984
FXUS63 KPAH 061949
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
249 PM CDT Mon May 6 2024

.KEY MESSAGES...

- Several rounds of showers and thunderstorms are expected
  through Wednesday night. Severe storms are possible early
  Tuesday morning and again later in the day and evening.

- A significant severe thunderstorm outbreak is appearing
  increasingly likely for Wednesday afternoon and evening.

- Warm and humid conditions through Wednesday, then a cooler
  spring- like airmass spreads across the region Thursday
  through the weekend.

&&

.DISCUSSION...
Issued at 249 PM CDT Mon May 6 2024

A mid level disturbance moving across the TN Valley region is
leading to isolated-scattered convection this afternoon. The most
concentrated lightning activity is south of us in TN, where the
better instability exists. This is also where 30-35 kts of 0-6km
shear resides. As this wave departs to our east, mainly dry
conditions are expected this evening into early overnight. Having
said this, there are a few models that generate some isolated
convection within a zone of warm advection as the main
instability/higher moisture axis lifts north across the area late
this evening and overnight. Maintained slight PoPs for this
possibility. After 09z most guidance depicts a line of thunderstorms
to move into our area from the west. While this line should be in a
weakening state into the early-mid morning, it could pose some
severe risk initially across our western counties. A plume of 1000
j/kg CAPE and increasing deep layer shear in excess of 40 kts will
spread into southeast Missouri by 10z. So wouldn`t be surprised to
see some 50-60 mph gusts for a few hours before the line weakens
further.

Recovery on Tuesday is somewhat dependent on how long the morning
convection lingers. Most guidance suggests clearing takes place and
a rather potent environment develops during the afternoon with 2500-
3000 j/kg mixed layer CAPE, dewpoints in the upper 60s to around 70,
and 0-6km shear of 50+ kts. A mid level jet max will be over
northern Illinois late in the day, with the most favored corridor
for storm development further northeast of our region across Indiana
and Ohio. This is where an SPC Day 2 Enhanced risk exists. The
threat is more conditional across our area, but the parameter space
in place suggests that all severe hazards would be possible if
storms develop. The most likely time for this to occur appears to be
later in the afternoon and into the evening (perhaps a 21z Tue-05z
Wed period). The threat likely be greatest east of the Mississippi
River, and potentially more focused across southwest Indiana and
west Kentucky. The SPC Day 2 slight risk may need to be upgraded for
part of this area, but there is a good amount of uncertainty still
with this period.

After a dry period overnight Tuesday, our attention turns to an even
more volatile situation unfolding on Wednesday. Guidance continues
to suggest a very favorable environment will exist across the Ohio
Valley that may lead to a significant severe thunderstorm outbreak
including very large hail, damaging winds, and tornadoes (some of
which may be strong). Instability will be very high, at least 3000
j/kg and potential at around 4000 j/kg. Dewpoints will be in at
least the low 70s and deep layer shear will be in excess of 50 kts.
The top 2 CIPS analogs for Wednesday`s event are two of our more
significant May events in the past 20 years: May 8, 2009 derecho (80-
100 mph winds) and May 6, 2003 tornado outbreak that resulted in 21
tornadoes in our cwa. SPC currently has a large Enhanced risk for
Day 3 and there`s a decent chance that portions of this may be
upgraded as the event grows closer. There are some timing
differences with some guidance suggesting the primary convection
remaining north of our cwa near the sfc low in LSX/ILX areas until
after 00z and then convection filling in along the front during the
evening across our area. Another possibility is that convection
fires in Missouri earlier in the day and moves in by midday or early
afternoon. We are still too far out in time to get too specific with
exact timing, but anytime in the afternoon and evening looks to be
in play.

Cooler and drier air moves into the region late week, with highs
only forecast to be in the upper 60s to low 70s by Friday (after low
to mid 80s on Tuesday and Wednesday). Some moderation back into the
70s is anticipated over the weekend. Upper level troughing digging
across the Great Lakes and Ohio Valley may lead to some rain chances
returning by Saturday.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1251 PM CDT Mon May 6 2024

Disturbance will lead to isolated-scattered convection
developing this afternoon, mainly focused across the east half
of the region. Lingering MVFR cigs (and even some IFR) are
expected to gradually lift to VFR levels by late afternoon. A
general lull in activity is expected this evening and early
overnight. After 09z a line of convection may spread eastward
across the area. It should be in a weakening phase through
early-mid morning. MVFR conditions are expected to accompany
this. Southerly winds will increase tomorrow morning with some
gusts of 20-25 kts anticipated.

&&

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

&&

$$

DISCUSSION...SP
AVIATION...SP