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

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FXUS63 KEAX 122042

342 PM CDT Sat Jul 12 2014

Issued at 340 PM CDT SAT JUL 12 2014

Hot and muggy conditions continue across the forecast area as good
insolation, southwest SFC flow, and moist boundary layer conditions
are contributing to heat indices approaching 100 degrees. Expect a
few more degrees of heating today, as temps should approach the 90
to 95 degree mark, with dew points remaining in the lower 70s. The
result will be a few hours this afternoon/evening of heat indices in
the 100 to 103 range. North of the forecast area, in central Iowa, a
surface boundary resides, characterized by the aforementioned
90s/70s south of the boundary with temps in the 60s to 70s north of
the boundary. This boundary will be the focus for afternoon
convection, mainly north of the forecast area. This boundary will
soon take on the form of a cold front and sag southward through the
evening hours. Areas of far northern Missouri will have the best
chance to see these evening thunderstorms before sunset. As the
boundary sags farther south it will continue to generate
precipitation, aided by mid level pressure height falls associated
with the upper trough. However, as the boundary approaches the
Interstate 70 corridor it will likely lose quite a bit of heating,
which will mitigate the widespread thunderstorm threat. Given the
cooling surface conditions and a fairly warm and dry 800-900 mb
layer it will be tough to get showers and thunderstorms to form
along the I-70 corridor during the overnight hours. That being said,
there is a chance that a few scattered showers could form tonight,
and have advertised PoPs accordingly.  But the best chance for
thunderstorm activity will definitely be north of I-70. Models then
hint at the boundary re-firing as it continues to sag south of the
forecast area, perhaps bringing a chance for some rain early Sunday
morning across areas south of I-70.

A fairly significant pattern change is then in store for the first
half of the upcoming work week. While the initial Saturday/Sunday
boundary will bring some cooler/drier air to the area, another shot
of cool/dry air will push into the area as a strong surface ridge
builds into the northern plains for the early part of next week.
There could be another shot at some light rain on Monday as some
forcing in the form of a mid level shortwave trough and stronger low
level ascent moves through, but these showers will be progressive so
precip amounts will be on the low side. Monday will begin the
cooling trend, as highs will likely remain in the upper 70s to lower
80s, then on Tuesday temperatures will likely remain in the lower to
middle 70s. While the surface ridge remains in place over the C/N
plains conditions will remain well below normal for July.
Temperatures will begin to recover and become more seasonal by the
end of next week, as the SFC ridge moves to the east, allowing for
southerly flow to recommence. By Thursday highs will be creeping
back near the 80 degree range, and by the end of the week, and into
the weekend temps will have come back up into the 80s.


.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1225 PM CDT SAT JUL 12 2014

Forecast still on track for areas of thunderstorm activity north of
the terminals through the evening hours. As the boundary sags
southward winds will eventually go light and variable. Concurrent
with the surface boundary could be periods of thunderstorm activity,
most likely during the late evening to overnight period. Confidence
in TS actually affecting the terminal is higher at KSTJ, with
confidence in TS at the terminal dropping quite a bit at KMCI and
KMKC. Will continue to carry VCTS group for now, and if convection
looks like it will make it into the terminals address it with future
forecast or AMD. Another concern for a brief 2-3 hour period of MVFR
CIGs also exists post frontal, but the saturated layer appears to be
shallow and short-lived, so left it out of this forecast.




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