535
FXUS63 KTOP 140851
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
351 AM CDT Wed Aug 14 2024

.KEY MESSAGES...

- A Heat Advisory remains in effect for much of the area this
  afternoon as heat index values climb to 100-107 degrees.

- Thunderstorms, some severe, impact the area this evening with large
  hail, damaging winds, and locally heavy rainfall being the
  main hazards.

&&

.DISCUSSION...
Issued at 351 AM CDT Wed Aug 14 2024

An upper ridge resides across the Southern Plains with a decaying
MCS pushing east across Nebraska. Precipitation on the southern
extent of this complex has built into far northern Kansas, but
intensity is lacking with all lightning behind confined north of the
stateline. Isentropic ascent on the nose of the low-level jet has
led to a band of storms from eastern Nebraska into northeast
Arkansas, but this will continue to be pushed east by the low-level
jet. Lingering precipitation ends this morning as increasing
southerly flow shunts a warm front north into southern Nebraska by
this afternoon. Morning cloud cover gives way to mostly sunny skies
and allows temperatures to reach into the 90s. Short-term guidance
has shifted the surface low slightly further north which brings an
attendant dryline into portions of central Kansas. As a result,
dewpoints may be lower than currently forecast which could limit how
high heat index values reach this afternoon. There still looks to be
at least a couple hour window for 100-105 degree heat indices in
this area as warmer temperatures behind the dryline could offset the
fall in dewpoint. Best chances for heat indices of 105-107 degrees
reside across east central Kansas where dewpoints will remain in the
low to mid 70s through the afternoon. The Heat Advisory remains in
effect through 7PM this evening.

A shortwave ejects across the Plains this afternoon and evening,
pushing a surface trough into the area. Ascent from the passing wave
and convergence along the surface trough will be sufficient for
convective initiation to occur between 5-7PM across central Kansas.
MUCAPE of 2000-3000 J/kg will support robust updrafts, but effective
shear of 25-30kts and a weakness in the 4-6km wind field could cause
updrafts to struggle to maintain intensity. Nonetheless, these
storms could be severe and produce large hail and damaging winds,
especially considering inverted-V profiles and DCAPE of 1000+. Storm
motions largely parallel to the surface trough could lead to
training of storms unless the advancing shortwave keeps the overall
complex of storms moving east. If storms train over the same areas,
the flooding potential increases with PWATs of 1.75-2.25",
supporting 1-3 inch per hour rainfall rates. The tornado threat is
low, but locally backed winds near the warm front could provide
enough vorticity for a spin up.

The surface trough stalls across the area on Thursday with several
perturbations in the flow passing through. The first wave could keep
some showers and storms around through the morning hours ahead of
the next wave that moves through during the afternoon and evening.
Key mesoscale details such as how much heating will take place after
any morning convection are uncertain, but the passing wave could
generate additional storms during the afternoon and evening. Shear
is better, but instability is weaker compared to the environment
that is expected this afternoon. If sufficient destabilization can
occur, strong to severe storms are possible with large hail,
damaging wind gusts, and locally heavy rainfall being the main
hazards.

The pattern turns drier overall Friday into the weekend. However,
passing waves of energy between the eastern trough and
southwestern US ridge bring periodic chances for showers and
storms. Temperatures remain right around climatological normals
for this time of year in the upper 80s to low 90s.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1225 AM CDT Wed Aug 14 2024

Low-end MVFR to IFR cigs are expected through mid-to-late morning
when low cigs are expected to scatter out. There is a low
chance for a few showers near KTOP/KFOE through 08z with better
chances for showers/storms coming late in the period. Coverage
of precipitation this evening remains uncertain, so have input
VCSH/VCTS for now and will refine with future issuances.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 1 PM this afternoon to 7 PM CDT this
evening for KSZ021-KSZ022-KSZ023-KSZ024-KSZ026-KSZ034-KSZ035-
KSZ036-KSZ037-KSZ038-KSZ039-KSZ040-KSZ054-KSZ055-KSZ056-KSZ058-
KSZ059.

&&

$$

DISCUSSION...Flanagan
AVIATION...Flanagan