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674
FXUS63 KTOP 240451
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1151 PM CDT Fri Jun 23 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Saturday)
Issued at 242 PM CDT Fri Jun 23 2017

PV lobes rotating around a broad Northern Plains longwave trough
provided enough support for isolated showers across Nebraska and
Kansas today, but these showers were on a downward trend and having
a minimal impact on the sensible weather. North to northwesterly
winds of 10 to 20 mph behind a departing cold front funneled
Canadian air southward into the region and helped keep highs in the
70s to around 80 today. Dewpoints also plummeted 20+ degrees over
the course of the day and were in the 40s and 50s by mid afternoon.
A high pressure ridge building southward down the High Plains will
bring clear and cool weather tonight and tomorrow with lows tonight
in the mid 50s and highs tomorrow in the upper 70s to around 80
(climatological high/low for Topeka is 87/66).

.LONG TERM...(Saturday night through Friday)
Issued at 242 PM CDT Fri Jun 23 2017

By Saturday night, surface high pressure will be situated over the
central U.S. with the broad mid-level trough centered over the Great
Lakes region resulting in northwesterly flow aloft.  The central
U.S. looks to remain under this northwesterly flow through Monday
night, with models showing a few embedded waves skimming across the
area, resulting in scattered precipitation chances.  The first of
these waves may skim north central to central KS Saturday night into
Sunday morning, however precipitation may be in the form of
sprinkles due to the large amount of dry air above the surface.  Two
additional shortwaves should bring better precipitation chances
Sunday night through Tuesday morning. However, model soundings show
nearly moist adiabatic lapse rates in place Sunday night, resulting
in very limited instability.  Mid-level lapse rates begin to steepen
some by Monday, so should see some scattered thunderstorms develop
during the afternoon with additional scattered thunderstorm chances
into the evening hours as the next shortwave tracks into the region.

A brief period of dry conditions is expected on Tuesday as the mid-
level flow becomes more zonal. Surface high pressure will shift
further into the southeastern U.S. with surface low pressure
advancing into the High Plains.  With this surface pattern in place,
expect increasing southerly/southwesterly winds through mid-week,
which will support the advection of warmer and more moist air into
the region.  The next embedded shortwave will track over the area
Tuesday night into Wednesday, resulting in additional scattered
thunderstorm chances. Scattered thunderstorm chances continue
Thursday into Friday as a mid-level trough deepens over the Rockies,
which will help to push surface low pressure further eastward into
Kansas. The associated cold front should stay just west of the CWA
on Thursday with models showing the front tracking southeastward
across the area on Friday. This front combined with additional
embedded shortwaves on the lee side of the trough tracking over the
area will support scattered thunderstorms Thursday into Friday.

As for temperatures, conditions will be quite pleasant Sunday and
Monday with highs in the upper 70s/low 80s and overnight lows in the
upper 50s.  Once the southerly flow increases on Tuesday and
persists through late week ahead of the cold front, expect a
moderating trend with highs rising back into the mid 80s to low 90s
by Wednesday and Thursday.  This southerly flow will also support
decent moisture advection, which will push dewpoint temperatures
back into the upper 60s to low 70s by mid week with heat index
values into the mid/upper 90s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1151 PM CDT Fri Jun 23 2017

VFR conditions are expected through the period. Light north winds
are expected as high pressure remains over the area.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Skow
LONG TERM...Hennecke
AVIATION...53