Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Nashville Tennessee
525 am CST Friday Dec 26 2014
Update...for 12z aviation.
Aviation...12z taf discussion.
VFR conditions expected throughout this taf cycle with light
southerly winds. High clouds will continue to stream into middle
Tennessee today. These will give way to a middle-layer cloud deck later
tonight ahead of an approaching weather system on Saturday.
Previous discussion... /issued 243 am CST Friday Dec 26 2014/
Discussion...surface high has moved to the east with a weak
gradient at the surface and excellent radiational cooling
underway. Return flow will increase during the day, with warmer
temperatures the next couple of days as a result. Storm system
currently brewing over the plains will move slowly eastward as we
head toward the weekend. By Saturday, look for deep moisture to
begin spreading across the region as the surface and 850 mb trough
approach the middle state with plenty of positive Omega and a high
probability of showers Saturday and Saturday night. At this time,
there appears to be too little instability for thunderstorms to
develop here ahead of the front. Storms will likely develop
further south but should just be showers for middle Tennessee.
Expect frontal passage Sunday or Sunday evening, with the European model (ecmwf) running a
little slower than the GFS. Temperatures will cool off
considerably following the front, and the GFS and European model (ecmwf) both hint
at a dry surface front and upper trough on Wednesday that will
drop temperatures even further.