algorithm tonight. 

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10 minutes ago, losetoa6 said:

Yea...the lower hieghts are a nice change . Also.. with the anomalous artic cold lurking so close by . Models have trended much quicker with the cold plunge  starting with 18z suite. Sunday early morning now with the crash

GFS has a similar trend 18hrs. 

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54 minutes ago, Bob Chill said:

What's really off is the midlevels aren't even marginal. Not even close to a sleet sounding either but the snowmaps pile it up hour after hour. TT is using the JB algorithm tonight. 

    What'a going on, I think (based off the NAM3), is that you have a huge slug of precip occurring during the evening hours - looks like well over an inch between 00z and 06z when the "snow" really piles up.    The soundings are really, really iffy in terms of sleet potential, but the model microphysics are allowing for some pingers to be mixed in with the rain.     Let's say that we have 1.3" of liquid falling and the model thinks that it's 60% rain and 40% sleet pellets:   we know that would not accumulate, but the tallying does 1.3" x 0.4 = 0.52" liquid of "snow (+ sleet) accumulation".   TT slaps a 10:1 ratio on that and gets 5.2" of "snow", while the Ferrier method will assign a way lower SLR since it knows that the frozen component is sleet and not snow.   

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1 minute ago, high risk said:

    What'a going on, I think (based off the NAM3), is that you have a huge slug of precip occurring during the evening hours - looks like well over an inch between 00z and 06z when the "snow" really piles up.    The soundings are really, really iffy in terms of sleet potential, but the model microphysics are allowing for some pingers to be mixed in with the rain.     Let's say that we have 1.3" of liquid falling and the model thinks that it's 60% rain and 40% sleet pellets:   we know that would not accumulate, but the tallying does 1.3" x 0.6 = 0.52" liquid of "snow (+ sleet) accumulation".   TT slaps a 10:1 ratio on that and gets 5.2" of "snow", while the Ferrier method will assign a way lower SLR since it knows that the frozen component is sleet and not snow.   

Man who does math at 11pm...yeesh lol :D

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a friendly reminder that when the NAM accumulated snow depth and Ferrier (from the nest) maps show much less than the 10:1 "snow" accumulation map, then the model is not predicting the snowfest that you think it is.....
I know...just asking what model is seeing to print that out...
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10 minutes ago, high risk said:

    What'a going on, I think (based off the NAM3), is that you have a huge slug of precip occurring during the evening hours - looks like well over an inch between 00z and 06z when the "snow" really piles up.    The soundings are really, really iffy in terms of sleet potential, but the model microphysics are allowing for some pingers to be mixed in with the rain.     Let's say that we have 1.3" of liquid falling and the model thinks that it's 60% rain and 40% sleet pellets:   we know that would not accumulate, but the tallying does 1.3" x 0.6 = 0.52" liquid of "snow (+ sleet) accumulation".   TT slaps a 10:1 ratio on that and gets 5.2" of "snow", while the Ferrier method will assign a way lower SLR since it knows that the frozen component is sleet and not snow.   

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40 minutes ago, high risk said:

    What'a going on, I think (based off the NAM3), is that you have a huge slug of precip occurring during the evening hours - looks like well over an inch between 00z and 06z when the "snow" really piles up.    The soundings are really, really iffy in terms of sleet potential, but the model microphysics are allowing for some pingers to be mixed in with the rain.     Let's say that we have 1.3" of liquid falling and the model thinks that it's 60% rain and 40% sleet pellets:   we know that would not accumulate, but the tallying does 1.3" x 0.6 = 0.52" liquid of "snow (+ sleet) accumulation".   TT slaps a 10:1 ratio on that and gets 5.2" of "snow", while the Ferrier method will assign a way lower SLR since it knows that the frozen component is sleet and not snow.   

I thought it would calculate the 40% instead. Either way, I can see why the snow maps would be off. This event might be too marginal to toss yet, at least for the northern tier.

edit: nevermind, I think you meant (1.3”)x(0.4). Makes sense 

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4 minutes ago, 87storms said:

I thought it would calculate the 40% instead. Either way, I can see why the snow maps would be off. This event might be too marginal to toss yet, at least for the northern tier.

 

    ugh.  Yes, I came out with the right "totals" but typed 0.6 where it should have been 0.4.    I've edited the original post.   People are right that math shouldn't be done at 11pm....

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