642
FXUS63 KTOP 011906
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
206 PM CDT Mon Sep 1 2025

.KEY MESSAGES...

- Cool fall-like temperatures persist through the week.

- Rain and a few thunderstorms linger through the evening, gradually
clear overnight.

- Seasonably strong cold front arrives Wednesday PM. Will have to
watch for a few strong to severe storms depending on the speed of
the front.

&&

.DISCUSSION...
Issued at 204 PM CDT Mon Sep 1 2025

On this first day of meteorological fall, a weak upper low remains
in place across southern Nebraska, part of broad troughing over the
eastern CONUS. This low should gradually drift southeast across the
area over the next 12-18 hours. At the surface, a somewhat diffuse
surface boundary is across north-central Kansas, separating light
northerly winds from more easterly winds. Given clearing skies and
surface heating in the vicinity, this boundary should be a focus for
additional showers and thunderstorms to develop over the next few
hours. Instability and shear are too meager to support much in the
way of severe weather. However there are some small pockets of
enhanced surface vorticity and low-level CAPE, so can`t completely
rule out a brief funnel in the vicinity of the boundary through
early evening. Farther east, thick cloud cover and scattered light
showers are keeping temperatures 5-10 degrees cooler, with many
spots still stuck in the 60s. Overnight, any showers and storms will
gradually taper off overnight as the upper system moves off to our
southeast.

Tomorrow will be another cool day underneath northwest flow aloft.
Subsidence behind this evening`s system should allow for sunnier
skies, which will at least help temperatures climb into the upper
70s. Wednesday, a much deeper and larger upper low will drop south
out of the Northern Plains, pushing a cold front south through the
area. Currently, a consensus of model guidance has the front passing
through during the late afternoon and evening hours. Instability
looks to increase to around 1500-2000 J/kg along the front, with
increasing mid-level winds supportive of around 40 kts of effective
shear. This would be supportive of a few severe storms, with hail
the initial main threat in any supercells, followed by more of a
wind threat if upscale growth can occur along the front. The main
uncertainty at this time is the speed of the front. A faster frontal
passage could keep storms from developing until south of the area,
or at the least keep storm coverage to a minimum.

Cooler and drier air is quickly ushered in behind the front
Wednesday night, allowing temperatures to near the upper 40s by
Thursday morning. The upper low continues to deepen over the Great
Lakes, supporting an impressively cool early autumn airmass over
much of the eastern CONUS. There is increasing confidence in a
secondary upper shortwave quickly dropping southeast Thursday night.
This would support a brief return of moisture and shower/storm
chances ahead of another cold front, again followed by drier air
Friday into early Saturday. The large upper low does gradually pull
off to the east by later in the weekend, but cool temperatures
should nevertheless persist for at least a few more days.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1158 AM CDT Mon Sep 1 2025

Winds will remain light and generally easterly through the
period. Cloud cover remains the main forecast challenge, as ceilings
should remain predominantly MVFR, locally IFR, but scatter out for a
time towards KMHK. Timing those gaps in the lower stratus will pose
tricky through the evening, though do expect some better clearing to
occur by tomorrow morning. Otherwise, expecting showers and a few
thunderstorms to redevelop this afternoon and early evening, again
mainly where earlier clearing can take place towards KMHK.

&&

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

&&

$$

DISCUSSION...Reese
AVIATION...Reese