897
FXUS63 KPAH 172216
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
516 PM CDT Sun May 17 2026

.KEY MESSAGES...

- Breezy south winds and lots of sun will allow temperatures to
  climb into the upper 80s and possibly lower 90s throughout the
  Quad State region Monday and Tuesday. Mild lows in the 60s
  and 70s are expected.

- A 40-70% chance of thunderstorms returns to the forecast
  Monday afternoon, with the best chances over southeast
  Missouri and southern Illinois. A few severe storms with a
  damaging wind and large hail threat are expected, especially
  across southern Illinois.

- More widespread showers and thunderstorms are expected Tuesday
  afternoon and night. At this time, severe storms cannot be
  ruled out, but locally heavy rainfall will definitely be a
  concern through the period.

- Cooler conditions with daily chances of showers and
  thunderstorms are expected for the end of the work week and
  the beginning of the Memorial Day weekend. It looks like it
  will be warming up through the holiday weekend, with daily
  chances of storms.

&&

.UPDATE...
Issued at 515 PM CDT Sun May 17 2026

Updated Aviation discussion for 00Z TAF Issuance.

&&

.DISCUSSION...
Issued at 150 PM CDT Sun May 17 2026

An elevated mixed layer has overspread the Quad State, leading
to a warm and dry day. The humidity has taken the day off over
west Kentucky and southwest Indiana where dewpoints have mixed
down well into the 50s. The targeted Lake Wind Advisory looks
good for today, and will likely be needed again Monday and
possibly Tuesday.

The cap is likely to hold through much of Monday, despite some
models generating some QPF over various parts of the Quad State.
However, there is a strong signal for an MCS to reach the I-64
corridor in southern Illinois around 21Z, and the strong south
winds running into its outflow boundary should allow it to
develop southward into southern Illinois and southwest Indiana.

Moderate to strong instability is expected ahead of the storm
complex, and shear will be healthy, too, so severe storms are
a decent bet, per the Slight Risk from SPC. Given the
instability, large hail will be a concern, but the 0-3km shear
vector will be from the southwest, so development into our
region will likely be upshear, which is not good for maintaining
an intense squall line and damaging wind threat. Of course,
there is already plenty of uncertainty just in getting the MCS
here in the first place, so this is all very conditional.
Subsequent changes to the expected path and timing of the MCS
could change the severe outlook across the Quad State. If the
MCS makes it and we are looking at upshear development, the
slower progression southward could lead to a heavy rainfall and
flash flooding threat given the highly anomalous precipitable
water values expected.

Another MCS from storms that formed on the cold front will
likely approach the area late Monday night, and should be
weakening significantly. The remnant outflow is likely to be a
focus for thunderstorm development in southeast Missouri and
southern Illinois possibly before noon. Of course there could
also be development on the cold front approaching from the
northwest. The environment ahead of the boundaries over the Quad
State should be at least moderately unstable, but the wind
fields seem to be quite muddled which gives pause for organized
severe potential. The precipitable water values Tuesday will be
in the 90th percentile of climatology or higher, so heavy
rainfall and possibly flash flooding may be a bigger concern
Tuesday and Tuesday night.

The trend in guidance is to have the cold front through the
entire area by early Wednesday, so temperatures will drop to
normal levels or below for Wednesday through Friday. We will
remain in southwest or west southwest flow aloft with plenty of
disturbances in that flow streaming over the Quad State. This
will result in daily chances of mainly afternoon showers and
thunderstorms. There could be some steep mid-level lapse rates,
so some elevated hail storms cannot be ruled out.

Looking ahead to the Memorial Day weekend, temperatures will be
warming up to normal and above through the weekend, and diurnal
thunderstorms are a decent bet.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 515 PM CDT Sun May 17 2026

With high pressure affixed to the east and low pressure
approaching from the west this package, the terminals remain
within a tight gradient for sustained southerlies, including
diurnal gustiness again tmrw. Some moistening of the profile
takes place over the back half of the package, as the low and
its associated front nears closer; this will lead to high end
MVFR to low end VFR bases (SCT-BKN) developing, including low
probs for -TSRA, esp going into the planning phase/heating
hours of the afternoon.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Lake Wind Advisory until 7 PM CDT this evening for ILZ075-081-
     085.
MO...Lake Wind Advisory until 7 PM CDT this evening for MOZ100.
IN...None.
KY...None.

&&

$$