153
FXUS63 KTOP 292328
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
628 PM CDT Tue Oct 29 2024

.KEY MESSAGES...

- Wind gusts around 50 mph through Wednesday morning.

- Thunderstorms are likely tomorrow (100%), some severe with
  damaging wind around 70 mph, hail up to the size of half
  dollars and a few tornadoes.

- Widespread rain is likely (60-80%) Saturday through Tuesday
  of next week with several inches of accumulation.

&&

.DISCUSSION...
Issued at 201 PM CDT Tue Oct 29 2024

A deepening surface trough and tight pressure gradient, combined
with a well-mixed boundary layer are leading to widespread wind
gusts of 50-60 mph this afternoon. These wind gusts will
continue through Wednesday morning as the boundary-layer is
expected to be mixed through the night.

Tomorrow, a deep upper-level and surface trough will move into
Kansas. Forecast conditions have grown increasingly favorable
for severe storms tomorrow afternoon and evening. The front is
now forecast to move through a bit later in the day tomorrow,
allowing for ample destabilization ahead of the front and an
opportunity for the upper-level wave and low-level jet to
coincide across eastern Kansas tomorrow evening. The 12 UTC
suite of models now favor isolated, discrete cells developing
in an environment characterized by ML CAPE of 1,500 J/KG,
effective shear of 50-60 knots and SRH of 300-500 m2/s2. This
favorable parameter space in combination with strong forcing via
the cold front, upper-level wave and low-level jet could
produce some higher end severe weather with wind gusts around 70
mph, a few tornadoes and hail around half dollar size. There
are a few scenarios depicted in the forecast model data. One
that appears to be growing more favorable is the formation of
some isolated cells ahead of the cold front across portions of
eastern Kansas (generally east of Manhattan an I-70 and south)
tomorrow afternoon (1-2pm) and a line of storms developing along
the cold front across central and north central Kansas. As the
front progresses eastward through the afternoon and into the
evening storms along the front are expected to strengthen as the
upper-level wave moves overhead and combines with an impressive
50-60 knot low-level jet. Bowing segments and supercellular
structures within the the line are likely given the strength of
the shear and forcing. All threats would be possible in these
features as with isolated cells that form ahead of the line. A
few flies in the ointment so-to-speak could be cloud cover
tomorrow afternoon and the shear orientation with respect to the
cold front. Cloud cover could lead to slightly lower instability
and shear vectors could lead to more upscale growth which would
lead to more of a wind threat and less of a tornado or hail
threat.

We get a break Thursday and Friday as high pressure sits
overhead. Numerous periods of showers and thunderstorms appear
likely Saturday through Tuesday as a deep, slow-moving
upper-level trough develops across the western CONUS and the
central Plains remain in a favorable location to be impacted by
waves exiting that trough. Ensembles indicate anywhere from two
to as much as six inches of rainfall is possible through next
week.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 628 PM CDT Tue Oct 29 2024

Gusty south winds continue through the period with gusts of
35-40kts expected. Confidence is increasing in MVFR stratus
building in Wednesday morning although uncertainty remains in
onset time and whether this stratus deck breaks up during the
afternoon. There could be a few storms during the afternoon
ahead of a cold front, but confidence in timing and location of
these initial storms is too low to include in TAF. Storms are
more likely as the front passes near the end or just beyond this
TAF period.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 7 AM CDT Wednesday for KSZ008-KSZ009-
KSZ010-KSZ011-KSZ012-KSZ020-KSZ021-KSZ022-KSZ023-KSZ024-KSZ026-
KSZ034-KSZ035-KSZ036-KSZ037-KSZ038-KSZ039-KSZ040-KSZ054-KSZ055-
KSZ056-KSZ058-KSZ059.

&&

$$

DISCUSSION...Jones
AVIATION...Flanagan