Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 011642
Area Forecast Discussion
National Weather Service Louisville KY
1242 PM EDT SUN MAY 1 2016
...Updated Aviation Discussion...
Issued at 1031 AM EDT Sun May 1 2016
...A few severe storms possible this afternoon...
The latest surface analysis depicts a broad, generally weak area of
low pressure located across portions of eastern IL and western IN
this morning. A quickly destabilizing airmass is in place to the
south of this feature, with temps rising into the low 70s and
dewpoints in the middle 60s. Satellite data shows plenty of
clearing taking place across portions of western KY and central KY
which should allow temperatures to continue to climb pretty quickly
through the early afternoon hours.
The latest hi-res model guidance suggests that convection may break
out as early as 1PM across portions of southern IN and north-central
KY, just to the southwest of the weak low pushing off to the
northeast through Indiana. Deep-layer shear profiles supporting
straight hodographs will favor strong/severe multicells and
potentially even some splitting supercell structures. Steep mid-
level lapse rates and enough dry air around 700mb will support both
locally severe hail and locally damaging wind gusts. The generally
weak convergence on the southwest flank of the surface low does lead
to some uncertainty of coverage, especially with southern extent.
But think areas along/north of I-64 have the best threat for a few
strong/severe storms this afternoon. Will be talking with SPC on
the potential for an upgrade to a Slight Risk.
.SHORT TERM (Now through Monday)...
Issued at 301 AM EDT Sun May 1 2016
After a day of mostly rain showers with a few thunderstorms
yesterday, convection has picked back up tonight as a shortwave
crosses the region. This disturbance will move off to the northeast
during the early morning hours and storms are expected to decrease
by around sunrise. A few strong storms will be possible before this
activity moves out with hail and gusty winds being the primary
We should see a mostly dry period through much of the morning in the
wake of this morning`s convection. This should allow temperatures to
warm nicely into the 70s to around 80. For the afternoon into the
evening hours, another shortwave will move into the lower Ohio
Valley. A weak surface low will track across IN with a cold front
moving into the area this evening and through the overnight hours
The thinking for this afternoon remains largely the same as
yesterday afternoon. Instability will increase with CAPE values
rising to 1500-2000 J/kg. Though hodographs will be relatively
straight, 0-6km shear values will be on the order of 50-60 knots. In
addition, we should have some dry air at mid levels. It still looks
possible for some strong to severe storms to develop this afternoon.
Large hail and damaging winds will be the main threats with the
strongest storms that do develop.
Storms will move out late this evening as the cold front moves
through. The latest model runs have been slowing the passage of this
cold front and hanging it up somewhere across south central KY or
northern TN. Another wave then rides northeast along the front
Monday. The latest guidance is in fairly good agreement that at
least southeast central KY should see quite a few showers on Monday,
so pops were increased to the likely category. In addition,
soundings do show some instability, so have added in a chance for
thunderstorms on Monday as well.
.LONG TERM (Monday Night through Saturday)...
Issued at 312 AM EDT Sun May 1 2016
The lingering cold front across the region will finally sweep
through Monday night, bringing a brief end to the rain. However, an
upper level wave moving in on Tuesday could bring some additional
very light showers. In the wake of the front Tuesday looks to be
cooler with highs only in the mid 60s.
For the latter half of the week a deep upper level trough will build
in across the eastern CONUS. This will bring with it some chances
for rain as well as continued cooler temperatures.
The best chance for rain will be on Wednesday into Wednesday night
as another cold front sweeps through the Ohio Valley. This front
will bring much cooler air in its wake with highs on Thursday
topping out only in the upper 50s to lower 60s across most of the
area. In addition, some showers will likely linger across the
Bluegrass region through this time frame.
The trough will slowly shift eastward through Saturday. This will
lead to moderating temperatures Friday into the weekend. Highs on
Friday look to top out in the mid to upper 60s with Saturday back
into the 70s across much of the area. A few showers will still be
possible across the Bluegrass Friday, but should be east of the area
.AVIATION (18Z TAF Update)...
Updated at 1241 PM EDT Sun May 1 2016
Confidence is growing that a cluster of thunderstorms will develop
just west of SDF over the next hour or two and move east into LEX
later this afternoon. Have timed this window out with a TEMPO
group, but will go prevailing once the storms begin to develop.
Expect IFR vsbys, gusty and variable winds, along with possibly some
hail with these storms. Confidence in convective coverage is not as
high at BWG, but still think a storm or two may impact the terminal
this afternoon. Outside of any storms, cigs should continue to mix
out to VFR with winds turning more to the WSW at 5-10 knots.
Convection will clear out tonight leaving VFR conditions. There may
be some low stratus development especially at LEX, but not high
enough confidence to include at this time. Additional showers will
move in from the southwest late in the period at BWG and into the
planning period at SDF.