984
FXUS63 KPAH 050801
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
301 AM CDT Sun May 5 2024

.KEY MESSAGES...

- An unsettled weather pattern will see scattered showers and
  storms starting this new week increase in coverage and
  intensity potential by mid week.

- Breezy south winds will pick up in similar fashion, offering
  30-35 mph gust potential Tuesday-Wednesday.

- A warm and relatively muggy air mass holds through mid week
  before a cool off with lower humidity returns spring like
  temperatures and dew points as we finish out the week and head
  into next weekend.

&&

.DISCUSSION...
Issued at 300 AM CDT Sun May 5 2024

Saturday convection looks like it was amplified during the
approximately 22-03z time frame by peak diurnal destabilization
along with a weak/subtle wave that presented some (15-20 units)
channelled vorticity advecting across portions of SEMO/SIL.
There was also a distinct but weaker (about 15 units) vort that
helped the convection fire east of the Lakes in the southern
Pennyrile. Shear was minimal, generally AOB 20 kts, as were
overall 700-500 MB lapse rates, at 5-6 C/KM, so these vorticity
maximas combined with the diurnal destabilization in the
warm/soupy air mass of low-mid 80s highs and mid 60s dew points
helped drive that (mostly) sub severe convection. The
environment presented today is less on all accounts thru about
21Z. After that, we start to see the presentation of the open
wave from the southern Plains begin to work its channelled
vorticity into SEMO from the Arkansan Ozarks. The NBM picks up
on this with likely-categorical pops spreading across the area
thru the evening and overnight as the low center tracks into
south-central MO by 12Z Monday. The air mass won`t be quite as
juiced as yesterday, but low-mid 60s dew points should still
help convective fueling coincident with the H8 LLJ cranking
upwards to near 40 kts by Monday morning. The new day 1 outlooks
general with marginal risk svr staying just to our south. With
better lapse rates and shear still lacking, we can`t argue that,
so we anticipate more of a heavy rain impact but cannot
altogther rule out the possibility of an isolated stronger cell
or potential thereof. The wave weakens upon its track
into/across the PAH FA Monday, which maintains high pops for us
but overall impacts lessen. Six hour QPF of 1/2-3/4" overnight
transitions to 1/4-1/3" during the day. The clouds/pops will
hold Monday highs in the 70s over all but the far southwest,
where some late day clearing helps bump highs up to around 80
there.

Teleconnected ridging is still signalled in the models and looks
to offer a relative pause with respect to pops heading into Monday
night. However, late Monday night into Tuesday morning, we do
see the models start to advect a well defined first lobe of
vorticity incoming from the next big storm system into/across
the FA. This will begin to uptick pops late Monday night in our
west as lapse rates start to inch above 6C and bulk shear
responds in kind with a similar increase as the nose of the
upper jet begins to swing into play. Likely to categorical pops
should then spread west-to-east across the FA Tuesday as these
features migrate thru, but the bulk moisture is slightly
displaced ahead of their arrival. Still, we like the broad
painting of slight risk severe for Tuesday, given the
bulk shear and lapse rate increases.

Another relative pause may occur Tuesday night, despite still
mid chance (west) to low likely (east) pops prevailing, as that
aforementioned convective episode shifts further east. Dew
points draw down into the lower 60s, maybe even upper 50s in our
far north, by early Wednesday morning, and embedded flow
waves/energy are displaced outside the bounds of the FA. This
pause is relative and short-lived, however, as the parent storm
is poised to move in Wednesday. Bulk shear takes off and lapse
rates balloon ahead of the arrival of its energy, Wednesday
afternoon-evening. It spawns surface cyclogenesis upon its
approach that warm sectors us with dew points again rising to
near 70F with max temps rising into the mid 80s. We`d expect
strong-severe storms to grow from Wednesday afternoon-evening
into Wednesday night as the surface cyclone tracks from MO-IL-
IN by Thursday morning. All modes severe along with heavy rain
potential look to be in the offerings, so SPC/WPC both respond
in kind with a broad painting of SLGT for our entire FA. In
addition to all of that, gradient winds pick up gusts with 30-35
mph potential both Tuesday-Wednesday.

Pops linger Thursday into Friday, but the air mass metamorphosis
is ongoing and completes. Temps and dew points draw down
markedly, from Wednesday highs in the low-mid 80s to upper 60s
and lower 70s by Friday. Dew points move from upper 60s/near 70
Wednesday, into the 50s Thursday and 40s Friday, offering a
refreshing break from the summer-like humidity that prevails
over the first half of the week.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 300 AM CDT Sun May 5 2024

Nightime microphysics curve of IR satellite imagery indicates a
spread of IFR-low MVFR bases ongoing across KMVN at this
writing. There may be some similar drops in VSBYS to MVFR at
times, but most modeling sticks with the MVFR base presentation.
These are expected to become prevalant at all terminals with
time, and prevail into the day, lifting into low VFR this
afternoon. While an isolated shower/storm cannot be ruled out,
most pcpn looks to hold off til the planning phase of the
forecast and beyond as an open waved low pressure system lifts
across the Ozarks. It will offer the chance for further flight
restrictions upon its lift over the area tonight.

&&

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

&&

$$