Leads to Discrepancies and Likely Errors In Outer Days of Forecast Periods
A fast wintertime weather pattern is setting up across the United States and it appears it will be with us for much of the month of December. It also appears this is higher likelihood of colder than previously forecast conditions during the month of December across the Tennessee Valley as several waves of arctic air pass over and through the region. Here are my forecast thoughts for Tuesday and why things could easily change in the forecast later this weekend into next week. Please note, ECMWF=European Forecast Model, CMC=Canadian Forecast Model and GFS=American Forecast Model.
Clouds breaking and gradual clearing. Still breezy. Wind chill values in the 30s
Low: 28 High: 44 Wind: WNW 10-15
Beginning mostly clear then becoming Mostly Cloudy with quite a thick shield of cirrus expected.
Low: 28 High: 51
Low: 31 High: 53
Continuing to follow the ECMWF and CMC over the GFS with regards to next Clipper and pattern
Mostly Cloudy with a 20% Showers,
Low: 31 High: 53
All depends on speed of Clipper. ECMWF much more pronounced with the feature as it has been for the last several days while the CMC has backed off of it some and now carries a weak front through on Saturday eve and GFS just brings through a weak front on Sunday itself. Due to consistancy, right now sticky with ECMWF. That would mean temperatures rising overnight Sat and falling on Sunday. Won’t quite go that route yet but will go with a milder morning and hold temps nearly steady for now.
Cloudy with a 40% Chance for Showers
Low: 41 High: 45
Cold Air Advection (CAA) to continue with a strong surge of Arctic air sinking into the Valley. GFS and ECMWF both come together on this solution. GFS grid shows possible flurries and is much colder with a high near 40 while the GFS mos prints out 51
Mostly Cloudy and Cold
Low: 30 High: 40-
Southern wave being indicated in the southern jet by all three models. CMC much faster, stronger and further north with it providing for a possible rain to snow for the Valley. GFS weakest with dominating high pressure over the Valley. ECMWF tending towards GFS but is a bit faster and much more pronounced with the wave but not like CMC, yet. Another note, GFS grids again much colder with highs in the mid 30s like the ECMWF while the MOS prints out 46.
Low: 25 High 38
GFS and ECMWF very similar to each other
Low: 23 High: 45