578
FXUS63 KTOP 250531
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1231 AM CDT Sat May 25 2024

.KEY MESSAGES...

- Increasing potential for a higher-end severe weather event
Saturday evening and night, especially along/south of I-70.

- Thunderstorm chances continue into Sunday before a relatively
quieter pattern arrives for next week.

&&

.DISCUSSION...
Issued at 308 PM CDT Fri May 24 2024

Our most recent cold front has moved off to the south and east this
afternoon, as the associated shortwave trough lifts north across the
Northern Plains. High pressure quickly moves overhead tonight,
allowing the northwest post-frontal winds to calm. Similar to
yesterday morning, expecting some very patchy shallow fog towards
sunrise, mainly in river valley locations across east-central
Kansas. Any fog that does develop will be short-lived, ending once
southeast winds increase tomorrow morning ahead of the next system.

Attention then turns to the next approaching trough Saturday
evening, as low pressure deepens to around 990 mb across western
Kansas. Strong mass response ahead of this low will advect higher
dewpoints quickly north. Some uncertainty in exactly how quick this
occurs, but a multi-model average takes the warm front to around
Interstate 70 by mid evening. This mid-evening timeframe (7-9 PM)
seems when convection is most likely to initiate towards central
Kansas, as stronger mid-level height falls overlap with increasing
low-level moisture and decreasing CIN. However if the better
moisture is slightly faster or slower than expected, could see
convective initiation as early as 5 PM or as late as 10 PM. Initial
storm mode is expected to be discrete or semi-discrete supercells,
given strong effective shear largely perpendicular to any
boundaries. Large to giant hail and damaging winds would be likely
with any supercell. Tornado threat would be more dependent on
moisture quality and timing, but the faster and deeper moisture
scenarios would see a strong tornado potential given 0-1 km SRH
quickly increasing as the LLJ ramps up by sunset. As the surface low
approaches by late evening and forcing increases, expecting a
transition to more of a linear mode. Moisture and low-level shear
further increase through late evening as thunderstorms move east.
The damaging wind risk will increase and the hail risk will decrease
as storm mode becomes more linear. A tornado threat will continue
with mesovortex potential within any MCS, given the degree of low-
level shear.

There are still several questions and potential failure
mechanisms regarding tomorrow`s severe weather threat. The
biggest is the aforementioned timing of the better moisture`s
arrival, which will impact the amount and timing of initial
supercells. In a slower scenario, it`s possible the greatest
coverage of mid-evening supercells stays south and east of the
area. And as usual, storm-scale interactions will play a role in
the coverage and severity of convection, and this is tough to
pin down before storms develop, let alone 24+ hours out.
Regardless, given the higher end potential of these storms and
their occurrence on a holiday weekend, keeping up to date with
the latest forecast information will be important.

The surface low continues east on Sunday, pushing the better
combination of instability and shear east of our area. We still may
a few storms capable of large hail Sunday afternoon across eastern
Kansas. Lingering moisture behind the low and cool temperatures
aloft keep instability around. By Memorial Day, we look to quiet
down as the upper low moves further east and surface high pressure
approaches. A few brief shower and thunderstorms chances will still
be possible through mid-week with weak shortwaves in northwest flow
aloft, but overall the pattern will be much drier. Temperatures look
to stay near or slightly below average, with highs near 80 and lows
in the 50s.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1231 AM CDT Sat May 25 2024

Light easterly winds tonight increase from the SSE through the
day with gusts of 20-25kts this afternoon-evening. Storms are
expected to develop across central Kansas and move towards
terminals late in the period. Confidence in timing and coverage
is low, so mentioned VCTS with this issuance; refinement will
be needed with subsequent forecasts.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Reese
AVIATION...Flanagan