Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 151733
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1133 AM CST Wed Nov 15 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 311 AM CST Wed Nov 15 2017

Early this morning, observations indicate a frontal boundary located
from roughly a line from Abilene to Marysville.  This boundary will
continue to progress southeast through the early morning, exiting
the area shortly after sunrise.  Ahead of this front, a broken line
of showers has formed.  Soundings indicate a cap still in place
inhibiting the formation of thunderstorms, although this cap is
weak. Continued to include the mention of thunder in the next couple
of hours early this morning as the cap continues to cool and erode
and possible isolated thunder may occur.  The low ceilings and
visibilities should improve relatively quickly behind this frontal
boundary, as clear skies are already noted in central Kansas.

Surface high pressure moves in behind this front resulting in a day
of clear skies and ample sunshine.  Highs look to reach into the mid
to upper 50s with northwesterly winds persisting through the
afternoon and early evening.  Some high clouds may advect into the
area early tomorrow morning, and lows tonight are much cooler than
previous nights near freezing.

.LONG TERM...(Thursday through Tuesday)
Issued at 311 AM CST Wed Nov 15 2017

Thursday, A positive tilt upper level trough will move onshore
across the pacific northwest as a low amplitude downstream upper
level ridge moves east across the plains. The center of the surface
ridge will shift east into the mid MS river valley as a lee surface
trough deepens across the high plains. Surface winds will become
southeasterly across the CWA. Expect mostly sunny skies and highs in
the mid to upper 50s.

Thursday night and Friday, the positive tilt H5 trough will move
east across the central Rockies and northern plains. The lee surface
trough across the highs plains will begin to translate east as a
surface trough across the Upper Midwest and extend southwest into
the southern high plains. Initially low-level winds will be more
southerly and wil advect residual moisture northward. As the
residual moisture moves northeast across OK into eastern KS the
resulting isentropic lift will cause areas of drizzle and light rain
showers to develop from south to north across east central KS after
6Z FRI. The rain showers and drizzle will develop northward across
northeast KS during the morning hours of Friday. During the mid and
late morning hours of Friday, the 850mb winds will veer to the
southwest and west causing the deeper residual moisture to shift
east of the CWA. The low cloud cover will shift east of the CWA
during the late morning and early afternoon hours, and with WAA
ahead of the surface trough, we should see highs reach into the
upper 60s to lower 70s.

Friday night and Saturday, The positive upper trough will move east
across the central and southern plains. Stronger CAA across the
central plains will cause a surface cold front to push southeast
across the CWA Friday evening. If there is enough residual moisture
behind the front, then there may be enough ascent ahead of the
positive tilt H5 trough for a few post frontal rainshowers to
develop. At this time vertical temperatures profiles look warm
enough to keep the precipitation in the form of rain. Any light rain
showers that develop will shift east of the CWA Saturday morning as
the positive tilt H5 trough axis moves east across the CWA and the
stronger ascent ahead of the H5 trough shifts east of the CWA.

Saturday night through Wednesday, The extended range model solutions
look to be more similar between the ECMWF and GFS through Tuesday,
with a broad longer wave length upper trough in the east and an
upper level ridge in the west. This will keep eastern KS in
northwesterly flow aloft and keep mainly dry conditions. The ECMWF
amplifies a southern stream upper trough into a closed upper low
over TX, which actually retrogrades southwest into central Mexico by
Thursday.

Thanksgiving day looks dry with partly cloudy skies and highs in the
upper 40s to mid 50s. The coldest airmass will be across the eastern
Great Lakes and northeast US. However, this pattern could change
over time.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1130 AM CST Wed Nov 15 2017

VFR conditions expected through the taf period. The winds will
gradually veer tonight, but the speeds will generally be under 5
kt. By tomorrow morning the winds will be out of the southeast and
increase by the end of the period.

&&

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

$$

SHORT TERM...Heller
LONG TERM...Gargan
AVIATION...Sanders



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