000
FXUS63 KPAH 161820
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
120 PM CDT Tue Apr 16 2024

.KEY MESSAGES...

- Chance for strong-severe storms this afternoon/evening through
  tonight.

- Low-Mid 80s continues through Thursday.

- Marginal-Slight risk for severe storms again Wednesday and
  Thursday afternoons.

- Turning cooler Friday through the weekend.

&&

.DISCUSSION...
Issued at 115 PM CDT Tue Apr 16 2024

Low pressure will be tracking from KS/NE to IA/MN over the
course of the day and night. All models produce a line of pre
frontal convection that migrates west-to-east across the PAH FA
from later this afternoon through tonight. You can see the
beginning of this coming together now over MO. The CAMs show
variance with onset timing here (some this afternoon, some not
til mid evening), while all extrapolate the convective line
across the area tonight. Strength of intensity is also a
variance amongst the member solutions. The air mass it
encounters includes a ribbon of surface dew points from the low-
mid 60s, with PM highs in the low-mid 80s. MUCAPEs range from a
few hundred across the central FA to nearly 1000 Joules/kg just
to our west, at 00Z. This area of instability migrates west-to-
east across the FA as the line moves in...with increasing
helicity values intersecting its axis by late evening and
continuing overnight. The models diminish the convective line
late tonight as it departs our east with dwindling CAPE and
helicity by 09-12z. 0-3KM Bulk Shear increases to 40-50 kts by
evening. Over time, 700-500MB lapse rates drop off about a
degree C from their peak around 7-7.5C, which is a limiting
factor to consider. The overall expectation is that linear
storms will peak w/hazards of damaging winds/hail but cannot
rule out isolated tornadoes esp tonight.

There is a consistent signal for a short-lived wane in
convective activity around daybreak Wednesday, then with diurnal
heating tmrw, we see another risk of severe materialize along
the lower Ohio River valley as the models spread 700-500 MB
lapse rates upwards to 8C across the area, coincident with the
occluding low`s track across WI and into the Great Lakes over
the course of the day. There is about 2000+ Joules of MUCAPE
available by tmrw pm, will there be enough moisture left after
the pre dawn work-over...the (relative) better chance is further
east in the FA...where some 60s dew points may still reside
(having fallen thru the 50s further west). With the
aforementioned lapse rates and a pool of -16C H5 temps rotating
overhead, we`re concerned about the possibility of large hailers
if any storms do or can manage their way this far south from
the parent feeder line into the low to the north. Damaging winds
and isolated tornadoes would be (relative) lesser hazards, but
still existent, respectively. The models other consistency here
is timing...with a mid morning to mid afternoon, short window of
diurnal timing with this episode. Gusty 30-35 mph gradient
winds will likewise be a continued sub headline hazard.

There is some downtime the remainder of Wednesday evening into
the overnight, before our eyes affix to the next storm threat.
Another risk of severe enters the picture late Wednesday night
into Thursday, as a low pressure wave rides out of the southern
Plains and lifts a warm front back into/across the FA upon its
approach. We see 0-1KM helicity values increase to 100+ in sync
with the boundary`s lift, suggesting perhaps a brief/isolated
tornado hazard, within a destabilizing air mass that bears
upward to 2000 Joules/KG MUCAPEs again by midday Thursday. The
overall severe threat maintains itself until the low lifts and
its cold front makes passage Thursday night...with damaging
winds/hail the main expected hazards until then.

This front`s passage is what allows the week ending blast of
cooler air to work in/across the FA, which ultimately transforms
highs/lows running 80s/60s back into the 60s/40s that rides out
for the remainder of our forecast.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 115 PM CDT Tue Apr 16 2024

Main concerns are the gusty southerly and southwesterly winds
today, and the showers and thunderstorms moving through tonight.
Winds are gusting to around 20-30 kts today and will continue to
be gusty tonight and into tomorrow. Showers and thunderstorms
are expected to ramp up this evening into tonight from west to
east. Stronger downpours could reduce visbys at the terminals.
Rain should be out of the area by midday tomorrow.

&&

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

&&

$$