936
FXUS63 KPAH 221907
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
207 PM CDT Sun Sep 22 2024

.KEY MESSAGES...

- A few waves of increased shower and thunderstorm activity is
  expected late this afternoon and again Monday night. A few
  severe storms are possible with damaging winds the primary
  concern. Locally heavy rainfall will occur with thunderstorms.

- A cold front moves through Tuesday leaving behind cooler and
  less humid conditions are expected for the rest of the week.

- Returning rain shower chances are becoming more likely towards
  the second half of the week into next weekend. Forecast
  confidence is below average in how a potential tropical system
  down in the Gulf of Mexico may interact with an upper-level
  disturbance in the vicinity of the region and anything that
  would be more impactful.

&&

.DISCUSSION...
Issued at 207 PM CDT Sun Sep 22 2024

A steady conveyor belt of mid and upper level moisture has
cloudiness spread over the northern half of the quad-state this
afternoon. The southern half of the area has received quite a
bit more broken sunshine through the last few hours and
temperatures are approaching 90 degrees with dewpoints in the
low 70s. MLCAPEs are around 1500 J/kg which is less than
yesterday, but deeper layer shear is stronger which will give us
at least some window for a few severe storms, with wind the
main threat. This risk focuses mainly over southeast Missouri
and far western Kentucky where instability has built up the
strongest and sfc-700mb theta-e differences are around 25-30 K.
A few radar returns are starting over south central Missouri
that appear to be on the leading edge of an area of diffluence
that will likely be the focusing mechanism for activity today.
The expectation is activity will start to pick up by 21-22z and
persist through 02-03z. Heavy rainfall rates are also likely
with PWATs around 2.00" but decent forward motion and dry
antecedent soil conditions should limit flooding risk.

A decrease in precip is expected through the overnight although
the chances never really go to zero anywhere before starting to
increase in the late overnight, after about 09z or so. A
relative increase in coverage with a return of a few
thunderstorms. After another early Monday lull a trough
approaches increasing large scale ascent and more widespread
showers and storms look likely to refire. Deep and lower level
shear looks reasonably favorable for some organized thunderstorm
activity but instability looks limited owing to cloud cover and
weak mid-level lapse rates. Models show an axis of a little bit
heavier rain on the leading edge of low-level moisture advection
but that could shift north to south a little bit from current
projections. A surface cold front moves through Tuesday morning
decreasing humidity.

By Tuesday night an upper level low drops into the Missouri
Valley and cuts off from the main flow. That will likely result
in a very tricky forecast Wednesday and Thursday. GFS/ECMWF also
bring a tropical cyclone into the Gulf coast region later this
week that may interact with that system. The 12z ECMWF positions
the upper low in a way to return quite a bit of moisture from
the southeast US and the impinging tropical system where the GFS
focuses that rainfall a little south of us. The NBM has a
20-40% all periods forecast which might could be improved upon a
little but its difficult to argue with it much given the
uncertainty given the fact that a cut-off low and a tropical
cyclone might be two of natures most cantankerous systems to
model at days 4-7.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1221 PM CDT Sun Sep 22 2024

High MVFR ceilings will slowly rise over parts of southeast
Missouri as convective clouds begin forming. Thunderstorm
development is expected over the region later this afternoon and
through early evening. A decrease in activity is then expected
after sunset. After midnight increased influence from an
approaching storm system is expected to lead to lower ceilings
with rain showers and embedded thunderstorms possible from about
08-15z. The new forecast calls for low MVFR ceilings although
IFR ceilings are possible. Below VFR ceilings are expected
through midday Monday with areas of rain and a few thunderstorms
remaining possible.

&&

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

&&

$$

DISCUSSION...JGG
AVIATION...JGG