Absolute Vorticity

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Dynamic mid/upper level system will shift east out of the
Plains and across the Great Lakes region tonight into Saturday.
An associated surface low situated near northwest MO early this
evening will deepen as it lifts northeast into the northern
Great Lakes through Saturday afternoon, with an attendent cold
front sweeping east across the Ohio Valley late tonight into
Saturday morning. This will be accompanied by impressive wind
fields with a 70+ knot 850 low level jet shifting east across
our area later tonight into early Saturday morning.

In continued southerly low level flow ahead of the front,
temperatures and dewpoints will continue to warm through
tonight, with lower 60 dewpoints possibly making it all the way
up into southwest portions of our area after midnight tonight.
This should allow for at least some weaker surface based
instabilities to advect/develop into our area through the
night, possibly up to around 500 J/kg or so across at least
southwest portions of our area. The CAMs continue to show a
fairly wide range of solutions as to how convection may possibly
develop later tonight with the pre frontal trough ahead of the
front and then also with how much convection may develop along
the front as it pushes east across our area Saturday morning.

Given the strength of the low level jet, would expect to see
fairly wide shower and embedded thunderstorm development across
our area after midnight tonight. The storms will likely start
off more elevated, but will then become more surface based as we
start to get into some better surface based instability ahead
of the front late tonight. Damaging winds remain the primary
threat, but given the strength of the low level wind fields, a
tornado or two will also be possible, with the main threat
looking to be in the 3 AM to possibly 10 AM time frame late
tonight into Saturday morning. While locally heavy rainfall will
be possible, especially with any training cells, the system
appears to be progressive enough to limit any widespread
flooding concerns.

As the front moves through, pcpn will taper off quickly from
the west with good CAA developing across the area. This will
allow for windy conditions through Saturday afternoon with
wind gusts in the 30 to 40 mph range likely. Temperatures will
also peak out early in the day with falling temperatures through
the afternoon.