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215
FXUS63 KTOP 132239
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
539 PM CDT Thu Jun 13 2024

.KEY MESSAGES...

- Hot and humid Today with afternoon heat indices of 101-110
  degrees. A Heat Advisory in effect from noon-8pm today.

- Isolated to scattered storms late this afternoon into the evening.
  These storms could be severe with large hail and damaging wind
  gusts being the main hazards.

- Above-normal temperatures continue into early next week.

&&

.MESOSCALE...
-- Changed Discussion --
Issued at 539 PM CDT Thu Jun 13 2024

Convection has begun along the frontal boundary in north
central KS, but has been slow to intensify to severe levels.
Regardless, MLCAPE values from the 20Z RAOB over 4000 J/kg and
0-6km shear near 40KT support the potential for supercell storms
with large hail. The last couple runs of the HRRR have shown
that these storms may be capable of wind gusts over 80 MPH as
well. Still some modest MLCIN and marginal shear across central
KS may be the reason for the gradual build up in intensity. The
window for severe storms looks to be through 10 or 11 pm
tonight.
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&&

.DISCUSSION...
Issued at 340 PM CDT Thu Jun 13 2024

Summer is in full swing across northeast KS this afternoon as
temperatures have soared into the mid to upper 90s, some seeing the
year`s first triple digit temperatures! Along with heat, persistent
southerly low-level flow has advected in a wide area of low to mid
70 degree dewpoints making it feel much hotter than air
temperatures. A heat advisory continues this afternoon across the
whole warning area for heat indices ranging from 100-110 degrees.

This pooled moisture has been in response to a deepening trough axis
and associated surface boundary moving southeast out of southern
Nebraska that will later become the focal point for convection, and
possibly a few severe storms. Taking a look at current convective
parameters show a capped warm sector ahead of the frontal boundary
that is currently positioned from west-central Kansas through
southeastern Iowa. Above the well-mixed BL, MLCAPE shows values
approaching 4500 J/kg in far northeastern Kansas where moisture
pooling has seemed to maximize ahead of the boundary. 0-6km shear
remains marginal, between 30-40 knots with the higher values hugging
the KS/NE border. As the frontal boundary continues to slide further
south into northeast KS, ML capping should slowly erode a bit with
RAP analysis having MLCIN around 20 J/kg just ahead of the boundary
by 7 PM today. Although convergence along this frontal boundary does
not appear overly strong, a few to scattered storms should develop
between 6-8 PM this evening and given the aforementioned
environmental parameters, storms will quickly become strong, and
possibly severe. That said, this severe set up seems highly
conditional for a few reasons and comes with some uncertainties...
first, storms may struggle to overcome the afternoon capping
inversion and not maintain themselves long enough to become
organized...second, if storms can develop, as they move southeast
into a less shear-dominated region, outflow boundaries may outrun
convection and spark up other convection away from the front. CAMs
(mainly the HRRR) have produces several runs of post-frontal
convection along and north of I-70 later this evening from storms
moving out of central KS. If these can persist, they will have ample
amounts of elevated instability to tap into, but will remain very
elevated. Cannot rule out an isolated wind gust if some of this
convection can cool the inversion a bit, but large hail (around
quarter-sized) will be the main threat.

By midnight tonight, convection will have mostly dissipated or moved
out of the area as the low-level boundary sags into southeastern KS.
The next chance for storms should hold off for most of the day
Friday as a large upper low moves out of NM, deepening a surface low
over the lee of the Rockies during the day. The best forcing remains
west of the area as isentropic surfaces and low-level flow keep the
best lift going upslope towards the surface low in Colorado.
Convection initiated near the mid-level vorticity max and surface
low during the day Friday will slowly push east during the day,
congealing into a complex of storms as it approaches central and
north-central KS. A few storms within this complex Friday night into
Saturday morning could be strong to severe with large hail up to
quarters and damaging winds to 60 mph.

The slow-moving upper-low hangs out into Saturday as the bit of
vorticity rounds the last axis of the trough. Thunderstorms will
again be possible during the afternoon and evening across central
and north-central KS with the enhancement of upper level support.
Shear and instability on Saturday across the area is out of
alignment for a widespread severe event with no obvious areas of
forced ascent within the warm sector, so confidence remains low in
most areas seeing strong any storms during the day. Highest
confidence remains mainly north of the area where better moisture
and instability reside. Because of the lack of confidence, did not
deviate much from NBM PoPs of 30%. Temperatures for the weekend and
early next week will get into the low to mid 90s, remaining fairly
muggy with low chances for rain.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
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Issued at 539 PM CDT Thu Jun 13 2024

Trying to determine whether convection impacts the terminals
with the effective boundary still north of them. The last few
runs of the HRRR suggest at least a tempo for TS is warranted
until 02Z or 03Z. Outside of the convection, VFR conditions are
forecast to prevail into Friday.
-- End Changed Discussion --

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT this evening for KSZ008-KSZ009-
KSZ010-KSZ011-KSZ012-KSZ020-KSZ021-KSZ022-KSZ023-KSZ024-KSZ026-
KSZ034-KSZ035-KSZ036-KSZ037-KSZ038-KSZ039-KSZ040-KSZ054-KSZ055-
KSZ056-KSZ058-KSZ059.

&&

$$

MESOSCALE...Wolters
DISCUSSION...Griesemer
AVIATION...Wolters