777
FXUS63 KTOP 291353
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
853 AM CDT Fri Aug 29 2025

.KEY MESSAGES...

- Scattered thunderstorm chances increase late Saturday through Monday
  as a cold front/upper disturbance slides through the region.

- After highs in the upper 70s this weekend, another surge of
  cooler air drops highs to the upper 60s to lower 70s Thursday
  and lows in the upper 40s to lower 50s Thursday and Friday
  Mornings.

&&

.UPDATE...
Issued at 853 AM CDT Fri Aug 29 2025

Looking at area web cameras and it appears the fog is mainly in
the river valley with most cameras along the main highways
showing improved visibilities. Forecast soundings suggest the
fog may linger until 10 am at TOP, but other observations (i.e.
FOE and EMP) are starting to see improvement in visibilities.
So with fog becoming more isolated and gradually improving over
the next hour, will go ahead and let the advisory expire at 9am.

&&

.DISCUSSION...
Issued at 406 AM CDT Fri Aug 29 2025

Early this morning a low amplitude upper ridge was centered across
NM, northward into central CO. An amplified upper trough was
located across the eastern US. A closed upper low was located across
the eastern Pacific, off the coast of OR.

A surface ridge of high pressure was centered across the mid MS River
Valley. A surface ridge axis extened westward into northeast KS.
A stationary front extended across north TX, then west-southwest
into southeast NM. A cluster of elevated storms were slowly
moving southeast across eastern CO into west central KS. These
storms will move southeast into northern OK during the morning
hours.

Dense fog was forming along and southeast of I-35. Therefore, I
placed a dense fog advisory out for portions of east central KS
through 9 AM. There are some high clouds moving in that may
cause the fog not to get too dense along the I-70 corridor but
low lying areas may see dense fog for the morning commute.

Today through Saturday:

A mid level perturbation will round the H5 ridge axis across the
southern high Plains Tonight into Saturday. The H5 trough will
dampen down the H5 ridge across the southern high Plains, causing
the northwesterly flow aloft to become more zonal across the Plains.
As the lead H5 perturbation moves east across the Plains, 850mb
moisture advection will increase across western and central KS,
and the combination of ascent ahead of the advancing
perturbation and isentropic lift will cause scattered to
numerous showers and thunderstorms to develop across western KS.
These showers and storms will move east into a more stable
environment across northeast KS, so they may dissipate before
reaching northeast KS and east central KS during the afternoon
hours. The best chance for showers and thunderstorms will be
across north central KS Saturday afternoon with a 30 to 60
percent chance. Most of northeast and east central KS will only
see a 10 to 20 percent chance of showers ans thunderstorms on
Saturday afternoon.


Saturday night through Tuesday night:

Rain chances will increase as a more amplified H5 trough digs
southeast across the northern high Plains into the central Plains
Saturday night into Sunday. The closed upper low over the eastern
Pacific will move east onshore across WA/OR. A down stream H5
trough will amplify across the southwest US, northward into the
Great Basin.

Several embedded perturbations within the northwest flow aloft will
provided chances for showers and thunderstorms Sunday night through
Tuesday.

The chance of rain will be dependent of the track of the
perturbations embedded within the northwesterly mid-level flow.
The rain chances will range from 20 to 50 percent.

Wednesday through Thursday:

Both the GFS and ECMWF model solutions show an amplified upper trough
digging southeast out of western Canada. The H5 trough amplifies
into a closed upper low across the upper Midwest. This will cause
strong low-level CAA across the northern Plains with a surface
front pushing southeast across the CWA WED afternoon. There may
be a few showers and storms along the front Wednesday afternoon
into Wednesday evening. A surface ridge of high pressure will
build southward across the CWA on Thursday. Highs Thursday
afternoon may only reach the mid to upper 60s.

Thursday night through Friday:

The upper low will shift east across the northern Great Lakes and
the center of the surface ridge will build southeast across OK
into the lower MS River Valley. Friday will be a bit warmer
with highs in the 70s after a cool morning start, with mid 40s
to lower 50s.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 630 AM CDT Fri Aug 29 2025

The dense ground fog should continue through 14Z at the
terminals, then lift by 15Z. MHK may see some MVFR stratus
through 16Z. After 16Z expect VFR conditons with light and
variable winds.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 9 AM CDT this morning for KSZ038-
KSZ039-KSZ040-KSZ054-KSZ055-KSZ056-KSZ058-KSZ059.

&&

$$

UPDATE...Wolters
DISCUSSION...Gargan
AVIATION...Gargan