Skip Talbot
EF5
Hopefully somebody who knows a bit more about meteorology can set me straight on this one as I feel like a newb on this topic. I was cruising the models two nights ago trying to pick targets for yesterday's chase. There was a sharp temperature gradient across central IL, but not associated with a wind shift like frontal boundaries typically possess. I didn't immediately realize it and somebody had to point out to me that the snow pack was causing the sharp temperature gradient. I guess I'm not used to dealing with large areas of snow when making a chase forecast.
Lots of folks were still calling this gradient a warm front, however. Is this correct? It didn't seem so to me, especially without the wind shift. It seems like the warm airmass kept heading north with the warm air advection and that only a thin layer near the ground was being cooled. There was a wind shift well north of the snow line, up by Kankakee, IL by early afternoon although the temperature gradient was much more diffuse up there then it was further south by the snow line. If I had to label it, this is where I would put the warm front on a surface chart.
What about this snow pack cooling the surface layer though? Obviously it's an instability killer for surface based storms, but does it also act like a stationary frontal boundary? Even though the models aren't showing it, do the winds back any north of the gradient? Do we get any sort of favorable directional shear enhancement near the snow line? It seemed that several of the tornadoes that occurred yesterday happened immediately south of the snow line as if this was indeed acting like a warm front, but perhaps this was just coincidence as the parameters were maximized there at the time.
Lots of folks were still calling this gradient a warm front, however. Is this correct? It didn't seem so to me, especially without the wind shift. It seems like the warm airmass kept heading north with the warm air advection and that only a thin layer near the ground was being cooled. There was a wind shift well north of the snow line, up by Kankakee, IL by early afternoon although the temperature gradient was much more diffuse up there then it was further south by the snow line. If I had to label it, this is where I would put the warm front on a surface chart.
![1932256_10151924739251931_1468390166_n.jpg](/proxy.php?image=https%3A%2F%2Ffbcdn-sphotos-g-a.akamaihd.net%2Fhphotos-ak-ash3%2Ft1%2F1932256_10151924739251931_1468390166_n.jpg&hash=9fbaf3f077706c563d1905b37b7f66e4)
What about this snow pack cooling the surface layer though? Obviously it's an instability killer for surface based storms, but does it also act like a stationary frontal boundary? Even though the models aren't showing it, do the winds back any north of the gradient? Do we get any sort of favorable directional shear enhancement near the snow line? It seemed that several of the tornadoes that occurred yesterday happened immediately south of the snow line as if this was indeed acting like a warm front, but perhaps this was just coincidence as the parameters were maximized there at the time.
![yesterday_filtered.gif](/proxy.php?image=http%3A%2F%2Fwww.spc.noaa.gov%2Fclimo%2Freports%2Fyesterday_filtered.gif&hash=878dd38f9307b5793c525591fad04b89)
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