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

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FXUS63 KEAX 220455

1155 PM CDT Tue Apr 21 2015

Issued at 332 PM CDT TUE APR 21 2015

A weak area of low level convergence over our far southern areas and
even further south is leading to a few showers and storms
developing. While instability is rather weak, cold air aloft is
allowing for steep lapse rates which may allow for a few strong
storms in the far southern forecast area this afternoon. Marginal
hail and a few strong wind gusts are possible.

Tonight, a weak cold front is expected to move through the region.
While this will likely be a dry frontal passage for most if not all
of the forecast area, there may be enough residual moisture in the
far southern portions of the forecast area to continue to support a
few showers or storms. Any storm tonight does not look to be strong
or severe, just perhaps a few rumbles of thunder possible.

With cooler and drier air moving into the region, patchy frost
continues to look possible across the northern tier of Missouri late
tonight and early tomorrow morning. One limiting factor may be that
winds don`t completely decouple with the surface high still to our
west. So the threat of frost looks to be in sheltered areas where
mixing is most limited.

Quiet weather is expected Wednesday into Thursday as ridging builds
east into the region. The upper pattern is somewhat messy with a
weak Rex block over the western states currently. This looks to
break down Wednesday into Thursday as another shortwave trough moves
into the Pacific Northwest and begins to shift the ridge east,
ultimately affecting our weather. Temperatures may continue to be
cooler than normal Wednesday as the cool high pressure area tracks
overhead. Some warming will occur Thursday as that high shifts east
and we see increasing heights and thicknesses.

The focus then shifts to a wave ejecting out of the southwest
Thursday night through Saturday. This actually looks to be the low
portion to the high over low Rex block out west. As this wave moves
across the Central Plains, moisture will stream northward leading to
showers and storms becoming widespread by Friday evening and
especially overnight. The threat of severe weather still looks low
across the forecast area. First, the surface low looks to be too far
south and west and not synced to the best diurnal heating to allow
for much development of instability over eastern Kansas and western
Missouri. Second, strong convection will be closely tied to the
surface boundary(s) which will be west of the forecast area through
the evening hours. As the upper wave moves east later in the day
Friday, forcing for ascent should allow for showers and storms to
become widespread over the region overnight. This looks to bring us
another round of needed rainfall but at the moment, the chance for
flooding rainfall looks to be rather low.

For Saturday, the upper wave will be departing to the east but there
may be some residual shower activity, especially in the morning
hours. Conditions should start to dry out during the afternoon and
evening hours as shortwave ridging builds east. But this may also be
short-lived as another upper trough moves across the area leading to
another chance for showers and storms Sunday evening and Sunday


.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1135 PM CDT TUE APR 21 2015

VFR conditions will continue through the period. Surface high
pressure to the northwest will bring persisting northerly winds
around 7-9 kts through Wednesday. A scattered cloud layer around 10
kft will continue to move over the area as northwest flow aloft




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