NZUS01 KLMK 160735
WRKLNG

Saturday and Saturday Night...

For Saturday, a large scale upper trough axis over the upper Midwest
will shift through the Midwest, Great Lakes, and the OH/TV Valleys
during the day on Saturday.  A large cold front will accompany this
trough axis and this feature will be the focus of shower and
thunderstorm activity.  Ahead of the front, the pressure gradient
will increase and that will lead to gusty southwest winds of 25-30
mph during the morning and into the afternoon hours.  An extensive
area of cloud cover will spread across the Ohio Valley during the
day, mainly impacting areas west of the I-65 corridor.  Highs along
and west of the I-65 corridor look to warm into the low-mid 70s,
with upper 70s to near 80 in areas east of I-65.

The latest guidance continues to push the front in a little faster
than in previous forecast.  As of this writing, the surface cold
front should be pushing across the IN/IL border by Saturday morning
and then crossing the Ohio River sometime between 18-21Z and then
slowly pushing into the Bluegrass region during the late evening
hours.  Ahead of the front, a band of widespread showers and
thunderstorms is expected.  Instability may be quite limited in
areas west of I-65 due to extensive cloud cover.  However, in areas
east of I-65, a pool of low level moisture will be available and
some diurnal heating may allow MLCAPE values to reach 800-1000 J/kg.
While the instability may be modest, model proximity soundings
continue to show rather strong low-mid level flow across the region
which would support organized convection. Overall flow is
unidirectional so convection would tend to be more linear in nature
with damaging winds being the main concern.  Best combination of
shear/instability looks to be just northeast of the CWA from across
mainly southern Ohio into portions of West Virgina where the new SPC
day 3 slight risk is located.

The highest chances of showers and storms on Saturday continues to
be from the mid-morning through the late afternoon as the frontal
boundary pushes through the region.  Overall confidence in the
frontal boundary timing has increased a bit with this forecast as
most model guidance has the frontal boundary east of the I-65
corridor by the evening hours.  While the front may be pushing
through the Bluegrass region at that time, extensive cloud cloud
cover and light rain showers may persist until mid-evenig or so.
Behind the front, the winds will shift to the northwest and will
remain gusty through the evening.  Temperatures are expected fall
sharply behind the front, with afternoon readings falling from the
70/80s to the low-mid 50s by mid-evening.  Convection looks to move
out of the forecast area by midnight or so with temperatures falling
into the lower 40s by sunrise Sunday.

Sunday through Wednesday...

Upper trough axis will pivot through the region on Sunday with a
much cooler/drier airmass filtering into the region through the day.
Highs on Sunday will likely remain in the upper 50s in the Bluegrass
region with lower 60s elsewhere.  High pressure will pass over the
region Sunday night and there is an increasing risk of frost across
the area, especially in the Bluegrass region where temperatures may
dip into the middle 30s.  Highs will begin to moderate on Monday
with readings in the lower 60s in the Bluegrass with mid-upper 60s
in the I-65 corridor and points west.  Highs will warm into the 70s
for Tuesday and Wednesday with a slight chance of showers/storms on
Wednesday.