Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 092335

Area Forecast Discussion
National Weather Service Topeka KS
535 PM CST Sat Dec 9 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday)
Issued at 301 PM CST Sat Dec 9 2017

Currently, a highly amplified Pacific western ridge / eastern
trough pattern remain in firm place over the CONUS. This has
resulted in largely north to south upper flow over the forecast
area. At the surface a weak backdoor cold front has meandered into
the area as evidenced by drier dewpoints from northeast to
southwest. Northerly to northwesterly winds have been in place
much of the day with gusts from earlier slowly dropping off as the
upper wave over the Great Lakes translates to the east relaxing
the pressure gradient. The aforementioned front will continue to
transition to a stationary boundary before returning northeast
during the day Sunday.

This boundary has setup a fairly sharp temperature gradient with
central Kansas seeing temps in the 50s and far northeast Kansas
holding in the upper 30s.  With a dry atmosphere in place and little
in the way of lift over the next 24-36 hrs, expect quiet weather to
be the rule with little in the way of cloud cover.  Highs on Sunday
warm into the 60s over north central Kansas to the mid 50s into far
northeast Kansas as 1000-500mb Thickness increases and H85 temps
warm to 5-10C over the area. Very High Fire Danger begins to
increase into the day on Sunday as well (see fire weather
discussion for details).

.LONG TERM...(Sunday night through Saturday)
Issued at 301 PM CST Sat Dec 9 2017

Very High Fire Danger concerns continue into Monday afternoon (see
fire weather discussion below).  Beginning Monday and again late
Wednesday into Thursday, a series of Alberta clipper systems quickly
dig into the Upper MS Valley and translate east into the Great Lakes
region.  This will in turn keep the forecast area under a back and
forth cooling and warming period as fronts enter and weaken over the
area only to return to the northeast in advance of the next system.
As a result, expect temps to sway from the upper 50s back to the
upper 40s after cold frontal passages.  Again, no sensible weather
is expected with any of these fronts as forcing for ascent remains
off to the northeast of the area and Pacific moisture does the same.
 Any return that develops is limited regarding southerly moisture,
so keeping a dry forecast in tact this forecast cycle.


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 511 PM CST Sat Dec 9 2017

VFR conditions expected through the period, with winds the primary
focus. Weak trof passes through tonight, with northwest winds
before and after its passage.


Issued at 301 PM CST Sat Dec 9 2017

Very High Fire Danger will impact a portion of the area over north
central Kansas on Sunday.  Winds return to the southwest briefly
overnight into the morning Sunday ahead of a weak surface trough.
Into the afternoon winds will increase with gusts topping out around
20-25 mph range.  As downslope flow influences the area a bit,
adiabatically warming and drying will take place with dewpoints
dropping yielding minRH values of around the low 20s over
northcentral Kansas.  Monday, a stronger cold front arrives again
with wind gusts increasing to the 30-35 mph range perhaps some
higher in places.  Cooler temps overall will keep minRH values a
little higher but still cause Very High Fire Danger on Monday this
time over the entire area of north central, northeast and east
central Kansas.




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