247
FXUS63 KTOP 221712 AAA
AFDTOP

Area Forecast Discussion...UPDATED
National Weather Service Topeka KS
1212 PM CDT Fri Sep 22 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 307 AM CDT Fri Sep 22 2017

Low to mid level southwest flow continues downstream of the western
CONUS trough. Winds gusty at times as low-level jet around 40kts
mixes down. Mid cloud has recently developed with shallow moisture
depicted on DDC 0Z sounding, and with the mixing temps remain in the
mid 70s to lower 80s. Surface low was moving northeast out of
western Nebraska.

Only minor changes in conditions from Thursday anticipated. With the
Nebraska low exiting, low-level height/pressure gradients are
weaker and more southerly, allowing for a very slightly drier and
cooler airmass to move in. Shallow moisture remains in a few levels
and should bring mostly clear skies but little if any forcing keeps
the forecast dry. Low-level jet is also weaker tonight though will
likely see some cirrus from front range convection enter at least
western areas. Have kept lows a bit above guidance mean.

.LONG TERM...(Saturday through Thursday)
Issued at 307 AM CDT Fri Sep 22 2017

Still looking warm for the weekend as southerly flow continues ahead
of the next upper level trough.  Highs in the upper 80s expected
Saturday, with only slightly cooler temperatures Sunday and Monday
as clouds begin to build in ahead of the front.  The main trough
very slowly progresses eastward Sunday, and precipitation chances
begin in north central Kansas Sunday night, although the main front
does not appear to move through until late Monday evening.  There
are still some timing differences with this passage, though, with
the ECMWF quicker to advance the front through northeast Kansas than
the GFS. Due to these differences, there is also some uncertainty on
when precipitation chances will end, with the GFS holding onto
precipitation in east central Kansas through Thursday, while the
ECMWF clears things out Wednesday night.  As the previous discussion
mentioned, still some broad brushing of PoPs due to model
differences late in the period.  After this frontal passage,
temperatures are expected to drop down to seasonable values Tuesday
onward with highs in the low to mid-70s.  Lows during this late week
time period will be in the 50s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1210 PM CDT Fri Sep 22 2017

VFR conditions will remain in place through the forecast period.
Wind gusts should subside by 01z with SSE sfc winds near 10 kts
expected overnight.

&&

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

$$

SHORT TERM...65
LONG TERM...Heller
AVIATION...Omitt