871
FXUS63 KTOP 251913
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
213 PM CDT Fri Sep 25 2026

.KEY MESSAGES...

- Another round of showers and storms are expected (60-90%) to lift
  northeast across the area tonight.

- There is a 30-60% chance for storms to develop Saturday evening. A
  strong storm or two cannot be ruled out.

- Periods of heavy rain are forecast for Tue through Thur next week,
  and several inches or rain could lead to a flooding risk.

&&

.DISCUSSION...
Issued at 213 PM CDT Fri Sep 25 2026

19Z water vapor imagery had the center of an upper ridge over the TX
gulf coast as an amplified upper trough moved towards the northern
Rockies. A couple low amplitude shortwaves were noted in the
southwest flow over the central plains. At the surface, high pressure
was located over the Upper Midwest with low pressure along the lee
of the Rockies. This pattern has favored continued southeasterly low
level flow and moisture transport north.

The initial wave and associated precip is moving east northeast out
of eastern KS as another shortwave comes out of west TX. This should
bring a lull in precip this afternoon before the next round of
showers and storms move though overnight. Mid level lapse rates are
progged to remain relatively shallow limiting instability for
storms. So the main risk looks to be localized heavy rain as a very
moist airmass remains over the plains. Think the storms within the
southwesterly flow should remain progressive enough to mitigate a
widespread flooding risk.

For Saturday, the question is whether we can clear out and warm up
for thunderstorms to redevelop. Mid level lapse rates could steepen
across central KS. If temps can warm into the lower 80s, some
moderate instability of around 3000 J/kg of MUCAPE could help spark
convection in the afternoon. At this time, there is a fair amount of
uncertainty whether we will clear out as the RAP tends to hang onto
low clouds well into the afternoon. Think the SWODY2 trend of
shifting the risk more towards south central KS is reasonable given
the chance for clouds to linger and limit destabilization. If things
do clear out, marginal bulk shear of 20 to 30KT may limit storm
organization to multi-cellular clusters and a wind risk.

Shortwave ridging is progged to redevelop over the central and
southern plains for Sunday and Monday with a break from the rain
chances. The main question in the forecast is how an upper trough
will evolve coming out of the southwestern U.S. next week. 12Z
operational solutions seem to be centering around the idea of a
cutoff low slowly lifting through the plains mid to late week next
week. However the 00Z ensembles were nearly evenly split on a close
versus a more phased open solution. So there remains a fair amount
of spread in the predictability of this pattern for Tuesday through
Friday. Nevertheless the signal for heavy rainfall is seen in the
ensembles with the GEFS and ECMWF ensemble indicating PWs will be 2
to 3 standard deviations above normal. The operational GFS progs PWs
to be over 2 inches by 12Z Wednesday. This is likely due to the fact
the models are absorbing the remnants of Polo into the upper trough
and bringing that tropical fetch of moisture into the plains. Most
guidance points to Tuesday night through Wednesday night as the best
timing for precip, but if the close solution prevails a slower
progression to the system with cyclogenesis could occur causing high
precip chances to persist through Friday. This leads to the heavy
rainfall risk next week. The NBM shows widespread 2 to 4 inches of
rain through Thursday. The 12Z GFS and ECMWF suggest 3 to 5 inches
are possible by Friday evening. Widespread rains of these magnitudes
even spread out over a few days could lead to flooding. So will have
to continue to monitor the trends with the storm system for next
week. Temperatures look to remain rather seasonal as the mean
westerlies remain across the northern tier of the county with no
obvious surge of cold air south seen in the operational or ensemble
solutions. Think the NBM/WPC forecast looks reasonable through next
week. There could be some adjustments to temps depending on how
next week`s storm system progresses east.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1158 AM CDT Fri Sep 25 2026

With the initial wave lifting north of the area, there is expected to
be a break from the SHRA before the next wave lifts across the
central plains tonight. Models show some drier air in low levels
advecting into eastern KS so outside of a SHRA, VFR conditions should
prevail. MHK is expected to have some MVFR CIGS for a few more hours
before the dry air moves in. There is a good signal for more SHRA and
TSRA overnight so have timed this based on a concensus of the CAMs.

&&

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

&&

$$

DISCUSSION...Wolters
AVIATION...Wolters