129
FXUS63 KPAH 280644
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
144 AM CDT Fri Jun 28 2024

.KEY MESSAGES...

- The heat and humidity returns today and Saturday with heat
  index values near to slightly above 100 degrees.

- 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 142 AM CDT Fri Jun 28 2024

Another period of hot and humid conditions is in store for Friday
and Saturday as southerly return flow advects in higher dewpoints in
the 70s with ridging aloft over the SE CONUS. The increase in
moisture will cause heat index values to peak near to slightly above
100 degrees. As a 500 mb trough digs across the Dakotas, subtle
height falls will begin to occur into the weekend. The CAMs show a
MCS over central Missouri Friday night decaying across the FA
Saturday morning as a shortwave passes by to the north. The FV3 is
an outlier with a line of showers and storms moving towards the
Mississippi around 12-14z while most other guidance amounts to just
a few isolated showers or storms at most.

Assuming there is not much in the way of morning convection, both
the NAM/GFS support MLCAPE between 2000-3500 J/kg developing by the
afternoon and SBCAPE peaking around 4000-5000 J/kg with dewpoints
well into the mid 70s. As a cold front sags south ahead of a 500 mb
trough that digs across the Great Lakes, an influx of theta-e around
350K sets up along the boundary. Model guidance supports the
potential for another MCS developing in central Missouri Saturday
evening and moving downstream across portions of the FA. Given DCAPE
over 1000 J/kg, steep low-level lapse rates around 7.5 C/km, and
effective bulk shear around 25-30 kts, isolated strong to severe
storms will be possible with damaging winds, small hail, and
lightning being the main hazards of concern with a liner storm mode.
The exact timing is still a bit uncertain, but would expect the risk
to gradually wane overnight with the loss of diurnal heating given a
typical high CAPE and low shear summertime setup.

The front may be slow to clear out Saturday night into Sunday
morning as the flow between 925-700 mb becomes parallel to the
aformentioned front with deep layer moisture still present. The
NAEFS ESATs shows PWATs above the 95th percentile between 2.00-2.25"
supporting the potential for torrential downpours with convection.
In fact, model soundings show warm rain processes will be quite
sufficient with the warm cloud layer reaching 15 kft. Despite the
soupy airmass, do think convection will move through fast enough to
limit any localized flooding issues to typical poor drainage in low-
lying areas. QPF looks to only be between 0.50 to 1.00 inches where
storms occur as it is also possible some locations see little
rainfall.

Behind the front, a 1027 mb sfc high pressure builds into the Ohio
Valley Sunday afternoon into Sunday night providing relief from the
heat and humidity. North-northeast winds associated with
anticyclonic flow advect in lower dewpoints in the 50s/60s as Monday
looks to be another pleasant day similar to yesterday. In fact,
maxTs struggle to reach 90 on Sunday and are progged by the NBM to
only reach the low to mid 80s on Monday. Given radiational cooling
Sunday night, some locations could even see minTs fall into the
upper 50s!

Moisture along with the heat looks to return in time for the 4th of
July as a ridge builds over the SE CONUS. The pattern also looks to
be fairly unsettled and potentially stormy through the second half
of next week as multiple shortwaves upstream eject south towards the
FA. Heat index values once again rise into the triple digits by
Wednesday.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1152 PM CDT Thu Jun 27 2024

Surface ridging will remain to the northeast providing light
winds overnight and clear skies. Surface flow increases from
the south by the afternoon, generally between 5-10 knots. VFR
conditions will continue.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.

&&

$$

DISCUSSION...DW
AVIATION...RST