Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 241911
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
211 PM CDT Fri Apr 24 2015

...Updated short term forecast...

.SHORT TERM...(Through Tonight)
Issued at 138 PM CDT FRI APR 24 2015

At 2 PM, a loosely defined warm front extended from just north of
Hays and Russel to just north of Newton...and was becoming
slightly better defined as it lifted north. Meanwhile, a very dry
low level airmass over southwest Kansas was pushing east
northeast, arcing from near Pratt to the northwest. The zone in
between these two features appears to be the favored area for
convective initiation some time around 3-4 PM. Storms that develop
in this region are expected to become supercellular and track
toward the east along the northward lifting warm front. Farther
east, the local forecast area was cloud covered at 2 PM, still in
the cool sector north of the warm front. However, the front is
still expected to lift north to near I-70 by late afternoon while
surface low pressure deepens in SW to SC Kansas. Convergence will
intensify along the front late afternoon and could force
additional convection immediately along the boundary. Any storms
that develop in this manner would likely be focused west of Topeka
through 8 PM, and would seem likely to lift north of the front and
become elevated in nature. This would lend to a large hail risk
unless a storm could root and track along the front, in which case
all hazards would be possible.

Will need to closely watch both of these areas of development as
the environment this evening will be characterized by ample low
level and 0-8 km wind shear, and some storm organization is
likely. However, there are periods of weakness in the mid level
wind fields and this could complicate storm mode in addition to
the strong forcing likely initiating clusters of storms rather
than isolated cells. The current thinking is that large hail will
be the primary hazard with some possibility for pockets of
damaging wind to develop. The entire area has a non-zero tornado
potential, but it appears that the best chance for semi-discrete
supercell structures and attendant tornado/very large hail threat
will be west of Topeka and generally within 40 miles North/South
of I-70 before 10 PM. As convective mode gets messier with
competing updrafts later in the evening, the potential for very
large hail diminishes, but ample wind shear, some surface based
instability, and strong forcing keeps at least some potential
hail, wind, and even a tornado into the early morning in east
central KS.

Finally, there is some potential for a few hours of training cells
along and just north of the warm front which could result in some
localized heavy rainfall amounts or even some flash flooding.
Moisture content of the air is not spectacular though so it would
take a few storms in quick succession to cause any flooding.

Storms will come to an end from northwest to southeast overnight,
with a few lingering showers or storms in the northeast through
sunrise.

.LONG TERM...(Saturday through Thursday)
Issued at 353 AM CDT FRI APR 24 2015

Upper trough`s exit across northern Missouri brings a gradual end
to precip Saturday. Cold air advection on north to northeast
winds behind the system brings a modest boundary south through the
area in the afternoon, though meager moisture and rising heights
preclude any mention of convection. Weak high pressure to the
north and a deepening low over the Southwest keeps east winds in
place for Sunday. Cloud cover looks rather prevalent for the
morning but mixing deep enough to still realize highs in the lower
60s. Still appears the upstream system will stay south of the area
into the work week, but at this point will keep small PoPs in the
south Sunday night into Monday night. Western ConUS/Rockies
ridging dominates conditions through the end of the forecast for
high confidence in dry weather. Main challenge should be
temperatures with still some influence of eastern Canadian trough
not far away, but moderation is likely for at least Tuesday and
Wednesday.

&&

.AVIATION...(For the 18Z TAFs through 18Z Saturday Afternoon)
Issued at 1232 PM CDT FRI APR 24 2015

MVFR ceilings continue for all sites, although slight improvement is
expected between between 21-22Z and the onset of thunderstorms.
TSRA will move west to east between 00-06Z with VCTS possible until
12Z.  Winds will begin to pick up towards the end of the period, and
VFR conditions should prevail from 12Z onward.


&&

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

$$

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






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