108
FXUS63 KEAX 181757
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
1257 PM CDT Wed Sep 18 2024

.KEY MESSAGES...

- Strong, potentially severe storms possible Thursday.

- Well above normal temperatures expected through Friday.
  Temperatures roughly 10-15 degrees above normal across the area.

- Widespread rain still likely this weekend.

&&

.DISCUSSION...
Issued at 303 AM CDT Wed Sep 18 2024

Upper-level ridging, being compressed between a deep western
trough and a closed upper low over the eastern CONUS, will lead
to unseasonably warm conditions today. 1000-850mb thickness
values increase substantially through the day as a result of the
upper ridging and strong warm adevection. This should lead to
temperatures near 90 this afternoon, ~1-2 degrees warmer than
Tuesday. Thursday looks even warmer as the upper ridging
strengthens and the thickness values increase in response. Highs
Thursday are likely to be in the lower to potentially middle
90s. These hot temperatures will occur with increasing moisture
into the area as strong warm and moist advection brings mid to
upper 60 degree dewpoints into the area.

That heat and humidity will lead to a moderately unstable airmass
across the area with SBCAPE values ranging from about 700-800 J/kg
at the 25th percentile of guidance to 1500-1600 J/kg at the 75th
percentile of guidance. With increasing flow aloft, deep-layer bulk
shear should range from about 28kts to 35kts across northern MO.
This combination will support strong to severe storms. Mean
convective inhibition of roughly -50 to -75 J/kg will be hard
to overcome during the day. Given this, it looks more likely
storms will develop during the evening as a cold front begins to
move into the area. Ensemble guidance shows this well with
relatively low probabilities during the afternoon and then much
higher probabilities after 00Z, especially across northern MO.
Lapse rates don`t look particularly steep aloft so the threat of
hail will mainly be a result of potential supercell structures,
given the shear. Models also show fairly strong low-level
curvature to hodographs across northern MO, suggesting there is
some potential for a tornado. Otherwise, strong winds look like
the most likely hazard.

For the weekend, the front that moves through Thursday night/
Friday, will stall in the vicinity of the forecast area. This will
lead to the potential for widespread and much needed rainfall.
Generally, it looks more likely that north of the river and
across far northwestern MO will see the heaviest rainfall. This
is where the highest probabilities of exceeding various
rainfall amounts reside. Our current forecast shows widespread
1"+ amounts across most of the forecast area, with 2-3" amounts
in far northwestern MO/ and northeastern KS. There is even a
small chance (about 10-15%) that northwestern MO exceeds 3" with
this event. If these rain totals come to fruition, it will help
greatly with the worsening drought conditions across the area.
Speaking of drought, this is the 2nd driest first 17 days of
September for Kansas City on record. Records for September date
back to 1888.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1218 PM CDT Wed Sep 18 2024

VFR conditions are expected to persist through the period.
Southerly winds between 10 and 13 knots with occasional gusts
up to 20 knots should continue this afternoon before relaxing
to 8 knots or less by this evening.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.

&&

$$

DISCUSSION...CDB
AVIATION...BMW