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

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FXUS63 KEAX 121940

National Weather Service Kansas City/Pleasant Hill MO
240 PM CDT Thu Oct 12 2017

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 18Z TAFS through 18Z Friday Afternoon)
Issued at 1214 PM CDT THU OCT 12 2017

Satellite imagery is showing the low stratus eroding rapidly on
its edges and breaking up in its interior. So the terminals should
see another hour or two of IFR ceilings before scattering out and
eventually clearing out this afternoon. Winds will remain
generally from the south through the forecast. Moisture continuing
to stream northward may lead to some mid level clouds late
tonight/early tomorrow morning. This looks to be around 5000 ft so
it should not have an impact.




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