802
FXUS63 KTOP 292329
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
629 PM CDT Tue Sep 29 2026

.KEY MESSAGES...

- Multiple rounds of rain are likely this afternoon through Thursday
evening. Heavy rain at times could lead to flooding, and a Flood
Watch remains in effect primarily for areas north of I-70 through
Thursday afternoon.

- As confidence in heavy rainfall increases, total rainfall amounts
have increased to a widespread 2-4" with locally higher amounts
around 6".

- A few strong or severe storms are possible Wednesday late
afternoon into early evening towards central KS, mainly for damaging
wind.

&&

.DISCUSSION...
Issued at 302 PM CDT Tue Sep 29 2026

Deep upper low is circulating over southern CA and western AZ, and
Hurricane Polo is seen merging into that system via water vapor
imagery early this afternoon. The main westerlies aloft are along
the US-Canada border. The sfc trough axis extends from north TX up
through the Central and Northern Plains with a long fetch of mid-
level moisture streaming from the upper low through the central part
of the country. As a result of all this, deeper moisture has
gradually moved from western KS into our forecast area throughout
the day. Isentropic ascent coupled with that moisture has brought
the first batch of rain into eastern KS this afternoon with weak
instability leading to isolated thunderstorms. This rain will
continue through the afternoon and most of the evening, bringing
moderate to heavy rain in spotty locations at times. CAMs indicate
there may be a short time period later this evening when the rain
lets up and becomes more scattered in coverage for a bit, but then
should pick up again during the overnight hours as the LLJ
strengthens. The high end of guidance shows a few isolated pockets
of 3+ inches could be possible by daybreak, though 1-2" appears more
likely for most.

There should be a bit more of a lull mid to late morning Wednesday
before the next round of rain moves in for the afternoon and
evening. The sfc low deepens and matures through the day with the
warm front pushing north during this time frame, although there
remain some differences in the position of the low, which will
impact where exactly the dryline and triple point set up. Forecast
soundings and hodographs show veering in the low levels through the
afternoon with CAPE increasing to 1000-1500 J/kg. The instability is
uncertain and could be lower if clouds and rain linger longer
through the morning without adequate clearing. However, low-level
shear could still be enough to provide a high-shear low-CAPE setup
which leads to some concern for low-topped supercells. Damaging wind
would be the main hazard for any storm that can grow strong enough,
and given the shear, it would be a short time window but cannot
entirely rule out the possibility of a quick tornado spinning up or
hail within any rotating updrafts. However, it should be noted that
continued heavy rain remains the primary concern. There is higher
confidence in the heavy rain and flooding threat regardless of the
instability, but a more convective nature would add to the potential
for intense rainfall rates in an environment that will already have
Pwat between 1.75-2".

As our forecast area ends up firmly within the warm sector later
Wednesday night into early Thursday morning, this should allow for
another break in the heavier rain especially south of I-70. However,
areas near the KS/NE border may still see showers and storms at
times through the night, which could exacerbate any flooding that
may be ongoing. Getting into daybreak Thursday, another batch of
rain looks to move from south to north from OK into east central KS.
The cold front gradually moves across the area through the day,
making for a wet day until it eventually moves out towards the
evening, and the upper low fills and merges into the westerlies to
the north. By the time all is said and done, most areas should see a
total of 2-4" with localized amounts around 6" spread over three days.
Felt the current Flood Watch well covered the areas where those
high- end amounts look most favorable based on 12z guidance, so have
made no changes to headlines at this time.

Drier and cooler weather is favored through the weekend into early
next week as zonal flow aloft transitions to northwest flow with a
strengthening ridge over the Four Corners region. High temperatures
drop to the 60s Friday, then warm up slightly to the lower 70s by
next Monday.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 626 PM CDT Tue Sep 29 2026

MVFR to IFR with rain, low stratus and occasional thunderstorms.
Widespread rainfall will continue largely through the period with
varying levels of intensity. Some isolated thunderstorms can`t be
ruled out at any point during the period, but confidence in any
particular thunderstorm impacting a terminal is too low for anything
other than a temp/prob mention at this time.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Thursday afternoon for KSZ008-KSZ009-KSZ010-
KSZ011-KSZ012-KSZ020-KSZ021-KSZ022-KSZ023-KSZ024-KSZ034.

&&

$$

DISCUSSION...Picha
AVIATION...Jones