Before I start with the forecast, I want to share a story. As I was driving up to the High Country, I stopped at a rest stop just east of Wilkesboro. An old man says to me "I like your shirt" (referring to the NC State logo I had on it). I told him I have been out in the real world for 10 days and he tells me "I graduated in the class of 58 as an engineer. Where are you heading?" I tell him and he says "Ohhh I used to live up in Boone, moved up there in the fall of 59. I just couldn't handle the winters up there." I quickly put two and two together and realize why he was saying that. His first year he had to deal with the 1959 - 1960 winter, the same winter that dropped 105" of snow in Boone (83" fell AFTER Valentines Day). He told me a story where his truck got stuck in a snow drift on Rivers Street, and how by the time the plow had gotten to him, the truck was completely buried in a snowdrift. He left the High Country in 1963, because apparently during that winter, it got so cold slush refroze between his brakes and his tires, rendering his front wheels inoperable. He ended up being towed to a dealership to chip the ice off of his brakes.
Please, if you have any winter stories, feel free to share!
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| Infrared - Water vapor (experimental, from CIMSS). Yellow = upper level divergence. Note the complete lack of outflow west of the circulation (because of shear). This divergence is where the exit region of the southerly jet is located. |
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| Upper level winds. Note that the yellow rings from the previous animation are where there is a decrease of upper level winds (and is to the right of this decrease). The surface low is also located downstream of the upper level low, meaning it's not ready to be listed as a named tropical system yet! |
First, lets have a look near Florida. We have a disturbance here, which has a medium chance of becoming a subtropical or tropical storm, especially when this southern trough decays. Because of strong wind shear, thunderstorm activity is east of the center. There is still an upper level low component to this, which is not over the center due to the shear. The low is sitting just downstream of a low level jet (the southern storm track). This jet is weakening: this should be conducive enough for a weak subtropical storm.
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| Infrared satellite image with vorticity contours (plot from CIMSS) |
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| Visible satellite with shear (yellow contours) and upper level wind flow (white). Plot from CIMSS |
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| 300mb winds for today (from weather.unisys) |
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| 1000mb temperature and pressure contours for tomorrow (from unisys) |
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| 300mb winds for tomorrow (from weather.unisys) |
The two blue/purple plots are upper level winds (this afternoon and tomorrow afternoon) with pressure contours and the plot on the right is a surface temperature plot (tomorrow afternoon). I would be really surprised to see a tropical cyclone designation before tomorrow. The decay of steering currents slow down this surface low and eventually the tropical low will drift into the Florida/Georgia coast. This is an area that needs the precipitation!
To our forecast:
Today: We are on the backside of a decaying trough, which will inhibit thunderstorm chances. Tomorrow and Sunday the southern component of the jet stream decays over the Southeast (the jet actually merges over Mexico/Southwest United States, which is very visible on the bottom plot). We are underneath an upper level ridge but high surface instability, particularly near the mountains, will inevitably allow for scattered pop-up thundershowers tomorrow afternoon. Between the upper level low (what may soon become a tropical cyclone) and the upper level ridge there will be slight upper level convergence over the Piedmont tomorrow, which will hinder thunderstorm formation there. I do think the inhibiting factor will be weak enough to allow for a stray pop-up storm here as well. Sunday will be mostly clear with a chance of an isolated showers (from the onshore flow from the tropical low). The isolated shower activity will be contained to east of the mountains and the eastern portions of the mountains. Note that the shower activity will be near stationary for both days.
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