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Wintry Possible Snow & Ice Threat Nov 14-15

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Brick Tamland said:
So, what's keeping this from happening? Because it is crazy for a model to show that much and there not be any frozen precip here.
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There is a strong warm nose aloft that is keeping this from being snow across NC/SC. The Tidbits maps see surface temperatures near freezing and calculate ice and cold rain of 33-34 as "snow" when in reality the only frozen precip will be in the immediate mountains. See the strong warm nose here.
fv3p_T850_us_9.png


Even the coldest portions of NC where the 850s are at or below 0C have a pronounced warm nose.
upload_2018-11-13_12-4-0.png
 
snowlover91 said:
There is a strong warm nose aloft that is keeping this from being snow across NC/SC. The Tidbits maps see surface temperatures near freezing and calculate ice and cold rain of 33-34 as "snow" when in reality the only frozen precip will be in the immediate mountains. See the strong warm nose here.
fv3p_T850_us_9.png


Even the coldest portions of NC where the 850s are at or below 0C have a pronounced warm nose.
View attachment 7359
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So, why can't the model take the warm nose into account?
 
Also note the warm air advection at the 850 and 700 levels is particularly strong due to the SE wind since the ULL is to our west/north.
nam3km_temp_adv_fgen_850_seus_49.png


Here's the 700mb level showing the warming temps aloft.
nam3km_temp_adv_fgen_700_seus_41.png
 
Brick Tamland said:
Maybe it would be better to just not post maps from Tropical Tidbits if they are not reliable.
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I agree, the methods used on Pivotal Weather are generally a bit more accurate and represent the overall atmosphere and sounding plots better as well. They're not perfect but you can see the vast difference between the two when ice and marginal temps are involved.
gfs_asnow_us_11.png


Snow.JPG
 
SnowNiner said:
Was just thinking the same thing. Well, at least now we know. FV3 just showed its hand....
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The FV3 snow map looks fine. It's the Tidbits clown maps that are the issue, not the GFS or FV3. Here is the FV3 with a better snow flag algorithm applied.
FV3.JPG

Compare with the Tidbits map for the same period.
fv3p_asnow_us_11.png


Also notice the p-type map on the FV3 for Tidbits correctly shows rain and ice in areas the snow map drops a foot or more of snow. The issue, again, is not with the model as it is with the Tidbits maps calculating ice and marginal 33-34 cold rain as snow.
fv3p_mslp_pcpn_frzn_us_8.png
 
accu35 said:
I don't think TT has an ice map, so there could be ice on there if so
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TT map includes ice like zr and ip and also includes marginal 33-34F temps in the snow map. It's inherently flawed and should not be used in a setup like this IMO.
 
snowlover91 said:
TT map includes ice like zr and ip and also includes marginal 33-34F temps in the snow map. It's inherently flawed and should not be used in a setup like this IMO.
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Last year we had this discussion about the Nam being overdone and December 7/8th storm hit, it was pretty darn close to it's accumulation TT map. But I get what your saying.
 
accu35 said:
Last year we had this discussion about the Nam being overdone and December 7/8th storm hit, it was pretty darn close to it's accumulation TT map. But I get what your saying.
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The difference in that storm though was the pivotal maps for the NAM were similar to the TT maps. Soundings are ultimately the best way to tell what’s going on but not many use those anymore.
 
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snowlover91 said:
The difference in that storm though was the pivotal maps for the NAM were similar to the TT maps. Soundings are ultimately the best way to tell what’s going on but not many people don’t use those anymore.
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I mean you can scroll through hour by hour and tell what’s falling as green and what’s falling as pink. Those TT precip maps will sucker you in though If you aren’t careful. Coldest rain of the season incoming
 
snowlover91 said:
The difference in that storm though was the pivotal maps for the NAM were similar to the TT maps. Soundings are ultimately the best way to tell what’s going on but not many use those anymore.
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I like the text soundings. Those bent line ones give me a headache. But soundings are great. And if there is a warm nose, it will likely be warmer than modeled.
 
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