Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 260010
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
710 PM CDT THU AUG 25 2016

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Friday)
Issued at 401 PM CDT THU AUG 25 2016

Additional chances for showers and thunderstorms are expected
tonight through tomorrow as the frontal boundary becomes somewhat
stalled out over southeast Kansas. Visible satellite imagery shows
some breaks in the cloud cover this afternoon across southeast
Kansas, which allowed destabilization to occur.  With decent
instability and shear in place, some scattered storms have begun to
develop along this boundary across northern Oklahoma and extending
into southeast Kansas. Short-range models have been struggling some
with precipitation trends today, but there is the potential for
these scattered storms to continue to develop northward along the
boundary into east central Kansas late this afternoon into early
this evening. With 1500-2500 J/kg of CAPE and around 40kts of 0-6km
shear, some storms in far east central Kansas may be strong to
severe, with damaging winds and hail being the primary hazards.
However, the greater potential for stronger storms is looking to be
just south of the forecast area in far south Kansas and Oklahoma
where the better forcing is located near the boundary.

Models show a shortwave lifting northeastward across the forecast
area overnight, and this wave should help to provide decent forcing
to support better chances for more widespread showers and
thunderstorms. Models have been trending a bit slower with the
advancement of this wave, and thus have slowed down the higher PoPs
until around midnight and later and persisting into Friday morning.
These overnight storms will be further supported by the low-level
jet and decent isentropic lift, but expect them to be more elevated.
There are slight model discrepancies with the best placement for
higher QPF amounts, however with PWAT values of 1.5 to 2.0 decent
rainfall rates can be expected overnight. With some areas of heavy
rainfall with last night`s storms and additional heavy rainfall
possible across east central Kansas, have gone ahead with a Flash
Flood Watch from 00z tonight to 12z Friday.  There is uncertainty
with how long precipitation will linger across the area Friday
morning, but expect another shortwave to approach the area Friday
afternoon/evening across northern Kansas, so have increasing PoPs
Friday afternoon across north central Kansas.  Instability of at
least 1000-2000 J/kg will be possible tomorrow with some uncertainty
in how strong 0-6km shear values will be, but could be strong enough
to support some strong to severe storms Friday afternoon.  With
ongoing cloud cover, expect high temperatures to only be in the mid
70s to low 80s.

.LONG TERM...(Friday Night through Thursday)
Issued at 401 PM CDT THU AUG 25 2016

Friday evening showers and storms will be ongoing as the mid level
shortwave trough lifts out over the northern plain. Warm advection
ahead of the wave will provide additional lift for widespread precip
across the area. Instability will be on the decrease during the
evening and overnight. There is not much of a surface front moving
through the area, but a well established cold pool from afternoon
convection could focus redevelopment as it pushes eastward. The 850
mb moisture transport vectors will become maximized over the
forecast area Friday night with pwat values around 1.75 inches. This
should support a slight chance for heavy rainfall and localized
flooding. Some showers may linger through Saturday morning as
southwest flow aloft continues. Within that southwest flow
additional shortwaves may lift over the central plains causing more
rounds of showers and storms through the weekend. None of these
waves appear to bring a front through eastern KS. This pattern is
forecasted to hold with an upper ridge anchored over the TN river
valley, which will continue to steer waves north of the area and a
plume of deeper moisture overhead. Although the chances of a
prolonged period of heavy rainfall is low at this point.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 643 PM CDT THU AUG 25 2016

Not much change since previous forecast. Thunderstorms from
northeast OK into southwest MO not moving north very fast so will
need to have upper system come across later tonight to provide
thunderstorm chances. Would expect cigs and vsbys to go down to at
least MVFR tonight with any storms that move through. Ceilings on
Friday morning should rise into the VFR category, and there will
be a chance for isolated thunderstorms again, but did not put in
TAFs.

&&

.TOP Watches/Warnings/Advisories...
Flash Flood Watch through Friday morning for KSZ026-037>040-
054>056-058-059.

&&

$$

SHORT TERM...Hennecke
LONG TERM...Sanders
AVIATION...GDP



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