Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 222327
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
627 PM CDT Sat Jul 22 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday)
Issued at 258 PM CDT Sat Jul 22 2017

This afternoon, a front can be seen bisecting the CWA generally from
east to west.  This front is not very strong in terms of temperature
differences, but moist dewpoints north of the boundary are clear
along with a shifting of winds.  Heat indicies today have once again
risen into the 100-111 degree range today and the Excessive Heat
Warning will continue until 8pm this evening.  Some hi-res guidance
begins to develop storms along the boundary due to convergence and
diurnal heating late this afternoon, with the NAM/GFS bringing in
precipitation mainly during the evening.  With the strong heating,
expect any cap to erode and any storms that do develop this
afternoon would most likely be unorganized in nature due to the
relatively weak effective shear of only 25-30 knots.  With a highly
unstable atmosphere and soundings indicating a deep, dry adiabatic
profile near the surface, strong downburst winds will be the main
hazard with any storms this afternoon.  Heavy rainfall will be
another concern with any storms and localized flooding is a
possibility.  A mid-level shortwave skims northeast Kansas overnight
and more showers and thunderstorms may form in western and central
Kansas and move eastward into the area keeping precipitation chances
for the entire area until the early morning.

By tomorrow morning, the front will be located just south of the
area expected to continue south into southern Kansas by the
afternoon.  Only slight chances for precipitation continue into the
afternoon in east central Kansas tomorrow.  Even with this frontal
passage, we will only see mild reprieve in hot temperatures with
highs expected to reach into the into the low and mid 90s.  With
only light winds and clearing skies, heat indicies Sunday will be in
the upper 90s.

.LONG TERM...(Sunday night through Saturday)
Issued at 258 PM CDT Sat Jul 22 2017

By Sunday night into Monday, a broad mid-level ridge will be
stretched out across much of the southern two-thirds of the CONUS,
with the CWA wedged between surface high pressure to the northeast
and surface low pressure to the northwest.  With this surface
pattern in place, winds will shift to the southeast and then south
Monday into Tuesday, resulting in a moderating trend in
temperatures. This southerly flow will also allow for some increased
moisture advection into the region through mid-week, so expect a
return of hot and humid conditions.  Afternoon high temperatures
will likely reach into the mid/upper 90s for much of the CWA Monday
through Thursday, with dewpoint temperatures rising into the upper
60s/low 70s.  With these hot and humid conditions in place, heat
index values will likely rise into the 100 to 105 degree range for
much of the CWA Tuesday through Thursday, with the highest heat
indices expected on Wednesday.  As a result, a Heat Advisory may
need to be considered for mid-week.

With the broad mid-level ridge in place early this week, conditions
will stay dry through early AM Tuesday before a couple of very weak
embedded waves bring the potential for a few isolated to scattered
storms on Tuesday.  Models show a mid-level trough skimming across
the Dakotas and into the Great Lakes region Tuesday into Wednesday,
which ultimately will help push a surface cold front eastward across
KS.  This boundary looks to extend into north central to far
northeast KS on Wednesday before gradually sliding southeastward
across the CWA on Thursday.  As a result, there is a potential for
scattered showers and thunderstorms Wednesday evening into Thursday,
with additional post-frontal thunderstorms possible Thursday night
through Friday.  This frontal passage will provide a bit of relief
to the heat with high temperatures Friday and Saturday dropping into
the upper 80s to low 90s.  With surface high pressure advancing into
the region behind the front, expect dry conditions for next weekend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 625 PM CDT Sat Jul 22 2017

Added some variable winds with the incoming storms as the
atmosphere is conducive to wind gusts. Otherwise convection
shifts to the south later this evening. Could see some MVFR clouds
but have as a scattered group at this time.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 8 PM CDT this evening for
KSZ008>012-020>024-026-034>040-054>056-058-059.

&&

$$

SHORT TERM...Heller
LONG TERM...Hennecke
AVIATION...67



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