IWX AFD:
"It looks like the low levels will be saturated Thursday morning so
we`ll have some work to do to get instability created ahead of our
thunderstorm chance later Thursday. Another stronger area of mid
level lapse rates push into the area during the day Thursday and
this helps to keep the lid on the area until the afternoon or
evening. We`ll probably need to wait until better large scale ascent
arrives to break this cap and, while the NAM pushes through a small
area of large scale ascent with an initial wave rotating through,
the better chance of such a cap break occurs later, towards 21-00z
time frame. Already by midday Thursday, 60 degree dew points work
into the area and PWAT anomalies reach 3 to 5 SDs above normal
closer to the arriving cold front 21-00z. It appears initial shear
may be perpendicular to the boundary, but will be quick to turn
parallel meaning any initial cells that area able to form out
in front of the boundary could have discrete characteristics,
but will be quick to congeal into a linear structure. 40 to 60
kts of effective shear swinging through and pockets of 200 units
of effective helicity will make wind damage and large hail the
main threats, but especially if those discrete cells are able to
form, there could be some rotating cells out in front of the
line. Depending on how quickly the line moves, there could be
some embedded vorticies within the line to make tornadoes a
threat as well, but confidence on those forming is lower than
the above two threats. Given the boundary parallel shear
tendency, flooding will be possible later in the line`s
evolution, but this would likely be from training cells as
opposed to backbuilding cells. The MBE vector appears strong
enough according to NAM Bufkit. It appears the strongest part of
the line will be out of the area by 11 pm or so but some rain
could lag the line."