Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 051045
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
645 AM EDT Sun Jul 5 2015
...Updated Aviation Discussion...
.SHORT TERM (Now through Monday)...
Issued at 255 AM EDT Sun Jul 5 2015
The synoptic pattern early this morning features generally weak
upper-level flow throughout much of the CONUS, except for the far
northern Plains through which a strong shortwave trough was
digging. An upper-level low located within the weak flow aloft was
over portions of TN as of this writing, which will be the main focus
of the short term.
The upper-level low continues to spread moisture northward into
portions of southern KY early this morning. Rainfall rates have
come down the past hour given the low-level jet associated
with this system veering more to the east. However, flash flood
guidance in the Lake Cumberland region is on the order of an inch an
hour, or an 1.5" over 3 hours. Therefore, even without very tall
convective cores, the moderate rains could be enough to create a few
issues. In coordination with JKL and OHX, decided to go ahead and
issue a Flash Flood Watch earlier, mainly to cover the previous
heavier rains and the expected steadier rains through this morning.
However, additional scattered storms are possible in this area this
afternoon so went ahead and ran it through 00Z this evening.
In regards to this afternoon, the upper-level low will be pushing
east. However, vort maxes spinning around it will likely help to
focus bands of convection, some of which will be west of the low`s
center. The latest hi-res guidance suggests some of this convection
may make it as far west as the I-65 corridor, so have brought the
slight chances a bit further west. Either way, don`t expect
coverage outside the far eastern CWA to be all that great, so think
most stay dry today. Highs will climb into the mid 80s over the
west where there will be less cloud cover and precip, but only in
the upper 70s over the east where cloud cover will linger through
much of the day.
All locations will dry out tonight as the upper low pushes well east
of the area. We may once again see some fog tonight, especially in
areas that see rain today. Lows will be in the mid to upper 60s.
On Monday, the pressure gradient will begin to tighten as a cold
front pushes into the Midwest. In the mid/upper levels, shortwave
ridging will be present in the wake of the upper low and ahead of
the approaching Midwest trough. Therefore, think any convection
will be sparse. Debated going completely dry with the forecast, but
soundings are generally uncapped and the ridging certainly isn`t
strong. However, think coverage will be 10% to 20% at best on
Monday afternoon. Given the southwest flow, temperatures will climb
well into the 80s, perhaps pushing the lower 90s in the typically
warmer spots. This is usually a type of day where temperatures
overachieve, but given the very wet soils and antecedent conditions,
didn`t get too carried away with high temps.
.LONG TERM (Monday Night through Saturday)...
Issued at 300 AM EDT Sun Jul 5 2015
A wet pattern takes shape again Monday night through Wednesday, as a
weakening cold front moves SE into the Ohio Valley and hangs up.
Best precip chances Tuesday into Tuesday night, after which forecast
confidence drops off. SVR chances are meager as instability is not
impressive and strongest dynamics track well to our north. However,
heavy rain will become a threat especially Tuesday night and
Wednesday as the front lays out nearly parallel to the flow aloft.
Given recent wet weather, it won`t take much to create additional
The latter half of the work week remains unsettled and could be
quite a wet pattern somewhere, but the models still don`t quite
agree on where that will be. ECMWF looks like the wetter solution as
it maintains a fairly flat upper pattern, while the GFS pumps up a
SE CONUS upper ridge, which would mean less precip coverage and more
of a diurnal signal. Still not confident enough to jump on either
solution just yet, but isolated/scattered POPs still seem a good bet
either way. The ongoing theme will continue where it`s near
impossible to pick out a completely dry day, but there are no
washout days either. Will keep diurnal temp ranges rather narrow,
with above normal nighttime mins, and daytime highs near or below
.AVIATION (12Z TAF Update)...
Issued at 645 AM EDT Sun Jul 5 2015
Restrictions will continue at KBWG and at KLEX this morning before
conditions improve at all sites through the afternoon. IFR cigs
will continue to be possible at KBWG through the mid-morning hours,
before conditions improve. It is looking increasingly likely that
KLEX will get in some shower activity this morning, but will leave
prevailing -TSRA out of the forecast for now as there does not
appear to be much lightning. With the rain moving through this
morning, KLEX will likely see MVFR vsbys and cigs.
Otherwise, conditions will improve to VFR at all sites late this
morning through early this afternoon. KLEX will stand the best
chance of seeing renewed showers/storms this afternoon, whereas KSDF
and KBWG should remain mainly dry. All sites will remain VFR this
evening into tonight, although some light fog may plague mainly KLEX
and KBWG toward the end of the period.
KY...FLASH FLOOD WATCH through this evening FOR KYZ066-067-075>078-