LONG TERM [Wednesday Night through Saturday]...
Model guidance continues to have difficulty resolving various long
term forecast issues during the latter portion of the period as
would be expected in such a fast moving pattern across the CONUS.
The period begins with high pressure across the region quickly
sliding eastward and a strong frontal system approaching Wednesday
night. The models are actually in decent agreement here with respect
to timing. It looks like another cold front will surge through the
region on Thursday bringing a good chance for showers and
thunderstorms. Kinematic fields are strong out ahead of the system
but instability will once again be in doubt given the limited period
of return flow ahead of the system. The 16/00z GFS and Euro do
generate some non-zero areas of surface-based instability ahead of
the frontal boundary so the severe weather potential - while still
uncertain - cannot be ruled out yet.
Beyond Thursday, the forecast continues to be highly variable. While
cooler and drier air will move in behind the front, how cold it gets
and for how long continues to change with each model cycle. This
batch of guidance keeps the bulk of the cold air wrapped up to the
north closer to the core of the mid level trough across the Eastern
Seaboard and with the fast moving pattern, shifts a ridge across the
central CONUS eastward by Saturday, resulting in a quick moderating
trend to temperatures. Given the current pattern and the lack of any
strong signals favoring a significant cold intrusion into the south,
will trend the forecast warmer at the end of the long term period.
Needless to say beyond Thursday, the long term forecast is much
lower confidence than usual given all the run to run model