571
FXUS63 KTOP 181055
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
555 AM CDT Sat Jul 18 2026

.KEY MESSAGES...

- Widely scattered showers are possible again this afternoon.

- Temperatures should trend warmer through Monday. Afternoon heat
  indices are forecast to be around 105 degrees Monday.

- A slight cool down is expected by the middle of next week with a
  chance for showers and storms late Wednesday and Thursday morning.

&&

.DISCUSSION...
Issued at 223 AM CDT Sat Jul 18 2026

07Z water vapor imagery showed little change to the overall pattern.
An upper low remained over west TX under a broad upper ridge over
the central plains as the mean westerlies stayed well north of the
forecast area. The surface pattern with high pressure over the
southern MS river valley and low pressure along the lee of the
central Rockies maintained southerly low level flow and humid
conditions.

With no real change in the pattern or airmass, there isn`t a lot of
change to the forecast. So a moist and conditionally unstable
airmass remains across the forecast area. And the latest RAP and NAM
progs show a weakness in the upper ridge over northeast KS in the
form of a weak shear or deformation axis. A general lack of or only
weak subsidence is not expected to be enough to prevent the diurnally
driven showers once again. Have included some 20 to 30 percent
chance POPs for isolated to scattered showers from midday through the
afternoon.

The upper ridge is still forecast to strengthen through Monday, but
the better height rises look to stay across the Rockies. This has
caused the blend to pull back slightly on highs for Sunday and
Monday. But the 00Z operational solutions still support highs in the
upper 90s and around 100 for Monday. So have kept the forecast close
to what it has been the last couple days. Then focus shifts to the
dewpoint forecast where the NBM is mixing out the moisture on Monday
with dewpoints falling into the lower 60s. With a south and southeast
wind, this seems to optimistic and may be a result of the GFS
influence and a lack of short term guidance. So kept dewpoints a
little closer the the seventy fifth percentile given the pattern. All
of this to say heat indices are expected to hit triple digits with
values up to 103 degrees for Sunday afternoon and around 105 degrees
Monday afternoon.

For Tuesday and beyond, models continue to show the upper ridge
shifting to the southern plains. Cluster analysis points to
continued uncertainty in the amplitude of the upper ridge/trough
pattern over North America. This potentially has a greater impact on
temps as a more amplified pattern could allow stronger surface
ridging to hang on. However a less amplified pattern may allow warm
air to advect north quicker. All of this points to greater spreads
in temps and the potential for some fluctuation in the forecast
through the end of the workweek. There remains reasonable confidence
in a slight cool down by Wednesday as a frontal boundary move south
on Tuesday. The pattern should also allow for potential
perturbations to affect the forecast area and operational solutions
continue to point to some shortwave energy rounding the upper ridge
Wednesday night and Thursday morning. Chance POPs look reasonable for
this time period.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 555 AM CDT Sat Jul 18 2026

An uncapped airmass with some weak deformation aloft is expected to
allow for widely scattered SHRA to develop this afternoon. Outside of
the SHRA, VFR conditions should prevail with just some temporary MVFR
conditions if precip moves over the terminals. Predictability of
location and timing remains low given a lack of surface feature to
focus convection. So will just keep a PROB30 group which has some
support from the MOS guidance.

&&

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

&&

$$

DISCUSSION...Wolters
AVIATION...Wolters