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

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FXUS63 KEAX 031143

643 AM CDT Fri Jul 3 2015

Issued at 418 AM CDT FRI JUL 3 2015

Surface observations across the area indicate a lack of any
discernible weather-making boundaries, with weak flow as an area of
weak low pressure sits over the Southern Plains. Little in the way
of warm air advection lift is evident on the isentropic charts, so
the showers and thunderstorms appear to be more attached to the broad
shortwave trough which has carved itself into the large scale
northwest flow aloft. Through the morning hours this trough will
continue its trek to the south/southeast, dragging with it the
better chances for rain. For the rest of the weekend the surface
ridge moves into the area along with mid level ridging should
provide the area with climatologically minimal chance for rain,
meaning there isn`t any obvious triggering mechanisms, and any
convection through the weekend will likely hinge on diabatic warming
and meso/micro scale forcing mechanisms. Went ahead and introduced a
dry Saturday (Independence Day) due to lack of any noticeable forcing
and a largely capped off environment. Sunday might bring a slightly
better chance for some rain despite again lacking any large
triggering mechanism. Soundings indicate that the atmosphere might
be less capped off, which would make it easier for a subtle forcing
mechanism to kick off a round of thunderstorms.

Rain chances max out in the Monday evening to Monday night time
period as a surface cold front moves through the area. The low level
forcing along the front will be nicely supplemented by a broad mid
level trough. The timing of the front might still need some
refining, but overall it looks like the cold front will nose into
northern Missouri around noon on Monday, then slide through the KC
Metro and central Missouri through the evening and overnight hours
Monday night into Tuesday. While there will likely be ample
instability to kick off strong storms, the shear looks rather weak
at this point, so will hold off on any excitement for severe
weather. However the actual mesoscale environment as well as
evolution of the system as it moves through might be the bigger
factors in severity, so will keep an eye on this system as it moves
in Monday evening. At any rate, PWAT values are anticipated to be
rather high, perhaps as high as 2 to 2.25 inches, so rain making
will be very efficient and could yield high rain totals despite the
progressive nature of the front.

The rest of the week has much uncertainty regarding the
precipitation chances. 12z ECMWF indicated a very similar scenario
as the 00z GFS, namely the boundary stalling just south of the area,
then lifting back to the north, with mid level zonal flow picking up
over the area. This scenario would likely yield several rounds of
moderate to heavy rain, exacerbating the flooding situation across
the area. The newest ECMWF (00z)took the frontal boundary farther
south, which would shunt the better rain chances south with it. This
scenario right now is the outlier among the operational models. so
will see if that trend continues.


.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 641 AM CDT FRI JUL 3 2015

Scattered showers near the terminals should stay south of I-70. Once
they clear out of the area there will be a few hours of MVFR/VFR CIGS
before VFR prevails for the forecast period thereafter.




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