Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO

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000
FXUS63 KEAX 231726
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1226 PM CDT Sat Sep 23 2017

.Discussion...
Issued at 301 AM CDT SAT SEP 23 2017

Above normal temperatures continue today, although thicker diurnal
cu and more efficient mixing of boundary layer moisture may keep
heat indices in the lower to mid 90s (versus near triple digits of
the past few days). A few isolated showers or storms are unlikely
but possible this afternoon across central MO in a narrow axis of
lower convective inhibition; however, the instability profile is
rather narrow and high-res models maintain a non-zero cap even
where it is relatively lowest, so have kept PoPs below the SChc
threshold.

Similar conditions are expected Sunday but with an even less
impressive instability profile during the afternoon, so have again
kept PoPs very low but non-zero and highs in the upper 80s to near
90 degrees. On Monday, the trough over the west will edge close
enough to the forecast area to begin providing some upper-level
support for isolated warm-sector thunderstorms, and thus have
broad chance PoPs for the afternoon. Storms developing along the
surface cold front may propagate eastward off the front and edge
into the forecast area by Monday night, resulting in gradually
increasing precipitation chances from Monday evening onward until
the front passes through Tuesday. Timing of the frontal passage
has continued to slow and now occurs midday Tuesday, however pre-
frontal precipitation and cloud cover will likely limit diurnal
instability, and any notable shear will lag behind the cold front,
keeping severe weather chances fairly low. PWATs will increase to
values around 75th to 90th percentile climatologically, and with
the potential for multiple rounds of precipitation, the main
concern will be heavy rain accumulations.

High pressure builds in more quickly than in previous model runs
(even despite the slower frontal passage) so have decreased PoPs
from Wednesday onward. Briefly below normal temperatures will
follow frontal passage, then temperatures should settle around
their seasonal normals by the end of the work week.

&&

.Aviation...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1226 PM CDT SAT SEP 23 2017

VFR conditions expected through much of the forecast period with
southeast winds of 8-12 kts this afternoon decreasing this
evening as daytime as the boundary layer decouples. Unfavorable
wind direction this evening should negate fog development Sunday
morning at STJ, with speeds again increasing towards the latter
half of the forecast period.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&

$$

Discussion...Laflin
Aviation...32



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