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

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000
FXUS63 KEAX 110421
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1121 PM CDT Tue Oct 10 2017

.Discussion...
Issued at 307 PM CDT TUE OCT 10 2017

Fairly decent mid/upper trough currently moving through the area,
developing some post frontal showers and thunderstorms across the
area. These showers are post frontal, since the frontal boundary
is well south/east of the forecast area. Temperatures at the
surface reflect this airmass behind the boundary, with
afternoon highs generally in the middle to upper 40s. These cool
surface temperatures mean that all thunderstorm activity is
elevated in nature and precludes much of a wind threat with this
activity. There have been a few reports of some pea-sized hail
with the more robust updrafts, so can`t rule out some occasional
small hail with these storms. These storms appear to be driven by
steep lapse rates - above the low level temperatures inversion -
associated with the cold air aloft within the mid/upper wave.
A cool overnight period tonight, where temperatures will reside
in the upper 30s across northern Missouri to the lower/middle 40s
elsewhere, could yield some isolated frost in low spots, where
temperatures could drop into the middle 30s. Overall, we are not
expecting widespread frost anywhere in the forecast area, but also
can`t completely rule out an isolated spot of frost in NW MO where
temperatures will be coolest.

Temperatures will warm through the week, with around 5-10 degree
increase in high temperatures through the end of the week. These
temperature increases will be aided by mid level ridging in the
wake of the exiting trough as well as warm air advection ahead of
a developing surface low over the High Plains region. By Friday
temperatures could go well into the 80s once again.

The next chance for rain across the area comes on Saturday into
Sunday. A ridge of high pressure will form over the southeastern
CONUS, which will act as a bit of a deterrent for any shortwave
troughing to move through the region. By late in the week
southwest flow aloft will develop between this SE CONUS ridge and
a trough over the PAC NW. For Saturday a frontal boundary will
likely stall somewhere over northern Missouri and NE Kansas,
creating a focus for precipitation. This boundary will likely not
move far, once it establishes its position, so the southwest flow
aloft and nosing-in LLJ could enhance the magnitude of convection.
The result could be a narrow corridor (roughly in the vicinity of
the stationary boundary, wherever it sets up) of heavy rain, with
high QPF. GFS progged PWAT values between 1.5-2.0 inches is
incredibly high for October, so should this scenario play out as
such, then there could be some flooding concerns through this
weekend. Uncertainly does lie in the position of the boundary.
Models have had the boundary in far northern Missouri, into SE
Iowa, but recent GFS has it shifted a little further south. Right
now, feel the best confidence lies in the boundary setting up
north of I-70, perhaps north of HWY 36 as well. Strong to severe
storms will also be possible with this activity given the high
CAPE/shear anticipated Saturday evening. A short wave trough will
push through the area Saturday night, which will effectively kick
the boundary loose, allowing it to progress southward. Rain
chances will increase along and south of I-70 as the boundary
pushes southward. Once the front clears the area surface high
pressure will dominate the area for the early part of next week.

&&

.Aviation...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1112 PM CDT TUE OCT 10 2017

MVFR ceiling heights will persist well into the overnight hours,
and cannot rule out brief periods of IFR ceilings. As surface
temperatures continue to cool and winds slacken, visibilities may
be slightly degraded to MVFR conditions, particularly just before
sunrise. Low-level stratus will begin to erode and advect
eastward by the mid-morning Wednesday with steadily improving
conditions expected heading into the afternoon.

&&

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

$$

Discussion...Leighton
Aviation...Welsh



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