375
FXUS63 KPAH 250857
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
357 AM CDT Sat May 25 2024

.KEY MESSAGES...

- Sunday has the potential to be a very volatile day with 2
  rounds of severe weather possible. The range of possibilities
  covers everything from the pre-dawn period through the
  evening. Confidence in the timing and location details
  remains low, but tornadoes, damaging winds, large hail, and
  flash flooding will all be possible.

- A much needed respite from the active weather pattern is in
  store for next week.

&&

.DISCUSSION...
Issued at 357 AM CDT Sat May 25 2024

Convection early this morning has weakened to well below severe
levels, and may take til sunrise or a bit after to clear all of
west Kentucky. Once it does, Saturday should be dry throughout
the region. A weak frontal boundary will slip south into the
Quad State this morning, but it will eventually wash out
somewhere across the region. This will bring some lower
dewpoints, upper 50s, into the far north/northwest, which will
take the edge off the humidity there. Otherwise, south winds
will increase tonight and push the boundary back north of the
area.

The 00Z guidance continues to show a wide range of possibilities
for severe weather Sunday and Sunday night. Guidance has shifted
back southward with the severe MCS expected to develop over the
Plains tonight. This MCS could reach southeast Missouri before
daybreak Sunday morning and could sweep eastward through the
entire area as early as 15Z. The question would then be how much
can the atmosphere recover for the afternoon or evening? Of
course, if the morning convection does not develop or impact
much of the region, then that would be more bullish for a major
severe weather event in the afternoon and evening.

Regardless of the timing or convective mode, the combination of
shear and instability continues to look very ominous,
especially Sunday afternoon and evening. The 00Z HREF mean
indicates 2000-4000 J/kg of surface-based CAPE with 200-400
m2/s2 of 0-3km storm-relative helicity (SRH). The 0-1km SRH is
generally in the 150-200 m2/s2 range, supportive of a tornado
threat. Substantial instability could develop as early as 15Z
Sunday. This parameter space would support initial supercells
with all severe hazards possible. However, the initial
supercells are likely to quickly develop into a severe MCS. The
greatest threat at this time appears to be for widespread
damaging winds in a well-developed MCS moving eastward across
some portion of the region, most likely across the northern half
of the area. There is a possibility of one healthy MCS in the
morning and a very strong one in the afternoon or evening.

We simply will not have much clarity until we see how tonight`s
convection evolves over the Plains. We may not have much time to
react to the convective evolution, but in the meantime we
should be prepared for widespread severe weather at any time
from early Sunday morning through Sunday evening.

A cold front will pass slowly across the region overnight Sunday
into Monday, as the upper storm system lifts northeast to the
Great Lakes. A small chance of showers and thunderstorms will
continue in the east through much of the day Monday, but the
humidity will be decreasing through the day. Temperatures will
still climb a bit above normal into the lower 80s.

The Quad State will be dry from Monday night through Thursday
with cyclonic northwest flow aloft and surface high pressure in
control. As the trough pushes farther east, warm advection may
get going for Friday into next weekend, and that results in
some chance of showers across the entire region Friday through
next Saturday. Temperatures will bottom out Wednesday and
Wednesday night when readings will be at or a few degrees below
normal, especially the lows. Temperatures will gradually climb
back above normal by Friday.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 625 PM CDT Fri May 24 2024

Showers and storms are moving eastward just north of the I-64
corridor early this evening. Additional storm development
southwest of St Louis has collapsed on approach to the Quad
State, leaving the cold front further west as the focus for late
evening development. Scattered showers and storms cross the
area by late night. MVFR cigs are likely along/behind the storms
with MVFR vsbys (brief IFR possible) with heavy rain. Breezy
winds out of the south will trend lighter but may gust with
storms. Following the cold front, winds shift to the northwest
and eventually north. Winds remain around 5 kts and variable
tomorrow with clearing skies.

&&

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

&&

$$

DISCUSSION...DRS
AVIATION...ATL