912
FXUS63 KTOP 281146
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
646 AM CDT WED SEP 28 2016

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 251 AM CDT Wed Sep 28 2016

Upper low continues to spin nearly in place over the Great Lakes
today, sending another shot of cooler air southward in the northerly
flow behind.  Overnight these northerly winds noted in Nebraska and
moving slowly southward, while stratus also moving southwestward
into Iowa and northeastern Missouri.  For today, a slight shift
downward expected in high temps as cool front moves in, and will
need to keep an eye on stratus as it moves southwest.  Highs
expected around 70 with winds diminishing later in the day.
Overnight models suggesting an increase in moisture in the boundary
layer, while winds over the inversion remain around 15-20kts.  Looks
at this time like could see some overnight stratus toward morning,
but NAM soundings saturate to surface and could be fog.  Think
stratus is more likely and have only added clouds to the late night
forecast at this time.  Lows forecast to fall into the 40s.

.LONG TERM...(Thursday through Tuesday)
Issued at 251 AM CDT Wed Sep 28 2016

Forecast through the end of the week and much of the weekend remains
dry and mild with upper ridge aloft remaining intact as the upper
low lingers in the Ohio Valley. Both available moisture and forcing
for ascent are very hard to come by. Best opportunity for some cloud
comes Thursday morning and then again late Friday night into
Saturday morning when the upper low retrogrades somewhat. Northerly
lower level flow keeps temperatures from warming considerably but a
slow increase remains in order into early next week. By this time
the upper trough along the Pacific Northwest gets a push east in
part from the upper wave now moving across northern portions of the
Bering Sea with southerly flow developing near the surface. Precip
chances do increase somewhat early next week but models and their
ensembles showing a wide variety of ways to handle the pieces of
energy in this trough keeping chances low. Could see some activity
as early as Sunday night as warm air advection increases aloft but
better chances come around Tuesday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 645 AM CDT Wed Sep 28 2016

UPDATED...Added LLWS for TOP/MHK sites until mixing improves
around 14z.
Anticipating VFR conditions through most of the period, will need
to watch for stratus or possible BR/FG late in the forecast
period. Stratus noted coming our way out of Iowa but expect will
break up to sct as gets this far south during the day.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...67
LONG TERM...65
AVIATION...67