544
FXUS63 KPAH 181824
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
124 PM CDT Mon Aug 18 2025

.KEY MESSAGES...

- Prolonged duration heat and humidity will linger through
  tomorrow with highs in the mid to upper 90s and heat index
  values ranging between 100 and 108 degrees through Tuesday. A
  Heat Advisory remains in effect through tomorrow afternoon.

- Scattered thunderstorms are forecast tomorrow afternoon and a
  few of these storms may produce strong to locally damaging
  wind gusts.

- A cold front will pass through on Wednesday allowing
  temperatures to fall back toward normal levels with another
  front slated for the weekend that may significantly reduce
  heat and humidity.

&&

.DISCUSSION...
Issued at 124 PM CDT Mon Aug 18 2025

Upper level ridging remains in control today with clear skies
and sweltering temperatures. Afternoon max temps in the high 90s
look likely with dewpoints in the low 70s. The only modest
relief has been very slightly drier air mixing down from aloft
in the afternoon heat. Parts of northern Arkansas and south
central Missouri, more on the periphery of the deep layer ridge,
have less dry air and are starting to see showers and
thunderstorms spark in the early afternoon heat. A few of these
could work into parts of southeast Missouri (mainly
Carter/Ripley Counties and vicinity) this afternoon but the
areas is largely expected to remain hot, humid and precip free.
a Heat Advisory remains in place and will through tomorrow.

Tomorrow an approaching shortwave trough and the increasingly
influence of Hurricane Erin to the southeast start to erode the
ridge. Coverage of showers and storms should increase as the
trough pulls a weak cooler-than-it-was front from the north.
The antecedent dry air in the mid levels and sticky humidity
down low result in a sfc-700mb theta-e differential around 30K
in most guidance so will be more alert than usual for
microbursts from any thunderstorms that get going. SPC has added
most of the area to a marginal risk for this threat in the newer
Day 2 outlook. The GFS mixes our dewpoints down into the mid 60s
but this seems overdone and convection allowing models and the
NAM keep it in the low 70s which gives us another day of Heat
Advisory conditions (peak heat index 105 and above) and about
2500-3000 J/kg of MLCAPE to work with in the afternoon. Shear is
essentially zero so these should be of the pulse variety but a
few localized severe thunderstorms appear possible. Slow storm
motion may lead to some areas of localized heavy rainfall as
well with projected PWAT values of 1.7" with warm cloud layer
depth over 12000 ft.

Behind this "front" we go from excessively hot to normal
seasonable heat and humidity for a few days with no precip
anticipated. Hurricane Erin looks to be helping keep our flow
out of the north for a few days as well with associated
subsidence also possibly contributing to lower overall humidity.

This weekend a large upper low gets going over southern Canada
sending a much more robust cold front into the area. There will
be a chance for showers and storms but the main impact should be
to lower heat and humidity into the low 60s or even upper 50s
with max temps in the low 80s which should feel like an entirely
different planet than what we have seen most of this summer.



&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1209 PM CDT Mon Aug 18 2025

VFR conditions are anticipated through the next 12-14 hours.
Some ground fog/patchy fog is possible pre-dawn with the highest
chances at CGI and MVN. VFR conditions are then expected through
the early daypart Tuesday with shower and thunderstorm chances
starting to rise after 18z.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Heat Advisory until 7 PM CDT Tuesday for ILZ075>078-080>094.
MO...Heat Advisory until 7 PM CDT Tuesday for MOZ076-086-087-100-
     107>112-114.
IN...Heat Advisory until 7 PM CDT /8 PM EDT/ Tuesday for INZ081-082-
     085>088.
KY...Heat Advisory until 7 PM CDT Tuesday for KYZ001>022.

&&

$$

DISCUSSION...JGG
AVIATION...JGG