Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 091752

Area Forecast Discussion
National Weather Service Topeka KS
1152 AM CST Sat Dec 9 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 301 AM CST Sat Dec 9 2017

An amplified pattern remains over the CONUS per the 08Z water vapor
imagery. An upper ridge remained over the western U.S. stretching
well into western Canada, while an upper trough remained over the
Great Lakes and southeast U.S. This left northwest flow that is
nearly meridional over the Great Plains. A shortwave was noted over
eastern IA moving into northern IL. At the surface, a low pressure
system associated with this shortwave was moving across WI into MI
with high pressure and dry air over the Great Plains.

Models show the shortwave energy over IA and IL remaining well east
of the forecast area with no obvious forcing immediately upstream
within the northwest flow aloft. Meanwhile a westerly low level wind
continues to keep dry air over the forecast area. So dry weather is
expected to persist. There are some low clouds upstream over eastern
SD and MN. Although it is questionable whether these clouds would
hold together to make it this far south once the boundary layer
begins to mix. Therefore think there should be more insolation today
with temps generally trending warmer. Some low level warm air
advection into central KS may create a decent gradient in temps from
west to east with highs approaching 50 over north central KS and
highs around 40 across northeast KS. There should be enough of a
pressure gradient overnight to keep winds from going calm. So lows
are expected to be similar to this mornings with most areas in the
20s. The usual low lying areas could see lower 20s while locations
on hill tops may remain in the upper 20s where there is more

.LONG TERM...(Sunday through Friday)
Issued at 301 AM CST Sat Dec 9 2017

Northwest flow continues on Sunday, but increasing heights allow
warmer air to move in from the west. Highs are expected to be in the
mid 50s to lower 60s. With the lack of return flow dew points remain
in the 20s, which force the relative humidities to drop into the 20
to 30 percent range. Without any fronts moving through the region
the pressure gradient is only strong enough for wind speeds around 5
to 15 mph with gusts up to 25 mph during the day Sunday. As a result
the fire danger will be very high across central KS where the RH is
forecasted to be the lowest. On Monday a strong shortwave trough
dives over the upper Midwest and Great Lakes region sending a cold
front into the area. In response to this wave the pressure gradient
will be much stronger, which translates into winds around 15 to 25
mph with gusts up to 35 mph. Therefore very high fire danger is
expected across the entire area on Monday. Certainly extreme fire
danger is not out of the question if the winds speeds approach
advisory criteria. A few more fronts track through the region
through the end of the week. Each with 50s prior to the arrival and
40s the following day. By the weekend there are signs that the upper
ridge out west begins to break down allowing the eastern trough to
weaken. Warmer than normal temperatures and dry conditions will be a
byproduct of this pattern.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1134 AM CST Sat Dec 9 2017

VFR conditions should prevail the entire period. A few notable
wind changes take place as a weak backdoor front stalls and then
returns into the overnight period. A weak surface trough enters
the area near morning. It is possible there could be a few hours
of LLWS conditions set up near the terminals. But, strength of
wind fields may actually keep conditions at bay. Something to
watch in the early morning hours if winds do calm completely.




SHORT TERM...Wolters
LONG TERM...Sanders
AVIATION...Drake is the U.S. government's official web portal to all federal, state and local government web resources and services.