Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 260533
Area Forecast Discussion
National Weather Service Louisville KY
133 AM EDT THU MAY 26 2016
...Updated Aviation Discussion...
Issued at 850 PM EDT Wed May 25 2016
The grids have been updated this evening to reflect the latest
trends. A decaying complex of showers and a few storms continue to
push through southern KY. This will continue to wane over the next
few hours, with most areas becoming dry around 06Z. Guidance then
diverges in their solutions for the overnight period. Have backed
off pops a bit, but still left 20-30 pops in overnight into Thursday
morning. It appears another wave will move through the WSW flow
aloft, which could induce some weak isentropic ascent atop some of
the boundaries left over by today`s convection. Don`t expect
coverage to be great, and really don`t expect too many thunderstorms
(will leave just slight chances for thunder). Otherwise, depending
on cloud cover, we could see some fog develop across southern KY
where the heaviest rains fell today. Will include patchy fog in the
grids, but again this will be dependent on clouds clearing out
through the overnight hours.
.SHORT TERM (Now through Thursday Night)...
Issued at 245 PM EDT Wed May 25 2016
Southwesterly flow over the past 12 to 24 hours has brought an
increase in Gulf moisture to central Kentucky and southern Indiana
characterized by dewpoints now in the low to mid 60s. A few
complexes of showers and storms mainly across southern Illinois and
southwest Kentucky have been slowly drifting east toward central
Kentucky early this afternoon but have been limited in intensity so
far by a less favorable CAPE environment and weak to nearly absent 0-
6 km shear.
For the remainder of this afternoon and the evening, the loosely
organized cluster of storms will drift further east toward the I-65
corridor. This may bring a period of showers and an occasional
rumble of thunder. However, as diurnal heating wanes, there should
be a decrease in coverage and intensity, giving way to mainly
showers and perhaps a thunderstorm. The highest precipitation
chances through midnight were confined to along and west of I-65.
Otherwise, plan a mild night with lows in the 60s. The baggy upper
level flow combined with the more moist environment support a
slight chance of a shower during the overnight.
For Thursday, another limited confidence forecast with a similar
setup as today. Models diverge both in time and place on passing
upper level impulses, so for the most part have continued 20 to 40
percent chances for the day, highest in the afternoon during peak
.LONG TERM (Friday through Wednesday)...
Issued at 250 PM EDT Wed May 25 2016
The main forecast concern in the long term is precipitation chances
as we head into the Memorial Day weekend and early next week.
By Friday, the upper level pattern will amplify more with the ridge
off the southeast US coast building while a negatively titled trough
swings through the central Plains and Upper Midwest. At the surface,
the lower Ohio Valley will likely be in between surface high to the
east and waves of low pressure to the north/northwest.
As weak impulses lift northeastward in the broad southwesterly flow
combined with diurnal heating will support the slight chances of
showers/storms each day though not every day or night will be a
washout. There remains some considerable uncertainty in the timing
of specific waves, so will continue with a broadbrush of chances.
Expect above normal temperatures in the low/mid 80s. Some upper 80s
are possible if cloud and shower coverage is less during the day.
.AVIATION (06Z TAF Update)...
Issued at 120 AM EDT Thu May 26 2016
Remnant mid and high clouds from Indiana through central Kentucky to
middle Tennessee will move east overnight. Most showers with this
moisture dissipated last evening, although there are several renewed
showers mainly in Tennessee. While additional scattered showers and
possible overnight, they should stay south of the 3 TAF sites.
Main concern overnight is fog development at BWG. Already, their
surface temp/dewpoint spread is low, and the site received over an
inch of rain Wednesday. Once mid clouds clear later this morning,
local vsbys should become MVFR and could go briefly IFR at times
before dawn. Caveat to this is model depiction of cloud development
around 5-6 kft later this morning which could help limit fog.
During the day Thursday, conditions will be VFR. At this time, it
appears any convective development should remain isolated/widely
scattered, with a slightly better chance at SDF where VCTS is
included in TAF during mid/late afternoon. However, any residual low-
level boundaries and any effect of current upstream convection as it
moves eastward could affect convective evolution over lower OH
Valley later today.