Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 190026

Area Forecast Discussion
National Weather Service Louisville KY
826 PM EDT Sun Aug 18 2019

.Forecast Update...
Updated at 826 PM EDT Sun Aug 18 2019

Generally quiet weather is expected to continue overnight. The best
chance of an isolated shower/storm will be north of I-64 as the
outflow boundary from central Indiana convection pushes south.

Some light fog will be possible in and around Hoosier National
Forest where some very light rain/sprinkles fell earlier this

Updated at 422 PM EDT Sun Aug 18 2019

Isolated showers have developed over the Blue Grass so have added a
very small PoP for a few hours in that area.


.Short Term...(This evening through Monday)
Updated at 255 PM EDT Sun Aug 18 2019

Hot and muggy conditions ongoing across the region at this hour.
Recent look ASOS/AWOS and KY Mesonet obs reveal temperatures in the
low to mid 90s, with the highest readings generally reserved for
bigger urban areas. Heat indices have been ranging from upper 90s to
low 100s, thanks to dewpoints in the upper 60s and low 70s.

Satellite imagery reveals an outflow boundary currently draped from
central IN through southern IL into southeastern MO. Showers and
thunderstorms have developed along it, and near term guidance
suggests more widespread development over the next several hours.
Modest instability along with meager deep layer shear should support
an organized severe threat to our west and north as highlighted in
Severe Thunderstorm Watch 598. As it approaches southern Indiana and
portions of our northern CWA by early evening, it will likely begin
to weaken as peak heating is lost. The SPC Day 1 Outlook does clip
our northern tier of southern Indiana counties with a marginal risk,
which doesn`t seem too unreasonable given our area will likely end
up as a transition zone from severe to strong/sub-severe convection.
Isolated showers and storms will likely persist into the first half
of the night in central Kentucky, but should begin tapering down
after midnight.

Another hot and muggy day will be in store tomorrow, with similar
temperatures that were observed today. Unlike today, though, there
won`t be much of a cap in place at all, and small mesoscale
boundaries may provide enough lift to trigger isolated storms during
the afternoon hours. The few folks lucky enough to see the isolated
storms will have some temporary relief from the heat.

.Long Term...(Monday night through Sunday)
Updated at 300 PM EDT Sun Aug 18 2019

Our area`s location on the east side of a central Plains ridge will
mean some continued uncertainty in storm chances Monday night, as
small impulses ride down the northwest flow aloft. NAM/GFS/00Z Euro
Means/SREF all have some QPF in our region, so will have to continue
to carry chances into the overnight. Yet another wave later Tuesday
afternoon could intersect with another hot day to generate scattered
cooling storms as we get into the evening hours.

Wednesday should be another hot one, as we see heat pooling ahead of
a cool front forecast to stall somewhere across our region. We
should once again see some cooling storms, as this front focuses
development. GEFS and Euro both keep rain chances along that stalled
boundary into Friday, especially across southern KY. GFS and CMC
both appear to push the front to far south based on the rest of the
ensemble members. Will maintain decent chances for rain Wednesday
through Friday given this spread of solutions, with temperatures
closer to normal as well.

Not much changes for the upcoming weekend either, though instead of
impulses riding down, the flow pattern will feature more of a
general trough over the area. Thus, we cannot clear any one region
of rain chances, but will keep them in the 20-40 percent range for
each afternoon/evening. Also, will keep temperatures near normal.


.Aviation...(00Z TAF Issuance)
Updated at 725 PM EDT Sun Aug 18 2019

VFR conditions are expected throughout this TAF cycle with the
exception of possible MVFR vis in fog at HNB near sunrise Monday
morning. At the beginning of the period, a diminished line of storms
will send remnant showers and a weakening gust front through HNB and
SDF. Model soundings show much less convective inhibition Monday
afternoon compared to today; therefore, isolated showers/storms will
be a possibility at all TAF sites. Though, confidence regarding
exact timing and location is too low to include in any TAF at this
time. Otherwise, expect SSW winds Monday afternoon through evening.




Short Term...DM
Long Term...RJS
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