There appears to be a growing confidence that there will possibly be severe weather in the Mid-Mississippi River Valley tomorrow ahead of an advancing cold front, especially tomorrow afternoon. Although there are still some uncertainties.
Currently the HRRR and RAP show a bit more backed system than the NAM does. The HRRR shows an "opening" of rain for Southern IL during the day Sunday, and also has the front a tad slower. Therefore having some cells developing early tomorrow afternoon across Southern IL and the rest of the region in the "Uncertainty" area. The Nam has a line beginning to form late morning from a boundary that was set during the very early morning storms in extreme Southern IL by late morning and ending by noon for that region. So, two completely different scenarios for Southern IL.
Although for areas to the south of that in the "Slight" area, both models agree that a line of storms will develop and move through Sunday afternoon and into the evening hours more east. Due to more of a linear structure, this will largely be a damaging wind threat, although it appears that there will be a chance for couple tornadoes based on recent model trends showing some lower-level wind shear (S/SSW winds lower and SW/WSW winds in the mid-levels), as well as low chances of hail, although if the CAPE values (instability) continue to rise, that may be more possible (currently 800-1,200).
Definitely something I will continue to watch and update! Stay tuned!
HRRR at 3pm Sunday
NAM at 2pm Sunday
NAM Forecast Weather sounding for Western Kentucky at 2pm Sunday.
Temperatures and Dew Points are in the mid 60s
ML Cape (area between the temperature (red line) and the air parcel (dotted line)) is 900+ (bottom left hand side) with a LI (Lifted index) value at -3 (anything less than 0 is unstable)
Wind shear (hodograph in the top left): showing winds at the surface 10-15mph from the S/SSW, and winds in the mid-levels 25+ out of the SW. Interesting with the little area of less wind at about 800mb
All of this shows severe weather is definitely possible along the cold front tomorrow afternoon!