National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KTOP 201740
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1240 PM CDT Wed Sep 20 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 244 AM CDT Wed Sep 20 2017

Both radar and IR imagery early this morning clearly show a surface
front entering north central Kansas near 07Z.  This boundary is
expected to bisect the CWA by mid-morning oriented from the
northeast to southwest, before stalling out through the afternoon
hours.  Not too much in the way of temperature change with this
front with highs in the 80s throughout northeast Kansas this
afternoon.  Dewpoints, on the other hand, will be significantly
drier west of this boundary by the afternoon leading to much more
pleasant conditions in this area than yesterday.  East of the front,
dewpoints once again reach into the low 70s leading to another hot
and muggy day. Soundings show a fairly stout cap over the area this
afternoon and into the evening which would prevent any storms from
forming along this boundary in the afternoon.  Some models do erode
this cap in the early evening, especially in east central Kansas
which may allow for a few scattered storms to develop across this
area during this timeframe. Sufficient CAPE is seen in this corridor
for storms to form, although 0-6 km bulk shear does look a bit weak
between 20-30 kts which will limit the overall widespread severe
potential. If anything were to form, marginally severe hail and wind
look to be the main threats.  Low temperatures range from the mid-
60s in north central Kansas to the low 70s in east central Kansas.

.LONG TERM...(Thursday through Tuesday)
Issued at 244 AM CDT Wed Sep 20 2017

Return flow quickly establishes on Thursday behind the front so
temperatures will be warm once again with highs in the low to mid
90s. Dew points will also be relatively high so afternoon heat
indices will be in the mid to upper 90s. Southerly winds remain
breezy with gusts approaching 30 to 35 mph Thursday and Friday. This
is all in response to a deepening longwave trough over the western
US. One of the associated shortwave troughs over Canada will get
absorbed by the westerlies and push a cold front into the central
and northern plains. It appears that this front will stay west of
the forecast area through a majority of the weekend. The main mid
level low pressure should be centered over the northern Rockies
during this time. By late weekend it appears that this low will
gradually get sheared out and begin to interact with a shortwave
trough digging through the southern extent of the longwave. That
energy will give it the final push causing the trough to lift out
over the plains therefore driving the front eastward. By sunday
night and Monday several rounds of widespread precipitation is
expected. There is no obvious sign of severe storms a this point,
but it can`t be completely ruled out on Monday given the right
timing. Plenty of time to watch that scenario play out though. It
could end up that extensive cloud cover inhibits the instability.
The precipitation should linger into Tuesday with the slow frontal
progression. By Wednesday the boundary pushes south of the area and
brings back more seasonal temperatures.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1239 PM CDT Wed Sep 20 2017

Mainly a cloud and wind forecast as front has bisected the
forecast area and then retreats northward tomorrow. Winds become
light and variable this evening before increasing and becoming
southerly once again Thursday morning.

&&

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

$$

SHORT TERM...Heller
LONG TERM...Sanders
AVIATION...67