Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 192321
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
521 PM CST Fri Jan 19 2018

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Saturday)
Issued at 310 PM CST Fri Jan 19 2018

Southerly winds along with diurnal heating this afternoon has
brought temperatures into the upper 40s and low 50s across northeast
Kansas.  A gradient between a system located off the coast of
California and the surface high over the southeastern US has allowed
winds to gust to near 20 mph during the afternoon hours, and
expected to continue through the evening.  Low level moisture is
expected to work its way north by Saturday morning, and models have
been bringing in low clouds and fog into the area.  With winds, a
stratus deck looks to be the most likely.  This will moderate
temperatures Saturday afternoon with highs in the upper 40s
expected.  Any precipitation chances look to hold off until Saturday
night.

.LONG TERM...(Saturday night through Friday)
Issued at 310 PM CST Fri Jan 19 2018

By Saturday night, a deep mid-level low will be digging into the
southwest US while, at the surface, a low pressure continues to
amplify in southeast Colorado. Soundings early Sunday indicate the
potential for some drizzle or freezing drizzle associated with
persistent weak lift. A surface boundary associated with the
inverted trough axis will bisect northeast Kansas Sunday, with
dewpoints reaching into the upper 40s and possibly low 50s in east
central Kansas by late afternoon.  Any freezing drizzle will change
over to rain by the afternoon as the column continues to saturate
and temperatures rise above freezing. The NAM keeps most MUCAPE just
east of the area while the GFS is more widespread over eastern
Kansas with values up to 200 J/kg seen late Sunday afternoon. There
is a brief period late afternoon/early evening where thunder will be
possible in far eastern Kansas.  If any storms do develop, 0-6km
bulk shear of 75 knots would allow some to become strong.  However,
storms would be quickly moving limiting severe potential temporally.
 Overnight Sunday, the surface low moves northwest across the area
and temperatures drop near or below freezing shortly after midnight
changing over precipitation to snow.  Models have been fairly
consistent with the dry slot setting up near east central Kansas
with the deformation zone nosing into northeast Kansas Monday
morning and afternoon.  Latest model runs place snowfall further
south than previous runs with a trace to an inch seen across most
areas north of I-70 and west of I-35.  Up to two inches will be
possible in very north central Kansas.  As the system moves out of
the area and temperatures warm on Sunday, snow will once again
changeover to rainfall.

As this system exits the area Monday, winds pick up with gusts up to
35 mph seen during the afternoon.  Precipitation will come to an end
late Monday and the gradient will relax causing winds to die down
Monday night.  From here, a dry forecast is expected for the rest of
the week with temperatures in the 40s or 50s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 521 PM CST Fri Jan 19 2018

Timing and height of stratus deck entering the terminals is the
main challenge. Widespread stratus of mainly MVFR levels upstream
in east and south Texas, and guidance is very similar in
restricting-level cloud entering the area around 12Z on south to
southwest winds, though heights do vary. Have kept levels toward
the middle of the spread in IFR conditions by 15Z and will watch
trends as this period approaches. Southwest winds around 1500 ft
AGL increase this evening but do not vary much in direction with
elevation, keeping LLWS unlikely.

&&

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

$$

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



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