454
FXUS63 KTOP 220734
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
234 AM CDT Sat Jun 22 2024

.KEY MESSAGES...

- Isolated to scattered storms are forecast today. The stronger
  storms may have damaging winds.

- Excessive heat is becoming more likely for Monday and Tuesday
  with heat indices up to 110 degrees F.

&&

.DISCUSSION...
Issued at 234 AM CDT Sat Jun 22 2024

07Z water vapor imagery showed upper ridging centered over the
southeast ridging into the southern plains while the mean
westerlies remained over the northern tier states. A shortwave
was noted moving east over the Canadian plains with a more
subtle wave lifting through the northern high plains. Surface
obs indicated a low pressure centered just north and east of GLD
while much of the central and southern plains maintained a warm
and moist boundary layer.

For today and tonight, the subtle wave to the north of the forecast
area should continue east and help bring a weak boundary into
northern parts of KS this afternoon. Low level flow is expected to
be veered to the southwest so convergence may not be the greatest
along the boundary. But CIN is also forecast to be weak with MUCAPE
values over 3000 J/kg along and just ahead of the boundary. Deep
layer shear is expected to only be around 30KT, so the main concern
is for collapsing updrafts with the potential for damaging winds.
RAP and NAM forecast soundings show over 1000 J/kg of downdraft CAPE
ahead of the boundary. And with the warm airmass and limited shear,
it could be hard for storms to sustain a hail stone long enough to
reach severe magnitudes. The uncertainty in the forecast is around
convective initiation. As mentioned there is not a lot of
convergence along the boundary and little if any dynamics to force
vertical motion in this conditionally unstable environment. Think
this is the reason why CAMs struggle to generate much convection
over eastern KS and the 00Z HREF keeps the higher probabilities just
east of the forecast area. Given the limited coverage depicted by
the CAMs have left POPs in the 30 to 50 percent range expecting
isolated to scattered storms. Today`s highs are forecast to be a
couple degrees warmer than yesterday with most places in the middle
90s. And dewpoints should still be around 70 degrees F especially as
the boundary slides south. Forecast heat indices are in the 100 to
105 degree range. Considered the need for a heat advisory
today, but the higher readings are only above 103 briefly. So
the limited scope of advisory level heat indices of around 105
will preclude an advisory at this time.

Surface ridging briefly moves in for Sunday bringing slightly cooler
temperatures to the region. By Monday and into Tuesday, models show
hot and humid temperatures back over the area with highs in the
upper 90s to around 100. With some consistency in the temp and
dewpoint forecast from the blend and operational solutions,
confidence that we may be dealing with excessive heat is
improving. The pattern for next week generally keeps an
elongated upper ridge along the gulf coast while the westerlies
remain over the northern states. This means the forecast is more
likely to be dependent on subtle perturbations within the flow
leading to a forecast with lower predictability. There are signs
from the operational solution for frontal boundaries to move
south Tuesday night and again Thursday night or Friday. This
would bring higher chances for precip, but confidence in the
solutions is only good for chance POPs of 50 percent or less.
Also the boundary Tuesday night should bring slightly cooler
temperatures and more manageable heat to the area for Wednesday
and Thursday.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1149 PM CDT Fri Jun 21 2024

A warm airmass should allow VFR conditions to prevail through
the forecast period. Forecast soundings and objective MOS
guidance shows boundary layer winds remaining up through this
morning with turbulent mixing expected to minimize the potential
for low level wind shear. There could be convection along a weak
boundary that moves into the area from the north this afternoon.
But CAMs show limited development along the boundary and
decrease confidence in TS at a terminal. So will reevaluate TS
chances with later forecasts.

&&

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

&&

$$

DISCUSSION...Wolters
AVIATION...Wolters