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

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FXUS63 KEAX 130522
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1222 AM CDT Fri Oct 13 2017

.Discussion...
Issued at |240 PM CDT THU OCT 12 2017

Main concern with the forecast is the potential for severe storms
Saturday afternoon and evening. A deep trough exists over the
western US with strong mid to upper level southwesterly flow. This
is leading to a strong lee side trough with strong southerly surface
winds as a result through the central and eastern Plains. This
strong southerly low level flow will help temperatures warm up
Friday and especially Saturday. It will also draw ample moisture
northward and by Saturday afternoon/evening precipitable water
values will be approaching 2 or even exceeding 2 inches,
depending on the model. The high amount of moisture available for
storms to work with may lead to localized flash flood threat. But
the strongly forced and progressive front should keep flooding
potential minimized.

Of greater concern is the strong shear that will be present within a
low/moderate CAPE environment. Models are showing 0-6km shear of 50
to 60 kts along and ahead of the front. This indicates there is a
good potential for organized/rotating thunderstorms. Initial cells
would then have the potential to be supercellular. 0-3km shear of 30
to 40 kts in a west to east manner is concerning because it favors
potential for rotation after the storms have congealed into a more
linear system. Even with veered surface winds, the strong dynamics
involved with this system lead to high helicity values along and
ahead of the the front. At the moment it seems like all potential
hazards are in play with this setup. While the strong dynamics
would favor damaging winds, a few tornadoes can`t be ruled out
given the strong shear and high helicity.

In the immediate wake of the front and into the day Sunday, strong
downward momentum transfer will lead to stronger winds at the
surface. Have increased surface winds a bit Sunday to account for
this, but it`s likely these will need to be increased with future
forecasts. Otherwise, cooler than normal temperatures can be
expected Sunday. Temperatures will rebound back to normal or
slightly above normal for the remainder of the week. The forecast
also looks dry through at least the middle of next week with no
other systems moving through after the Saturday system.

&&

.Aviation...(For the 06Z TAFS through 06Z Friday Night)
Issued at 1216 AM CDT FRI OCT 13 2017

Low level wind shear becoming a higher concern with winds more out
of the southwest around 45 kts at 220 degrees at 1500 feet.
Surface winds around 5 to 10 knots increase the chances for some
wind shear through the night. Expect VFR conditions there after
with a wind shift to the northeast associated with a surface
boundary. Some rain showers will be possible north of KSTJ, but
those showers should remain away from the terminals themselves.


&&

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

$$

Discussion...CDB
Aviation...Leighton



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