Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 301045
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
645 AM EDT Tue Jun 30 2015
...Updated Aviation Discussion...
Issued at 620 AM EDT Tue Jun 30 2015
Convection to our west is fading fast, leaving only light stratiform
rain in its wake. Still, we should see some clouds move across the
Louisville metro for a few hours this morning...enough to change the
forecast wording from mostly sunny to mostly cloudy for the day.
Tweaked hourly pops as well, but overall 12-hour rain chances remain
Other change was to expand the fog wording, with areas covering more
area. Latest satellite fog product shows a stretch along the middle
of the forecast area that matches up with observations of reduced
visibilities. Issued a special weather statement about this fog
.SHORT TERM (Now through Wednesday)...
Issued at 325 AM EDT Tue Jun 30 2015
A shortwave, noted on early morning water vapor imagery, is sparking
off a few elevated storms across southern IL. These are on track to
reach our western CWA before daybreak, so have added in some rain
chances. Main feature should be another another shortwave, now over
central Wisconsin. This feature is sparking storms over east central
Illinois. Expect lift associated with this system to reach our
northern counties by late morning. Clearing ahead of it should allow
for some heating and subsequent storm development.
The early onset of precip may make it difficult for storms to get
too strong. Still, soundings indicate some potential for near-severe
downbursts as well as wet bulb temperatures a little lower than
Monday, leading to perhaps some hail reports.
With loss of heating, we should see coverage of storms diminish.
Then expect an MCS to develop over the MO/IA region overnight and
head southeast toward our region for Wednesday morning and leading
to likely rain showers/storms through the day. Given the cloud
cover, expect temperatures to be cooler for Wednesday, compared
today`s highs in the low to mid 80s.
.LONG TERM (Wednesday Night through Monday)...
Issued at 327 AM EDT Tue Jun 30 2015
Overall upper pattern will continue to feature ridging across the
western CONUS, with varying amplitude troughing over the eastern
CONUS. The combination of embedded disturbances within the NW flow
aloft over the Ohio River Valley, and a quasi-stationary frontal
boundary in the vicinity will continue to bring rounds of showers
and storms through the weekend. While models generally agree on the
pattern, main challenges will be timing of individual perturbations
within the NW flow over the Ohio River Valley, and with positioning
of a frontal boundary that stalls out somewhere near or over our CWA
to end the week and through the weekend. Current data would suggest
that 2-3 inches of rain will be possible across central and southern
KY through early next week. Locally higher amounts can`t be ruled
Wednesday Night - Sunday Night...
Sensible weather under this pattern through the end of the week will
feature rounds of showers and t-storms associated with individual
disturbances and peak heating. Given conditional destabilization
each day and general enhancements in deep layer shear with each
disturbance, a risk of severe storms will be possible south of where
the boundary sets up. As has been the case, localized damaging winds
and very heavy rain will be the main threats along with marginally
severe hail and lots of cloud to ground lightning. Overall, models
have trended a bit further south with placement of synoptic features
which will put the focus for heaviest rain and most activity over
central and southern KY.
High temperatures during this time will generally be characterized by
upper 70s and low 80s, dependent on thunderstorm activity and
placement of the synoptic boundary each day. Lows each night will
generally be in the mid and upper 60s.
As we start the new work week, upper pattern looks to flatten out a
bit as southern CONUS ridging pumps up. This would likely bring an
increase in temperatures/humidity with a continued active pattern as
more disturbances dive through the flow. Highs during this time will
likely begin to rise to the 85-90 range.
.AVIATION (12Z TAF Update)...
Issued at 645 AM EDT Tue Jun 30 2015
Do have some reduced visibilities in the KBWG/KLEX corridor. These
should improve over the next hour or two. Next up will be rain
chances. Expect scattered storms to start developing by late
morning, with best coverage in the mid to late afternoon. Tried to
time the tempo groups with the highest rain chances in the public
forecast, with chance for gusty winds and at least MVFR conditions
at KLEX/KSDF. Winds will become variable as storms dies down this
evening. Cannot rule out additional fog Wednesday morning, but that
will depend on timing and location of today`s storms.