Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 232338
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
638 PM CDT FRI SEP 23 2016

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Saturday)
Issued at 250 PM CDT Fri Sep 23 2016

A slightly less hot and humid airmass has moved in compared to
recent days with some cumulus developing in daytime heating. Cloud
field more impressive to the south with 19Z dewpoints back into the
lower 70s along the Red River. Upper flow becomes more meridional as
the deep upper low slides east through Utah per water vapor imagery.

Deep moisture will return late tonight into Saturday as the upper
low enters Wyoming tonight, with energy still progged to split to
the northeast and south during the day. PW values look to be
commonly near 1.75 inches in by mid afternoon with broad, large-
scale lift increasing with time. Associated cold front still remains
to the east through the day, but expect the lift to be enough to
bring at least scattered precip by late afternoon in the moist
atmosphere. Have made some small adjustments to precip chances, but
believe coverage will generally increase from west to east from late
tonight into the late afternoon hours. Heavy rain threat appears low
through the afternoon with mainly scattered activity and dry
antecedent conditions. The timing and persistence of the precip and
cloud will play a sizable role in severe weather potential with
upper level winds around 40kt providing some shear, though mainly
unidirectional in nature. Still appears severe weather chances will be
small with instability tempered by cloud. Have kept highs in the 80s
but spreads across small areas could be notable where precip can
linger.

.LONG TERM...(Saturday night through Friday)
Issued at 250 PM CDT Fri Sep 23 2016

By Saturday night, a deep mid-level trough will be present across
the Rockies with surface low pressure advancing eastward across
western KS.  Models have been trending a bit slower with the
eastward progression of this front, having the boundary still just
west of the CWA by early Saturday evening and finally moving into
far eastern KS by Sunday morning. Southerly flow ahead of this
frontal passage will allow abundant moisture advection into the area
with PWATs of 1.5 to 2.0 inches.  The best moisture axis is looking
to set up across east central KS overnight into Sunday morning, with
periods of moderate to heavy rainfall possible.  As a result, total
rainfall accumulations of 1-2+ inches will be likely.   With the
front finally progressing east of the area late Sunday morning, post-
frontal precipitation will diminish from west to east through the
day.  With little to no instability present behind the front,
precipitation on Sunday will predominantly be in the form of showers
with some isolated thunder possible.

Surface high pressure will quickly surge into the region behind the
frontal passage, and this northerly flow will support decent cold-
air advection. The combination of cloud cover, exiting
precipitation, and northerly winds will result in high temperatures
only reaching into the low 70s on Sunday.  With clearing skies by
Sunday night, radiational cooling will cause overnight low
temperatures to plunge into the upper 40s to low 50s. These cooler
than normal conditions will continue for the early part of next week
as the surface high moves over the region, resulting in highs in the
low/mid 70s and lows in the 40s. Conditions will begin to moderate
slightly by mid-week as the surface high shifts east of the area,
resulting in a return of southerly winds. There is uncertainty with
regards to precipitation chances late next week as there are timing
differences between the GFS/ECMWF with a shortwave lifting
northeastward across the Central Plains. As a result, have only some
slight chance PoPs at this time for Thursday into Friday.|

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 636 PM CDT Fri Sep 23 2016

VFR conditions are likely through the TAF period. Scattered
thunderstorms are expected to approach MHK after 12Z with off and
on storms through the day. These storms should hold off until
later in the day, closer to 22Z for TOP/FOE before warranting
inclusion in the TAF.

&&

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

$$

SHORT TERM...65
LONG TERM...Hennecke
AVIATION...Barjenbruch



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