FXUS63 KTOP 232042

Area Forecast Discussion
National Weather Service Topeka KS
342 PM CDT Sat Jun 23 2018

.SHORT TERM...(This evening through Sunday Night)
Issued at 340 PM CDT Sat Jun 23 2018

Mostly sunny skies prevailed this afternoon as the embedded mid-
level wave that tracked over the region earlier this morning lifted
northeast of the area. This ample sunshine will allow afternoon
high temperatures to warm into the mid/upper 80s.

The forecast becomes more challenging as we monitor conditions
overnight through Sunday and Sunday night. Models show a mid-level
trough diving southward across the Rockies overnight, with the trough
axis pivoting eastward across the Central Plains Sunday into Sunday
night. This advancing trough will help to shift surface low
pressure into the Central and Southern Plains, with the center of
the surface low likely being centered over/near the Oklahoma/Texas
panhandles. Current surface observations show an expansive region of
mid-60 to low/mid 70 dewpoints across Oklahoma and Texas this
afternoon. With light winds in place through tonight, don't expect
much in the way of moisture advection overnight. However, the
increasing pressure gradient from the eastward-advancing low
pressure system will allow the southerly winds to quickly advect
upper 60 to low 70 dewpoints into the area through the morning hours
and keep this moist air in place through the afternoon hours. Model
uncertainties still exist with regards to how quickly this surface
low and associated front will progress eastward across the outlook
area, with the 12z NAM solution remaining a noticeable outlier.
While a few models still show the potential for some scattered
overnight/early morning convection associated with a passing mid-
level embedded shortwave further enhanced by the low-level jet, the
better model consensus currently keeps conditions dry before the
cold moves into the region during the day. This solution would
support a better-primed and untapped environment for convective
development later in the day, and thus, increases the concern for
severe thunderstorms.

Aside from the 12z NAM (which has been discarded for this forecast
package), model solutions show the associated front stretched across
central KS by late afternoon/early evening, thus allowing ample time
for daytime heating and destabilization of the atmosphere (with
afternoon highs reaching into the mid/upper 80s). Decent mid-level
lapse rates should support MUCAPE values of 1500-3500 J/kg. This
strong instability combined with decent low-level helicity values
and strong 40-50+ kt 0-6km bulk shear values supports the potential
for severe thunderstorm development with all severe modes possible
(damaging winds and large hail being the primary hazards). Ongoing
storms are likely through the overnight hours into Monday, with GEFS
ensembles showing the QPF mean being between 2-3" for much of the
CWA. With moderate to heavy rainfall possible Sunday afternoon and
evening, flash flooding and river flooding will become increasing
concerns. Due to continued uncertainty amongst the models with
regards to the convective evolution of this system, have opted to
hold off on considering any flood headlines at this time, but will
consider it for future updates.

.LONG TERM...(Monday through Saturday)
Issued at 340 PM CDT Sat Jun 23 2018

Lingering showers and storms from the frontal passage should still
be lingering across northern and eastern KS by Monday morning, with
additional scattered precipitation possible through the afternoon
and evening hours as the surface low gets hung up north of the CWA.
With the front potentially stalling out across eastern KS or western
MO, this boundary would be the focus for additional strong to severe
thunderstorm development Monday afternoon and evening as model
soundings show decent lapse rates to support sufficient
destabilization through the day and strong deep-layer shear
remaining in place across the area. The mid-level low will finally
progress further northeast toward the Great Lakes region Monday
night into Tuesday with additional chances for scattered showers and
storms as a southeastward-sagging front tracks across the CWA. With
similar atmospheric conditions in place, cannot rule out the
potential for additional strong to severe thunderstorms with this

By mid-week, a broad mid-level ridge will build across much of the
CONUS. With this pattern in place, expect a noticeable warm-up for
mid to late week as high temperatures soar into the mid/upper 90s
(and possibly near 100 degrees). With models showing ample low-
level moisture remaining over eastern KS with dewpoints rising into
the 70s, expect heat indices to soar into the low/mid 100s from
Tuesday through Saturday. At this time, the highest heat indices
look to be on Wednesday with readings forecast into the mid/upper
100s. As a result, anticipate that there will be a need for heat
headlines by mid-week.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1228 PM CDT Sat Jun 23 2018

For the 18z TAFs, VFR conditions are expected through the period
with light southerly winds. By the end of the TAF period, short-
range models show the potential for showers and thunderstorms to
be advancing eastward toward the TAF sites, with increasing
chances for storms by Sunday afternoon and evening.




SHORT TERM...Hennecke
LONG TERM...Hennecke
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