Ottawa, Kansas 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

368
FXUS63 KTOP 200929
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
429 AM CDT Thu Aug 20 2026

.KEY MESSAGES...

- Dense Fog Advisory issued for northern KS with some patchy fog
expected further south in low-lying areas especially.

- Isolated to widely scattered showers and storms may develop late
tonight into Friday morning, although better chances (30-50%) come
late Friday night into Saturday morning.

- There are additional chances for showers and storms early next
week, but low predictability of timing and location leads to low
confidence.

- Temperatures stay near or slightly below average through the middle
  of next week.

&&

.DISCUSSION...
Issued at 428 AM CDT Thu Aug 20 2026

Upper pattern is becoming more amplified with a ridge over the
Desert Southwest and a strengthening trough to our east, putting us
in northwest flow aloft which will persist for the next several
days. At the surface, the ridge axis is placed to our north over
eastern Nebraska, although high pressure will continue to have an
influence on our weather for today. Have been monitoring satellite,
observations, and especially webcams for fog development and
expansion southwest into more of our CWA. Dense Fog Advisory has
been issued across the Hwy 36 corridor where it is more prevalent
based on the aforementioned sources. Further south and further away
from the ridge axis, fog should be patchier in nature, but still
can`t rule out some quick drops in visibility in low-lying spots and
areas near water. Forecast soundings show the moisture is shallow
and should mix out around 14-15z.

After fog lifts, the late morning and afternoon look to be mostly
sunny with temperatures similar to yesterday -- low 80s for
northeastern areas, upper 80s approaching 90 further south. The
surface high slowly slides east throughout the day, leading to light
winds gradually turning southerly toward the evening. There is low
confidence in a subtle perturbation aloft leading to some convection
late tonight and overnight. Short-term models have not been
consistent in developing this activity in central NE/KS during this
time period, and the LLJ isn`t overly strong. Even so, its position
would tend to favor more of southern Nebraska. More recent guidance
has delayed the development of any isolated or scattered storms
until Friday morning, and exactly how soon has also varied from run
to run. That said, if anything were to develop and clip parts of
north central KS overnight tonight, soundings show these to be high-
based and the environment would support a conditional severe threat
with isolated damaging winds or large hail. If the later trend holds
and clouds/rain hang on longer Friday, then temperatures may not be
as warm as currently forecast.

The more discernible shortwave aloft is progged to develop
thunderstorms in southwestern Nebraska Friday evening. If these
track far enough east closer to midnight, then once again soundings
show enough elevated instability and shear to support a wind and
hail threat.

Following any lingering rain Saturday morning, skies should clear
out for a dry afternoon and evening. While temperatures the next
several days will be dependent on clouds and precipitation, medium-
range guidance seems to be coming into better agreement on a back
door cold front entering the area Saturday night into Sunday,
leading to cooler highs on Sunday. The pattern remains rather
nebulous through the first half of next week as we remain on the
northeast periphery of the upper ridge, which keeps us close enough
to any embedded perturbations that are difficult to predict the
timing and location of this far out. At this time, Sunday and
Tuesday bring the next best chances for rain, but PoPs are limited
to 40% or less for any given time frame given the low predictability
of these features.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1242 AM CDT Thu Aug 20 2026

Main challenge this period will be fog through the early morning
hours. Terminals are on the southwest edge of the most favorable zone
for fog, and think this setup leans more towards patchy shallow fog
as opposed to deeper, more widespread fog. Forecast soundings show
some elevated winds off the surface that would point towards shallow
fog as well. Potential is there for some brief drops to IFR or even
LIFR vis at times though, so haven`t made changes to vis in tempo
groups or timing. Once fog mixes out, it should lift to stratus
briefly before clearing completely. VFR with light winds otherwise.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM CDT this morning for KSZ008-KSZ009-
KSZ010-KSZ011-KSZ012.

&&

$$

DISCUSSION...Picha
AVIATION...Picha