FXUS63 KLMK 132321

Area Forecast Discussion
National Weather Service Louisville KY
721 PM EDT Sat Jul 13 2024

...Updated Aviation Discussion...


*   Scattered thunderstorms mainly along and west of I-65 this
    afternoon. Brief heavy rain, gusty winds, and lightning will be
    main threats.

*   Triple-digit heat index values could return Sunday afternoon and
    are likely early next week.

*   Shower and storm chances look to increase by the middle of next
    week as a frontal boundary sinks into the area.


Issued at 324 PM EDT Sat Jul 13 2024

One cluster of thunderstorms has developed in the moderately
unstable airmass over the region, and is likely triggered by the
weakened, but still present, MCV left over from yesterday/last
night. These storms should mainly pose a lighting, brief heavy
rainfall, and gusty wind threat. Overall, expecting sub-severe type
of activity given the lack of deep layer shear and weak mid level
lapse rates. Can't rule out an isolated severe, but it is not
anticipated at this time.

Otherwise, convection should taper off this evening as it slowly
progresses mainly in areas along and west of I-65. This is where 20-
30% chances will be advertised. Looking for another mild night with
lows in the 60s and low 70s. Given mostly clear skies, and
light/calm winds, do think some fog will be worth monitoring. Have
patchy/areas of fog advertised for now.

Looking for heat and humidity to continue ramping up tomorrow as
high temperatures are expected to be more solidly into the mid 90s.
In addition, dew points are expected to be in the lower 70s across
portions of our NW CWA. This will likely yield peak indices into the
100 to 105 degree range during the afternoon. Will issue a Special
Weather Statement to advertise the heat/humidity. Could get some
relief in the afternoon as a passing shortwave possibly sparks
isolated to scattered thunderstorms across our N CWA. We are close
on Heat Advisory criteria, but given the chances for convection not
confident enough to go with a headline. Plus, most of the area
should stay just below the 105 degree threshold, while a few areas
may briefly touch it.


Issued at 324 PM EDT Sat Jul 13 2024

Sunday Night - Tuesday

Dry weather is expected for Sunday night and
into the first half of next week, thanks to sfc high pressure
sitting over the southeastern US and quasi-zonal flow aloft.
Temperatures will be well above normal for Monday and Tuesday, with
highs forecast to hit the upper-90s. Dewpoints hitting the low-70s
will likely translate to heat indices above 100F, and possibly
topping out around 105F. Not much relief will be expected Monday
night as temperatures will struggle to get into the low-70s. The
urban islands may even stay in the upper 70s overnight. Hot and
mostly dry expected for Tuesday as well, though will introduce a 15-
20% PoP beginning in the afternoon and into the evening as a weak
impulse rides through the flow aloft. A few isolated storms will be
possible, but the better chances will come Wednesday.

Wednesday - Saturday

An upper low well north of the Great Lakes will be the driving force
for a cold front to sag southward through the Ohio Valley. This will
bring enough forcing and moisture convergence to develop showers and
storms for the mid-late week. PWATs will increase to nearly 2
inches, supporting heavy rainfall. Soundings continue to show
instability peaking around 2500 J/kg but meager shear values, so a
few storms are expected, but just not too confident on severe
potential yet. DCAPEs may be high enough for a marginal wind threat
with storms collapsing, but organized convection still appears

PoPs may linger through Thursday morning as the front pushes south
of our area. In a post-frontal regime, temps on Thursday should be
quite nice for mid-July, with low-80s expected. Dry weather settles
back into the forecast by Thursday evening, and is expected to
continue for Friday and into the weekend. Temps will warm back to
near normals and in  the upper-80s as we get into the weekend.


Issued at 721 PM EDT Sat Jul 13 2024

After a few storms moved over the terminals, the last ones are now
dissipating. The remainder of the evening and overnight hours will
consist of thinning skies and calm to light winds. With recent
precip, some MVFR fog may develop over LEX and HNB tonight.
Confidence on this occurring is low given persistence from the
previous night. on Sunday, winds will pick back up by mid-morning
from the southwest around 5-8kts and diurnal Cu will begin to