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MLK Weekend Event - Making Lemonade Out of Lemons


Bob Chill
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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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41 minutes ago, nj2va said:

3k NAM same time. Seems NWS Pitt isn’t favoring that look above given the text of the watch for the mountains. 

LWX posted watches for the I81 counties in NVA and MD. 

1495DC91-F169-4BFB-80DE-92A51782BA2E.png

NAM is by itself. Either a major win coming or overdoing things as usual. Rgem is obviously warmest but fair support that says NAM is likely too cold.

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3 hours ago, Ralph Wiggum said:

NAM is by itself. Either a major win coming or overdoing things as usual. Rgem is obviously warmest but fair support that says NAM is likely too cold.

I should have added, I'm not tracking this for Arlington...I'm tracking for McHenry/Garrett County as I'll be at my house there this weekend.   I agree that the cities will see rain from this and the story will be the drop in temperatures.  Euro is warmer than the NAM but is still colder than RGEM by a considerable amount.  

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