two waves, second with snow.

well the first wave is moving through the area with a sfc low now on the IA/IL border southwest of the davenport area, looks almost stationary but barely moving off the northeast it looks like. we have been socked under some descent rain all afternoon as well as northwest IL, eastern IA, and southern WI. there were some thunderstorms earlier today down near macomb and still a slight chance of a rumble of thunder.

looking at upper air data off meso-analysis, the low is vertically stacked all the way up. what will be interesting to watch is what goes on around here tomorrow night into thanksgiving on thursday. the 2nd wave is still up in canada but will begin to dive southeast into the U.S. and will be in the dakotas by morning and in MN in the afternoon. this 2nd wave looks to be a tad stronger then the one moving through the area now. this will slow down the departing first low and a trough will develop and rotate around the west side of the low. it will reinforce the cold air with the upper low moving into eastern IA by late tomorrow night and bringing 850 temps down to -3 and colder.

progs are showing very nice UVV and the possibility of a trowal like feature developing tomorrow evening with the best lift setting up from eastern IA to southwest/southern WI. most models do have the defo band/trowal on them but the exact location of it is the challenge. DVN also mentioned some convective development possible due to the steep mid-level lapse rates. the question is when the changeover from rain to snow occurs. the last few runs the GFS has been a tad warmer with the boundary layer temperatures, where the NAM and EURO are colder. with as much lift associated with this system and the really cold air aloft, I would think to go with the NAM and EURO and the faster changeover, but will have to be monitored.

MKX did put out a SWS for their CWA with the possiblity of 3-4 inches of snow in a small area saying the most snow should accumulate south and west of a line from the dells down to burlington. right now think the best area for the most snow would be from the DBQ/CWI/freeport area on northeast to south of MKX but we will have to see. wouldn't be suprised to see an inch or so down this way on grassy surfaces if the band can make it this far south. some models are showing that, here is an example...

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/hiresw/12/images/hiresw_slp_048l.gif

with this being the 12hr QPF forecast

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/hiresw/12/images/hiresw_p12_048l.gif

going to interesting to see what the 0z NAM says as well as the new short range models later on. wouldn't be suprised to see a 4 inch amount somewhere if a nice band can set itself up and drop some moderate to heavy snow for a short period. nice having something exciting to watch and forecast and getting giddy with winter getting underway.



Matt