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971
FXUS63 KTOP 211928
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
228 PM CDT Fri Jun 21 2024

.KEY MESSAGES...

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- Isolated air mass showers and thunderstorms possible today
  (15-20%). These are not expected to be severe.

- Heat builds for Saturday afternoon with heat indicies
  approaching heat advisory criteria. Showers and storms
  possible Saturday PM along a frontal boundary, some could
  become strong/severe with damaging wind gusts.

- Dangerous heat returns again Monday and Tuesday with
  widespread heat indices ranging from 100-110 degrees.
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&&

.DISCUSSION...
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Issued at 228 PM CDT Fri Jun 21 2024

Another hot and humid summer day is in the forecast today as
afternoon high temperatures will again warm into the low 90s area-
wide. As the PBL has mixed over the past several hours, diurnal cu
has overspread northeastern KS. With weak isentropic ascent, some
isolated showers/storms have developed within this cu field with
persistent 20% PoPs to continue over the afternoon and early evening
to account for these airmass showers/storms. Taking a look at the
synoptic features across the country, a large, retrograding upper-
level ridge remains parked over the southeastern CONUS as a trough
axis and embedded vorticity maximums eject into the high Plains. The
associated coupled jet extending from the 4-corners to the Dakotas
should push some mid and high clouds into the area this afternoon
and evening, as seen on the latest satellite trends.

By Saturday morning, the trough axis over the south-central Rockies
will continue to eject mid-level energy into the central Plains,
deepening a surface low across northeastern CO and western NE. As
the wave pushes northeast into the northern Plains into Saturday
afternoon, the surface low will track across the KS/NE border,
increasing low-level flow over eastern KS. Hot 850 mb temps,
downsloping winds and PBL mixing ahead of the surface low/frontal
boundary will lead to very warm temperatures Saturday afternoon.
Expect highs to reach the mid to upper 90s as moisture advection
pushes low to mid 70 degree dewpoints north into the area. Heat
indicies under these conditions will push heat advisory criteria,
ranging from 100-105 degrees during peak heating hours. CAMs depict
the surface boundary getting into north-central KS by the early
afternoon hours that may provide some relief in the heat across
north-central KS, but only by a few degrees. While heat indices will
be approaching advisory criteria, it is important to note that if we
factor in the wind aspect during the afternoon, conditions will feel
slightly more tolerable than if there was less wind. This is
highlighted by the WBGT (wet bulb global temperature) as
south/southwesterly winds sustained between 15-20 mph and gusts to
30 mph keep WBGTs in the low to mid 80s. That said, it will be very
warm tomorrow, so if you plan to be out in the sun and heat, make
sure to stay hydrated and take breaks when necessary.

As the surface boundary slides across the area Saturday afternoon,
scattered storm development will become possible with some storms
becoming strong/severe. There has been a bearish trend in short
range guidance for the coverage of storms along the boundary,
especially until the late afternoon and evening hours. Uncertainty
resides in the fact that instability mostly stays behind the
boundary, there will only be marginal levels of deep shear along and
ahead of the front with weak mid-level lapse rates. This does not
point to a large hail risk within storms, but a damaging wind gust
to 60 mph could be realized with the strongest updrafts Saturday
afternoon and evening. Precipitation will exit to the east by
Saturday evening as surface ridging builds in from the north.

The remainder of the weekend and into early next week will remain
dry with oppressive heat building back into the area by Monday and
Tuesday with the continued retrogression of the mid-level ridge.
Upper 90s to low 100s will be expected across the area and with the
humidity still in the area, heat indices will approach 110-115
degrees. The highest confidence in much of the area seeing heat
advisory conditions comes Monday while Tuesday could be altered a
bit with a change in timing of the system moving in during the
afternoon and evening. The heat does not appear to last into
Wednesday as mid-level energy rounding the ridge axis pushes a
surface boundary across the area Tuesday evening, shifting winds to
the northwest and increasing precipitation chances across the area
Tuesday night into Wednesday.
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&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1234 PM CDT Fri Jun 21 2024

Main aviation hazard over the period will be isolated showers
and a few rumbles of thunder this afternoon within the developed
cu field. Added mention of VCTS to account for the scattered
storms across the area today. There will be some marginal LLWS
overnight at all terminals, but kept out of the TAF since the BL
should remain mixed with low-level winds fairly unidirectional.
Later in the TAF, south/southwest winds will increase mid
morning tomorrow ahead of a frontal boundary with gusts upwards
of 30 mph.

&&

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

&&

$$

DISCUSSION...Griesemer
AVIATION...Griesemer