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

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FXUS63 KEAX 190443

National Weather Service Kansas City/Pleasant Hill MO
1143 PM CDT Wed Oct 18 2017

Issued at 402 PM CDT WED OCT 18 2017

Satellite imagery this afternoon continues to show a rather flat
pattern in place across the CONUS, with a few shortwave troughs
embedded in the flow. First shortwave trough is currently moving
across Central Canada, and is dragging a bit of a frontal boundary
through the Plains States. But, it is too far north, and moisture
locally is too low to produce anything other than a bit of increased
cloud cover today. This will allow southerly winds and well above
normal temperatures to continue through the end of the work week and
beginning of the weekend. The second, and more notable, feature for
our forecast is a trough seen swinging across the Gulf of Alaska
into the Pacific Northwest this afternoon. As this trough moves east
over the next 48 hours a more pronounced front will develop and then
begin sweeping across the Plains Friday night through Saturday, and
will end up being the main focus for the forecast over the next few

Overall, models have maintained their constancy for the late work
week and weekend arrival of the cold front and associated
thunderstorm activity. Ahead of the front, southerly winds will be a
bit breezy, helping bring Gulf moisture north, resulting in
precipitable water values in the 1.5 inch range as the front pushes
into the forecast area early Saturday. Decent isentropic lift ahead
of the front will likely result in scattered pre-frontal showers or
thunderstorms starting as early as the pre-dawn hours of Saturday
across the western half of Missouri, with more robust convection
initiating during the later afternoon and evening hours as the front
pushes across the region. Shear along the front will not be lacking
as many models highlight bulk shear values increasing during the day
from 20 knots to well above 30 knots as the front moves through.
However, as is typical of Fall systems, there is a lot of shear but
the warm sector instability may be a bit low. That said, NAM is a
bit more aggressive with instability compared to GFS or GEM
solutions, and this will merit continued attention over the next
couple of days. Currently consensus solutions leave the shear over
balancing the instability, but if the NAM validates with higher
instability we may have a window of opportunity for strong to severe
storms along the front between 4 PM and 10 PM Saturday evening with
primary threats being strong damaging winds. And, with precipitable
water values so high, torrential rain resulting in local flooding
issues could accompany the storms.

The front will push through Saturday night, tanking the storms with
it. Current majority of the solutions then point to a cool surface
high swinging into the Central Plains. This will knock our
temperatures down for next week with highs in the 60s.


.Aviation...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1142 PM CDT WED OCT 18 2017

VFR conditions expected through the forecast with light south
winds overnight and into the day tomorrow. The one exception may
be KSTJ where overnight temperatures in the mid 40s and calm winds
may promote some river valley fog around sunrise.




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