884
FXUS63 KTOP 172309
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
609 PM CDT Sat Aug 17 2024

.KEY MESSAGES...

- Showers and thunderstorms are possible (30 to 50 percent)
  Sunday afternoon and evening, some of which could be strong.

- Below normal temperatures are expected to start off the
  workweek.

- The forecast has highs back into the 90s heading into next
  weekend.

&&

.DISCUSSION...
Issued at 222 PM CDT Sat Aug 17 2024

An upper ridge remained centered over the southern high plains
per the 19Z water vapor imagery. The ridge axis extended north
over the northern plains and a closed upper low was noted off
the coast of OR. A shortwave looked to be lifting northeast
through UT. Surface obs showed weak high pressure ridging into
northeast KS from the north.

Main challenge with the forecast is timing the weak disturbances
rounding the upper ridge. And then there may not even be a wave
spark convection per the isolated storms across central NEB which
appear to be a result of some modest warm air advection in the mid
levels. The 12Z operational models are converging on a common idea
of a shortwave diving southeast Sunday afternoon and evening. There
is a good response to this wave seen in the isentropic surfaces with
increasing lift and saturation in mid levels. So confidence in
isolated to scattered showers and storms is increasing and have POPs
in the 30 to 50 percent range by Sunday evening. NAM and RAP
forecast soundings suggest elevated CAPE values could be around 1000
J/kg. Combined with bulk shear around 50KT with effectively a
straight line hodograph, there is some potential for organized
updrafts and severe storms.

By Monday models build a stronger surface high into the central
plains with some drier air. This brings into question whether there
is enough moisture for precip Tuesday night and the operational
models have backed off on QPF. This has resulted in the NBM coming
in with POPs less than 10 percent for Tuesday night and into
Wednesday. Then the upper ridge axis begins to slide east over the
central plains limiting the chances for shortwave energy to affect
the area. So the only chances for precip in the forecast is on
Sunday and Sunday night.

The stronger surface ridge Monday should bring below normal temps
for the first of the workweek. Then temps are forecast to warm as
the upper ridge moves overhead and southerly return flow
redevelops. This should push highs back into the 90s by
Saturday. The NBM reflects these trends nicely and have not
made and changes.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 607 PM CDT Sat Aug 17 2024

VFR at terminals with light easterly winds overnight and
increasing high clouds by sunrise, limiting overall fog
development at KTOP. Added a mention of VCSH aft 17Z at all
sites with some uncertainty on timing and coverage of showers
and isolated TSRA during the afternoon. Mid clouds around 10 kft
are most likely with showers given lack of low level moisture
with this system.

&&

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

&&

$$

DISCUSSION...Wolters
AVIATION...Prieto