243
FXUS63 KTOP 040920
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
420 AM CDT Sat May 4 2024

.KEY MESSAGES...

- Showers and thunderstorms taper off this morning.

- Classic severe weather setup Monday PM as a strong system
approaches. All modes of severe weather will be possible.

&&

.DISCUSSION...
Issued at 413 AM CDT Sat May 4 2024

Showers and thunderstorms continue early this morning, just ahead of
the cold front. Despite 1000-1500 J/kg of CAPE and 35-40 kts of
effective shear, increasing CIN has limited severe weather. Have
seen a few reports of 40-50 mph wind gusts and half inch hail as the
line moved across Clay/Riley Counties, and think this will remain
roughly the upper limit of activity through the next few hours.
Precipitation tapers off by late morning as the front pushes south
and east of the area. Lingering clouds into the afternoon will
generally keep high temperatures in the upper 60. For Sunday, a weak
surface low develops along the old boundary to our south and lifts
northeast. The NAM is an outlier with a stronger and farther north
low, resulting in more widespread rain, but most other guidance
keeps just lighter showers across portions of east-central Kansas.
Continued cloud cover will again keep highs in the upper 60s.

Attention then turns to Monday, as a deep upper low becomes
negatively tilted over the Central Plains. As a developing lee
cyclone pulls deep moisture northward, a dryline will become
established across central Kansas, eventually becoming overtaken by
a cold front. This is a classic setup for severe weather, with a
potent combination of strong effective shear (40-50 kts) and
moderate to strong ML CAPE (2000-3500 J/kg) ahead of a dynamic
system. The most likely scenario is for supercells to develop along
the dryline during the afternoon hours, moving northeast and
gradually growing upscale into the evening across eastern Kansas.
There are still a few questions related to the timing of the trough
and overall shear profile. Some guidance has some low-level veer-
back of the winds earlier in the afternoon, which could cause for
messier storm modes if earlier initiation occurs. But there is
better agreement in enlarged low-level hodographs by evening as the
LLJ strengthens, with any veer-back confined to upper levels where
it could actually be favorable by providing better venting to
cells. Any discrete or semi-discrete supercells during this
late afternoon through mid-evening timeframe would likely have
the most significant severe potential, including damaging winds,
very large hail, and tornadoes. The precise details and
magnitudes of the hazards will become more clear over the next
couple days.


For the middle of the week, the deep upper low will become almost
stationary over the north-central CONUS. Several embedded shortwaves
will round the base of the upper low, keeping low (20-30 percent)
PoPs in place across eastern Kansas. Still looks like Monday night`s
cold front remains quasi-stationary to our southeast, with 70-80% of
guidance keeping appreciable instability southeast of Anderson
County. Still close enough to watch, particularly Wednesday when a
stronger shortwave may try to shift the front slightly back north.
Highs generally stay in the 70s through the week, though this will
of course depend on cloud cover and the exact position of the quasi-
stationary frontal boundary.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1227 AM CDT Sat May 4 2024

Line of showers and thunderstorms ahead of a cold front will move
through KMHK around 0830z and KTOP/KFOE around KFOE, give or take an
hour. Precipitation only looks to last for a couple hours at any one
spot. Winds veer to the northwest behind this line as the cold front
moves through, with ceilings falling to MVFR and possibly IFR at
times. These lower ceilings gradually clear through the afternoon,
with 10-13 kt northwest winds weakening after sunset.

&&

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

&&

$$

DISCUSSION...Reese
AVIATION...Reese