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Unless the evolution of the pattern
during the day was considered (effects included layer lifting
associated with incoming mid and upper tropospheric trough, layer
lifting associated with phased divergent quadrants of two jet
streaks, low level warm and moisture advection as well as diurnal
heating), an evaluation of the initial sounding in the Midland
area (minimal initial CAPE and even minimal potential CAPE assuming
afternoon convective temperature were to be achieved) could be
deceptive.
The ETA forecast sounding for 00 UTC shows
the effects of the incoming trough with stronger midlevel winds
and steepening of the lapse rate above the cap due to advection
and layer lifting AND considerable moistening of the surface
layer. This sounding could be thought of as typical of any in
the area between Midland and Lubbock on the afternoon of April
10.
The actual verification showed that Midland
remained capped but that a strong southeasterly flow contributed
to greater shear than forecast, with storm-relative helicities
(for a hypothetical storm) in the Midland area on the order of
250 m2s2. In reality, further north actual s-r helicities were
on the order of 350 m2s2 or larger (500 m2s2 for the right moving
storm that came out of Gaines County).
The forecast sounding provided a reasonable
estimate of afternoon/evening conditions in the south Plains
and northern Permian Basin area of TX.
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