799
FXUS63 KPAH 021858
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
158 PM CDT Tue Jul 2 2024

.KEY MESSAGES...

- A Heat Advisory will be in effect from 12-7 PM CDT Wednesday
  for parts of southeast MO, southern and southeast IL, western
  KY, and southwest IN.

- Strong to severe thunderstorms are possible Wednesday
  afternoon and evening and again late Thursday night. Damaging
  wind gusts and heavy rain/flash flooding will be the primary
  hazards.

- Turning drier and more comfortable for the weekend, with a
  small chance of thunderstorms returning to the forecast early
  next week.

&&

.DISCUSSION...
Issued at 158 PM CDT Tue Jul 2 2024

Today and Tonight...High pressure centered over the Mid-
Atlantic continues to bring plenty of sunshine and seasonably
warm temperatures. As southerly return flow increases, dew point
temperatures will continue to creep towards 70 degrees and
higher overnight. This will bring much warmer low temperatures
tonight, only falling into the lower to middle 70s in most
areas.

Wednesday through Friday...The heat and humidity will surge back
into the area Wednesday. High temperatures will reach the lower
to middle 90s as 850 mb temperatures climb to 20-25C and dew
points continue to climb into the middle to upper 70s. However,
the potential for debris cloud cover and possibly a few showers
and storms from storms firing to our NW in the morning and
early afternoon hours complicates things. Felt confident enough
to issue a Heat Advisory from 17-24z Wednesday for most of the
area, save for parts of southeast MO and southwest IL (from
Perryville, MO, to Wayne City, IL and points to the north and
west).

As the afternoon progresses, an approaching cold front will
trigger scattered thunderstorm development in the afternoon and
evening hours. Model guidance shows about 2000-4000 J/kg of
MLCAPE developing, and modest shear of 25-35 kts in the lowest 6
km. DCAPE values will also be robust, at 1000-1500 J/kg. This
will support clusters and small bowing structures with a
damaging wind threat primarily. Heavy rain and potentially some
flash flooding will also be a concern. With the frontal boundary
becoming stationary through the forecast area, multiple rounds
of training storms are possible. The latest NAEFS guidance
continues to show PWAT values in the 95-99th percentile and
along with similar values of 1000-850 mb specific humidity. The
latest WPC QPF has trended a bit south with the heaviest rain
axis, with an area of 2-4" forecast across parts of southeast MO
into southwest IL. Elsewhere is still progged to receive
roughly 1-2" of rain through Thursday night.

For Independence Day activities on Thursday, showers and
thunderstorms will persist through the morning and early
afternoon hours before a bit of break arrives for the mid/late
afternoon and evening hours. There will likely still be areas of
precipitation, but the overall intensity looks to be light.
However, it will still be very humid, with dew point
temperatures in the middle to upper 70s continuing into the
evening. High temperatures will again reach the lower 90s, with
heat index values in the 95-105 degree range. Cannot rule out
needing another Heat Advisory for parts of the area as well
Thursday afternoon.

Another weak shortwave will kick off more thunderstorms
Thursday night to our west in the Ozarks, and these look to
reach our region very late Thursday night into Friday morning.
Cannot rule out a few strong to severe storms with this activity
either, especially if they grow upscale into an MCS. Damaging
winds and heavy rain would again be the primary threats.

The shower and thunderstorm activity will gradually sag south of
the region Friday afternoon into Friday night. High
temperatures will be a bit cooler on Friday, in the middle to
upper 80s. Less humid air will filter into the area Friday
night, allowing low temperatures to fall into the 60s.

Saturday through Monday...H5 heights will gradually increase as
we go into the weekend, with an upper-level low across the
northern Great Lakes. This will filter slightly cooler and less
humid air into the area. High temperatures will still reach the
middle to upper 80s, with dew point temperatures in the middle
60s. Overnight low temperatures will be comfortable as well,
mainly in the 60s. Our next chance of precipitation will arrive
late Sunday night into Monday as a shortwave trough moves into
the central Great Plains.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1135 AM CDT Tue Jul 2 2024

High pressure will keep skies mostly clear through late tonight,
with some passing high cirrus over EVV and OWB being the only
clouds of note. Mid and high cloud coverage will increase
towards daybreak Wednesday from ongoing storms to our NW. Steady
S winds around 5-10 kts will veer slightly to the SSW after 14z
Wednesday, sustained at 7-10 kts with gusts up to 15-20 kts
possible at EVV and OWB.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Heat Advisory from noon to 7 PM CDT Wednesday for ILZ077-078-
     083-086>094.
MO...Heat Advisory from noon to 7 PM CDT Wednesday for MOZ087-
     108>112-114.
IN...Heat Advisory from noon CDT /1 PM EDT/ to 7 PM CDT /8 PM EDT/
     Wednesday for INZ081-082-085>088.
KY...Heat Advisory from noon to 7 PM CDT Wednesday for KYZ001>022.

&&

$$

DISCUSSION...DWS
AVIATION...DWS