Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 231744
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1244 PM CDT SAT JUL 23 2016

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 320 AM CDT SAT JUL 23 2016

Lower level airmass was largely unchanged Friday into Friday night
with the exception of cooler air via weak elevated convection. This
will again present another day of very hot/humid condition potential
and all guidance agrees on this. The challenge, as seen in overnight
radar trends, is handling of additional elevated precip as well as
how the area will be impacted by outflow from more persistent
convection in central Nebraska. Upper ridge obviously becoming
"dirtier" with high-level moisture pushing east and a bit south
around its periphery. Details of where forcing will be sufficient
for precip production is difficult at best, but most guidance is
similar in flow around 600mb turning from north to southwest in the
morning hours, sourcing drier air which should end appreciable
precip chances by midday. Airmass below this level is dry in an
relative sense so the amount of precip reaching the ground is also
in question. AS for the outflow, pressure rises behind the MCS are
not impressive, and MCV and radar trends suggest a east to
northeast track, so believe outflow impacts will be small and brief.
Will keep the heat headline going with apparent temps above 100
expected to dominate the afternoon with values around 110 possible.
Overnight, precip trends look to increase again with cold front
making its way through Nebraska and upper levels looking to saturate
farther southeast with suggestions of better forcing aloft.

.LONG TERM...(Sunday through Friday)
Issued at 320 AM CDT SAT JUL 23 2016

An upper level shortwave through will move across southern Canada
and Northern Plains and Great Lakes region on Sunday. This will
suppress the upper ridge across the Central Plains. The upper flow
will gradually become west northwest Sunday through Tuesday as the
upper high pressure retrogrades into the western U.S.. A series of
upper shortwave troughs will move across the Plains in the Wednesday
through Friday time frame in a more northwesterly upper flow regime.
A frontal boundary will move slowly into north central and northeast
Kansas on Sunday. Current consensus would keep the frontal boundary
across the northern counties and into parts of western and central
Kansas. This will keep much of the area in the warm sector for the
bulk of the day. Highs temperatures will range from the mid 90s to
around 100 south of the front with lower 90s to the north. Dew
points in the mid 60s in north central Kansas to the lower 70s in
east central Kansas will yield afternoon heat indices around 105
degrees, so will continue with the excessive heat warning through
Sunday evening. Expect scattered showers and thunderstorms to
develop along the front on Sunday in a weakly sheared environment.
Expect more pulse type storms with isolated heavy rainfall given the
high precipitable water content in the atmosphere. The frontal
boundary moves into east central or southeast Kansas on Monday as
high pressure moves southeast across Iowa. Expect some isolated to
scattered non severe convection and shear remains weak across the
area. As mentioned previously mid level shortwaves will move
southeast across the Central Plains from late Tuesday through
Friday. A frontal boundary will be present across parts of the
forecast area in north central and northeast Kansas through the
period. Expect the development of an MCS or two through this period
as well as convection along the frontal boundary. Timing of the
waves will be resolved in the future, so for now will keep chance
pops going in the forecast. Tuesday night and Wednesday look
favorable for higher precipitation chances early in the period when
a moderately strong wave is forecast to move across the area. Low
level jet interactions and isentropic lift along with good moisture
transport will increase the chances of training storms and locally
heavy rainfall. Monday and Tuesday highs are expected to be near
seasonal values in the lower to mid 90s, then cool into the 80s to
lower 90s Thursday and Friday. Lows mainly in the upper 60s to lower
70s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1236 PM CDT SAT JUL 23 2016

VFR conditions are expected throughout the period. LLWS is
introduced at all terminals beginning at 05Z as LLJ increases to
near 40 knots. Winds will veer Sunday morning as a cold front
approaches the area. Showers and thunderstorms are possible
late tomorrow morning, however confidence is too low to introduce
at this point.

&&

.TOP Watches/Warnings/Advisories...
Excessive Heat Warning until 7 PM CDT Sunday for KSZ021>024-026-
034>040-054>056-058-059.

Excessive Heat Warning until 7 PM CDT this evening for
KSZ008>012-020.

&&

$$

SHORT TERM...65
LONG TERM...53
AVIATION...Baerg



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