740
FXUS63 KTOP 181746
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1246 PM CDT Mon Aug 18 2025

.KEY MESSAGES...

- Hot weather continues through Tuesday with a 20 to 40% chance
  of showers and thunderstorms.

- A slight cool down is forecast for Wednesday and Thursday
  before a more noticeable cool down happens this weekend.

&&

.DISCUSSION...
Issued at 235 AM CDT Mon Aug 18 2025

07Z water vapor imagery showed broad upper ridging across the
southern US. A shortwave was noted moving east along the SD/NEB
state line. Up stream water vapor showed a closed upper low off
the British Columbian coast with a short wave trough lifting
over the Pacific Northwest. Surface obs continued to show low
pressure over the central high plains and high pressure over the
MS river valley maintaining a southerly low level flow and a
warm and humid airmass.

A narrow axis of isentropic lift has spawned showers and storms just
north of Republic county and into eastern NEB. The latest RAP and
NAM show the better lift and saturation remaining just north of the
state line, but a stray shower cannot be ruled out across north
central KS for the next few hours. By mid morning the isentropic
lift is expected to weaken.

By this evening a surface front is progged to setup across southern
NEB with good moisture pooled along it. This feature is expected to
be the focal point for additional thunderstorms tonight and into
Tuesday. Confidence in overall coverage of storms is marginal since
there doesn`t seem to be a consistent picture of precipitation from
the models. In general it looks like convection off the higher
terrain is probably going to track east along the boundary. Rain
cooled air from the storms is expected to push the effective
boundary into the forecast area by Tuesday, when outflow boundaries
and convectively induced vorticity passes over the forecast area.
Surprisingly the models do not want to generate a lot of QPF during
the day Tuesday. Am not sure why this is, but have kept some chance
POPs into the evening given a conditionally unstable airmass in
place. Its just the lack of large scale forcing that may limit
coverage. Temps today should be fairly similar to yesterday with
heat indices around 100 in the afternoon. Clouds may tend to keep
temps a few degrees cooler for Tuesday.

By Wednesday models show the surface ridge nosing into northeast KS.
This should push the better moisture south of the forecast area with
no obvious forcing for vertical motion. Thursday and Friday are
shaping up to be dry too as the upper ridge centered over the Four
Corners leans over with ridging extending into the middle MO river
valley. The upper ridging may delay the cooler temps for a few days.
By Friday the models show good insolation with some warm air
advection from the west pushing highs to around 90.

Northwest flow is progged to develop by the weekend. This should
allow cooler air to move south. Ensembles are fairly similar in the
overall pattern but differences in the cluster analysis show up with
the strength of shortwave energy moving through the Upper Midwest.
This could impact the location of return flow and warm air advection
this weekend. So confidence in the operational runs depiction of QPF
Saturday and Sunday night is a little lower. Don`t see anything to
push me away from the NBM initialization which has some low end POPs
late Friday night when a front may be pushing south and again
Saturday night with some potential warm air advection precip.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1245 PM CDT Mon Aug 18 2025

Storms have been weakening, but have been slow to dissipate as
they push south. They should remain mainly south of terminals
the rest of this afternoon with high clouds overhead. Overnight
and into Tuesday morning, scattered thunderstorms may develop
again along a weak frontal boundary. CAMs haven`t been very
consistent in coverage and location, so will go with a PROB30
mention at all TAF sites as confidence is too low to go any
more aggressive than that. VFR conditions are forecast otherwise
with light southerly winds turning east to northeast late in
the period.

&&

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

&&

$$

DISCUSSION...Wolters
AVIATION...Picha