901
FXUS63 KPAH 281912
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
212 PM CDT Fri Jun 28 2024

.KEY MESSAGES...

- Trend is for higher dewpoints and more uncertain convective
  coverage Saturday. Heat Advisory issued for part of the area.

- A front will bring the next chance of showers and storms on
  Saturday. The greatest risk looks to be Saturday evening into
  Saturday night when isolated strong to severe storms will be
  possible. Damaging winds, small hail, torrential downpours,
  and lightning are the main concern.

- Brief relief from the heat and humidity is in store Sunday
  into Monday before turning uncomfortable again in time for the
  4th of July. The pattern also turns unsettled by the middle of
  the week.

&&

.DISCUSSION...
Issued at 212 PM CDT Fri Jun 28 2024

Dewpoints are rising on modest south winds this afternoon. We
are already back into the low 70s across much of the area. With
the moisture advection we are seeing some mid level clouds
that coupled with MCS blowoff are providing some respite from
the heat. Very rich lower column and surface moisture sits just
to our south and is expected to make its way overhead by
Saturday afternoon. Despite this moisture flux, poor 700-800mb
lapse rates/an inversion from residual subsidence will set out
convective temperature in the upper 90s which leads me to
believe home grown convection will be hard to produce. There is
a fairly consistent signal for an MCS to develop across central
MO and IL tonight which may impact areas north of Rte 13 and
parts of far northwest KY and SWIN. The expectation for now is
that at least enough residual cloud cover from this activity
will keep temperatures just cool enough to not quite reach
advisory threshold there. To the south heat index values of
105-110 seem reasonably likely in the afternoon hours so a Heat
Advisory has been issued with this forecast package.

Saturday afternoon and into the evening large scale ascent
increases in response to a mid/upper level shortwave. This
should initiate storms to our northwest that will then work to
the east and southeast. There will be plenty of potential
instability, with MLCAPE values 2000-2500 J/kg in the late
afternoon but a residual inversion around 850 mb may limit
coverage unless cold pools can upscale and organize. This may
be somewhat challenging given the fairly modest deep and mid
level shear and fairly moist column overall. PWAT values are
projected to be 2.2-2.4" with wet bulb zero heights over 14,000
ft. This looks like a recipe for robust updrafts that struggle
to organize, but if a few do they may briefly become capable of
damaging wind. Its going to take quite an effort to produce much
hail however given the freezing levels and weak deep layer shear.
Rainfall rates will be very efficient and some isolated
flooding may also come into play with storm motions likely to be
fairly slow in weak westerly shear.

A "cooler than it was" front then moves through Sunday morning.
We get another brief respite from the highest heat and humidity
through Sunday and Monday with Monday really looking pretty
pleasant.

Not to get too spoiled we get back into the humidity Tuesday
afternoon with a day that looks pretty similar to today. The
deeper moisture return then gets to work with a stronger and
broader upper trough to create an unsettled pattern that looks
to lead to showers and storms through the holiday before
another front possibly moves in for the weekend. Shear and
instability may come together for some type of wind/severe
threat the 3rd through 5th but there is no real screaming
signal. There will have to be a pretty big shift however to
avoid at least some disruption to July 4th outdoor activities.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1219 PM CDT Fri Jun 28 2024

VFR conditions with moderate south winds are forecast for the
rest of the day. Overnight tonight fog may become an issue,
particularly CGI-MDH-MVN. Convection may also be a factor in
the late overnight and early morning but the trend, for now, is
for it to hold off until after the current TAF period.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Heat Advisory from noon to 7 PM CDT Saturday for ILZ084-085-
     088>090-092>094.
MO...Heat Advisory from noon to 7 PM CDT Saturday for MOZ076-086-
     087-100-107>112-114.
IN...None.
KY...Heat Advisory from noon to 7 PM CDT Saturday for KYZ001>013-
 017-022.

&&

$$

DISCUSSION...JGG
AVIATION...JGG