Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 280436
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1136 PM CDT Thu Apr 27 2017

...AVIATION UPDATE...

.SHORT TERM...(This evening through Friday)
Issued at 256 PM CDT Thu Apr 27 2017

Isentropic lift and moisture depth will gradually increase this
afternoon ahead of our next weather system for tonight and tomorrow.
Currently seeing widespread 20-30 dBZ echoes across central Kansas,
but based on surface obs/high res soundings, only a fraction of this
is reaching the ground as rain. Did start with light POPs for this
afternoon given this off chance of a shower lifting northward, with
increasing POPs into the night as the deeper lift and saturation
arrive. An elevated ribbon of MUCAPE will manifest itself above the
H850-H750 front lifting northward between 03-09Z, bringing with it
the chance for convection/scattered thunderstorms. The upper level
dry slot will punch across the area Friday mid-morning and should
bring precipitation to an end except in the far northern CWA.
However, low clouds should linger through much of the day,
especially north of the warm front which will bisect the CWA from E-
W by 18Z.

.LONG TERM...(Friday night through Thursday)
Issued at 256 PM CDT Thu Apr 27 2017

The Friday night through Sunday forecast really has not changed
much from previous periods. The broad long wave trough will remain
to our west for the majority of this time frame, kicking out a
steady stream of upper level short wave troughs into a very moist
environment across the Plains. It remains likely that the local
forecast area will remain on the cool side of the storm system
with only periodic bouts of elevated instability present to
support occasional bouts of thunderstorms embedded within the
otherwise rain shower environment. Severe thunderstorms appear
very unlikely in the local area at this time due to limited
instability and a stable boundary layer. The heart of the upper
trough is expected to trek over northeast KS on Sunday with a
well-organized deformation zone and TROWAL on the northwest to
west side of the upper trough. The end result is that over the
entirety of the period now through Sunday still points to 1.50 to
3 inches for the entire forecast area, but it should be mostly
spread out over time to limit the flooding potential. Some RFC
guidance suggests potential for generally minor river flooding so
will monitor this potential closely but looks like minimal impacts
at this time. On the cold side of the system, ample cold air will
be pulled into the storm system and may actually support a band of
rain mixing with snow across north central and perhaps northeast
KS. The limiting factor will be surface temperatures in the mid
30s but may be sufficient for a quick bout of snow accumulating on
grassy areas.

Beyond this period, northwest flow and generally cool temperatures
will prevail through the long term. Another storm system is
forecast to develop over the Plains by mid week but is currently
expected to be focused south of the forecast area so have
generally low end pops at this time.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday)
Issued at 1136 PM CDT Thu Apr 27 2017

Biggest challenge remains ceiling heights through the day Friday.
The RAP continues to be the less restrictive model with lower CIGS
coming in later and lifting sooner while the NAM brings in IFR
CIGS and never really takes them out. Most of the guidance seems
to try to lift a warm front north of the KS river by the afternoon
implying some VFR CIGS remain possible. So will maintain the
current forecast with VFR CIGS eventually developing.
Unfortunately the frontal boundary moves south during the early
evening so the lower CIGS are likely to return. Precip chances
look to diminish by late morning as the upper system regroups to
the west.

&&

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

$$

SHORT TERM...Skow
LONG TERM...Barjenbruch
AVIATION...Wolters


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